This study aimed to investigate the effects of a nitrite composite substitute (NSCS) composed of several natural substances (0.03% monascus red, 0.04% Nisin, and 0.03% rosemary) on the eating quality, total bacterial count, nitrite residue, and other indices of yak meat sausages during storage (1, 3, 5, 7, and 9 d), and to clarify the substitution effect of NSCS on nitrite in minced meat products. Results showed that NSCS exerted positive effects on improving the eating quality of yak meat sausages, reducing the total bacterial count and nitrite residues by substituting nitrite. Specifically, on day 9, the NSCS-treated group exhibited the highest water-holding capacity (86.1%), which was 15.5% higher than that of the nitrite-treated group (P<0.05). The cooking loss rate of the NSCS-treated group was significantly lower than that of the nitrite-treated group (P<0.05), and also significantly lower than that of the control group except on day 7 (P<0.05). During the storage period of 1~9 d, there was no significant difference in the total bacterial count between the NSCS group and the nitrite group, and both were significantly lower than that of the control group (P<0.05). On day 1, the nitrite residue in the nitrite-treated group reached the maximum of 28.3 mg/kg, which was significantly higher than those in the NSCS-treated group and the control group (P<0.05). On day 9, the nitrite residue in the nitrite-treated group dropped to the minimum of 11.2 mg/kg. Meanwhile, there was no significant difference in nitrite residue between the NSCS-treated group and the control group. In conclusion, NSCS can replace nitrite to a certain extent in the processing of yak meat sausages. This finding provides important reference significance for the development of green and organic yak meat products, and also offers theoretical references for research on nitrite substitutes in other minced meat products.

This study aimed to elucidate the molecular mechanisms by which basic amino acids (L-arginine/L-Arg, L-lysine/L-Lys, L-histidine/L-His) regulated oxidation resistance and gel network formation in yak meat myofibrillar protein (MP). Different concentrations (0.08%, 0.15%, 0.30%, 0.60%, w/v) of each amino acid were added to the MP system. Changes in structural properties (solubility, turbidity, surface hydrophobicity, secondary and tertiary structures) and oxidation indicators (carbonyl content, total and active sulfhydryl content) of MP, as well as gel properties (water-holding capacity, cooking loss, whiteness, strength, rheological behavior), were systematically analyzed. Results demonstrated that basic amino acids synergistically improved gel performance by neutralizing charges to reduce intermolecular repulsion, inducing conformational unfolding to expose hydrophobic groups and active sulfhydryls, and regulating secondary structures (L-Lys/L-Arg promoted α-helix to β-sheet conversion, while L-His maintained concurrent increases in both), but their effects exhibited concentration and type dependencies. In beneficial aspects, L-Lys and L-Arg significantly enhanced solubility (86.38% for 0.60% L-Arg,~25% higher than control) and reduced turbidity (suppressing aggregation). These structural optimizations combined with disulfide crosslinking from exposed active sulfhydryls formed uniform gel networks, specifically increasing water-holding capacity by~25% (L-Lys/L-Arg groups at 0.30%) and reducing cooking loss (58% reduction for 0.30% L-Lys), while significantly enhancing storage modulus G' at high temperatures (≥70 ℃, L-Lys≥0.30%, L-Arg 0.60%). L-His acted mildly, mainly increasing gel strength by 4.2% at 0.60% concentration via stabilizing α-helix/β-sheet coexistence. L-Lys and L-Arg reduced gel whiteness with increasing concentration. High concentrations (especially 0.60% L-Arg) intensified protein oxidation damage (peak carbonyl content: 5.54 nmol/mg) due to excessive unfolding and self-oxidation. In summary, L-Arg and L-Lys showed advantages in optimizing solubility, inhibiting aggregation, and promoting crosslinking through charge interactions and structural transformation, serving as effective strategies for improving gels of high-myoglobin, low-fat yak meat MP, yet requiring concentration control to balance oxidation risks. L-His provides a milder alternative. Practical applications can select amino acid types based on product requirements, offering a theoretical basis for developing low-sodium, low-phosphorus yak meat products.

The study examined the effects of oxygen, light, temperature, non-covalent bonds, and metal ions on the precipitation amount, as well as the protein, starch, pectin, and tannin content in the supernatant of Sichuan bran vinegar, to determine the key factors influencing turbidity reversion. Using transmittance as the response value, the clarification conditions were optimized via single-factor experiments combined with response surface methodology (RSM). The results indicated that oxygen and temperature were critical factors promoting turbidity reversion, with significantly shorter turbidity reversion time under aerobic conditions compared to anaerobic conditions, and higher temperature further accelerating the process. Investigations into non-covalent interactions revealed that the addition of NaCl and guanidine hydrochloride disrupted electrostatic forces and hydrogen bonds, significantly reducing precipitation while increasing the protein, starch, pectin, and tannin content in the supernatant. This suggested that electrostatic interactions and hydrogen bonds facilitated macromolecular complexation and subsequent precipitation. Metal ions (Fe³⁺, Ca²⁺) had no significant effect on turbidity reversion. The optimal clarification conditions determined by single-factor and RSM optimization were: acidic protease dosage of 2.10 g/L, treatment time of 2.20 h, treatment temperature of 30 °C, and standing time of 2 h, achieving a transmittance of 85.75%±0.24%. This study provides a data foundation for understanding the mechanism of turbidity reversion and offers practical solutions for industrial production of Sichuan bran vinegar.

In order to investigate the effects of postharvest ambient temperature on the physical characteristics and volatile components of jasmine flowers, J. sambac 'Shuangban-moli' flowers buds was employed as experimental materials in this study. The physical characteristics of jasmine flowers (bulk density, moisture content, floral temperature, jasmine pile temperature, CO₂ concentration, and O₂ concentration) were examined under different postharvest ambient temperatures (29±2, 35±2, and 41±2 ℃, humidity: 85%±3%). Automated thermal desorption-gas chromatography-mass spectrometry (ATD-GC-MS) was employed to analyze the volatile components of jasmine flowers under different postharvest ambient temperatures. The results showed that the physiological activities of jasmine flowers were suppressed, and the blooming process was delayed at the postharvest ambient temperature 29 ℃. In contrast, it was more conducive to their fragrance release, and jasmine flowers exhibited the highest degree of blooming, the peak flowering condition, and the faster blooming process at the postharvest ambient temperature 35 ℃. Sensory evaluation also indicated that jasmine flowers had a rich aroma and pure white color at the postharvest ambient temperature 35 ℃. A total of 102 volatile components were identified from jasmine flowers maintained at different postharvest ambient temperatures, including 28 esters, 19 terpenes, 15 alcohols, 11 alkanes, 7 aromatic hydrocarbons, 4 halogenated hydrocarbons, 4 aldehydes, 2 cyclic hydrocarbons (non-aromatic), 2 ethers, 2 ketones, 2 phenols, 2 acids, and 4 other substances. Jasmine flowers exhibited significantly higher relative abundance of some volatile components during the flower starts blooming stage, flower fully blooming stage, and flower starts senescence stage at the postharvest ambient temperature 35 ℃ compared to other temperatures (P<0.05). As the key contributors to the "fresh floral scent" of jasmine flowers, such as α-farnesene and trans-caryophyllene etc terpenes with floral and fruity fragrances had significantly higher relative content during the flower starts blooming stage and flower fully blooming stage at the postharvest ambient temperature 35 ℃ than other temperatures (P<0.05). In summary, it was beneficial for jasmine flower blooming and fragrance release at the postharvest ambient temperature 35 ℃.

In order to improve the functional properties of pea protein isolate (PPI), such as solubility, emulsification, foaming capacity, and broaden its application in the food industry, in this study, PPI was selectively extracted using ammonium sulfate precipitation, and was covalently grafted with chitosan oligosaccharides (COS), carrageenan oligosaccharides (CAS), alginate oligosaccharides (AOS), and agaric oligosaccharides (AGS) at an oligosaccharide-to-protein ratio of 20% using cold plasma (CP) induction. The effects of this non-thermal covalent grafting with marine oligosaccharides on the solubility, thermal stability, foaming capacity, and emulsifying properties of PPI were investigated. The results showed that CP treatment induced effective and rapid covalent grafting between PPI and marine oligosaccharides. The highest grafting rate (17.89%) was observed in the PPI-COS combination. In terms of mixtures, the solubility of the covalent complexes was significantly improved (P<0.05) after CP induction relative to those without CP treatment, in the order of AGS/PPI-CP>COS/PPI-CP>CAS/PPI-CP>AOS/PPI-CP. Among them, AGS/PPI-CP showed the highest solubility (0.775 mg/mL), while COS/PPI-CP exhibited the greatest foaming capacity (146.67%), emulsifying activity (123.21%), and emulsion stability (37.73%). These enhancements significantly improved the interfacial adsorption of PPI, contributing to greater stability at both air-water and oil-water interfaces. In conclusion, non-thermal covalent grafting of marine oligosaccharides with CP was effective in enhancing the functional properties of PPI. These findings provide valuable guidance for the development of functional pea protein-based food products and related applications.

This study aimed to investigate the effects of konjac glucomannan (KGM) with varying molecular weights on the structure and gel properties of myofibrillar protein (MP) derived from frozen Antarctic krill. Using Antarctic krill MP as the research object, we compared the degradation of KGM with molecular weights of 1.5974×10⁶ Da (HMW KGM), 1.2769×10⁶ Da (MMW KGM), and 0.6912×10⁶ Da (LMW KGM) during the freezing storage process at −18 ℃. The effects on structure properties (chemical bond level, carbonyl content, surface hydrophobicity, particle size, myofibril breakage index) and gel properties (water-holding capacity, hardness, elasticity, thermodynamic) were analyzed at 0, 60, 120, and 180 days. Compared to the blank control group (MP without the addition of KGM enzymatic hydrolysis products), the MMW KGM group exhibited the highest holding capacity, hardness, and elasticity after being frozen for 180 days, with values of 67.66%±2.58%, 375.85±6.78 g, and 2.78±0.08 g, respectively. Meanwhile, the MMW KGM group demonstrated the highest levels of ionic bonds, hydrogen bonds, and disulfide bonds, measuring 27.87±1.03, 20.98±1.12, and 5.19±0.12 mg/g, respectively, while the contents of carbonyl groups and surface hydrophobicity were the lowest. This suggested that MMW KGM was effective in inhibiting the oxidation of MP. Additionally, after 180 days of freezing, the results of particle size, myofibrillary rupture index, and thermodynamic index indicated that the spatial structure of MP in the MMW KGM group was the most stable. These findings confirmed that the addition of MMW KGM provided the most effective freezing protection for the MP of Antarctic krill, which offered theoretical support for the use of enzymatically hydrolyzed KGM as an antifreeze agent during the freezing and storage of aquatic products.

This study aimed to investigate the hydrolysis characteristics of walnut protein hydrolysates and identify low-bitterness antioxidant peptides derived from them. Four proteases—papain, chymotrypsin, alkaline protease, and acid protease—were used to hydrolyze walnut proteins, and the degree of hydrolysis of the resulting hydrolysates was evaluated. The study focused on alkaline protease treatment at varying hydrolysis durations (2, 4, and 6 h), examining the degree of hydrolysis, yield, molecular weight distribution, bitterness response value, and amino acid composition of the hydrolysates. Low-bitterness antioxidant peptides were subsequently identified from the hydrolysates with reduced bitterness. Results showed that alkaline protease effectively hydrolyzed walnut proteins, achieving the highest degree of hydrolysis (55.60%±0.46%) and yield (48.86%±0.99%) after 6 h. As hydrolysis time increased, the proportion of high molecular weight components decreased, while that of low molecular weight components increased. The hydrolysate obtained after 4 h of hydrolysis exhibited the lowest bitterness response value, characterized by minimal proportions of hydrophobic and bitter amino acids in its composition, and displayed significant antioxidant activity. Two non-bitter peptide sequences, YWL and FFL, were identified from the 4 h hydrolysate. Molecular docking analysis indicated that these peptides could effectively bind to the Keap1 protein through hydrogen bonding and hydrophobic interactions, thereby exerting antioxidant effects. This study provides a theoretical foundation for the development of high-quality, low-bitterness walnut-derived antioxidant peptides, offering valuable insights for their potential applications in functional foods and nutraceuticals.

This study established a novel magnetically induced electric field-enzymatic hydrolysis (MIEF-EH) coupled technology for the sustainable taurine extraction from abalone viscera byproducts. The results of the study indicated that the optimal extraction conditions were as follows: an excitation voltage of 1400 V, an electric field frequency of 50 kHz, a flow rate of 25 L/h, and a reaction time of 1 h. Under the optimal conditions, MIEF-EH achieved a taurine yield of 12.36 mg/g, significantly (P<0.05) outperforming both individual methods (such as MIEFE, microwave, enzymatic hydrolysis and hydrothermal) as well as other coupled approaches (microwave-enzymatic hydrolysis and hydrothermal-enzymatic hydrolysis). SEM revealed pronounced particle-size reduction and the formation of a loose, porous microstructure, correlating with improved taurine extraction. Subsequent purification via ion-exchange resin yielded taurine with 92.29% recovery and 96.78% purity, while ethanol precipitation achieved 95.30% recovery and 94.43% purity. The chemical structure and molecular mass of the purified taurine were confirmed through multi-technique validation (FT-IR, MS, and ¹H NMR). All physicochemical properties complied with the specifications of the Chinese National Standard for Food Additive Taurine (GB 14759-2010). In summary, the MIEF-EH coupled technology developed in this study provides a feasible technological pathway for green conversion of abalone viscera waste into high-purity natural taurine.

In order to explore the effects of different drying processes on the physical properties, active ingredients and antioxidant capacity of pumpkin powder, the vacuum freeze drying (VFD), hot air drying (HAD), and heat pump drying (HPD) were used for drying pumpkin and characterized by SEM, XRD, and FTIR. The results showed that the pumpkin powder of VFD had the smallest particle size (the D₅₀ was 54.63±0.90 μm), great intact color, the best adsorption and solubility, but the flow and filling properties were poor. The pumpkin powder of VFD had the highest content of active ingredients such as total phenolics (3.56±0.02 mg/g), and the strongest antioxidant capacity, and in HAD and HPD, the total phenol, total flavonoid and the antioxidant capacity of pumpkin powder were higher at 50~60 ℃, while the content of vitamin C, β-carotene were higher at 40~45 ℃. The pumpkin powder of VFD had smooth surface and internal pores, lower relative crystallinity compared to HAD and HPD, but there was no difference in the types of functional group. The results can provide experimental basis for choosing suitable pumpkin process.

To enhance the sensory quality of gluten-free highland barley flour products, this study investigated the effects of incorporating a highland barley flour-zein composite gel (at levels of 0%, 10%, 20%, 30%, 40% and 50%, mass fractions) on the dough processing characteristics and noodle quality. The results showed that with the increase of the addition amount from 0% to 50%, the peak gelatinization temperature of dough freeze-dried powder increased from 76.57 ℃ to 83.58 ℃, the breakdown value decreased from 876.00 cP to 349.67 cP, and the setback value decreased from 1141.00 cP to 816.67 cP. After adding composite gel, the viscoelasticity of the dough was enhanced, and the microstructure also confirmed that zein formed a continuous network structure, and the composite gel network could provide structural support for highland barley dough. Compared with the 0% addition of composite gel, the highland barley noodles with 40% compound gel had good cooking quality and texture characteristics, and the cooking loss of highland barley noodles was reduced by 55.75%, the breakage rate was reduced by 76.67%, the hardness was increased by 58.09 N, and the sensory score was higher than that of the other noodles. In conclusion, the highland barley flour-zein gel network serves as a structural support mechanism in gluten-free highland barley doughs and significantly improves cooking quality in highland barley noodles.