Effects of roasting temperature and time on aldehyde formation derived from lipid oxidation in scallop (Patinopecten yessoensis) and the deterrent effect by antioxidants of bamboo leaves

Effects of freeze-thaw cycles on texture and protein digestive properties of scallop adductor muscles: Role of protein oxidative changes

This study investigated the effects of freeze-thaw cycles (F-T cycles) on texture and protein digestive properties of scallop adductor muscles and the underlying mechanisms involved. Results showed that F-T cycles significantly increased free radical intensity of scallop adductor muscles and oxidation level of scallop protein. Simultaneously, the protein oxidative degradation occurred, as evidenced by increased levels of TCA-soluble peptides and water-soluble Hyp, which led to myofiber breakage and decreased textural properties. Nile Red staining showed that F-T cycles-induced oxidation promoted protein aggregation, which in turn reduced protein digestibility. Peptidomics analysis further showed that F-T cycles-induced oxidation altered the enzymatic cleavage sites in scallop protein, resulting in an increased abundance of macromolecular peptides (>2500 Da) and decreased release of bioactive peptides. These results highlight the role of protein oxidation in the deterioration of texture and protein digestibility of scallops during frozen storage, providing a basis for improving quality preservation strategies.

Advancing Butter Cookie Quality: Low-Oxygen Baking as a Dual Approach for Sensory Enhancement and Acrylamide Mitigation

This study investigated the impact of oxygen concentrations during baking on flavor, sensory perception, and acrylamide content in butter cookies. Cookies were baked at 190 and 210 °C under three oxygen levels (5, 10, and 21%). Key quality parameters, including moisture content, texture, color, flavor volatiles, and acrylamide content, were measured, and sensory evaluation was conducted using 55 judges. Principal component analysis was implemented to elucidate relationships among physicochemical properties, aroma profiles, and safety metrics. Results demonstrated that baking under low oxygen concentrations significantly reduced acrylamide formation, exemplified by a reduction from 95.8 to 58.5 μg/kg at 190 °C and 116.6 to 53.1 μg/kg at 210 °C, respectively. Notably, baking at 190 °C with 5% oxygen was identified as the optimal condition, balancing sensory quality and safety by minimizing the formation of harmful substances. These findings provide a promising strategy for improving the safety and quality of baked goods through controlled oxygen levels during processing.

Uncovering quality changes in oysters (Crassostrea hongkongensis) during frozen storage based on lipidomics and proteomics

This study investigated quality changes in oysters during frozen storage through physicochemical analysis, quantitative lipidomics, and quantitative proteomics. Results showed that the quality of oysters progressively deteriorated with increasing freezing time and temperature, as evidenced by color darkening, texture softening, reduced water-holding capacity, and increased TVB-N levels. Simultaneously, protein oxidation and lipid oxidation were observed, resulting in increased carbonyl, disulfide bonds, dityrosine, TBARS, and Schiff base content, and decreased free sulfhydryl groups. Lipidomics analysis revealed oxidation and hydrolysis of polyunsaturated lipids in oysters during storage, with PC being preferentially oxidized. Proteomics analysis revealed extensive oxidation and degradation of structural proteins, particularly MHC and filamin-C. Correlation analysis further highlighted oxidative degradation of polyunsaturated lipids and structural proteins as major contributors to the quality decline of oysters during frozen storage. This study sheds light on the mechanisms of quality deterioration in frozen oysters and provides valuable guidance for enhancing their preservation quality.

Insight into the effect of GSH curing treatment on the flavor formation of chicken meat

Glutathione (GSH) is an important precursor of meat flavor. This study aimed to evaluate the effect of GSH-curing on the flavor of cooked chicken. GSH-cured chicken with different concentrations and uncured chicken (blank) were roasted separately and comprehensively analyzed in terms of flavors, odor-active compounds, free amino acids, and fatty acids profile. Volatile flavor compounds were analyzed using solid-phase micro-extraction (SPME) along with GC-MS, GC-O/AEDA, and odor activity value (OAV) calculations. The results showed that the contents of most flavors derived from the Maillard reaction increased due to GSH-curing treatment, such as 2-methylthiophene, 3-methylthiophene, 2-methylthiazole, and 5-methylthiazole, while the lipid degradation flavors reduced, like hexanal, heptanal, and (E,E)-2,4-decadienal. In particular, during sensory analysis, the cured sample with 1.6 mmol GSH had the greatest roasted meaty odor. In addition, GSH curing results in the increased formation of key odor-active substances (OAV ≥ 1), such as 2-acetylthiazole.

Advance in aldehydes derived from lipid oxidation: A review of the formation mechanism, attributable food thermal processing technology, analytical method and toxicological effect

The aldehydes derived from lipid oxidation are highly active electrophilic compounds including saturated aldehydes, dialdehydes, olefin aldehydes and hydroxyl aldehydes. The active groups like carbonyls, C=C bond, and hydroxyl groups make them prone to participate in chemical reactions with protein, phospholipids, which can further affect food properties. In addition, aldehydes can attack the nucleic acids and thiol group of endogenous antioxidants, result in oxidative stress and biological damage of cells, which usually serve as the direct trigger of various diseases. However, their structure-activity relationship has not received enough attention. Therefore, to provide a comprehensive understanding of reactive aldehydes on food safety and human health, the formation mechanism of aldehydes, attributable fundamental thermal processing, analytical methods, and toxicological effects based on the structure-activity relationship, have been reviewed and discussed. It was indicated that aldehydes generation exerted significant specificity of fatty acids substrate. Significant structure-activity relationships for the toxicological effects of aldehydes could be observed. Effective, accurate and eco-friendly detection techniques should be established based on the inherent advantages and limitations for food quality preservation and safety assurance.

Effects of phenolic acid grafted-chitosan hydrocolloids on the aldehyde contents from lipid oxidation in golden pompano (Trachinotus blochii) fillets during pan-frying

The effects of phenolic acid grafted-chitosan hydrocolloids (CS-g-GA/FA) on aldehyde contents from lipid oxidation in golden pompano fillets during pan-frying was investigated with an established high-performance liquid chromatography-mass spectrum method. Results indicated that pan-frying induced profound lipid oxidation and aldehydes generation with propanal, hexanal, nonanal, trans, trans-2,4-decadienal, and 4-hydroxy-2-nonenal as the abundant species. CS-g-FA and CS-g-GA effectively decreased their contents by 23.74-27.42 %, 61.69-67.42 %, 41.83-53.91 %, 29.91-48.79 %, and 61.57-65.39 % after 3 min. Most aldehyde contents decreased with the extension of pan-frying time due to the volatilization and reaction. In terms of substrate depletion, CS-g-phenolic acids effectively inhibited unsaturated fatty acids oxidation due to their decent antioxidant activity than CS. The significant lower retention rates of aldehydes in the CS-g-phenolic acids groups compared with control in chemical mode confirmed the carbonyl ammonia condensation. These results suggested that CS-g-phenolic acids serve as novel coating to reduce hazardous compounds during aquatic products thermal processing.

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.

Effects of pan- and air fryer-roasting on volatile and umami compounds and antioxidant activity of dried laver (Porphyra dentata)

This study aimed to investigate the impact of pan- and air fryer-roasting on the volatiles, umami compounds, antioxidant activity, and sensory attributes of dried laver (Porphyra dentata). To assess the influence of time and temperature, pan-roasting was conducted at temperatures of 250, 300, and 350 °C for 5, 10, and 15 s, respectively. For air fryer-roasting, dried laver was roasted at 160, 170, and 180 °C for 2, 4, and 6 min, respectively. In both roasting methods, the levels of 1,5-octadien-3-ol and 1-octen-3-ol significantly decreased (p < 0.05) with increased time and temperature. The Equivalent Umami Concentration ranged from 94.89 to 518.09 g MSG/100 g. The antioxidant activity significantly increased (p < 0.05) with higher roasting temperatures and longer durations, whereas pigment content significantly decreased. The browning index increased by 64% and 43% for the pan and air frying methods, respectively. The samples pan-roasted at 300 °C for 15 s obtained the highest sensory scores.

Comprehensive determination of fatty acids in real samples without derivatization by DMU-SPME-GC methods

The comprehensive determination of fatty acids without derivatization, including short-chain fatty acids (SCFAs), medium-chain fatty acids (MCFAs) and long-chain fatty acids (LCFAs), is a big challenge but powerful for lipidomics in biology, food, and environment. Herein, the dual mode unity solid-phase microextraction (DMU-SPME) combined with gas chromatography-flame ionization detector (GC-FID) or mass spectrometry (MS) was proposed as a powerful method for the determination of comprehensive free fatty acids in real samples. Under the optimized DMU-SPME conditions, the proposed method has good linearity (R2 ≥ 0.994) and low limits of determination (0.01-0.14 mg/L). In the stability analysis, the intra-day relative standard deviation was 1.39-12.43 %, and the inter-day relative standard deviation was 2.84-10.79 %. The recoveries of selected 10 fatty acids in real samples ranged from 90.18 % to 110.75 %, indicating that the method has good accuracy. Fatty acids ranging from C2 to C22 were detected in real samples by the untargeted determination method of DMU-SPME combined with gas chromatography-mass spectrometry (GC-MS). The DMU-SPME method proposed in this study can be used for lipid metabolism analysis and free fatty acid determination in the fields of biology, food, and environment.

Effect of non-enzymatic browning on oysters during hot air drying process: Color and chemical changes and insights into mechanisms

Hot air drying (HAD) is an extensive method used on oysters and it causes the most intuitive change, a color change. However, the mechanism of color change remains unclear. This study showed that oysters underwent browning during the HAD process. The colorimetric parameter L* decreased while a* and b* increased, all of which were well described by the first-order color kinetic model. Mechanistically, the HDA process induced the oxidative browning of phenols and the generation of Maillard reaction products (5-hydroxymethylfurfural and hydrophilic pyrrole). Meanwhile, the HAD process caused lipid oxidation, leading to the reduction of phosphatidylethanolamine and the generation of reactive carbonyl compounds (aldehydes and α-dicarbonyl compounds). Moreover, the accumulation of hydrophobic pyrroles, a lipid-induced Maillard-like reaction product, was observed. These results suggest that, in addition to phenolic oxidation, sugar- and amino acid-mediated non-enzymatic browning reactions, lipid-mediated Maillard-like reactions play important roles in oyster darkening during the HAD process.

Effect of heme proteins on the lipid molecule profile and aroma formation during hot air drying of non-smoked bacon

Heme proteins and their derivatives play important roles in inducing lipid oxidation to produce volatile compounds during bacon drying. This study investigated the effects of heme proteins and their derivatives (hemoglobin, myoglobin, nitrosylmyoglobin, hemin, Fe2+, and Fe3+) on lipid and volatiles profiles in the washed pig muscle (WPM) model. The results of the study indicated that the inducers primarily caused the oxidation of glycerophospholipids. Furthermore, hemoglobin and myoglobin had the most significant impact, and their potential substrates may include PE (O-18:2/20:4), PE (O-18:1/20:4), PC (16:0/18:1), and PE (O-18:2/18:2). Nitrosomyoglobin has limited ability to promote lipid oxidation and may protect ether phospholipids from oxidation. The analysis of the volatiles in the model revealed that heme proteins and their derivatives have the ability to induce the production of key aroma compounds. The descending order of effectiveness in inducing the production of aroma compounds is as follows: hemoglobin, myoglobin, hemin, and nitrosylmyoglobin. The effectiveness of Fe2+ and Fe3+ is similar to that of nitrosylmyoglobin.

Effect of marinating with green tea extract on the safety and sensory profiles of oven-baked oyster

Baked oyster is a popular seafood dish around the world. The present study investigated the effect of various concentrations of a green-tea extract (GTE) marinade on the safety and sensory profiles of oysters baked for different durations. The results showed 10 g/L of GTE and 10-min baking time was the optimal combination, as supported by significantly attenuated lipid oxidation (35.29 %) and Nε-(carboxyethyl)lysine (CEL) content (48.51 %) without appreciable negative impact on the sensory or nutritional quality of the oysters. However, high concentrations of the marinade or prolonged baking promoted protein oxidation and Nε-(carboxymethyl)lysine (CML) formation likely through the pro-oxidative action of the GTE phytochemicals. Correlation analysis further revealed the main factors that affected CML, CEL, and fluorescent AGEs generation, respectively. These findings provide theoretical support for the protective effect and mechanism of GTE against quality deterioration of baked oysters and would help broaden the application of GTE in the food industry.

Mechanism of color change in Antarctic krill oil during storage

Antarctic krill oil (AKO) is reddish-orange in color but undergoes changes during storage. To investigate the color deterioration and potential mechanisms involved, the changes in color, endogenous components (astaxanthin, fatty acids, and phospholipids), and reaction products (aldehydes, α-dicarbonyl compounds, and pyrroles) of AKO upon storage were determined. Although the visual color of AKO tended to darken upon storage, the colorimetric analysis and ultraviolet-visible spectrum analysis both indicated a fading in red and yellow due to the oxidative degradation of astaxanthin. During storage of AKO, lipid oxidation led to the formation of carbonyl compounds such as aldehydes and α-dicarbonyls. In addition, phosphatidylethanolamines (PEs) exhibited a faster loss rate than phosphatidylcholines. Moreover, hydrophobic pyrroles, the Maillard-like reaction products associated with primary amine groups in PEs accumulated. Therefore, it is suggested that the Maillard-like reaction between PEs and carbonyl compounds formed by lipid oxidation contributed to color darkening of AKO during storage.

Exploring the metabolomic landscape: Perilla frutescens as a promising enhancer of production, flavor, and nutrition in Tan lamb meat

Addressing health-related concerns linked to the metabolite profile of lamb meat has become paramount, in line with the growing demand for enhanced flavor and taste. We examined the impact of Perilla frutescens seeds on Tan lamb growth, carcass traits, and metabolite profiles. Three diets were employed: a low-concentrate group (LC), a high-concentrate group (HC), and a PFS group (the LC diet supplemented with 3% Perilla frutescens seeds) on a dry matter basis. Forty-five male Tan-lambs (approximately six months) with similar body weights (25.1 kg ± 1.12 SD) were randomly assigned to one of these three groups for 84-day feeding, including an initial 14-day adjustment phase. The supplementation of PFS resulted in increased average daily gain (P < 0.01) and improved carcass quality and meat color (P < 0.05). Additionally, it led to an enhancement in omega-3 polyunsaturated fatty acids (P < 0.05) and a reduction in the omega-6/omega-3 ratio (P < 0.05). Using gas chromatography-mass spectrometry, 369 volatile compounds were identified with enhanced levels of acetaldehyde and 1,2,4-trimethyl-benzene associated with PFS (P < 0.05). Among the 807 compounds identified by ultra-high performance liquid chromatography-mass spectrometry, there were 66 significantly differential compounds (P < 0.05), including 43 hydrophilic metabolites and 23 lipids. PFS supplementation led to significant alterations in 66 metabolites, with three metabolites including 2,5-diisopropyl-3-methylphenol, 3-hydroxydecanoic acid, and lysophosphatidylcholine (15:0) emerging as potential PFS-related biomarkers. The study indicates that PFS supplementation can enhance Tan-lamb growth, feed efficiency, and meat quality, potentially providing lamb meat with improved flavor and nutritional characteristics.

Phenolic diversity and antioxidant potential of different varieties of bamboo leaves using LC-ESI-QTOF-MS/MS and LC-ESI-QqQ-MS/MS

Bamboo is a highly sustainable plant with a wide variety of leaves, yet little is known about its bioactive composition. Therefore, this study aims to characterize the phenolic profile and antioxidant capacity of 11 different varieties of bamboo leaves using liquid chromatography coupled with mass spectrometry. As a result, 81 phenolic compounds were tentatively identified, 29 of which were identified for the first time in the literature for bamboo leaves. The tentatively identified compounds fell into five classes (hydroxybenzoic and hydroxycinnamic acids, flavones, flavanones, and flavonols). The concentration of phenolic compounds ranged from 103 to 1291 mg/100 g. Among the provisionally identified compounds, there was a predominance of derivatives from the luteolin and apigenin group, with orientin and schaftoside being the majority in each group, respectively. The leaves also showed significant variation in antioxidant activity, highlighting the potential bioactive composition of bamboo leaves for future applications in the food industry.

Purification and Identification of Peptides from Hydrilla verticillata (Linn. f.) Royle with Cytoprotective and Antioxidative Effect against H2O2-Treated HepG2 Cells

Antioxidant peptides were purified from Hydrilla verticillata (Linn. f.) Royle (HVR) protein hydrolysate by ultrafiltration, gel filtration chromatography, and semipreparative reversed-phase HPLC and identified by UPLC-ESI-MS/MS. Therein, TCLGPK and TCLGER were selected to be synthesized, and they displayed desirable radical-scavenging activity to ABTS (99.20 ± 0.56-99.20 ± 0.43%), DPPH (97.32 ± 0.59-97.56 ± 0.97%), hydroxyl radical (54.32 ± 1.27-70.42 ± 2.01%), and superoxide anion (42.93 ± 1.46-52.62 ± 1.11%) at a concentration of 0.96 μmol/mL. They possessed a cytoprotective effect against H2O2-induced oxidative stress in HepG2 cells in a dose-dependent manner. 1.6 μmol/mL of the two peptides could perfectly protect HepG2 cells from H2O2-induced injury. The TCLGPK exhibited higher antioxidant activity and cytoprotective effect than TCLGER. Western blot and molecular docking results indicated that the two peptides achieved antioxidant ability and cytoprotective effect by combining with Kelch-like ECH-associated protein 1 (Keap1) to activate the Keap1-nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response elements signaling pathway, leading to the activity and expression of the related antioxidases in the pathway significantly up-regulating and the intracellular reactive oxygen species level, lipid peroxidation, and cell apoptosis rate significantly down-regulating.

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.

Lipidomics reveals the relationship between lipid oxidation and flavor formation of basic amnio acids participated Low-Sodium cured large yellow croaker

The effects of basic amino acids on lipid oxidation and the formation of volatile compound in low-sodium cured large yellow croaker were investigated. Basic amino acids contribute a lot in inhibiting the degradation of phospholipids, especially l-lysine. Lipid oxidation was also inhibited by basic amino acids, and the total oxidation of groups could be sorted as low-sodium (LS) > control (C) > l-Histidine participated LS group (LS-His) > l-Arginine participated LS group (LS-Arg) > l-lysine participated LS group (LS-Lys). PC 18:1/20:5, PC 16:0/18:1, triacylglycerol (TG) 16:1/20:5/22:6, etc., were found to be key differential lipid metabolites, and 1-propanol, 2-methyl, gamma-hexalactone, etc. were recognized as key differential volatile compounds. The results of correlation analysis showed that alcohols and esters were positively correlated with TG molecules composed of saturated fatty acids and monounsaturated fatty acids. These findings provided new insights into the relationship between flavor formation and the degradation and oxidation of lipids.

Texture and volatile profiles of beef tallow substitute produced by a pilot-scale continuous enzymatic interesterification

Edible beef tallow (BT) has been widely used in Sichuan hotpot due to its unique flavor and texture. However, BT should not be consumed in excess caused by its trans-fatty acids and cholesterol issues. In this study, a BT substitute was prepared after enzymatic interesterification in a pilot-scale packed-bed reactor using soybean oil and fully hydrogenated palm oil (4:3, w/w) as feedstock. The products were characterized against BT in terms of fatty acid/triacylglycerol compositions, solid fat content, polymorphism, and melting/crystallization behaviors to select the most promising BT substitute. The optimal flow rate was 120 mL/min. Changes in volatile compounds during stir-frying and simmering were also investigated for Sichuan hotpots made with these two oils. The volatile compounds of BT substitute were similar to that of natural BT. The findings will contribute to expanding the base oil categories of Sichuan hotpot oils.

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.

Synergistic Effect of Combined Treatment with Allicin and Antioxidant of Bamboo Leaves and Preservation of Bullfrogs (Lithobates catesbeiana) during Refrigeration Storage

The effects of allicin and antioxidant of bamboo leaves (AOB) on the quality of bullfrogs (Lithobates catesbeiana) during refrigerated storage (4 °C) were investigated. The quality changes in samples treated with deionized water (CK), allicin solution (All), antioxidant of bamboo leaves (AOB), and allicin solution combined with AOB solution (AA) in microbiological, physicochemical, and sensory evaluation were analyzed, respectively. The results demonstrated that combination treatment inhibited the increase in total viable counts, delayed the decrease in amino acid content, and retarded the sensory deterioration. Preservative treatment has an inhibitory effect on the early storage of PBC, which can reduce PBC by about 1.0 log CFU/g. The reduction in thiobarbituric acid (TBA) content and total volatile basic nitrogen (TVB-N) content indicated that combination treatment could better restrain the lipid oxidation and degradation of protein than the CK group and single-treatment group. In addition, the TVB-N content in the AA group still did not exceed the threshold on the 14th day. As a consequence, combination treatment prolonged the shelf life of bullfrogs for another six days. Therefore, allicin and AOB with excellent antioxidant and antimicrobial activity could be an effective approach to delay the biochemical reaction of refrigerated bullfrogs. This study has provided a potential approach for increasing the shelf life of bullfrogs and preserving their quality during refrigerated storage.

A curcumin-crosslinked bilayer film of soy protein isolate and chitosan with enhanced antibacterial property for beef preservation and freshness monitoring

In this study, antibacterial and antioxidant bilayer films were prepared by using curcumin (Cur) crosslinked soy rotein isolate (SPI) and chitosan (CS). Molecular docking simulations and multispectral analysis revealed that hydrogen bonding and hydrophobic interactions were the primary driving forces that promoted the self-assembly of the bilayer films. The tensile strength, the UV-blocking properties and the hydrophobicity was greatly improved of the bilayer antimicrobial films. Moreover, water vapor permeability, thermal shrinkage and opacity were all reduced significantly. In addition, the composite films with curcumin demonstrated effective antioxidant activity and a slow release characteristic. Morphology observation of the bacteria by AFM revealed that the antibacterial bilayer film had a significant damaging effect on the cell structures of S. aureus and E. coli due to the dual antibacterial effect of curcumin and chitosan. SPI + Cur-CS antimicrobial bilayer film effectively inhibited the growth of bacteria and extended the shelf life of beef. According to the findings, SPI + Cur-CS antimicrobial bilayer film can be used as an active package material for beef preservation and freshness monitoring.

Effect of lipid oxidation on quality attributes and control technologies in dried aquatic animal products: a critical review

Aquatic animals are viewed as a good source of healthy lipids. Although drying is an effective method for the preservation of aquatic animal products (AAPs), the whole process is accompanied by lipid oxidation. This article reviews the main mechanism of lipid oxidation in the drying process. It also summarizes the effects of lipid oxidation on the quality of dried aquatic animal products (DAAPs), including nutrients, color, flavor, and hazard components, especially for those harmful aldehydes and heterocyclic amines. In addition, it concluded that moderate lipid oxidation contributes to improving the quality of products. Still, excessive lipid oxidation produces hazardous substances and induces health risks. Hence, to obtain high-quality DAAPs, some effective control technologies to promote/prevent lipid oxidation are introduced and deeply discussed, including salting, high-pressure processing, irradiation, non-thermal plasma technology, defatting treatments, antioxidants, and edible coating. A systematic review of the effect of lipid oxidation on quality attributes and control technologies in DAAPs is presented, and some perspectives are made for future research.

Antarctic krill (Euphausia superba) oil high internal phase emulsions improved the lipid quality and gel properties of surimi gel

In the study, high internal phase emulsions (HIPEs) prepared from Antarctic krill oil (AKO) were added into surimi and the effects on gel properties, lipid quality and stability were investigated. It is found that HIPEs-added groups exhibited higher gel strength and lower cooking loss than Oil-added counterparts. HIPEs-added groups had higher proportion of capillary water, and microstructure of HIPEs-added gels showed fewer large voids and small size droplets. HIPEs-added groups also showed less pronounced myosin heavy chain band. HIPEs- and Oil-added gels showed > 3500 mg/kg EPA + DHA and 0.4-0.8 mg/kg astaxanthin, and most HIPEs-added groups had higher levels of them but lower TBARS values. Results suggest AKO-HIPEs could reduce the intervention by lipids on myosin crosslinking during gelation, and protect fatty acids and asxtanthin from oxidation due to oxygen-isolation led by their high accumulation. Thus, AKO-HIPEs can be applied to fortify ω-3 PUFA and maintain good gel properties in surimi product.

The Inhibitory Effects of Hydroxytyrosol, α-Tocopherol and Ascorbyl Palmitate on Lipid Peroxidation in Deep-Fat Fried Seafood

This study aimed to investigate the inhibitory effects of hydroxytyrosol, α-tocopherol and ascorbyl palmitate on lipid peroxidation in squid, hoki and prawn during deep-fat frying and refrigerated storage. Fatty acid analysis using gas chromatography (GC) showed that the seafood had a high omega-3 polyunsaturated fatty acid (n-3 PUFAs) content, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The total content of n-3 fatty acids in their lipids was 46% (squid), 36% (hoki) and 33% (prawn), although they all had low lipid contents. The oxidation stability test results showed that deep-fat frying significantly increased the peroxide value (POV), p-anisidine value (p-AV) and the value of thiobarbituric acid reactive substances (TBARS) in squid, hoki and prawn lipids. Meanwhile, antioxidants delayed the lipid oxidation in fried seafood and sunflower oil (SFO) used for frying, albeit in different ways. The least effective of all the antioxidants was α-tocopherol, as the POV, p-AV and TBARS values obtained with this antioxidant were significantly higher. Ascorbyl palmitate was better than α-tocopherol but was not as effective as hydroxytyrosol in suppressing lipid oxidation in the frying medium (SFO) and in the seafood. However, unlike the ascorbyl palmitate-treated oil, hydroxytyrosol-treated oil could not be used for multiple deep-fat frying of seafood. Hydroxytyrosol appeared to be absorbed in the seafood during multiple frying, thus leaving a low concentration in the SFO and making it susceptible to oxidation.

Effects of Low-Temperature and Low-Salt Fermentation on the Physicochemical Properties and Volatile Flavor Substances of Chinese Kohlrabi Using Gas Chromatography–Ion Mobility Spectrometry

To explore the effect of low-temperature and low-salt fermentation on the volatile flavor substances of Chinese kohlrabi, low-temperature and low-salt fermented Chinese kohlrabi (LSCK) and traditional high-salt fermented Chinese kohlrabi (HSCK) were produced. The physicochemical and texture properties of the two kinds of Chinese kohlrabies were evaluated. Headspace gas chromatography-ion mobility spectrometry (GC-IMS) and electronic nose (E-nose) were used to analyze the volatile flavor substances of the kohlrabi. The results showed that the total acid content significantly decreased (p < 0.05), while protein and reducing sugar contents significantly increased (p < 0.05) by low-temperature and low-salt fermentation. A total of 114 volatile flavor substances were identified. The alcohol, ketone, pyrazine, ether, and nitrile contents in LSCK were significantly higher than those in HSCK (p < 0.05). Moreover, the unpleasant flavor from the 3-methylbutyric acid formation was effectively depressed in LSCK. The principal component analysis (PCA) and orthogonal partial least squares discrimination analysis (OPLS-DA) models established by multivariate statistical analysis significantly distinguished the two types of kohlrabies. Multivariate statistical analysis suggested that 16 volatile flavor substances with VIP >1, including tetrahydrothiophene, ethyl 3-(methylthio)propanoate, 3-methylbutyric acid, hexanenitrile, and 3-methyl-3-buten-1-ol, could be used as potential biomarkers for identifying LSCK and HSCK. The E-nose analysis further demonstrated that there was a significant difference in overall flavor between the LSCK and HSCK. The present study provides support for the development of green processing technology and new low-salt Chinese kohlrabi products.

Effect of drying processes on the occurrence of lipid oxidation-derived 4-hydroxy-2-hexenal and 4-hydroxy-2-nonenal in Spanish mackerel (Scomberomorus niphonius)

In this study, dry-cured Spanish mackerel (Scomberomorus niphonius, DCSM) was prepared via three different methods (hot-air drying, cold-air drying, and sun drying). The content of 4-hydroxy-2-hexenal (HHE) and 4-hydroxy-2-nonenal (HNE) derived from lipid oxidation in whole processes was investigated by HPLC-MS/MS. The changes in fatty acid composition were detected by GC-MS, and the degree of lipid oxidation was evaluated by the levels of acid values (AV), peroxide values (POV), and thiobarbituric acid-reactive substances (TBARS). The results showed that the drying process significantly accelerated lipid oxidation in DCSM. The contents of HHE and HNE were significantly increased after processing. The content of HHE was higher by 18.44-, 13.45-, and 16.32-folds compared with that of HNE after three different processes, respectively. The HHE and HNE contents fluctuated upward during the hot-air and cold-air drying process. However, the contents of HHE and HNE increased time-dependent during the sun drying process, with the highest values of 86.33 ± 10.54 and 5.29 ± 0.54 mg/kg fish among the three different processes. Besides, there was a significant positive correlation between HHE contents and n-3 fatty acids content in hot-air drying and sun drying processes (Pearson's r = .991/.996), and HNE occurrence was closely related to n-6 fatty acid content in sun drying process (Pearson's r = .989). Regression analysis indicated that the content of HHE and TOTOXTBA values in DCSM showed good linear relationships (R 2 value = .907), which suggested that the content of HHE could be used to estimate the oxidative deterioration of dry-cured fish products.

Optimization of HS-SPME-GC-MS for the Determination of Volatile Flavor Compounds in Ningxiang Pork

This study attempts to explore the suitable conditions for the detection of volatile flavor compounds (VFCs) in Ningxiang pork by headspace solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS). Ningxiang pigs were harvested from a slaughterhouse and a longissimus dorsi sample was collected from each animal. The VFCs of Ningxiang pork can be strongly impacted by the detection conditions (columns, weight of meat samples, heat treatment time, equilibrium conditions, and extraction conditions) that need to be optimized. Our results also provided the optimal test conditions: weighing 5 g of meat samples, grinding for 30 s in a homogenizer, heat treatment at 100 °C for 30 min, equilibration at 70 °C for 30 min, and extraction at 100 °C for 50 min. Furthermore, the feasibility and representativeness of the test method were confirmed based on principal component analysis and a comparison of the three pork VFCs. These findings offer researchers a unified and efficient pretreatment strategy to research pork VFCs.

Physicochemical and Antioxidant Properties of Nanoliposomes Loaded with Rosemary Oleoresin and Their Oxidative Stability Application in Dried Oysters

Lipid and protein oxidation is a main problem related to the preservation of dried aquatic products. Rosemary oleoresin is widely used as an antioxidant, but its application is limited due to its instability and easy degradation. Nanoliposome encapsulation is a promising and rapidly emerging technology in which antioxidants are incorporated into the liposomes to provide the food high quality, safety and long shelf life. The objectives of this study were to prepare nanoliposome coatings of rosemary oleoresin to enhance the antioxidant stability, and to evaluate their potential application in inhibiting protein and lipid oxidation in dried oysters during storage. The nanoliposomes encapsulating rosemary oleoresin were applied with a thin-film evaporation method, and the optimal amount of encapsulated rosemary oleoresin was chosen based on changes in the dynamic light scattering, Zeta potential, and encapsulation efficiency of the nanoliposomes. The Fourier transform-infrared spectroscopy of rosemary oleoresin nanoliposomes showed no new characteristic peaks formed after rosemary oleoresin encapsulation, and the particle size of rosemary oleoresin nanoliposomes was 100-200 nm in transmission electron microscopy. The differential scanning calorimetry indicated that the nanoliposomes coated with rosemary oleoresin had better thermal stability. Rosemary oleoresin nanoliposomes presented good antioxidant stability, and still maintained 48% DPPH radical-scavenging activity and 45% ABTS radical-scavenging activity after 28 d of storage, which was 3.7 times and 2.8 times higher than that of empty nanoliposomes, respectively. Compared with the control, the dried oysters coated with rosemary oleoresin nanoliposomes showed significantly lower values of carbonyl, sulfhydryl content, thiobarbituric acid reactive substances, Peroxide value, and 4-Hydroxynonenal contents during 28 d of storage. The results provide a theoretical basis for developing an efficient and long-term antioxidant approach.

Lipid oxidation in fragrant rapeseed oil: Impact of seed roasting on the generation of key volatile compounds

This work sought to identify the influence of roasting on lipid oxidation-derived volatile compounds in fragrant rapeseed oils (FROs) via gas chromatography–mass spectrometry and gas chromatography–ion mobility spectrometry. Seven volatiles could be regard as aroma-active compounds by application of odor activity value (OAV ≥ 1) calculation, and caused fatty-like, nutty-like, and green-like notes. After 60 min of roasting, the OAVs of hexanal, octanal, (E,E)-2,4-heptadienal, and nonanal in FROs were greater than 3. The same compounds, including hexanal, (E,E)-2,4-heptadienal, nonanal, 1-octanol, and nonanoic acid were also detected in the model systems of lipid oxidation. Notably, the values of p-anisidine, conjugated dienes, and conjugated trienes increased significantly (p < 0.05). Furthermore, correlation analysis showed that hexanal, (E,E)-2,4-heptadienal, and nonanal have a significant positive correlation with the oxidative degree of FROs (R = 0.70–0.94, p < 0.05). Thus, the three above-mentioned aldehydes could serve as important markers for FRO quality during roasting.

Unraveling inhibitory effects of Alpinia officinarum Hance and curcumin on methylimidazole and acrylamide in cookies and possible pathways revealed by electron paramagnetic resonance

The synchronous mitigative effects of Alpinia officinarum Hance (AOH) and curcumin on the generation of methylimidazole and acrylamide in cookies were investigated. Possible mechanisms related to quenching free radicals, reducing lipid oxidation and eliminating carbonyl intermediates were explored by electron paramagnetic resonance (EPR) and HPLC. The total methylimidazole and acrylamide contents raised with an increase in heating temperature and time, and reached a maximum at 200 °C for 11 min. AOH and curcumin reduced methylimidazole and acrylamide simultaneously; the maximum inhibition rates for methylimidazole and acrylamide were 51.55% (0.015% curcumin) and 73.66% (1.5% AOH). Alkyl free radicals and HO· were proved to be the critical free radicals for methylimidazole and acrylamide, AOH and curcumin quenched these radicals in a dose-dependent manner. The lipid oxidation, active carbonyl intermediates glyoxal, methylglyoxal, and acrylaldehyde were also reduced by AOH and curcumin simultaneously, which may be resulted from the quenching of free radicals.

Water distribution and key aroma compounds in the process of beef roasting

The key aroma compounds and water distribution of the beef at different roasting times (0, 3, 6, 9, 12, 15, and 18 min) were identified and analyzed. The results showed that the L^* value increased considerably before peaking and then decreased. On average, a^* values decreased significantly first and then kept stable, while b^* values increased first and then decreased. A total of 47 odorants were identified in all samples, including 14 alcohols, 18 aldehydes, 6 ketones, 1 ester, 3 acids, 4 heterocyclic compounds, and 1 other compound. Among them, 11 key aroma compounds were selected and aldehydes and alcohols predominantly contributed to the key aroma compounds. The fluidity of the water in the beef during the roasting process was decreased, and the water with a high degree of freedom migrated to the water with a low degree of freedom. The correlation analysis showed that water content and L^* were negatively correlated with key aroma compounds of the samples, while M₂₁ was positively correlated with key aroma compounds.

Identifying celiac disease-related chemicals by transcriptome-wide association study and chemical-gene interaction analyses

Celiac disease (CeD) is one of the most common intestinal inflammatory diseases, and its incidence and prevalence have increased over time. CeD affects multiple organs and systems in the body, and environmental factors play a key role in its complex pathogenesis. Although gluten exposure is known to be the causative agent, many unknown environmental factors can trigger or exacerbate CeD. In this study, we investigated the influence of genetic and environmental factors on CeD. Data from a CeD genome-wide association study that included 12,041 CeD cases and 12,228 controls were used to conduct a transcriptome-wide association study (TWAS) using FUSION software. Gene expression reference data were obtained for the small intestine, whole blood, peripheral blood, and lymphocytes. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses using the significant genes identified by the TWAS and conducted a protein–protein interaction network analysis based on the STRING database to detect the function of TWAS-identified genes for CeD. We also performed a chemical-related gene set enrichment analysis (CGSEA) using the TWAS-identified genes to test the relationships between chemicals and CeD. The TWAS identified 8,692 genes, including 101 significant genes (p_adjusted < 0.05). The CGSEA identified 2,559 chemicals, including 178 chemicals that were significantly correlated with CeD. This study performed a TWAS (for genetic factors) and CGSEA (for environmental factors) and identified several CeD-associated genes and chemicals. The findings expand our understanding of the genetic and environmental factors related to immune-mediated diseases.

Effect of Palm Oil-Carnauba Wax Oleogel That Processed with Ultrasonication on the Physicochemical Properties of Salted Duck Egg White Fortified Instant Noodles

The present study permutes edible palm oil (PO) into oleogel by incorporating carnauba wax (CW) at two different concentrations (5 g/100 g and 10 g/100 g, w/w) and processing using ultrasonication. The prepared oleogels (OG1: PO-CW (5 g/100 g); OG2: PO-CW (10 g/100 g); and OGU1: PO-CW (5 g/100 g) with ultrasonication, and OGU2: PO-CW (10 g/100 g) with ultrasonication) were compared with PO (control) to deep fry salted duck egg white (SDEW) fortified instant noodles. The impact of different frying mediums on the physicochemical properties of SDEW noodles was investigated. SDEW instant noodles that were fried using OGU and OG samples had a higher L* and b* but lower a* values than those that were fried in PO (p < 0.05). Among the oleogel-fried samples, noodles that were fried in OGU2 and OG2 effectively lowered the oil uptake and showed better cooking properties than OGU1- and OG1-fried noodles, respectively (p < 0.05). Textural attributes such as higher hardness, firmness, chewiness, tensile strength and elasticity, and lower stickiness were noticed in the samples that were fried in OGU, followed by OG and PO (p < 0.05). Scanning electron microstructure revealed a uniform and smoother surface of noodles fried in OGU and OG, whereas the PO-fried sample showed an uneven and rough surface with more bulges. Noodles were tested for fatty acid compositions, and the results found that oleogel-fried noodles retained more unsaturated fatty acids than the control (p < 0.05). During storage of the frying medium after frying the noodles, OGU and OG had higher oxidative stability with lower TBARS, PV, p-AnV, and Totox values than PO at room temperature for 12 days. Overall, using oleogel as frying media improved the physicochemical and nutritional properties of SDEW noodles. This finding could be beneficial for food industries to produce healthy fried food products for consumers.