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Chinese traditional fermented vegetables are made from fresh vegetables through microbial metabolism and a series of chemical reactions. During the fermentation process, the microbial community structure is complex, and the dominant microorganisms at different stages play different roles, which has a great impact on the quality, flavor and safety of fermented vegetables. Based on this, this article reviews the effect of the microbial diversity on the quality, flavor, and safety of Chinese traditional fermented vegetables as well as the abiotic factors affecting the microbial diversity, aiming to provide a theoretical basis for improving the quality and safety of fermented vegetables.

During the freezing, storage, and thawing process, physicochemical changes occur in raw meat, which will inevitably lead to quality deterioration mainly including decreased water-holding capacity and the deterioration of color and texture. The quality deterioration can be effectively reduced by novel freezing and its assistive technologies. This article summarizes the quality deterioration mechanism of raw meat during freezing and frozen storage, and reviews the approaches for improving frozen meat quality, such as novel freezing techniques, cryoprotectants, novel packaging techniques and novel thawing techniques, which will provide a theoretical basis and technical guidance for improving the quality of frozen meat.

Transglutaminase (TGase), an efficient protein cross-linking agent, has been widely applied in the meat industry to enhance the quality of meat products by modifying the structure of myofibrillar protein (MP) and consequently improving the heat-induced gel properties of MP. Meanwhile, degree of cross-linking (DCL) is the most important indicator to evaluate the cross-linking effect catalyzed by TGase, which is of particular importance for analyzing the effect of covalent cross-linking catalyzed by TGase on the conformational characteristics, physicochemical properties, and gel properties of MP. Therefore, this article systematically reviews the influential factors of DCL in TGase-catalyzed covalent cross-linking of MP, and dissects the molecular mechanisms of the effect of exogenous additives and novel processing technologies on TGase-catalyzed cross-linking. The aim of this article is to establish the relationship among structural modification, molecular mechanism and quality improvement for TGase-modified MP, which will provide innovative theoretical and technical support for the development of new types of meat products.

Myofibrillar protein (MP) is an important protein in muscle, which can form a three-dimensional gel network structure upon heat treatment, ultimately influencing the quality of meat products. In the meat industry, hydrocolloids from different are incorporated to enhance the gel strength, water-holding capacity and functional properties of MP gel and finally optimize the quality of meat products. However, many factors affect the interaction between MP and hydrocolloids during the formation of heat-induced MP gelation, which in turn affects MP gel properties. In this article, the gelation mechanism of MP is systematically reviewed, the interaction mechanism between different hydrocolloids and MP is discussed, and the key factors influencing the regulatory effect of hydrocolloids on the formation of heat-induced MP gel and the effect of hydrocolloids on MP gel properties are summarized. We anticipate that this review will lay a theoretical foundation for establishing the key technical system based on hydrocolloids to regulate the quality of meat products and also provide technical guidance for future practical application.

Nitrite has been used widely in meat products because of its unique properties, especially its role in promoting the color development of meat products and its bacteriostatic effect. Searching for nitrite alternatives has become an urgent topic for the meat industry due to consumers’ concerns about the potential health risk associated with nitrite and consumers’ demand for natural products with a clean label. As a natural pigment substance, zinc protoporphyrin (ZnPP) has a significant advantage in promoting the color development of meat products. This paper introduces the properties, formation mechanism, quantitative analysis and distribution in meat products of ZnPP, with a focus on the factors influencing ZnPP formation. Finally, future prospects for the application of ZnPP are discussed in order to provide new ways for the development of the low-nitrate meat processing industry.

The level of cholesterol in the body is closely related to human health. Although cholesterol has many irreplaceable physiological functions, high cholesterol is one of the causes of many cardiovascular and cerebrovascular diseases. With more extensive and in-depth research on probiotics, many strains have been proved to have a good cholesterol-lowering effect, and their cholesterol-lowering effect has aroused more and more attention. Thus, the development and application of cholesterol-lowering probiotics have a bright future. In this paper, the mechanism of cholesterol synthesis and metabolism in the human body is briefly introduced in terms of its intake, synthesis, conversion and transport. The in vitro cholesterol-lowering mechanism of probiotics by absorbing and binding cholesterol as well as producing cholesterol-lowering metabolites, and the in vivo cholesterol-lowering mechanism of probiotics by inhibiting the intake and synthesis of cholesterol, promoting its transformation and regulating its transport are reviewed. Finally, the evaluation strategies for cholesterol-lowering probiotics are summarized including in vitro tests, animal experiments and clinical studies. This review is expected to provide a reference for the development of probiotic strains with a potent cholesterol-lowering effect.

Microbes can cause food spoilage and waste, and even cause diseases posing a threat to human health. Being different from the traditional sterilization technology, photodynamic inactivation is a non-thermal physical sterilization technology based on the biological activity of natural antibacterial substances under light. It is characterized by remarkable microbial killing efficacy, simple operation, low cost, environmental friendliness, and can well maintain food flavor, color and nutritional value. This paper mainly summarizes the principle of photodynamic inactivation, outlines the major microorganisms in foods and the mechanism of photodynamic inactivation of microorganisms, and reviews the current status of the application of photodynamic inactivation in foods. We believe that this review will provide theoretical support for the application of photodynamic inactivation in the food field.

A hydroxyl radical generating system consisting of 0.1 mmol/L FeCl3, 0.1 mmol/L ascorbic acid, and various H2O2 concentrations (0, 0.25, 0.5, 1.0, 2.5, 5, 10 and 25 mmol/L) was established and used to investigate the interaction mechanism of differently oxidized myofibrillar proteins (MPs) with 3-methyl butanal, pentanal, hexanal and heptanal. First, the binding capacity of oxidized MPs to the four aldehydes were determined by gas chromatography-mass spectrometry (GC-MS). Then, ultraviolet (UV) absorption spectroscopy, fluorescence spectroscopy (quenching mechanism and thermodynamic analysis) and circular dichroism (CD) spectroscopy were used to reveal the interaction mechanism between oxidized MPs and aldehydes. The results showed that heptanal had the strongest binding capacity with MPs, and the binding capacity of oxidized MPs with a H2O2 concentration of 1.0 mmol/L to all four aldehydes was the highest (P < 0.05). UV absorption spectra and fluorescence spectra demonstrated that oxidized MPs interacted with the four aldehydes via static and dynamic quenching. The maximum absorption peaks of both tyrosine and tryptophan residues were red-shifted with an increase in heptanal concentration, indicating that the tyrosine and tryptophan residues of MPs were exposed to a more hydrophilic environment. Thermodynamic analysis showed that the interaction between MPs and heptanal was mainly driven by hydrophobic interaction. The CD spectra showed that the α-helix content decreased from 19.24% to 16.88% (P < 0.05) and the β-sheet content increased from 24.59% to 26.47% (P < 0.05) with increasing heptanal concentration, and the structure of MPs changed from the ordered to the disordered state. This study provides a theoretical basis for flavor regulation of meat products.

Using pea protein isolate (PPI) and pullulan (PUL) as raw materials and allicin (AC) as an antibacterial substance, nanofiber materials were prepared by electrospinning technology. The influence of allicin concentration on the structural and morphological characteristics, diameter distribution and antibacterial effects of nanofibers were investigated. Fourier transform infrared spectroscopy (FTIR) indicated that allicin was wrapped in the composite nanofibers. Scanning electron microscopy (SEM) showed that spherical structures of different sizes appeared around the nanofibers due to the addition of allicin. The size of the spherical structures increased (P < 0.05) with an increase in allicin concentration, while the nanofiber diameter gradually decreased (P < 0.05). With increasing allicin concentration up to 15%, the elastic modulus and tensile strength of the composite nanofibers gradually increased (P < 0.05), and the elongation at break gradually decreased (P < 0.05). Additionally, the composite nanofibers with more than 10% allicin exhibited an obvious bacteriostatic effect, and it was strongest at allicin concentrations of 15% and 20%, with inhibition zone diameters of 16.5 and 12.8 mm against E. coli and S. aureus, respectively. This research will provide data support and a theoretical basis for the development and application of new green food packaging nanomaterials.