Deep-fried flavor: characteristics, formation mechanisms, and influencing factors

Heat transfer enhancement mediated by moisture diffusion improves the volatile profiles of meat stir-fried with high-temperature short-time

The effect of the heating intensity on the volatile profiles of stir-fried pork slices was explored from the angle of moisture diffusion, which alters the thermal reaction rate. Infrared thermography was used to visually monitor the surface temperature difference between the medium and meat slices to aid in interpreting moisture diffusion behavior. Lower water activity and specific heat capacity mediated by moisture diffusion enriched volatile traits. The difference in moisture diffusion between the low-level fire (LF) group and high-level fire (HF) groups occurred mainly after 1 min of stir-frying. At this stage, 3-methylbutanal, 4-methylthiazole, dihydro-2-methyl-3(2H)-furanone, methylpyrazine, etc. were examined in the HF group, indicating the occurrence of the Maillard reaction, Strecker degradation, and lipid-Maillard interactions, which was supported by the results of free amino acids (FAAs) and Fourier transform infrared spectroscopy (FTIR). Additionally, short-term stir-frying with HF (< 1 min) could obtain the volatile characteristics produced by long-term stir-frying with LF (> 1 min), which might be due to shell formation on the surface of the HF-treated samples in the early stage, accompanied by thermal reactions to produce volatile compounds. This work provides a scientific basis for traditional cooking thought that stir-frying with HF is more fragrant and offers support for the transformation of traditional dishes from kitchens to factories.

Effect of sous vide cooking technology on the quality, protein structure, microstructure, and flavor of yellowfin tuna (Thunnus albacares)

The study investigated the comparative effects of sous vide cooking and traditional high-temperature cooking on the quality characteristics, protein structure, microstructure, and volatile flavor compounds of yellowfin tuna (Thunnus albacares). The sous vide treatment groups (55 °C, 60 °C, 65 °C) exhibited a reduction in cooking loss, hardness, and chewiness of the fish while significantly preserving its original elasticity, cohesiveness, and color. In contrast, traditional high-temperature cooking alters the degradation of secondary and tertiary protein structures, resulting in muscle fiber contraction, damage to tissue integrity, and loss of internal moisture. Gas chromatography-mass spectrometry analysis revealed that the concentration of primary odor compounds at a sous vide temperature of 55 °C was minimized. This reduction contributes to decreased formation of undesirable odor substances while positively influencing flavor profiles. These findings suggest that sous vide cooking technology can effectively enhance both the texture and flavor profile of yellowfin tuna.

Correlation of physicochemical properties and volatile profiles with microbiome diversity in cucumber during lightly-pickling in seasoning liquid

Lightly-pickled cucumber is a popular pickled product in Asian countries. However, its quality and microbial alteration during pickling and its correlation between microorganisms and quality are still unclear. Changes in physicochemical properties, volatile organic compounds (VOCs), and microbial community during lightly-pickling cucumbers in seasoning liquid and their relationships were investigated. Results showed that the hardness and fracturability decreased with pickling time, modeled by a zero-order kinetic model. The color became brown and dark as pickling extended. Sixty-four VOCs were identified and 13 aroma-active compounds were found using GC-O and odor activity values. (E,Z)-2,6-nonadienal, hexanal, and (E,E)-2,4-heptadienal were the characteristic aroma markers essential for differentiating among the samples with different pickling times. At the genus level, Delftia and Stenotrophomonas dominated in the bacterial community, and Rhodotorula and Naganishia are the dominant fungal genera. The correlation analysis revealed that one bacteria (Acinetobacter) and two fungi (Naganishia and Rhodotorula) were strongly related to quality loss and off-flavors in cucumbers in the late pickling process. This study provides an important reference for facilitating the quality control of lightly-pickled cucumber during processing.

Flavor of Peanut oil: An overview of odorants, analytical techniques, factors affecting flavor characteristics

Peanut oil is appreciated for its high nutritional value and distinctive properties, also recognized as one of the major vegetable oils. Flavor is a significant characteristic that not only determines the quality of peanut oil but also significantly influences consumer acceptance. The odor-active compounds in hot-pressed and cold-pressed peanut oil, flavor analysis methods (extraction, qualitative, quantitative, and sensory evaluation), and the effects of raw materials, pretreatment techniques, and oil extraction methods on peanut oil flavor have been thoroughly examined in this review. Possible production paths of some important aroma-active chemicals are also suggested, along with a list of more than two hundred odorants found in hot and cold-pressed peanut oil from the literature. Future challenges in flavor analysis approaches lay in the successful connection of experimental data with sensory experience. Processing techniques should be further improved to produce peanut oil with superior flavor and nutrient content.

Flavor formation and phospholipids degradation of crayfish meat treated by boiling combined air-frying during accelerated storage

Thermal treatment is an essential processing method in crayfish processing. This study analyzed the changes in lipids and volatile compounds in crayfish muscle subjected to three thermal processes: boiling (BO), air-frying (AF), and boiling combined air-frying (BO-AF). Aldehydes and heterocyclic compounds were found to be the predominant volatile compounds in crayfish muscle during thermal processing and storage. The intensity of lipid oxidation (POV, TBARS and p-AnV) was greatest in AF, and was notably lower in BO-AF. the total concentration of free fatty acids (FFAs) was highest in the AF group (4.14 mg/g) after processing, followed by BO (3.26 mg/g) and BO-AF (2.04 mg/g). During storage, the FFAs content gradually decreased, with generally lower levels observed at 65 °C compared to 45 °C. A total of 383 phospholipid species were identified, phosphatidylethanolamine being the primary difference lipid type in BO (26.7 %) and AF (36.7 %), while fatty acids were the main differential lipid types in BO-AF group, under the comparison between processed and stored. Overall, the BO-AF method improved the flavor sensory and decreased lipid oxidation, compared to the other two methods. These findings provide valuable insights into the effects of different thermal processing and storage methods on the quality and safety of crayfish muscle.

Comparison of extraction and refinement techniques for volatile compound analysis in camellia oil

The processing techniques of camellia oil, containing freshly squeezed (FSCO), refined (DFCO), cold-pressed (OFCO), and hot-pressed (RFCO), significantly influence flavor compounds and organoleptic properties. In this study, the preference for FSCO and RFCO was revealed by sensory evaluation due to the "fruity" and "roasted" flavors, respectively. Flavor differences among oils were accurately distinguished by the E-nose. A total of 77 and 116 odorants were identified by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and gas chromatography-mass spectrometry (GC-MS), respectively. The gas chromatography-olfactometry (GC-O) and detection frequency analysis identified 34 active-aroma compounds with DF ≥ 2. Aroma recombination and omission experiments further confirmed that (E)-2-nonenal and nonanal, derived from the degradation of unsaturated fatty acids, significantly contributed to "green" and "fruity" aromas. Notably, these concentrations positively correlated with sensory preference. This study provides valuable insights into the flavor identification of camellia oil and the improvement of processing techniques.

Ultra-Processed Food Consumption Is Associated With Poor Diet Quality and Nutrient Intake Among Adolescents in Urban Slums, Kenya

Objectives

To assess the caloric contribution of ultra-processed foods (UPFs), factors associated with UPFs energy intake and investigate the relationship between UPFs energy intake, diet quality and nutrient intake among adolescents in urban slums, Kenya.

Methods

A cross-sectional household study amongst adolescents (10-19 years, N = 621) collected socio-demographic and dietary intake data. Global Diet Quality Score (GDQS); mean and percentage total energy intake (%TEI) from UPFs; and nutrient intakes were computed. Regression analysis assessed the factors associated with UPFs energy intake, and the association between %TEI from UPFs and diet quality.

Results

Mean daily energy intake was 1,604 kcal (±550), 25.2% from UPFs. Higher leisure screen time (≥2 h/day) [OR = 1.9 (1.2-3.1)] was associated with UPFs energy intake. Household wealth index (quintile five vs. one) [OR = 2.6 (1.3-6.0)] was associated with non-UPFs energy intake. UPFs (%TEI) was inversely associated with GDQS score (quartile four vs. one) [β = -2.9 (-3.4 to -2.1)]. Adolescents with higher %TEI from UPFs (quartile four) had highest total energy, total fat and saturated fat; and lowest protein, fibre, iron, calcium and zinc intake.

Conclusion

UPFs contribute substantially to adolescents' energy intake and are linked to poor diet quality and nutrient intake.

Unravelling the formation of characteristic aroma of traditional braised pork through untargeted and targeted flavoromics

Untargeted flavoromics and targeted quantitative analysis of key aroma compounds, and analysis of dynamic change of aroma precursors concentration were used to investigate the aroma evolution of traditional braised pork and the underlying mechanism. The results indicated that lipid oxidation dominated at early cooking stage (0th-45th min), resulting in an increased concentration of most aldehydes, alcohols, ketones, such as hexanal, heptanal, octanal, nonanal, (E)-2-octenal, benzaldehyde, 1-octen-3-ol, and 2,3-octanedione, accompanied with an enhanced unpleasant fatty odor. From 45th to 73rd min, the seasonings alleviated excessive oxidation of unsaturated fatty acids accompanied with decreased aldehydes. Moreover, the diffusion of glucose and amino acids from seasonings to lean meat promoted the consumption of endogenous ribose and amino acids in meat through Maillard reaction, and facilitated the formation of dimethyl trisulfide, dimethyl disulfide, methanethiol, and 2-furfural, which contributed to the meaty, sauce-like, and sweety aroma, thus formed the characteristic aroma of traditional braised pork.

Feeding systems change yak meat quality and flavor in cold season

Yak meat is in high demand due to its unique flavor. Thus this research utilized GC × GC-ToF-MS to discover important flavor compounds in yak meat raised during the cold season under different feeding systems: traditional grazing (TG), grazing-based supplementation (GS), and stall-feeding (SF). Meat quality results showed that SF significantly improved meat's lightness and tenderness (P < 0.05), as compared to TG. Intramuscular fat (2.7 g/100 g) was highest in the SF, followed by the GS (2.46 g/100 g) and the TG (1.57 g/100 g), whereas protein content was similar in the GS and TG, but again higher in the SF. β-carotene and Vitamin E were highest in the GS and TG groups (P < 0.05), respectively. Essential, fresh, and total amino acids were richer in the SF and TG than in the GS group (P < 0.05). TG exhibited a significantly elevated level of n-3 PUFA compared to the SF and GS systems (P < 0.05). Flavoromics analysis identified 736, 721, and 869 flavor substances in the TG, GS, and SF groups, respectively with six as key flavor compounds (ROAV ≥ 1) in all belonging to aldehydes, ketones, and heterocyclic compounds. The pyruvate, glycolysis/gluconeogenesis, and phenylalanine metabolic pathways significantly contributed to the yak meat flavor. Network analysis showed a complex significant positive correlation between amino acids in meat and Vitamin A in fodder (P < 0.05). Altogether, this study provides a basis for selecting a suitable meat production system that benefits producers and consumers by ensuring an annual supply of fresh meat.

Improving the Biostability of Extra Virgin Olive Oil with Olive Fruit Extract During Prolonged Deep Frying

This study explores approaches to enhancing the biostability of extra virgin olive oil (EVOO) supplemented with olive fruit extract (OFE) enriched with hydroxytyrosol (HTyr). The investigation focuses on prolonged deep frying (DF) conditions at 170 °C and 210 °C, over durations ranging from 3 to 48 h, with the aim of improving sensorial attributes, polyphenolic content, and thermal oxidative stability. Parameters, such as acidity, peroxide value (PV), K232, K270, ΔK, phenolic compounds, and sensory attributes, were monitored. The PV did not exceed the standard limit in HTyr-EVOO at 210 °C/24 h; however, in non-supplemented EVOOs, it remained within the limits only up to 210 °C/18 h. Acidity stayed within the acceptable limit (≤0.8) at 170 °C/24 h in both enriched and non-enriched EVOOs. K232 values were ≤2.5 in HTyr-EVOO fried at 170 °C/18 h. K270 and ΔK did not exceed the limits in HTyr-EVOO at 170 °C/3 h, whereas they surpassed them in non-supplemented oils. Additionally, HTyr and tyrosol levels were significantly higher (p < 0.05) in HTyr-EVOOs. Phenolic compounds, including verbascoside, pinoresinol, 1-acetoxypinoresinol, and phenolic acids, such as chlorogenic, vanillic, homovanillic, 4-dihydroxybenzoic, and caffeic acids, were detected in HTyr-EVOOs. Oxidized secoiridoid derivatives increased significantly as DF progressed. Moreover, sensory analysis revealed that positive attributes in EVOOs-such as fruity, bitter, and pungent notes-decreased significantly with increasing temperature and frying duration (p < 0.05). Beyond 210 °C/6 h, these attributes were rated at zero. However, HTyr-EVOOs exhibited lower rancidity compared to non-enriched oils under identical conditions, attributed to the protective effect of HTyr. In conclusion, HTyr-EVOOs demonstrated thermal stability up to 210 °C/6 h, retaining desirable sensory qualities, higher phenolic content, and reduced degradation. These findings indicate that natural OFEs have strong potential as food additive in deep fried EVOOs, enhancing sensory properties, health benefits, and overall oil stability. This innovation provides a practical solution for the food industry by improving the biostability and versatility of EVOO. Further research is recommended to investigate various EVOO categories and oils from diverse origins.

Identification and selection of volatile compounds derived from lipid oxidation as indicators for quality deterioration of frozen white meat and red meat using HS-SPME-GC-MS combined with OPLS-DA

This work aimed to investigate the effects of frozen storage on volatile compounds of white meats (chicken and duck) and red meats (pork, beef, and mutton). The samples were stored at -18 °C for 0, 2, 4, 10, 18 weeks, and volatile compounds were analyzed by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry. Results indicated that the total amounts of volatile compounds increased with frozen storage duration of meats. The correlations were observed between frozen storage duration and levels of 2-ethyl-1-hexanol, tetradecane, nonanal, decanal, octanal, tridecanal, benzaldehyde, pentadecane, propanoic acid,2-methyl-,3-hydroxy-2,2,4-trimethylpentyl ester, heptadecane, and hexanal (r = 0.7456-0.9873). Levels of octanal and propanoic acid,2-methyl-,3-hydroxy-2,2,4-trimethylpentyl ester in white meat and benzaldehyde in red meat versus frozen storage duration fitted very well with zero-order reactions. Therefore, it was concluded that changes in volatile compounds derived from lipid oxidation may be used as indicators of quality deterioration during frozen storage of meat.

Determination of main lipids and volatile compounds in unconventional cold-pressed seed oils through chromatographic techniques

The purpose of this study was to characterize unconventional cold-pressed seed oils (rosehip, strawberry, blackcurrant, carrot, plum, pomegranate, radish, and raspberry) as novel alternative edible oil source. A chemical characterization of different lipid components (total fatty acid composition, triacylglycerols, and vitamin E) and volatiles responsible for the particular aroma of these oils was reported. All the oils showed a content of unsaturated fatty acids, mainly oleic, linoleic, and α-linolenic acid, that potentially contribute to the prevention of cardiovascular diseases, in the range of 80%-90%. Moreover, an isomer of α-linolenic acid, namely, punicic acid, was quantified at a level of near to 40% in pomegranate seed oil. Triolein was the most abundant triacylglycerol in most of the analyzed seed oils, with the exception of raspberry and strawberry dominated by trilinolein and pomegranate seed oil, composed for almost 50% of tripunicine. The highest content of vitamin E was found in pomegranate oil (256 mg/100 g), while the lowest amount was found in strawberry (65 mg/100 g). Overall, >300 compounds were identified from volatile profile of oil samples. Among these, aldehydes were the predominant molecule class identified in plum, pomegranate, and strawberry oils, while terpenes were the main volatiles in blackcurrant, carrot, and rosehip oils. Extremely low values were obtained for atherogenicity (0.05-0.10) and thrombogenicity (0.07-0.30) nutritional indices in all the investigated oils. Principal component analysis of the lipid profile was used as strategy to discriminate and classify the samples, highlighting their similarity related to the presence of beneficial compounds. PRACTICAL APPLICATION: Unconventional food products can find wide applicability in both cosmetic and food industry as alternative source that harmonize with consumers' preferences for personal care and nutraceutical purpose. They often address food security, sustainability, and nutritional challenges. Within this context, the chemical characterization of both major (triacylglycerols and total fatty acid composition) and minor components (volatile compounds and vitamin E) was useful to demonstrate that the cold-pressed seed oils here investigated are rich in essential nutrients. Hence, they can cater to specific dietary needs, thus creating new markets in food tech, agriculture, and biotechnology industries.

Decoding the effects of brining time on the sensory quality, physicochemical properties and flavor characteristics of marinated grass carp meat

This study aimed to explore the effects of different brining times on the sensory, physicochemical properties, and volatile organic compounds (VOCs) of marinated grass carp (MGC). The results showed that different brining time changed the sensory quality, color and texture. The moisture content increased significantly with the extension of brining time, while the salt content, protein content, thiobarbituric acid reactive substances (TBARS), and total volatile basic‑nitrogen (TVB-N) decreased (p < 0.05). Free amino acids indicated that sweet amino acids significantly decreased, but bitter and umami amino acids increased. E-nose and E-tongue could clearly distinguish different MGC samples, and gas chromatography ion mobility spectrometry (GC-IMS) identified a total of 72 VOCs. Among them, 11 key VOCs were screened based on the variable importance of predicted component value (VIP) and relative odor activity value (ROAV), and they showed a high correlation with MGC quality. This study provides a theoretical foundation for enhancing the quality and improving the flavor of MGC.

Effect of Frying Temperatures and Times on the Quality and Flavors of Three Varieties of Lentinus edodes

The effects of frying times (1, 2, 3, and 4 min) and temperatures (140, 160, 180, and 200 °C) were investigated on the nutritional components, color, texture, and volatile compounds of three Lentinula edodes varieties (808, 0912, and LM) from Guizhou, China. Increased frying time and temperature significantly reduced the moisture, polysaccharide, and protein contents, while increasing hardness and chewiness, and decreasing elasticity and extrusion resilience, negatively impacting overall quality. Optimal umami and sweet amino acid retention were achieved by frying at 160 °C frying for 1-3 min or 140-180 °C for 2 min. Nine volatile compounds were identified, with sulfur-containing compound levels decreasing and ketone, aldehyde, pyrazine, and other volatile compound levels increasing as frying progressed. At temperatures above 180 °C, variety 808 displayed a duller appearance, while variety LM experienced significant water and protein loss, making them unsuitable for frying under these conditions. Conversely, variety 0912 demonstrated superior characteristics, such as retaining higher levels of aspartic acid and sulfur-containing compounds, resulting in a sweeter taste. Overall, frying for 2-3 min at 160-180 °C can preserve high nutritional quality and taste and enhance flavor characteristics relatively well. These findings provide a theoretical basis for the deep processing and utilization of Lentinula edodes and for standardized industrial production.

Vegetable Oils and Their Use for Frying: A Review of Their Compositional Differences and Degradation

This review provides an overview of the main vegetable oils of different botanical origin and composition that can be used for frying worldwide (olive and extra-virgin olive oil, high-oleic sunflower oil, rapeseed oil, peanut oil, rice bran oil, sunflower oil, corn oil, soybean oil, cottonseed oil, palm oil, palm kernel oil and coconut oil) and their degradation during this process. It is well known that during this culinary technique, oil's major and minor components degrade throughout different reactions, mainly thermoxidation, polymerization and, to a lesser extent, hydrolysis. If severe high temperatures are employed, isomerization to trans fatty acyl chains and cyclization are also possible. The factors conditioning frying medium degradation are addressed, including oil composition (unsaturation degree, fatty acyl chain length and "free" fatty acid content, and presence of beneficial and detrimental minor components), together with frying conditions and food characteristics. Likewise, this review also tackles how the frying oil and other processing conditions may impact on fried food quality (oil absorption, texture, flavor and color). Finally, potential health implications of fried food consumption are briefly reviewed.

Effects of different thermal methods and degrees on the flavor of channel catfish (Ictalurus punctatus) fillets: Fatty acids, volatile flavor and taste compounds

The effects of different thermal processing conditions on the flavor profiles of channel catfish were evaluated in terms of fatty acids, volatile flavor and taste compounds using steaming, boiling, roasting, and microwaving with different degrees. After thermal processing, 72 volatile organic compounds were detected, including 20 hydrocarbons, 5 ketones, 20 aldehydes, 7 heterocyclic compounds, 12 alcohols and others. Meanwhile, the contents of unsaturated fatty acids like oleic acid and linoleic showed a significant decline due to their heat-sensitive properties. With regard to taste compounds, thermal processing contributed to umami amino acids and free nucleotides conversion, with the initial glutamate and IMP contents of 15.87 and 164.91 mg/100 g in raw samples mainly increasing by 2.8-10.3 and 14.4-105.5 mg/100 g in processed ones. Compared to other methods, microwaving had limited effects on flavor compounds, and steaming and roasting had better performance to improve the flavor complexity of channel catfish.

Synthesis of lipophilic vitamin C and evaluation of its antioxidant performance in sunflower seed oil frying

The present study involved the synthesis and analysis of a lipophilic form of vitamin C, namely tetrabutyryl vitamin C ester (TVCE). TVCE is synthesized by a simple one-step method, combining the advantages of VC and butyric acid. Its antioxidant efficacy on sunflower seed oil frying was evaluated by assessing lipid oxidation parameters including peroxide number (POV), carbonyl number (CV), and paraniline number (pAV). Furthermore, changes in the fatty acid composition of the oil were monitored using techniques such as infrared spectroscopy (IR), nuclear magnetic resonance (NMR), and gas chromatography (GC). The findings demonstrated that lipophilic vitamin C exhibited superior protection against oxidation during frying compared to vitamin E, suggesting that it may be an effective fat-soluble antioxidant. The study provides a new field for the utilization of vitamin C and a new idea for the development of efficient antioxidants.

Changing the horizon of food frying from the use of liquid oil to semi-solid gel

Deep fat frying is the most adopted process of producing fried food products; it involves mass and heat transfer to form fried products with good colour, crispiness, flavour, taste, and texture. However, frequent consumption of these products is a concern due to higher oil content that poses threats to human health. Hence, there is a need to find an alternative frying medium for deep fat frying of food products to obtain fried products having lower fat content. The structuring of liquid oil to convert it into semi-solid gel by the process of oleogelation forms oleogel. The use of oleogel as a frying medium gives fried products with good oxidative, textural, and sensory attributes. The Oleogelator used in the formulation of oleogel plays a significant role in maintaining the stability of oleogel. An increase in the oleo gelator concentration decreases the oil uptake in the fried product. The superior product quality and high consumer acceptance of oleogel fried products indicate that oleogel is a potential frying medium. The scope of the present review is to cover the heat and mass transfer perspective of the deep fat frying process, factors responsible for oil uptake in fried products, formulation and components of semi-solid system, discussion on various characteristics of semi-solid system as frying medium, comparative assessment of oil uptake in food fried in oleogel and conventional oil and finally covering specific examples showing the efficacy of liquid oil oleogel as a frying medium.

Unraveling the mysteries of melanoidins: insights into formation, structure, and health potential in fermented blacken foods

Fermentation is widely known for its ability to enhance the food nutritional ingredients, and its products are with improved texture, flavor, and nutritional. Fermented blacken foods (FBF) are a unique group of foods characterized by their darker hue while retaining nutritional benefits. Despite their popularity, research on melanoidins, the compounds responsible for the characteristic color and health-promoting properties of FBF, remains limited. This review summarizes the formation, extraction, purification, structural features, and health benefits of melanoidins in FBF. The relationship between preparation methods, and physicochemical properties and bioactivities was elucidated. The formation of melanoidins in FBF, influenced by the Maillard reaction (MR) and microbial metabolic activity is analyzed, highlighting the dynamic nature of melanoidin synthesis in fermentation systems. Furthermore, the review addresses the characteristics of FBF production processes and the role of microorganisms and enzymes in melanoidin formation. Melanoidins in FBF exhibit diverse chemical compositions and molecular structures, influenced by precursor molecules, reaction pathways, and environmental factors. These compounds contribute to the sensory attributes, stability, and bioactivity of FBF including antioxidant, antimicrobial, and prebiotic properties. This review underscores the importance of melanoidins in FBF and their influences on food quality, nutrition, and health.

Characterization of flavour components and identification of lipid flavour precursors in different cuts of pork by phospholipidomics

The lipids and volatile compounds in pork from different parts, including the loin, belly, shoulder and hind leg were analyzed by triple quadrupole tandem time-of-flight mass spectrometer (Q-TOF/MS) and gas chromatography-olfactometry-mass spectrometry (GC-O-MS), respectively. Partial least squares regression (PLSR) and Pearson correlation analysis were utilized to establish the relationship between the lipids and volatile compounds. A total of 8 main flavour substances, 38 main phospholipids, and 32 main fatty acids were identified. The results showed that the key flavour compounds were mainly derived from unsaturated fatty acids and phospholipids containing unsaturated fatty acids, including oleic acid (C18:2n6c), α-Linolenic acid (C18:3n3), arachidonic acid (C20:4n6), PE O (18:1/20:4), PE O (18:2/20:4), and PE O (18:2/18:2), etc. Understanding the relationship between flavour compounds and lipids of pork will be helpful to control the quality of pork.

Comprehensive characterization of the differences in metabolites, lipids, and volatile flavor compounds between Ningxiang and Berkshire pigs using multi-omics techniques

This study was conducted to comprehensively characterize, metabolites, lipids, and volatile flavor compounds of NingXiang (NX) pigs, Berkshire (BKS) pigs, and their crossbred (Berkshire × Ningxiang, BN) pigs using multi-omics technique. The results showed that NX had high intramuscular fat (IMF) content and meat redness. The metabolite and lipid compositions were varied greatly among three pig breeds. The NX pigs exhibited distinctive sweet, fruity, and floral aroma while BN pigs have inherited this flavor profile. 2-pentylfuran, pentanal, 2-(E)-octenal, and acetic acid were the key volatile flavor compounds (VOC) of NX and BKS pork. The VOCs were influenced by the composition and content of metabolites and lipids. The NX pigs have excellent meat quality traits, unique flavor profiles, and high degree of genetic stability regarding flavor. The study deepens our understanding of the flavor of Chinese indigenous pigs, providing theoretical basis to understand the meat flavor regulation under different feeding conditions.

Effect of different processing steps in the production of beer fish on volatile flavor profile and their precursors determined by HS-GC-IMS, HPLC, E-nose, and E-tongue

Beer fish is characterized by its distinctive spicy flavor and strong beer aroma. Currently, there is a lack of comprehensive research analyzing the changes in taste and volatile compounds that occur during the processing of beer fish. Thus, this study used HS-GC-IMS, electronic tongue, and electronic nose to investigate the changes in flavor components during various processing stages of beer fish. The obtained results were subsequently analyzed using multivariate statistical analysis. The results showed that the final beer fish product (SF) had the greatest amount of free amino acids (888.28 mg/100 g), with alanine, glutamic acid, and glycine contributing to the taste of SF. The inosine monophosphate (IMP) content of beer fish meat varied noticeably depending on processing stages, with deep-fried fish (FF) having the greatest IMP content (61.93 mg/100 g), followed by the final product (SF) and ultrasonic-cured fish (UF). A total of 67 volatiles were detected by GC-IMS, mainly consisting of aldehydes, ketones, and alcohols, of which aldehydes accounted for >37%, which had a great influence on the volatile flavor of beer fish. The flavor components' composition varied noticeably depending on the stage of processing. PLS-DA model screened 35 volatile flavor components (VIP > 1) as markers; the most significant differences were 1-propanethiol, isoamyl alcohol, ethanol, and eucalyptol. Ultrasonic processing, frying, and soaking sauce can significantly improve the formation of flavor compounds, resulting in a notable enhancement of the final beer fish's umami taste and overall flavor quality.

Effect of cooking methods on volatile compounds and texture properties in millet porridge

To instruct the production of millet porridge, the effect of cooking methods on flavor and texture of millet porridge was investigated. A total of 91 volatiles were detected and most volatile compounds decreased with cooking time, e.g. alcohols. The esters as major volatiles had a high content in electric rice cooker (IC). Multiple chemometric results indicated that volatiles from different cooking methods were distinguished respectively. Texture analysis indicated that the hardness of millet porridge prepared in IC had a more dominant decrease trend than electromagnetic oven and the electric pressure cooker before 40 min. In conclusion, different cooking methods had a more significant influence on the volatiles than cooking time, while the texture is opposite. The comprehensive sensory score reached its peak in IC-30 min. The comprehensive sensory scores of IC and EC decreased with the prolongation of cooking time. This study helps to improve the sensory attributes of millet porridge.

Hydrophobic polyethylene film prepared by film blowing process for preservation of fried shrimp rolls

Hydrophobic coatings have wide applications, but face challenges in food flexible packaging in terms of poor adhesion and inadequate wear resistance. Health hazards and poor adhesion drive the search for novel hydrophobic coatings substitutes. Here, we introduced rationally synthesized carnauba wax-SiO2 microspheres as a component to composite polyethylene (PE) film construction, and created a wear-resistant hydrophobic composite PE film via the blown film technique. The resultant hydrophobic composite film demonstrated an enhanced water contact angle from 86° to above 100°, coupled with favorable mechanical properties such as wear resistance, tensile strength and effective barrier performance against water vapor and oxygen. Upon implementation in the preservation of a Cantonese delicacy, Chaoshan fried shrimp rolls, it was observed that at 25 °C, the carnauba wax-SiO2-PE composite packaging film extended the shelf life of the product by 3 days compared to pure PE film.

Use of egg yolk phospholipids to improve the thermal-oxidative stability of fatty acids, capsaicinoids and carotenoids in chili oil

Phospholipids can act as antioxidants in food. In this study, egg yolk phospholipids (EPL) and sunflower oil were utilized in making chili oil, and proton nuclear magnetic resonance spectroscopy was employed to quantify the concentrations of fatty acyl groups, carotenoids, capsaicinoids in chili oil according to their specific signals in the spectra. The results showed that the changes in the concentrations of fatty acyl groups in the control samples were greater than those in the EPL-treated samples at the same frying temperature, while the contents of carotenoids and capsaicinoids were significantly lower than those of the EPL-treated samples when fried at 150 °C (p < 0.05). Two-way ANOVA indicated that frying temperature and EPL treatment, as well as their interaction had significant impacts on the thermal-oxidative stability of chili oil (p < 0.05). The results suggest that EPL may act as antioxidants during frying, and EPL can improve the thermal-oxidative stability of chili oil.

A comprehensive review of the mechanism, changes, and effect of deep fat frying on the characteristics of restructured foods

Restructured foods are a blend of various ingredients that are dried or fried to obtain a ready-to-eat product. Several frying techniques have been employed viz., deep fat, microwave, vacuum, air, and spray frying. Deep-fat frying is the most common technique used for products that have improved texture and sensory characteristics. It facilitates various transformations that include starch gelatinization, protein denaturation, nutrient loss, non-enzymatic browning, lipid oxidation, etc. This physicochemical change alters both the product and the fried oil quality. The frying conditions will also influence the product characteristics and affect the properties of the fried product. This review focuses on the mechanisms and transformations during deep fat frying. The properties, namely physical, chemical, sensory, thermal, rheological, and microstructural changes of restructured foods were discussed. Thus, a better understanding of mechanisms and properties at optimum frying conditions would yield the desired product quality.

Peanut oils from roasting operations: An overview of production technologies, flavor compounds, formation mechanisms, and affecting factors

Fragrant peanut oils (FPOs) are commonly defined as edible peanut oils having strong natural roasted peanut flavor without peculiar unpleasant odors and produced from peanut kernels through roasting/steaming and pressing operations, etc. The flavor of FPOs plays a crucial role in their acceptability and applications and their flavor profiles are an important factor in determining their overall quality. This paper presents a systematic literature review of recent advances and knowledge on FPOs, especially their flavors, in which it is focused on the evaluation of volatile compounds, the factors influencing the formation of flavor compounds, and formation mechanisms of those typical flavor compounds. More than 300 volatiles are found in FPOs, while some key aroma-active compounds and their potential formation pathways are examined. Factors that have big influences on flavor are discussed also, including the properties of raw materials, processing technologies, and storage conditions. Ultimately, the paper highlights the challenges facing, including the challenges in flavor analysis, the relationship between volatile compounds and sensory attributes, as well as the opening of the blackboxes of flavor formations during the processing steps, etc.

Development of a lexicon for the sensory description of edible insects commercially available in Australia

Sensory lexicons provide an important tool for describing the sensory properties of emerging, unfamiliar foods such as edible insects. This study sought to establish and validate a sensory lexicon for the description and differentiation of edible insects commercially available in Australia and prepared using common preservation and cooking methods (freeze-drying, hot-air drying, roasting, sautéing and deep-frying). Five species were evaluated, including house crickets (Acheta domesticus), yellow mealworm larvae (Tenebrio molitor), king mealworm larvae (Zophobas morio), tyrant ants (Iridomyrmex spp.) and green tree ants (Oecophylla smaragdina). Following generic descriptive sensory analysis methods, a trained panel (n=8) developed a sensory lexicon of 29 aroma and flavour descriptors, and 16 texture descriptors. Vocabulary were then categorised and ordered to generate a sensory wheel. Due to a lack of cross-over in sensory attributes between species, sub-categories of species-specific vocabulary were also generated for each insect. The lexicon enabled sensory profiling of commercially available edible insect samples which revealed large variation in aroma, flavour, and texture attributes due to both species and preparation method. This work provides a platform for development of a globally relevant edible insect sensory lexicon. International collaboration will enable expansion of the lexicon for use with other insect species and preparation methods, insect-derived ingredients (such as insect powder, defatted insect powder and textured insect protein) and in different cultural settings. As the industry grows, the applicability of vocabulary for differentiating within species and between competitive products should also be assessed.

Quality Properties and Flavor-Related Components of Beef Longissimus Lumborum Muscle from Four Korean Native Cattle Breeds

This study was carried out to assess the quality properties, components associated with taste and aroma of beef as a function of breed. For this purpose, steers from four Korean native cattle breeds: Hanwoo (n=10), Chikso (n=10), black Hanwoo (n=12, BHW) and Jeju black cattle (n=12, JBC) were used. The steers all were raised under identical conditions and finished at a similar age of around 30-months old. Following 24 h of slaughter, all longissimus lumborum muscles were collected and used for analysis of meat quality, fatty acids, and flavor-related components (metabolic compounds, free amino acids, and aroma volatiles). The Hanwoo presented a significantly higher intramuscular fat content (IMF, 22.85%) than the BHW (11.78%), Chikso (9.25%), and JBC (9.14%; p<0.05). The meat of Hanwoo breed showed lighter and redder color, and lower shear force value (p<0.05). The JBC presented a "healthier" fatty acid profiles as it had a higher total unsaturated fatty acids content (p<0.05). With regard to flavor-related components, Hanwoo also had higher total contents of free amino acids and metabolites associated with umami and sweet tastes, and fat-derived volatile compounds (aldehydes, alcohols, and ketones) associated with fatty aroma. It may be concluded that there was a considerable difference in the meat quality properties among breeds. The variations of IMF content and flavor-related components may be the main factors contributing to the typical flavors of beef among the four Korean native cattle breeds.

Contribution of lipid to the formation of characteristic volatile flavor of peanut oil

Lipid is an important precursor for volatile flavor formation, but it is not clear how to study the reactions involved in forming key volatile flavor compounds in peanut oil. In this paper, we innovatively established a flavor research model to investigate the contribution of different chemical reactions to the aroma compounds of peanut oil. The results showed that lipid participation in thermal reactions is necessary for forming major aroma compounds in hot-pressed peanut oil. Compared to the Maillard reaction, the lipid oxidation-Maillard reaction produces more compounds with 46 volatile substances identified. During the heating process, six new key substances were formed and the level of unsaturated fatty acids decreased by 7.28%. Among them, linoleic acid may be an important precursor for the formation of aroma components of hot-pressed peanut oil. Our study could provide theoretical guidance for understanding the volatile flavor mechanism of peanut oil and improving volatile flavor.

Characterization of key aroma compounds of fried pepper sauce under different pretreatment processes

Fried pepper sauce (FPS) is renowned among consumers for its distinct aroma profile and rich nutritional composition. However, the primary aroma components of FPSs, crucial for quality assurance, remain unclear. Therefore, this study aimed to delve deeper into the unique aroma profile of FPSs by analyzing samples subjected to various pretreatment methods (including three heat-moisture treatment processes: soaking at 60 °C, soaking at 100 °C, and steaming, and three crushing processes: mashing, mincing, and horizontal knife cutting). FPS samples were analyzed by quantitative descriptive sensory analysis (QDA), gas chromatography-olfactometry-mass spectrometry (GC-O-MS), relative odor activity value analysis (rOAV), principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and partial least squares regression analysis (PLSR). The QDA results revealed that the overall aroma profile of FPS products was characterized by chili-like, fatty, and herbal notes. GC-MS identified 115 volatile components in FPSs, primarily alkenes, ketones, and acids, with varying concentrations across samples. According to the rOAV (>1) and GC-O, 11 compounds were identified as key aroma contributors to FPS aroma, including 2-methylpropanal, acetic acid, 3-methylbutanal, methional, eucalyptol, benzeneacetaldehyde, linalool, (E)-2-nonenal, (2E)-2-decenal, (2E,4E)-deca-2,4-dienal, and (E,Z)-2,4-decadienal. PCA and PLS-DA were employed to assess aroma differences among nine FPS samples. Screening for VIP > 1 and p < 0.05 identified 8 and 12 key marker compounds influenced by different crushing methods or heat-moisture treatments, respectively. PLSR indicated that the sensory attributes were greatly related to most aroma-active compounds. These findings provide novel insights into FPS aroma attributes, facilitating precise processing and quality control of fried pepper sauce products.

Recent advances in enzymatic modification techniques to improve the quality of flour-based fried foods

Flour-based fried foods are among the most commonly consumed foods worldwide. However, the sensory attributes and nutritional value of fried foods are inconsistent and unstable. Therefore, the creation of fried foods with desirable sensory attributes and good nutritional value remains a major challenge for the development of the fried food industry. The quality of flour-based fried foods can sometimes be improved by physical methods and the addition of chemical modifiers. However, enzyme modification is widely accepted by consumers due to its unique advantages of specificity, mild processing conditions and high safety. Therefore, it is important to elucidate the effects of enzyme treatments on the sensory attributes (color, flavor and texture), oil absorption and digestibility of flour-based fried foods. This paper reviews recent research progress in utilizing enzyme modification to improve the quality of flour-based fried foods. This paper begins with the effects of common enzymes on the physicochemical properties (rheological property, retrogradation property and specific volume) of dough. Based on the analysis of the mechanism of formation of sensory attributes and nutritional properties, it focuses on the application of amylase, protease, transglutaminase, and lipase in the regulation of sensory attributes and nutritional properties of flour-based fried foods.

Effect of cinnamon powder on quality attributes and off-flavor in fried chicken drumsticks made from long-term thawed Korean native chicken

The effect of cinnamon powder on the quality and mitigation of off-flavor in fried chicken drumsticks made from long-term thawed Korean native chicken (Woorimatdag No. 1, WRMD1) was investigated. The WRMD1 drumsticks were categorized into 5 groups: conventional thawing (16 h, CT), long-term thawing (48 h, LT), cinnamon powder added into 'LT' as marinade (0.03%, CM) or incorporated into the batter (1.35%, CB), and long-term thawing with cinnamon powder incorporated both in the marinade and batter (0.03% + 1.35%, CMB). The crude fat content was significantly higher in the CT and CMB than that of the CB. The CM, CB, and CMB showed significantly lower levels of 2-thiobarbituric acid reactive substance compared with the CT and LT. The predominant fatty acids in all treatments were C18:1n9, C18:2n6, and C16:0. The LT displayed lower total unsaturated fatty acid content than the CT (P < 0.05). The CM effectively decreased lipid oxidative volatiles, such as 1-octanol, 1-octen-3-ol, and 2-octen-1-ol, (E), in the LT (P < 0.05). Both the CM and CB showed an inclination to increase specific pyrazines associated with pleasant notes compared with the LT, and showed higher levels of pyrazines, such as pyrazine, 2-ethyl-6-methyl-, and pyrazine, 3-ethyl-2,5-dimethyl-, than those of the CMB (P < 0.05). The CM contained higher levels of 2,3-butanedione when compared with the other groups (P < 0.05). Multivariate analysis demonstrated that cinnamon had an effect in discriminating the treatment groups with cinnamon addition from both the CT and LT, whereas the CM, CB, and CMB formed distinct clusters. The CM and CMB received significantly higher aroma scores from panelists in comparison to the other groups. These findings suggest that the CM (0.03% cinnamon powder) can be used to enhance the aroma in fried WRMD1 drumsticks by reducing or masking the off-flavor volatiles associated with long-term thawing.

The Characterization of the Key Aroma Compounds in Non-Smoked Bacon by Instrumental and Sensory Methods

The aroma profiles in non-smoked bacon were investigated via GC-O-MS, GC × GC-TOFMS, and GC-IMS. GC-O-MS is advantageous for detecting aldehydes. GC × GC-TOFMS is more sensitive to hydrocarbons and alcohols, while GC-IMS detects a balanced range of categories. Only 9 of the 239 detected volatiles were identifiable by all three methods. Therefore, the combination of all three methods proved to be the most effective way to comprehensively analyze the aroma profiles of bacon. Recombination and omission tests were performed using aroma compounds with a flavor dilution (FD) factor greater than 27; five volatiles were identified as key aroma compounds in non-smoked bacon, including hexanal, (E,E)-2,4-decadienal, 1-octen-3-ol, dihydro-5-pentyl-2(3H)-furanone, and 3-methyl-butanoic acid. Among these, hexanal and 1-octen-3-ol exhibited relatively high FD factors and odor activity values (OAVs), so they were confirmed as the primary contributors. Meanwhile, seven volatiles contributed to the unique aroma of non-smoked bacon in different regions. The difference in the aroma of bacon in different regions is mainly due to the content of various volatiles rather than the type. A comprehensive analysis of the aroma in non-smoked bacon can reveal theoretical information for improving the process and quality control of the product.

Dissecting Maillard reaction production in fried foods: Formation mechanisms, sensory characteristic attribution, control strategy, and gut homeostasis regulation

Foods rich in carbohydrates or fats undergo the Maillard reaction during frying, which promotes the color, flavor and sensory characteristics formation. In the meanwhile, Maillard reaction intermediates and advanced glycation end products (AGEs) have a negative impact on food sensory quality and gut homeostasis. This negative effect can be influenced by food composition and other processing factors. Whole grain products are rich in polyphenols, which can capture carbonyl compounds in Maillard reaction, and reduce the production of AGEs during frying. This review summarizes the Maillard reaction production intermediates and AGEs formation mechanism in fried food and analyzes the factors affecting the sensory formation of food. In the meanwhile, the effects of Maillard reaction intermediates and AGEs on gut homeostasis were summarized. Overall, the innovative processing methods about the Maillard reaction are summarized to optimize the sensory properties of fried foods while minimizing the formation of AGEs.

Identification of dynamic changes in volatile compounds and metabolites during the smoking process of Zhenba bacon by GC-IMS combined metabolomics

Zhenba bacon is a traditional cured bacon product with a rich history that originated from Zhenba County, Shaanxi Province. This study aimed to investigate the patterns of volatile compound formation and changes in metabolites during the smoking process in Zhenba bacon. Firstly, the sensory properties and physicochemical properties of Zhenba bacon were analyzed. Gas chromatography-ion mobility spectrometry (GC-IMS) and nontargeted metabolomics technology were used to analyze Zhenba bacon from different smoking stages. The results show a gradual increase in the sensory acceptance and volatile flavor compounds such as aldehydes, ketones, and esters with the prolongation of smoking of Zhenba bacon. LC-MS analysis identified 191 co-expressed differentially metabolites, with amino acid and lipid metabolism being the main metabolic pathways according to KEGG enrichment analysis. Temporal expression analysis of bacon metabolites at each stage revealed a decrease in harmful steroid hormones such as cortisone and an increase in amino acids and lipid metabolites, such as arginine, lysine, acid, and cholesterol, that contribute to the flavor of bacon. In summary, duration of smoking increased, the amount of flavor substances in Zhenba bacon gradually increased, and the safety and quality of bacon reached the optimal level after 32 days of smoking. This study provides valuable insights into the dynamic changes in volatile flavor compounds in Zhenba bacon and establishes a theoretical foundation for quality control during its production.

Volatile aroma compounds of passion fruit seed Oils: HS-GC-IMS analysis and interpretation

The physicochemical properties, fatty acid composition and volatile aroma compounds of cold-pressed passion fruit seed oils were analyzed. The oils were rich in linoleic acid, oleic acid and volatile compounds. A total of 108 volatile compounds including 17 aldehydes, 23 alcohols, 21 esters, 19 ketones, 6 acids, 9 alkenes, 5 pyrazines and 8 others were identified using HS-GC-IMS. The significant differences of volatile compounds in the purple and yellow passion fruit seed oils were observed via the GalleryPlot graph and distinguished by principal component analysis. The results showed that acids, alcohols, esters and ketones were major aromatic compounds in purple passion fruit seed oils, which contribute to flavors such as flowery, fruity, creamy, yogurt. Whereas the contents of aldehydes, pyrazines, alkenes were higher in yellow passion fruit seed oils, which contributes to fatty and nutty odors. The findings filled in our understanding of volatilization characteristics in passion fruit seed oils.

Efficient preparation of oyster hydrolysate with aroma and umami coexistence derived from ultrasonic pretreatment assisted enzymatic hydrolysis

In the study, an efficient protease Neutrase®-Flavourzyme® (NF) was screened to prepare the umami-aroma flavor oyster hydrolysate. The effect of protease and ultrasonic pretreatment (UP) assisted by the optimal protease on the flavor substances was investigated. The results demonstrated that the optimal UP-NF (450 W) showed a higher amino acid nitrogen content of 0.34 g/100 mL compared to the NF, and 19 major aroma compounds including octanal, decanal, nonanal, benzaldehyde, 2-undecanone, and 1-octen-3-ol were obtained. Additionally, the free amino acid and fatty acid spectrum indicated that the formation of flavor compounds was primarily due to the oxidation of linoleic and linolenic acids and the degradation of amino acids. Furthermore, taste analysis proved that increased umami and saltiness resulted from the accelerated release of Glu, Asp and 5'-IMP. Overall, UP-NF proved to be an effective method for producing umami-aroma flavor, facilitating further processing of oyster products for the application.

Effects of Heating Treatment on the Physicochemical and Volatile Flavor Properties of Argentinian Shortfin Squid (Illex argentinus)

In this study, the effect of different heating temperatures (80, 90, 100, and 121 °C) on the physicochemical and volatile flavor properties of fried mantles (Argentinian shortfin) was investigated. The squid mantles were soaked in a maltose syrup solution (20% w/v) for 10 s and fried in soybean oil for 10 s (160 °C), vacuum-packed, and processed at different temperatures for 10 min. Then, the squid mantles were subjected to colorimetric analysis, sensory evaluation, free amino acid analysis, and texture profile analysis. In addition, the volatile organic compounds (VOCs) in the squid mantles were analyzed. The results revealed that lower treating temperatures (80 and 90 °C) improved the chromatic and textural properties, along with organoleptic perception. Additionally, the content of amino acid in the squid mantles treated at 121 °C was significantly lower than that of the samples treated at other temperatures (p < 0.05). Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) was used to detect 41 VOCs, including their monomers and dimers. Among these detected VOCs, the contents of alcohols, ketones, and pyrazines were positively correlated with temperature. However, the content of aldehydes in the squid mantles gradually decreased as the heating temperature increased (p < 0.05). The combined HS-GC-IMS and E-nose results revealed that the lower temperatures (80 and 90 °C) were more suitable for flavor development and practical processing. This study provides valuable information for properly controlling the heating process of squid products, as well as flavor and practical applications for the aquatic industry.

Mechanism underlying the tenderness evolution of stir-fried pork slices with heating rate revealed by infrared thermal imaging assistance

This study aimed to explore the mechanism of cooking intensity on the tenderness of stir-fried pork slices from the perspective of the changes in temperature distribution. Infrared thermal imaging was used to monitor the distribution of temperature. Results showed that the high-level heat (HH) treatment could improve tenderness. When the center temperature increased to 100 °C, the shear force of samples from the low-level heat (LH) group increased by around 3-fold, and HH reduced this upward trend. This result was mainly attributed to the shorter heating time undergone by the HH-treated samples compared to the LH treatment, which resulted in less structural shrinkage and faster passing through the protein denaturation interval of the samples. These changes alleviated temperature fluctuations caused by water loss. This explanation could be confirmed by the results of T2 relaxation time and Fourier transform-infrared spectroscopy (FT-IR). However, the LH treatment caused a slower rise in oil temperature due to more moisture migration, which required the samples to undergo longer thermal denaturation, leading to a deterioration in tenderness. Moreover, histological analysis revealed that the greater integrity of endomysium in the HH group inhibited water loss and oil absorption, which contributed to obtain low-fat meat products with higher tenderness. This study provides support for the industrialization of traditional pork cuisines using oil as the heating medium.

Fried food consumption, genetic risk, and incident obesity: a prospective study

Background and aims: Genetic and dietary factors contribute to adiposity risk, but little evidence supports genetic personalization of fried food intake recommendations for the management of obesity. This study aimed to assess the associations between fried food consumption and adiposity incidence and whether the associations were modified by an individual's genotype. Methods: We included 27 427 participants who had dietary data assessed by a validated 24 h dietary recall and available anthropometric information from the UK Biobank study. The genetic risk score (GRS) was calculated using 940 BMI associated variants. Results: With an average of 8.1 years of follow-up, 1472 and 2893 participants were defined as having overall obesity and abdominal obesity, respectively. Individuals in the highest categories of fried food consumption were positively associated with the risk of obesity (HR = 1.31; 95% CI 1.10-1.56) and abdominal obesity (HR = 1.27; 95% CI 1.12-1.45) compared with the lowest categories. Moreover, fried food consumption had a significant interatction with obesity GRS for abdominal obesity risk (P interaction = 0.016). Fried food intake was associated with a higher abdominal obesity risk (HR = 1.59, 95% CI: 1.25-2.00) among participants with a lower genetic risk. Conclusions: Our findings indicated that fried food consumption had a higher abdominal obesity risk among individuals with a lower genetic risk, suggesting the restriction of fried food intake for this group of people.

Identification and comparison of aroma and taste-related compounds from breast meat of three breeds of Korean native chickens

This study was aimed to identify and compare the taste-related compounds (nucleotide-related compounds, free amino acid contents, and fatty acid composition) and aroma (volatile organic compounds [VOC]) compounds in the chicken breast meat from 3 kinds of Korean native chicken (KNC), namely Hanhyup 3 (HH3), Woorimatdag 1 (WRMD1) and Woorimatdag 2 (WRMD2). Among the 3 breeds, WRMD1 had significantly higher IMP and AMP contents than HH3. WRMD2 exhibited higher levels of umami and sweet-taste amino acids and oleic acid composition compared to HH3 (P < 0.05). HH3 showed a higher composition of unsaturated fatty acids than WRMD2 (P < 0.05). On their discrimination by flavor composition, some compounds including aspartic acid were analyzed as important compounds. Regarding aroma compounds, unique aroma compounds were detected for each breed and some compounds such as isopropyl myristate, p-cresol, (S)-(+)-3-Methyl-1-pentanol, and cyclic octa-atomic sulfur were expected to be utilized as key compounds in discrimination of the 3 breeds. From the result of this study, the differences on the flavor compounds of three breeds were elucidated and key compounds for their discrimination were presented.

Elucidating the effect of different processing methods on the sensory quality of chestnuts based on multi-scale molecular sensory science

Chestnuts are known for their unique flavor and nutritional value. However, the flavor changes in chestnuts after processing remain unclear. Multi-intelligent sensory technologies and headspace solid-phase microextraction-arrow gas chromatography-mass spectrometry (HS-SPME-Arrow-GC-MS) combined with multivariate statistical analysis were applied to evaluate the effect of packaging and heat sterilization procedures on the sensory quality of chestnuts. The results showed that the significant variations (p < 0.05) between the different chestnut processing methods were revealed via the electronic eye (E-eye), electronic nose (E-nose), and electronic tongue (E-tongue). The packaging had a more significant influence on the sensory quality of the chestnuts than heat sterilization procedures. HS-SPME-Arrow-GC-MS identified 83 volatile compounds. The processed chestnuts exhibited higher aldehyde, ester, and alkene concentrations, while N2 packaging was more favorable to flavor elicitation and retention. Therefore, combining intelligent sensory techniques with GC-MS can rapidly determine the chestnut quality and guide industrial production.

Mechanisms of the Formation of Nonvolatile and Volatile Oxidation Products from Methyl Linoleic Acid at High Temperatures

The impact of the oxidation of linoleic acid cannot be overlooked in daily food consumption. This study used gas chromatography-mass spectrometry (GC-MS) to identify both nonvolatile oxidation products and volatile oxidation products of methyl linoleic acid at 180 °C and density function theory to investigate oxidation mechanisms. An analysis of nonvolatile oxidation products revealed the presence of three primary oxidation products. The three primary oxidation products were identified as hydroperoxides, peroxide-linked dimers, and heterocyclic compounds in a ratio of 2.70:1:3.69 (mmol/mmol/mmol). The volatile components of secondary oxidation products were found including aldehydes (40.77%), alkanes (19.89%), alcohols (9.02%), furans (6.11%), epoxides (0.46%), and acids (2.50%). DFT calculation proved that the secondary oxidation products mainly came from peroxides (77%). Finally, we look forward to our research contributing positively to lipid autoxidation and human health.

Dual functional roles of nutritional additives in nutritional fortification and safety of thermally processed food: Potential, limitations, and perspectives

The Maillard reaction (MR) has been established to be a paramount contributor to the characteristic sensory property of thermally processed food products. Meanwhile, MR also gives rise to myriads of harmful byproducts (HMPs) (e.g., advanced glycation end products (AGEs) and acrylamide). Nutritional additives have attracted increasing attention in recent years owing to their potential to simultaneously improve nutritional quality and attenuate HMP formation. In this manuscript, a brief overview of various nutritional additives (vitamins, minerals, fatty acids, amino acids, dietary fibers, and miscellaneous micronutrients) in heat-processed food is provided, followed by a summary of the formation mechanisms of AGEs and acrylamide highlighting the potential crosstalk between them. The main body of the manuscript is on the capability of nutritional additives to modulate AGE and acrylamide formation besides their traditional roles as nutritional enhancers. Finally, limitations/concerns associated with their use to attenuate dietary exposure to HMPs and future perspectives are discussed. Literature data support that through careful control of the addition levels, certain nutritional additives possess promising potential for simultaneous improvement of nutritional value and reduction of AGE and acrylamide content via multiple action mechanisms. Nonetheless, there are some major concerns that may limit their wide applications for achieving such dual functions, including influence on sensory properties of food products, potential overestimation of nutrition enhancement, and introduction of hazardous alternative reaction products or derivatives. These could be overcome through comprehensive assay of dose-response relationships and systematic evaluation of the diverse combinations from the same and/or different categories of nutritional additives to establish synergistic mixtures.

Dynamic changes in the water and volatile compounds of chicken breast during the frying process

The influence of frying times (0, 2, 4, 6, 8, and 10 min) on the continuous changes in the water distribution and the concentrations of key volatile compounds in chicken breast during the frying process were studied. The fried chicken samples could be distinguished by PCA of E-nose and PLS-DA of GC-MS. A total of 40 volatile compounds were identified by GC-MS, and 28 compounds were verified to be the key compounds after further screening by OAVs. The T22 was increased first and then decreased, while the M22 and M23 in fried chicken were considerably decreased and increased with increasing frying time, respectively. The content of the water and the total peak area of LF-NMR in fried chicken samples during the frying process significantly decreased, and the water was transferred from high to low degrees of freedom. In addition, water content, T21, T22, M22 and L* value were positively correlated with most alcohols and aldehydes, and were negatively correlated with pyrazines, while a*, b*, M23 and all amino acids were positively correlated with pyrazines and were negatively correlated with most alcohols and aldehydes. The results may guide the production processes of fried chicken and help produce high-quality chicken products.

Exploring the effects of lipid oxidation and free fatty acids on the development of volatile compounds in grouper during cold storage based on multivariate analysis

To investigate the relationship between lipid oxidation and the development of volatile compounds (VOCs) in grouper lipid during cold storage, lipids were extracted from grouper as a single-factor study to avoid the complex interactions between microorganisms and proteins. Lipid oxidation during storage and the content of 12 long-chain fatty acids (FAs) in grouper lipids were evaluated. The HS-SPME-GC-MS technique was used to analyze the VOCs in grouper lipids, and a total of 13 key VOCs, primarily comprising alcohols and aldehydes, were screened. Pearson correlation analysis showed a strong acorrelation between these 13 key VOCs, which influenced the overall flavor of grouper lipids, and lipid oxidation, mainly involving secondary oxidation of lipids and the oxidation of long-chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Possible solutions for grouper lipid deterioration were proposed, providing a reference for maintaining the overall quality of grouper and regulating flavor formation.

Study on the thermal oxidation of oleic, linoleic and linolenic acids by synchrotron radiation photoionization mass spectrometry

RATIONALE

Cooking oil fumes contain numerous hazardous and carcinogenic chemicals, posing potential threats to human health. However, the sources of these species remain ambiguous, impeding health risk assessment, pollution control and mechanism research.

METHODS

To address this issue, the thermal oxidation of three common unsaturated fatty acids (UFAs), namely oleic, linoleic and linolenic acids, present in vegetable oils was investigated. The volatile and semi-volatile products were comprehensively characterized by online synchrotron radiation photoionization mass spectrometry (SR-PIMS) with two modes, which were validated and complemented using offline gas chromatography (GC)/MS methods. Tunable SR-PIMS combined with photoionization efficiency curve simulation enabled the recognition of isomers/isobars in gaseous fumes.

RESULTS

SR-PIMS revealed over 100 products, including aldehydes, alkenes, furans, aromatic hydrocarbons, etc., such as small molecules of formaldehyde, acetaldehyde, acrolein, ethylene and furan, which are not readily detected by conventional GC/MS; and some unreported fractions, e.g. ketene, 4-ethylcyclohexene and cycloundecene(E), were also observed. Furthermore, real-time monitoring of product emissions during the thermal oxidation of the three UFAs via SR-PIMS revealed that linolenic acid may be the major source of acrolein.

CONCLUSION

SR-PIMS has been demonstrated as a powerful technique for online investigation of cooking oil fumes. This study achieved comprehensive characterization of volatile and semi-volatile products from the thermal oxidation of oleic, linoleic and linolenic acids, facilitating the traceability of species in cooking fumes and aiding in exploring the thermal reactions of different vegetable oils.

A review on the frying process: Methods, models and their mechanism and application in the food industry

Frying is one of the most popular and traditional processes used in the food industry and food services to manufacture products that are high in quality and with unique sensory characteristics. The most common method of frying is deep-fat frying, used worldwide due to its distinct flavor profile and sensory aspects, which leads to physio-chemical changes at both macro and micro levels. One of the major concerns with deep-fried foods is their high oil content, and a variety of metabolic disorders can be caused by overconsumption of these foods, including heart disease, obesity, and high cholesterol. Due to their enticing organoleptic properties with their delicious flavor, pleasing mouthfeel, and unique taste, making them irresistible, it is also responsible for undesirable and unacceptable characteristics for consumers. Oil absorption can be reduced by developing novel frying methods that limit the amount of oil in products, producing products with fewer calories and oil while maintaining similar quality, flavor, and edibility. In addition, different pretreatments and post-frying treatments are applied to achieve a synergistic effect. The transfer of mass and heat occurs simultaneously during frying, which helps to understand the mechanism of oil absorption in fried food. Researchers have discovered that prolonged heating of oils results in polar compounds such as polymers, dimers, free fatty acids, and acrylamide, which can alter metabolism and cause cancer. To reduce the oil content in fried food, innovative frying methods have been developed without compromising its quality which also has improved their effect on human health, product quality, and energy efficiency. The aim is to replace the conventional frying process with novel frying methods that offer fried food-like properties, higher nutritional value, and ease of use by replacing the conventional frying process. In the future, it might be possible to optimize frying technologies to substantially reduce fried foods' oil content. This review focuses on a detailed understanding of different frying techniques and attempts to focus on innovative frying techniques such as vacuum frying, microwave cooking, and hot-air frying that have shown a better potential to be used as an alternative to traditional frying.

Physicochemical Properties and Volatile Organic Compounds of Dairy Beef Round Subjected to Various Cooking Methods

To evaluate the effect of different cooking methods on the physicochemical quality and volatile organic compounds (VOC) of dairy beef round, twelve beef round pieces were divided into four groups: raw, boiling, microwave, and sous-vide. The sous-vide group had a higher pH than the boiling or microwave groups. The boiling group exhibited the highest shear force and CIE L*, followed by the microwave and sous-vide groups (p<0.05). The sous-vide group received higher taste and tenderness scores from panelists (p<0.05) and showed significantly higher levels of aspartic and glutamic acids than the other groups. The sous-vide and microwave groups had the highest oleic acid and polyunsaturated fatty acid levels, respectively. The sous-vide group had significantly higher hypoxanthine and inosine levels than the other groups. However, the microwave group had higher inosine monophosphate levels than the other groups. The sous-vide group had a higher alcohol content, including 1-octen-3-ol, than the other groups. Octanal and nonanal were the most abundant aldehydes in all groups. (R)-(-)-14-methyl-8-hexadecyn-1-ol, p-cresol, and 1-tridecyne were used to distinguish the VOC for each group in the multivariate analysis. Sous-vide could be effective in increasing meat tenderness as well as taste-related free amino acid (aspartic acid and glutamic acid) and fatty acid (oleic acid) levels. Furthermore, specific VOC, including 1-octen-3-ol, 2-ethylhexanal ethylene glycol acetal, and 2-octen-1-ol, (E)-, could be potential markers for distinguishing sous-vide from other cooking methods. Further studies are required to understand the mechanisms underlying the predominant association of these VOC with the sous-vide cooking method.