This study investigated the effects of a low-sodium salt mixture (0.4 mmol/L, concentration ratio of NaCl to KCl = 2:1) added with L-lysine (L-Lys) or L-arginine (L-Arg) at concentrations of 1, 3, and 5 mmol/L on the structure and gel properties of myofibrillar protein (MP) using the salt mixture added with 1 mmol/L pyrophosphate (PP) as the control. The results indicated that compared with conventional salt treatment (0.4 mol/L NaCl + 1 mmol/L PP), the low-sodium salt + PP treatment slightly but not significantly improved the water-holding capacity, texture, and rheology of MP gels. Compared with its combination with PP, the low-sodium salt mixture combined with basic amino acids (L-Lys and L-Arg) promoted the transformation of α-helix into other secondary structures and induced alterations in the surface properties of MP. Furthermore, the addition of L-Arg significantly reduced the average particle size and increased the solubility of MP. The addition of 5 mmol/L L-Arg decreased the average particle size by 22.1% and elevated the solubility by 330.9% (P < 0.05). The incorporation of basic amino acids enhanced the storage modulus (G′), reduced the cooking loss, and improved the water-holding capacity of MP gels. Low-field nuclear magnetic resonance (LF-NMR) analysis revealed that the addition of basic amino acids resulted in an overall shortening of the relaxation time of immobilized water in MP gels, which signifies a reduction in the mobility of water molecules within the gel matrix. Scanning electron microscopy (SEM) showed that the addition of basic amino acids promoted the formation of a more fine, uniform and compact microstructure during the heatinduced gelation of MP. In conclusion, basic amino acids (especially L-Arg) can significantly improve the solubility and gel properties of MP under the condition of “low sodium and no phosphorus”, which provides a theoretical basis and reference for the development of healthy meat products.

With the implementation of the Outline of “Healthy China 2030” Plan and the continuous enhancement of consumers’ concept of healthy diet, “low salt and phosphorus free” healthy meat products have gradually become a trend of development in the meat products industry. However, simply reducing the addition of NaCl and polyphosphates will seriously affect the cooking yield and quality of the final products. Therefore, it is of great significance to seek green and healthy alternatives to NaCl and polyphosphates. In recent years, the basic amino acids arginine, lysine and histidine have attracted extensive research attention for their application as substitutes for NaCl and polyphosphates in the meat products industry. This paper reviews the latest progress in the study on the regulatory effects of basic amino acids on the structure, solubility, and emulsification and gelation properties of myofibrillar proteins, as well as the underlying mechanisms. Meanwhile, the effects of basic amino acids on meat quality (color, water retention, texture characteristics, and oxidation stability) are also summarized. Hopefully, this review will provide a theoretical basis for the follow-up research and practical application of basic amino acids in the meat industry.

Epigallocatechin-3-gallate (EGCG), one of the important catechins in tea, is reported to have a variety of bioactivities. However, EGCG is not fully utilized due to its poor liposolubility and stability, as well as low bioavailability. Acetylation modification of EGCG is an effective method to improve these limitations. Total acetylated epigallocatechin gallate (AcEGCG) is the fully acetylated product of EGCG. Compared to EGCG, AcEGCG has higher liposolubility, stability and bioavailability. Moreover, its physiological functions, such as anti-ultraviolet, cell damage repair and anti-cancer functions, are better than those of EGCG, suggesting a wide range of application prospects in the fields of food, medicine and chemical industry. This review will summarize recent advances in the synthesis, purification, physicochemical properties and bioactivities of AcEGCG, in order to provide a reference for further research, development and utilization of AcEGCG.

This study was conducted in order to investigate the mechanism of the effect of adding different concentrations of L-lysine (L-Lys) on the gelling properties of porcine myofibrillar protein (MP) damaged by repeated freeze-thaw cycles. The changes in the conformation, solubility and gelling properties were analyzed by means of circular dichroism (CD) spectroscopy, intrinsic tryptophan fluorescence spectroscopy, a rheometer, a texture analyzer and a scanning electron microscope. The results showed that the addition of L-Lys caused an increase in the α-helix content and intrinsic tryptophan fluorescence intensity of freezing-damaged MP. The solubility of freezing-damaged MP gradually increased with increasing L-Lys concentrations, the storage modulus (G’), gel strength, cooking loss and gel whiteness gradually decreased, and the gel microstructure became gradually more uniform. On the whole, the addition of L-Lys significantly reduced the gel strength and cooking loss of repeatedly frozen-thawed MP gel by changing the conformation, and could thus improve the water-holding capacity and tenderness of freezing-damaged meat.

The effects of punicalagin (P) and sodium pyrophosphate (SPP) and their combination (P + SPP) on the oxidative stability and gel properties of myofibrillar protein (MP) under oxidative stress were studied. The results showed that the addition of P and SPP effectively inhibited the increase of carbonyl content and the decrease of free amino content induced by oxidation, and the combination of P and SPP had the best effect; however, neither single nor combined additives effectively inhibited the decrease of sulfhydryl content induced by oxidation. The addition of P promoted protein unfolding induced by oxidative stress and significantly inhibited the increase of protein particle size (percentage inhibition of 10.50%) induced by oxidation. It had no significant effect on protein solubility or rheological properties during heat-induced gelation, but significantly improved the cooking loss and texture deterioration of heat-induced MP gels under oxidative stress. The addition of SPP also promoted protein unfolding induced by oxidation, inhibited the increase of protein particle size (percentage inhibition of 17.65%), increased the solubility of oxidized MP by 9.78%, significantly changed the rheological behavior of MP during heat-induced gelation, and resulted in a 42.56% reduction in the cooking loss of heat-induced gels, while texture indexes such as gel strength were significantly reduced. The combination of P and SPP had a similar effect on the heat-induced gel properties of MP as the addition of SPP alone. Moreover, the antioxidants used in this study significantly increased the oxidative stability of MP and the water-holding capacity of its heat-induced gel, but the effects on the gel texture characteristics were closely related to the type of antioxidants.

The effects of partially replacing NaCl with KCl combined with composite saltiness enhancers on the quality properties of Harbin red sausage were investigated. Three formulas were evaluated: the control (SF1: 100% (m/m) NaCl), low-sodium (SF2: 70% NaCl + 30% KCl, m/m), and composite low-sodium (SF3: 70% NaCl + 20% KCl + 10% flavoring substitutes (3.5% maltodextrin + 4% L-lysine + 1% L-alanine + 0.5% citric acid + 1% calcium lactate), m/m) groups. After 35 days of storage, no significant differences (P > 0.05) in moisture content, water activity, pH value, color, total bacterial count, or most texture attributes were noted among the formulations. However, compared to SF1, SF3 significantly reduced hardness and thiobarbituric acid reactive substance values (P < 0.05). Sensory and E-tongue analyses confirmed that SF3 exhibited significantly lower bitterness scores than SF2. Therefore, the SF3 formula potentially reduces NaCl content by 30% in Harbin red sausages while maintaining favorable sensory acceptability.

This study investigated the effects of L-arginine (Arg) and transglutaminase (TG) on the quality of sausage made from repeatedly frozen-thawed pork. The results indicated that Arg and TG, alone and in combination, improved the oxidative stability of the sausage and significantly increased the storage modulus (G’) of minced pork throughout the heating process. Arg treatment alone significantly increased the bound water content and decreased the free water content(P < 0.05), significantly reduced the cooking loss (P < 0.05) and lowered the chewiness of the sausage by 280.9 g. TG treatment alone slightly increased the bound water content and significantly decreased the free water content (P < 0.05), but did not reduce the cooking loss. The combined treatment with Arg and TG enhanced the chewiness and significantly reduced the cooking loss (P < 0.05), indicating a synergistic effect. The addition of Arg and TG also resulted in a denser microstructure and significantly improved the overall acceptability of the sausage (P < 0.05).

The effect of different content of lysine (Lys, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, m/m) on the texture characteristics and water holding capacity (WHC) of transglutaminase (0.4%)-induced mixed surimi gels was explored. The results showed that 0.2% Lys obviously improved the gel strength, textural properties, and WHC of the mixed surimi gels (P < 0.05). However, superfluous Lys (0.4%–0.5%) played a significant negative impact. That’s because 0.2% Lys facilitated the non-covalent interactions and non-disulfide covalent interactions between surimi proteins, promoted the formation of a fine and dense gel microstructure. While high content of Lys induced the formation of excess ε-(γ-Glu)-Lys isopeptide bonds but weakened the non-covalent interactions between surimi proteins, resulting in an irregular and heterogeneous microstructure with large voids. In conclusion, moderate Lys can effectively improve the quality of mixed surimi gels, thereby providing a new and effective strategy to develop phosphorus-free surimi products.