Alcohol-induced liver damage (ALD) remains a global health burden with limited therapeutic options. To address this challenge, this study developed a water-in-oil (W/O) emulsion encapsulating the oligopeptide KRQKYD, using Jinhua ham fat (JHF) as the oil phase, aiming to enhance the oligopeptide’s digestive stability and ameliorate ALD by regulating intestinal homeostasis. The results confirmed that the W/O emulsion (containing 60% oligopeptide solution) had high encapsulation efficiency (96.37% ± 9.43%), which significantly enhanced the gastrointestinal digestion stability of KRQKYD—with 86.48% ± 2.20% of KRQKYD retained after 120 minutes of simulated intestinal digestion, a rate markedly higher than the 60.84% ± 1.84% retention of free KRQKYD. Moreover, in C57BL/6 mouse models of ALD, oral administration of the emulsion (400 mg/kg B.W., containing 60% oligopeptide solution at 55.6% w/w) significantly reduced serum levels of alanine transaminase (ALT), aspartate transaminase (AST), and malondialdehyde (MDA) compared to ethanol-treated mice (P < 0.05), with efficacy superior to that of KRQKYD or JHF alone. Mechanistically, the emulsion exerted multifaceted protective effects through synergistic actions of its components: KRQKYD promoted the proliferation of Akkermansia muciniphila by alleviating intestinal oxidative stress, while JHF enriched Lactobacillus by replenishing long-chain fatty acids, collectively restoring microbial balance (e.g., reducing Proteobacteria and increasing Verrucomicrobia). Concurrently, KRQKYD upregulated the NRF2/HO-1 pathway, and JHF activated the AhR/NQO1 pathway, which together reduced hepatic ROS accumulation and enhanced the activities of SOD and GSH-Px. Additionally, the emulsion strengthened intestinal barrier function by increasing Occludin and Claudin-1 expression, thereby reducing LPS leakage; this, in turn, inhibited the LPS-TLR4-NF-κB cascade and lowered hepatic levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6). Furthermore, in terms of lipid metabolism, the emulsion downregulated SREBP1c-mediated lipid synthesis and activated AMPK-dependent lipid oxidation, ultimately decreasing hepatic triglyceride accumulation. This study demonstrates that the W/O emulsion enhances KRQKYD stability and exerts synergistic effects with JHF, providing a novel strategy for the oral delivery of bioactive oligopeptides to ameliorate ALD by targeting gut-liver crosstalk.

One of the problems facing the field of meat industry is that reducing the fat content may cause the texture of meat products to deteriorate. In this study, the effects of the addition of different amounts (0%, 1%, 2%, 4%, and 8%) of Lactarius delicious to fat-reduced emulsified sausages on its cooking loss, water distribution, microstructure, texture properties, physicochemical properties, and sensory characteristics were evaluated. The cooking loss of fat-reduced emulsified sausages significantly decreased upon the addition of Lactarius delicious (P < 0.05); the addition of 2% of Lactarius delicious decreased this parameter by 60%. The results of low-field nuclear magnetic resonance (LF-NMR) showed that the addition of 2% of Lactarius delicious significantly increased the peak area ratio of immobile water and reduced the peak area ratio of free water (P < 0.05), indicating that Lactarius delicious can improve the water-holding capacity of the sausage. Adding Lactarius delicious increased the number and distribution uniformity of water holes in fat-reduced emulsified sausage, and thus improved its microstructure, with the most pronounced effect being observed at an addition level of 2%. The addition of Lactarius delicious had no significant effect on the pH value, but made the color of the final product darker. The textural properties and sensory scores of emulsified sausages decreased significantly after reducing fat, while the addition of 2% of Lactarius delicious significantly improved the textural properties and increased the sensory evaluation scores of fat-reduced emulsified sausages to levels similar to those of regular emulsified sausages (P < 0.05). In conclusion, adding Lactarius delicious is an effective method to improve the texture of fat-reduced sausages, and the optimal addition level is 2%.

In order to explore the effects of different thermal sterilization conditions on the quality of sauced duck neck, the quality characteristics of sauced duck neck subjected to one of three heat treatment conditions (90 ℃/15 min, 90 ℃/30 min or 121 ℃/15 min) or not subjected to heat sterilization were evaluated using an amino acid analyzer, high performance liquid chromatography, an electronic nose and an electronic tongue, etc. The results showed the contents of protein, fat, thiamine and salt in sauced duck neck decreased with the increase in sterilization temperature or time, while these parameters decreased significantly upon high-temperature sterilization (121 ℃/15 min) (P < 0.05). Sensory evaluation showed that high-temperature sterilization reduced the meaty aroma, produced off-odor, and lowered the umami and saltiness scores significantly (P < 0.05). The electronic nose effectively distinguished all treatment groups except the unsterilized group and the 90 ℃/15 min group. Collectively, the electronic tongue data and flavor nucleotide and amino acid analysis showed that thermal sterilization conditions had a significant effect on the umami and saltiness of sauced duck neck (P < 0.05), and the main taste substances causing the change of the umami taste were glutamate, 5’-guanosine acid and 5’-inosine acid. Finally, we conclude that low-temperature and long-time sterilization has a positive effect on the quality of sauced duck neck, while high-temperature sterilization has an unfavorable effect on it.

Myoglobin is a pigment protein that mainly exists in the sarcoplasm of muscle cells and its functional properties contribute to and improve the color of meat and meat products during processing, preservation and consumption. There are many factors that can influence the structural change of myoglobin during the processing and storage of meat and meat products, which in turn can lead to changes in its functional properties. In this article, the recent studies on the structural changes and the consequent changes in functional properties of myoglobin during the processing and storage of meat products are reviewed so as to provide guidance for the quality control of meat and meat products.

Color is one of the most important sensory quality indexes of fermented meat products. Addition of nitrite makes traditional fermented meat products have a good color. However, nitrite can be transformed to N-nitrosamine in the human body, which is a potential carcinogen and can cause health problems. Therefore, it cannot meet the green and safety requirements in food manufacturing. In recent years, the chromogenic effect of microorganisms has been discovered and excavated, indicating the potential to replace nitrite in fermented meat products. In this review, the color conversion mechanism of fermented meat products is introduced in detail, and recent progress in research on the chromogenic mechanism of microorganisms is summarized. The important functions of five key enzymes in microbial color development and two dominant strains used to make fermented meat products are outlined. This review may provide novel ideas for the green and healthy development of fermented meat products.

In order to explore dynamic changes in the physicochemical characteristics and microbial diversity of modified atmosphere packaged braised chicken during refrigeration, high-throughput sequencing technology and traditional isolation and identification methods were combined to study the physical and microbial changes of modified atmosphere packaged (25% CO₂/75% N₂) braised chicken during storage at 4 ℃ for 10 days. The results showed that total volatile basic nitrogen (TVB-N) content and total bacterial count increased significantly during storage (P < 0.05). pH decreased significantly in the late storage period (P < 0.05). Thiobarbituric acid reactive substance (TBARS) levels tended to be stable at the end of storage (P > 0.05). These changes were related to the gas composition in modified atmosphere packaging. The microbial species richness of braised chicken was the highest at the early stage of storage, and then decreased gradually. At the initial stage of storage, the relative abundance of Enterobacteriaceae, Acinetobacter and Aeromonas were high. At the middle and late stages of storage, the relative abundance of Weissella and Enterobacter were high. The relative abundance of Weissella, Enterobacter, Lactococcus and Leuconostoc increased gradually during the whole storage period and their growth was dominant. Six species of spoilage organisms were isolated and identified, namely, Lactobacillus curvatus, Bacillus cereus, Bacillus safensis, Serratia liquefaciens, Hafnia sp. and Enterobacter sp., which could be the major causes of the rot of braised chicken under modified atmosphere packaging conditions.

Fermented meat products are a typical representative of traditional meat products, which are highly appreciated by consumers for their unique flavor, texture, and nutritional value. Traditional fermented meat products are often produced by natural fermentation, and different fermentation environments lead to variability in the flavor of fermented meat products. Microorganisms, especially common ones such as lactic acid bacteria, staphylococci, yeasts and molds, play a crucial role in the flavor formation of fermented meat products. Microorganisms in fermented meat products can promote the formation of flavor compounds through protein hydrolysis, amino acid and lipid metabolism, fatty acid metabolism, and carbohydrate metabolism. Herein, we review the types and formation mechanism of volatile flavor compounds in fermented meat products, focusing on the metabolic pathways of the major microorganisms (lactic acid bacteria, staphylococci, yeasts and molds) affecting the flavor formation of fermented meat products. Through this review, we hope to provide a theoretical basis for regulating the flavor properties of fermented meat products.

Fresh lamb rolls were selected for frozen storage for up to 6 months, with regular sampling at 1-month intervals. The trend in the color of lamb rolls during the storage period was systematically analyzed, and their changing patterns were comprehensively evaluated by measuring the degree of fat oxidation and the oxidative degradation of proteins. The results showed that as the storage time increased, the color of lamb rolls changed significantly, mainly manifested by a decrease in the brightness and redness values, and an increase in the yellowness value. This change began to appear in the second month of storage and leveled off in the fifth month. During frozen storage, the relative content of oxymyoglobin declined markedly (P < 0.05), whereas the relative content of metmyoglobin showed an opposite trend (P < 0.05), which was closely related to the color change of lamb rolls from bright red to dark brown. After 6 months, the total sulfhydryl content decreased by 65.9%, the relative content of metmyoglobin increased to 27.1%, and the carbonyl content and thiobarbituric acid reactive substances (TBARS) value increased by 2.15 times and 30.6%, respectively. In addition, fluorescence and ultraviolet spectroscopy showed that myoglobin heme iron porphyrin structure was damaged, and hemoprotein was oxidized and degraded. The secondary structure of myoglobin changed with frozen storage time, the relative content of α-helix decreased, while the relative contents of β-sheet and β-turn increased. This further confirmed that myoglobin was oxidized and degraded, which in turn affected the color stability of lamb rolls during storage.

The purpose of this study was to clarify the effect of the combination of antifreeze and immersion freezing on the quality of frozen prepared beef steaks. Four groups were set up: ⅰ) control group, vacuum packaging before frozen storage; ⅱ) antifreeze group, incorporation of antifreeze during tumbling vacuum; ⅲ) immersion freezing group; and ⅳ) antifreeze + immersion freezing group. Beef steaks were frozen at -30 ℃ for up to 90 days. The thawing loss, juice loss, cooking loss, texture characteristics, shear force, color and thiobarbituric acid reactive substances (TBARS) value were measured after 0, 30, 60 and 90 days, and the microstructure was observed. The results showed that compared with the other treatment groups, the thawing loss, juice loss, cooking loss and TBARS value were significantly decreased in the antifreeze + immersion freezing group. In addition, for the combined treatment group, the brightness and redness values were higher, and muscle fiber arrangement was orderly and tightest among the four groups. Conclusion: The combination of immersion freezing and antifreeze can not only make the tissue structure of prepared beef steaks more compact to maintain better water retention capacity, but also keep its color stability.

The study evaluated the stability of an oligopeptide (Lys-Arg-Gln-Lys-Tyr-Asp, KRQKYD) and its transport mechanism by simulating gastrointestinal digestion and a model of human intestinal Caco-2 monolayer cells in vitro. In this study, the effects of environmental factors (temperature, pH and NaCl concentration) and simulated gastrointestinal digestion on the stability of KRQKYD were evaluated by indicators of the levels of alanine transaminase (ALT), aspartate transaminase (AST) and malondialdehyde (MDA) in an alcoholinduced hepatocyte injury model. The results showed that KRQKYD still maintained satisfactory hepatocyte-protective activity after treatment with different temperatures (20−80 ℃), pH (3.0−9.0), NaCl concentration(1%−7%) and simulated gastrointestinal digestion, which indicated that KRQKYD showed good stability to environmental factors and simulated gastrointestinal digestion. Furthermore, the intact KRQKYD could be absorbed in a model of Caco-2 monolayer cells with a P_app value of (9.70 ± 0.53) × 10⁻⁷ cm/s. Pretreatment with an energy inhibitor (sodium azide), a competitive peptide transporter inhibitor (Gly-Pro) and a transcytosis inhibitor wortmannin did not decrease the level of transepithelial KRQKYD transport, indicating that the transport mechanism of KRQKYD was not associated with energy dependent, vector mediated and endocytosis. The tight junction disruptor cytochalasin D signif icantly increased the level of transepithelial KRQKYD transport (P＜0.05), suggesting that intact KRQKYD was absorbed by paracellular transport.