Changes in aroma components and potential Maillard reaction products during the stir-frying of pork slices

The Effect of Frying Conditions on the Physical and Chemical Quality Attributes of Clearhead Icefish (Protosalanx hyalocranius) During Deep Frying and Air Frying

The effect of frying conditions on the quality attributes of clearhead icefish under deep frying and air frying was evaluated using the Soxhlet extractor method, colorimeter, and textural analyzer. With the increasing frying temperature and time, the water loss, oil uptake, volumetric shrinkage, redness, yellowness, browning index, hardness, crispiness, the dispersion of textural data, and sensory scores in deep-fried and air-fried samples increased (p < 0.05); the lightness, whiteness, and thiobarbituric acid reactive substances (TBARS) decreased (p < 0.05), while crispiness showed no significant difference (p > 0.05). Compared to deep-fried samples, air-fried samples showed a 15.6-20.8% and 63.2-64.7% decrease in the water content and oil content, respectively. Volumetric shrinkage, hardness, and crispiness of the air-fried samples increased 30.3-68.4%, 53.5-53.7%, and 53.0-59.1%, respectively, relative to deep-fried samples. Air-fried samples displayed a decreasing uniformity in color. Therefore, frying temperature and time conferred a desirable color and texture to the fried clearhead icefish by affecting mass transfer, Maillard reactions, and lipid oxidation reactions. In addition, the difference in quality attributes between deep-fried and air-fried products was attributed to the difference in heat transfer mode. The study aims to provide a theoretical basis for the application of two frying methods and the production of high-quality fried foods.

Dynamic changes in microbial communities during sweet flour sauce fermentation and their correlations with physicochemical properties and volatile compounds

Sweet flour sauce is a traditional fermented condiment in China, known for its distinct sweet and savory flavor profile. During the fermentation process, the dominant bacterial genera were Ralstonia and Bacillus, and the dominant fungal genera were Aspergillus, Issatchenkia, Clavispora, and Zygosaccharomyces. In addition, total acidity (TA) and amino acid nitrogen (AAN) in different fermentation stages were determined by the acidometer titration method, and reducing sugar (RS) was determined by the 3,5-dinitrosalicylic acid method. The correlation network revealed TA, RS, and AAN were closely related to multiple microorganisms. TA showed significant positive correlations with Gluconobacter, Candida, and Clavispora. RS was positively correlated with Geotrichum, and AAN was positively correlated with Methylobacterium-Methylorubrum and Zygosaccharomyces. Correlation network analysis was also conducted to show the significant correlations among 2 bacterial genera, 9 fungal genera, and 16 characteristic volatile compounds. In general, the relationships between fungus and volatiles were more significant, with a wide range of yeasts exerting significant functions in forming flavor compounds, whereas most bacteria were negatively correlated with volatiles. Among fungi, Clavispora and Meyerozyma were positively associated with furfural, methional, 5-methyl-2-phenyl-2-hexenal, 2-isopropyl-5-methylhex-2-enal, and benzeneacetaldehyde. Zygosaccharomyces exhibited strong correlations with acetic acid, 2-furanmethanol, phenylethyl alcohol, and 2-methyl-1-butanol. These findings can be used to better understand and manage the fermentation process, making it possible to improve the quality of sweet flour sauce by enriching key microorganisms. PRACTICAL APPLICATION: During the fermentation of sweet flour sauce, the metabolic activities of microbial communities exerted an important function in forming unique sensory and nutritional properties. These findings revealed significant correlations among microorganisms, vital physicochemical indices, and key volatiles, providing a theoretical foundation for regulating the fermentation process, enhancing product qualities, and developing functional strains.

Trends in pretreatment and determination methods for furfurals in foods: Update since 2017

BACKGROUND

Furfurals, key derivatives of Maillard reactions commonly found in everyday foods, have been identified as having significant toxic effects on human health. Excessive intake of furfurals can lead symptoms such as weight loss, poor nutrient metabolism which followed by disease occurrence. The severe carcinogenicity, mutagenicity and genotoxicity of furfurals were well recognized recently. In response, international organizations have established strict limits on the allowable levels of furfurals in food products. Therefore, it is of paramount importance to implement control which mediated by modern pretreatment and analytical techniques, towards the daily accessibility of furfurals.

SCOPE AND APPROACH

This review seeks to present a comprehensive overview of recent advancements in the pretreatment and analytical techniques for furfurals in food from 2017 to 2023. Various pretreatment methods, such as liquid phase microextraction, solid phase extraction, solid phase microextraction, and QuEChERS, as well as analytical technologies like liquid chromatography-based methods and gas chromatography-based methods, are thoroughly discussed in terms of their mechanisms, benefits, and limitations.

KEY FINDINGS AND CONCLUSIONS

Currently, various pretreatment and analytical techniques with advantages and limitations had been proposed. The development of novel materials does facilitate the optimization and application of microextraction based pretreatment platforms which share with enhanced extraction efficiency. In addition, the development of novel targeting/sensing materials along with the utilization of high-resolution mass spectrometry could promote the determination sensitivity. In future, development of novel absorbents which mediates more desirable pretreatment methods, and automated and miniaturized on-site analytical instruments for furfurals determination still deserve indepth invesigation.

Inactivation activity and mechanism of high-voltage pulsed electric fields combined with antibacterial agents against Alicyclobacillus spp. in apple juice

Alicyclobacillus spp. are crucial factors affecting the quality of fruit juice, so it is very important to control their contamination. In this study, the inactivation activity and mechanism of high-voltage pulsed electric fields (HVPEF) combined with antibacterial agents against Alicyclobacillus spp. in apple juice were investigated. It was found that under the optimal conditions of electric field strength 9.6 kV/cm, treatment time 20 min, frequency 1000 Hz, and duty ratio 50 %, HVPEF treatment could reduce bacteria by 1.89-4.76 log CFU/mL. Moreover, the inactivation activities of six antibacterial agents (propyl paraben, glycerol monocaprate, octyl gallate, heptyl paraben, nisin, carvacrol) alone and their combination with HVPEF were further investigated. The results showed that with the combined treatment, the minimum bactericidal concentrations of carvacrol, nisin, and heptyl paraben were reduced by >50 % to 1 mg/mL, 10 IU/mL, and 0.02 mg/mL, respectively. Based on this, the most resistant strain of A. acidoterrestris (DSM 3922) was identified to elucidate the inactivation mechanism. It was demonstrated that the antibacterial process could alter the permeability and fatty acid composition of the cell membrane, causing the cells to deform and shrink, leading to leakage of intracellular proteins, and also affect the synthesis of ROS and ATP, ultimately resulting in bacterial death. In addition, the various treatments had no significant effect on the soluble solids content, titratable acid, soluble sugar content, organic acids and aroma components of apple juice. The combination of HVPEF treatment and antibacterial agents could effectively maintain the quality of apple juice.

Key aroma compounds associated with umami perception of MSG in fried Takifugu obscurus liver

Monosodium glutamate (MSG) is a basic representative of umami taste, but it exerts adverse effects as reported in several studies. Enhancing umami perception through aroma-taste interactions is a potentially useful approach as a flavor enhancer to reduce future MSG intake. We identified the aroma compounds in fried Takifugu obscurus liver, then studied the effect of aroma compounds on perceived umami taste using the sensomics approach. A total of 117 volatile compounds were identified from the fried liver. Thereinto, 30 volatile compounds related to five basic tastes were detected by gas chromatography/olfactometry-associated taste analysis. Aroma compounds associated umami, sweet and salty perception in the fried Takifugu obscurus liver showed the potential to enhance umami perception of MSG solutions. Three aldehydes, i.e. heptanal, (Z)-4-heptenal and 2-methylbutanal, significantly enhanced the umami intensity perception of an MSG solution (p < 0.05). The use of aroma compounds to enhance umami perception is considered as a promising tool, further broadening the research area of umami science for application as flavor enhancers in the food industry. In addition, this study also provides an insight into revealing aroma-taste interaction.

Characterization of flavor profile of Steamed beef with rice flour using gas chromatography-ion mobility spectrometry combined with intelligent sensory (Electronic nose and tongue)

The intelligent senses (Electronic nose and tongue), were combined with headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) and free amino acid were used in combination to determine the aroma and taste components during the processing of Chinese traditional dish Steamed beef with rice flour (SBD). The findings revealed that E-nose and E-tongue, could clearly distinguish and identify the aroma and taste of SBD. A total of 66 volatile substances and 19 free amino acids were identified by HS-GC-IMS and amino acid analyzer, respectively. The highest contribution to aroma in the production of SBD was alcohols, esters and aldehydes. Further analysis of relative odor activity showed that 3-Methylbutanol-D, 3-Methylbutanol-M and 3-Methylthio propanal is the marinating stage (T2) main aroma components. Ethyl 3-methylbutanoate-M and Ethyl 3-methylbutanoate-D were the main aroma components in the seasoning stage (T3). Additionally, the calculation of the taste activity value showed that Glutamic contributed significantly to the umami of SBD. Alanine was a representative taste component in the marinating stage (T2), while Proline, Aspartic, Lysine, Glutamic, Valine, Arginine, and Histidine were characteristic amino acids of the seasoning stage (T3). Consequently, this study offers valuable insights into the industrial-scale production and flavor regulation of SBD products.

Difference comparison of characteristic aroma compounds between braised pork cooked by traditional open-fire and induction cooker and the potential formation cause under electromagnetic cooking

The characteristic aroma compounds of braised pork were identified through molecular sensory science and PLSR analysis, and the difference between two cooking methods, traditional open-fire (BPF) and induction cooker (BPC), was compared. Seventeen aroma compounds with odor activity values (OAVs) > 1 were identified in both samples. BPF revealed higher OAVs for most of the aroma compounds compared to BPC, and the higher aroma quality. Aroma recombination and omission experiments confirmed that twelve aroma compounds significantly contributed to the characteristic aroma of braised pork, and eight compounds such as hexanal, (E)-2-octenal, and methanethiol were further confirmed as important contributors by PLSR analysis. Furthermore, PLSR analysis clarified the role of aldehydes such as hexanal, (E)-2-octenal, and (E,E)-2,4-decadienal in contributing to fatty attribute, whereas methanethiol was responsible for the meaty aroma. These characteristic aroma compounds mainly derived from lean meat due to its high content of phospholipids, and the exogenous seasonings contributed to the balanced characteristic aroma profile of braised pork by altering the distribution of these characteristic aroma compounds. Variations in heating parameters affected the formation of lipid oxidation and Strecker degradation products, which might explain aroma discrepancy between braised pork cooked by two methods with different heat transfer efficiencies.

Analysis of composition and source of the key aroma compounds in stir-fried pepper tallow

Stir-fried pepper tallow is widely used in cooking due to its special flavor, particularly in hot-pot dishes. However, the composition and source of the key aroma compounds in stir-fried pepper tallow are poorly understood, resulting in uneven quality. Here, the key aroma compounds were screened using flavor dilution factors (FD) and odor activity values (OAVs). A total of 41 odorants compounds were identified. Of these, 20 compounds with FD ≥ 8 were aroma-active compounds. Furthermore, among these 20 compounds, 15 with OAVs ≥ 1were the key aroma-active compounds and most of these (13 out of 15 odorants) were produced from pepper. Glycosides in pepper are the precursors of the most of these key aroma compounds. It may be possible to improve the flavor quality of stir-fried pepper tallow by hydrolyzing glycosides. These findings should help to establish a standard to assess and improve the quality of stir-fried pepper tallow.

Design of colloid structure to realize gel salt reduction: a review

Excessive consumption of salt is associated with increased incidence of cardiovascular diseases, hypertension, diabetes, and other health issues. However, it is challenging to find appropriate strategies that balance sensory qualities while achieving sodium reduction as salt plays a crucial role in providing desired appearance, texture, and taste. The impact of hydrocolloid properties (addition and type) on saltiness perception were reviewed. Additionally, considering the interactions between food components, both covalent and noncovalent, we propose designing specialized colloidal structures capable of binding sodium ions to enhance salt-taste perception. The effects of hydrocolloids on the physicochemical, structural, and sensory qualities of gel foods are then discussed. Finally, by addressing current issues with low-salt foods and consumer demands, we provide a future outlook for low-salt food development. The selection of suitable hydrocolloids and precise control of the addition are crucial considerations for achieving salt reduction. The interaction between hydrocolloids and other food components can be utilized to design specialized colloidal structures, thereby accomplishing gel-based salt reduction and enhancing properties. This review serves as a theoretical reference for developing healthy, nutritious, and flavorful low-salt foods that can aid in the prevention and mitigation of diseases associated with excessive salt consumption.

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.

Inactivation activity and mechanism of pulsed light against Alicyclobacillus acidoterrestris vegetative cells and spores in concentrated apple juice

Alicyclobacillus acidoterrestris has received much attention due to its unique thermo-acidophilic property and implication in the spoilage of pasteurized juices. The objective of this study was to evaluate the sterilization characteristics and mechanisms of pulsed light (PL) against A. acidoterrestris vegetative cells and spores in apple juice. The results indicated that bacteria cells in apple juice (8-20°Brix) can be completely inactivated within the fluence range of 20.25-47.25 J/cm2, which mainly depended on the soluble solids content (SSC) of juice, and the spores in apple juice (12°Brix) can be completely inactivated by PL with the fluence of 54.00 J/cm2. The PL treatment can significantly increase the leakage of reactive oxygen species (ROS) and proteins from cells and spores. Fluorescence studies of bacterial adenosine triphosphate (ATP) indicated that the loss of ATP was evident. Scanning electron microscopy and confocal laser scanning microscope presented that PL-treated cells or spores had serious morphological damage, which reduced the integrity of cell membrane and led to intracellular electrolyte leakage. In addition, there were no significant negative effects on total sugars, total acids, total phenols, pH value, SSC and soluble sugars, and organic acid content decreased slightly during the PL treatment. The contents of esters and acids in aroma components had a certain loss, while that of alcohols, aldehydes and ketones were increased. These results demonstrated that PL treatment can effectively inactivate the bacteria cells and spores in apple juice with little effect on its quality. This study provides an efficient method for the inactivation of A. acidoterrestris in fruit juice.

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.

Effects of cooking methods on aroma formation in pork: A comprehensive review

Pork is widely consumed and appreciated by consumers across the world, and there are various methods of cooking pork. This study aimed to summarize the effects of different heat transfer media on pork flavor and the sources of flavor compounds. The cooking methods are classified based on the heat transfer media used, which include water and steam (e.g. steaming, boiling, and stewing), heat source or hot air (e.g. baking and smoking), oil (e.g. pan-frying, stir-frying, and deep frying), and other cooking technologies. The objective is to provide a reference for researchers studying pork cooking methods and flavor components.

Correlation Analysis between Volatile Compounds and Quality Attributes in Pork Tenderloin in Response to Different Stir-Frying Processes

Volatile compounds and physicochemical properties of meat are significantly changed by cooking processes. This study explored the influence of different stir-frying temperatures and times on the dynamic changes of the physicochemical characteristics and volatiles of pork tenderloin and determined the correlation between them. Results showed that time played more of a role than temperature. At the same temperature, the water content decreased (p < 0.05) and the cooking loss increased (p < 0.05) with stir-frying time extending. The L* value and the b* value showed first an increasing and then decreasing trend (p < 0.05), while the a* value significantly increased (p < 0.05). The higher the cooking temperature of sample, the faster the indexes changed. In stir-fried samples, 50 volatiles were identified. Correlation analysis showed that among the quality attributes, b* value and water content had the strongest impact on volatiles. The water content was negatively correlated with most of the compounds attributed to the desired aroma of stir-fried samples, while the correlation between the b* value and these volatiles was positive. Hence, changes in the types and contents of volatiles in stir-fried pork tenderloin could be predicted by detection of b* value and water content.

Changes of lipid oxidation, volatile and taste-active compounds during pan-heating of pork belly

This study investigated the mechanisms underlying the evolution and formation of aroma and taste-active compounds of pork belly in representative traditional pork cuisines during pan-heating. The results revealed that as the temperature increased to 110 ℃, the unsaturation of fatty acids decreased from 60.25 % to 58.71 %, while the content of free radicals and secondary oxidation products increased. At the later heating stages, the addition of spices and increased heating temperature (150 ℃) led to continuous increments in the contents (from 958.20 μg/kg to 1511.88 μg/kg) and diversity of volatile compounds in pork belly, imparting the unique aroma. Additionally, the accumulation of low-molecular-weight peptides, free amino acids, and nucleotides not only provided the substrate for thermal reactions and their synergistic effects, but also contributed to the desired taste quality. These findings offered insights into the flavor formation mechanisms of traditional pork cuisines and provided direction for further research.

4-Methylimidazole, a carcinogenic component in food, amount, methods used for measurement; a systematic review

4-methylimidazole (4-MEI) is widely used industrially. This carcinogenic component has been reported in some types of food. It is usually produced by the caramelization process in food, drinks and caramel coloring. The possible mechanism for the formation of this compound in food is the Maillard reaction. In order to estimate the amount of substance 4-MEI in food, a systematic study was conducted. The selected keywords were 4-methylimidazole, 4-MEI, beverage, drink, meat, milk, and coffee. 144 articles were obtained from the initial search. The articles were evaluated and finally, the data of 15 manuscripts were extracted. Based on the data extracted from selected articles, the highest amount is reported in caramel color, coffee, and cola drinks. In 70% of the selected studies, the analytical method was based on liquid chromatography. In this method, there is no need for derivatization. SPE columns were used to extract samples in most manuscripts. According to per capita consumption, the most exposure to 4-MEI is through coffee. In high risk food products, regular monitoring with analytical methods with high sensitivity is recommended. Furthermore, most of the selected studies were about the validation method, so few samples were selected. It is recommended to design more studies with a high sample size to accurately evaluate this carcinogenic compound in food.

Metabolomics reveals the effects of different storage times on the acidity quality and metabolites of large-leaf black tea

Most aged tea has superior sensory qualities and good health benefits. The content of organic acids determines of the quality and biological effects of aged tea, but there are no reports of the effect of storage on the composition and relative proportion of acidic compounds in black tea. This study analyzed and compared the sourness and metabolite profile of black tea produced in 2015, 2017, 2019 and 2021 using pH determination and UPLC-MS/MS. In total, 28 acidic substances were detected, with 17 organic acids predominating. The pH of black tea decreased significantly during storage from pH 4.64 to pH 4.25 with significantly increased in l-ascorbic acid, salicylic acid, benzoic acid and 4-hydroxybenzoic acid. The metabolic pathways ascorbate biosynthesis, salicylate degradation, toluene degradation, etc. were mainly enriched. These findings provide a theoretical basis to regulate the acidity of aged black tea.

Effects of traditional and advanced drying techniques on the physicochemical properties of Lycium barbarum L. polysaccharides and the formation of Maillard reaction products in its dried berries

This study explored the effect of three different industrial drying methods on the physicochemical, nutritional, and safety profile of goji berries. The hot-air (HD) and microwave drying (MD) methods yielded berries with relatively high polysaccharide content, while vacuum freeze-drying (FD) yielded dried berries with better sensory qualities but relatively less polysaccharide content. The polysaccharides obtained from the HD and MD berries had lower molecular weight, high antioxidant activity and high degrees of Maillard reaction. Further investigations revealed that all three methods, in particular HD and MD, generated high levels of intermediate Maillard reaction products (55.8-86.3 mg/kg) and advanced glycation end-products (fluorescent intensity of 26784-51712), based on significant reduction of reducing sugar and amino acids in the HD and MD berries (p < 0.05). These findings highlight the need to scrutinize the effectiveness of traditional and emerging drying technologies used to produce safe fruits.

Advanced Glycation End Products: A Comprehensive Review of Their Detection and Occurrence in Food

The Maillard reaction (MR) is a complicated chemical process that has been extensively studied. Harmful chemicals known as advanced glycation end products (AGEs), with complex structures and stable chemical characteristics, are created during the final stage of the MR. AGEs can be formed both during the thermal processing of food and in the human body. The number of AGEs formed in food is much higher compared to endogenous AGEs. A direct connection exists between human health and the build-up of AGEs in the body, which can result in diseases. Therefore, it is essential to understand the content of AGEs in the food we consume. The detection methods of AGEs in food are expounded upon in this review, and the advantages, disadvantages, and application fields of these detection methods are discussed in depth. Additionally, the production of AGEs in food, their content in typical foods, and the mechanisms influencing their formation are summarized. Since AGEs are closely related to the food industry and human health, it is hoped that this review will further the detection of AGEs in food so that their content can be evaluated more conveniently and accurately.

Dual bacterial strains TTI for monitoring fish quality in food cold chain

Most microbial time-temperature indicators (TTIs) considered only one spoilage strain. This research compared single and dual spoilage strains-based microbial TTI for quality changes of chilled grouper fish (Epinephelus fuscoguttatus x E. lanceolatus) fillet products during distribution. The next-generation sequencing (NGS) and traditional plate count approach showed that Pseudomonas fragi and Vibrio parahaemolyticus were specific spoilage bacteria at 7 and 15°C. A dual-strain TTI response provides more accurate results than a single-strain TTI and provides an irreversible color change from yellow to reddish-brown, showing levels of fish freshness. The microbial TTI comprises fish spoilage bacteria strains with 3 log CFU/ml, a nutrient broth supplemented with 2% NaCl as a medium, and phenol red with 0.25 mg/ml as a pH indicator. Overall, this study points to the applicability of a dual-strain microbial TTI as a valuable tool for monitoring fish quality changes during cold chain break condition.

Effect of Traditional Stir-Frying on the Characteristics and Quality of Mutton Sao Zi

The effects of stir-frying stage and time on the formation of Maillard reaction products (MRP) and potentially hazardous substances with time in stir-fried mutton sao zi were investigated. Furosine, fluorescence intensity, Nε-(1-carboxymethyl)-L-lysine (CML), Nε-(1-carboxyethyl)-L-lysine (CEL), polyaromatic hydrocarbons PAHs), heterocyclic aromatic amines (HAAs), and acrylamides (AA) mainly presented were of stir-fried mutton sao zi. The furosine decreased after mixed stir-frying (MSF) 160 s due to its degradation as the Maillard reaction (MR) progressed. The fluorescent compound gradually increased with time during the stir-frying process. The CML and CEL peaked in MSF at 200 s. AA reached its maximum at MSF 120 s and then decreased. All the 5 HAAs were detected after MSF 200 s, suggesting that stir-frying mutton sao zi was at its best before MSF for 200 s. When stir-frying exceeded the optimal processing time of (MSF 160 s) 200 s, the benzo[a]pyrene peaked at 0.82 μg/kg, far lower than the maximum permissible value specified by the Commission of the European Communities. Extended stir-frying promoted MRP and some hazardous substances, but the content of potentially hazardous substances was still within the safety range for food.

Assessment of traditional clarifiers on the adsorption of ochratoxin A in Cabernet Sauvignon red wine and their kinetics

The effect of clarification on the elimination of Ochratoxin A (OTA) in wine was studied and the adsorption behavior of different clarifiers was evaluated. The results showed that OTA in wine can be effectively eliminated by gelatin with an adsorption rate of 28.59%, followed by chitosan (24.7%), bentonite (22.5%) and polyvinylpyrrolidone (PVPP) (7.6%). The clarification process was significantly affected by the clarifiers and OTA concentration. In addition, the experimental kinetic data for OTA removal were also evaluated by different equations. It displayed that the adsorption of gelatin and PVPP can be simulated by Pseudo-first order equation and Elovich equation, while that of chitosan and bentonite followed Pseudo-second order equation. The adsorption behavior of gelatin, chitosan and bentonite can fit Freundlich equation, Temkin equation and Dubinin-Radushkevich, and that of PVPP can only fitted by Langmuir equation. The thermodynamic parameters further revealed that the adsorption of OTA in wine was non-spontaneous.

Comprehensive Evaluation of Flavor in Charcoal and Electric-Roasted Tamarix Lamb by HS-SPME/GC-MS Combined with Electronic Tongue and Electronic Nose

To prevent the pollution generated during charcoal roasting of tamarix lamb, environmental-friendly electric is gradually applied in meat processing. The profile and formation of flavor in roasted tamarix lamb were evaluated using HS-SPME/GC-MS combined with E-nose/-tongue. Results indicated that charcoal-roasted tamarix lamb exhibited the higher taste of umami and sourness in E-tongue and had higher contents of alcohols, aldehydes, ketones, alkanes, and aromatics in E-nose, while the electric ones exhibited the higher taste of sweetness and bitterness and had higher contents of nitrogen oxides, terpenes, aromatics, and organic sulfur. Compared with charcoal, application of the electric significantly decreased the numbers of key volatile compounds with VIP > 1 (markers) and the contents of most markers.

Development of a time-temperature indicator based on Maillard reaction for visually monitoring the freshness of mackerel

Due to the highly cost-effective and maneuverable property, Maillard reaction-based time-temperature indicators (TTIs) are considered ideal devices for temperature track and quality indication. The objective of this study was to develop a cold-sensitive TTI based on the Maillard reaction reflecting the freshness of chilled seafood. Firstly, the color evolution trends of a series of Maillard reaction-based TTIs were investigated and the xylose-lysine group represented obvious color change. Fourier transform infrared (FTIR) spectroscopy revealed the color change was associated with the formation of CN bond in melanoidin. Simultaneously, the relationships of the color change of TTI with time and temperature were established. The activation energy value (Ea) of TTI was close to that of mackerel. There existed a good relevance (R² = 0.98) between the color change of TTI and the total volatile basic nitrogen content of mackerel, suggesting this novel TTI might have the potential to monitor the freshness of mackerel.

Comprehensive Evaluation of Volatile and Nonvolatile Compounds in Oyster Cuts of Roasted Lamb at Different Processing Stages Using Traditional Nang Roasting

Nang roasting is a traditional lamb processing method in Xinjiang (China) with a history of thousands of years. This study comprehensively evaluated the volatile and nonvolatile compounds of oyster cuts of roasted lamb at different processing stages of Nang roasting using gas chromatography mass spectrometry and amino acid automatic analyzer, respectively. Results indicated that aldehydes were the dominant profiles of volatile compounds, and hexanal, nonanal, octanal, (E)-2-nonenal, (E, E)-2,4-decadienal, (E, E)-2,4-nonadienal and 1-octen-3-ol were the key volatile compounds or aroma contributors to roasted oyster cuts. Isoamylol and 3-hydroxy-2-butanone could differentiate fresh and marinated oyster cuts from roasted ones; (E)-2-nonenal, (E, E)-2,4-decadienal, 1-octen-3-ol, hexanal, octanal, nonanal and (E, E)-2,4-nonadienal could differentiate Nang roasted oyster cuts of 60 min from those of 15, 30 and 45 min. Umami amino acids and sweet amino acids are the dominant profiles of nonvolatile compounds; glutamic acid, alanine and 5′-IMP were the key free amino acids or taste contributors to roasted oyster cuts. Glutamic acid, alanine and 5′-IMP could differentiate fresh and marinated oyster cuts from roasted samples. This work provided theoretical support for the control of flavor attributes of roasted lamb with traditional Nang roasting.