Surface iridescence is often found in raw meat and meat products with intact muscle tissue, which is produced due to the interaction between light and the microstructure of meat. However, consumers often misunderstand that this phenomenon is linked to stale or contaminated meat. This article reviews the cause of the formation of iridescence in meat and the factors influencing it. This review discusses meat microstructural features affecting light scattering and microstructural changes during storage and processing as well as the two principal theories about iridescence formation (surface grating and multi-layer interference), and summarizes the methods used to evaluate and characterize meat iridescence and the techniques used to control and eliminate it. We hope that this review will provide a theoretical basis for future research in food science and meat production and consumption.

Tenderness is one of the most important meat quality attributes. It is closely related to the selling price, consumer satisfaction and willingness to repeat purchase. Recently, plant-based meat and cultured meat are gaining great popularity, which pursue mimicking the sensory properties of meat including the unique texture. This paper reviews the major factors influencing meat tenderness and recent progress in research on meat tenderness. Firstly, the definition and evaluation methods of meat tenderness and are briefly introduced. Secondly, the major factors influencing meat tenderness and the underlying mechanism are thoroughly discussed from the perspectives of sarcomere length, connective tissue and proteolysis. Finally, the methods used to regulate meat tenderness and the latest research progress are briefly described. We expect that this review will provide theoretical support for the traditional meat industry, as well as the research and development of meat analogues and 3D-printed meat, etc.

Not only can addition of plant proteins into meat products relieve the pressure of environmental protection caused by increasing consumption of animal products, but also meet consumer demands for animal welfare and healthy diets. Moreover, incorporation of plant proteins can modulate the quality of minced meat products and bring diversity to the market. In this paper, the application of plant proteins in minced meat products is reviewed. Common plant proteins and their functions are introduced, and special emphasis is placed on discussing the effects of plant protein addition on gelling properties, water-holding capacity, color, flavor, and nutritional properties of minced meat products. This review is expected to provide support for the application of plant proteins in minced meat products and quality improvement.

In order to investigate the effect of oxidation on the emulsifying properties of porcine skin gelatin, porcine skin gelatin was incubated with different concentrations of hydrogen peroxide (0, 10, 20 and 30 mmol/L) for simulated oxidation, and an emulsion was prepared by using the oxidized gelatin. The results showed that with increasing hydrogen peroxide concentration up to 30 mmol/L, the emulsifying activity index (EAI) increased from an initial level of 21.1 m²/g (unoxidized) to 34.3 m²/g. The emulsion stability index (ESI) decreased with the increase in hydrogen peroxide concentration. In addition, increasing oxidation degree led to an increase in the water contact angle of gelatin, which promoted the adsorption of gelatin at the oil-water interface and reduced the interfacial tension at the oil-water interface. Compared with the unoxidized group, the zeta potential value decreased from 9.61 to 5.94 mV after oxidation with 30 mmol/L hydrogen peroxide, indicating that the electrostatic repulsion between emulsion droplets decreased. Confocal laser scanning microscope (CLSM) showed that the emulsion droplets stabilized by oxidized gelatin was smaller in size. In summary, the oxidation treatment increased the hydrophobicity of gelatin, promoted its adsorption at the oil-water interface, and reduced the interfacial tension at the oil-water interface, which was conducive to the formation of smaller droplet size and enhanced the emulsifying activity of gelatin. However, the decrease in electrostatic repulsion between emulsion droplets increased the flocculation and aggregation of oil droplets and weakened the emulsion stability.

In order to study the effects of rigor mortis and salt content on the gel properties of surimi, surimi gels with sodium chloride contents of 1%, 2%, and 3% (m/m) were made from pre- and post-rigor silver carp (Hypophthalmichthys molitrix) muscle, and their texture characteristics, rheological properties, water distribution, microstructure, and intermolecular forces were measured and analyzed. The results showed that compared with the surimi gel made of post-rigor muscle and low salt content, the gel strength, resilience, cohesiveness, storage modulus (G’), loss modulus (G”), immobile water fraction, and water-holding capacity of the surimi gel made of pre-rigor muscle and high salt content increased, and the hardness and whiteness decreased. Scanning electron microscopy (SEM) images showed that compared with the surimi gel made of post-rigor muscle and low salt content, the surimi gel made of pre-rigor muscle and high salt content had a denser structure with smaller pores. In summary, the surimi gel made of pre-rigor muscle and high salt content has better quality characteristics in terms of texture characteristics and water-holding capacity than the post-rigor group and low salt content group.

To investigate the effect of different concentrations of sodium chloride (NaCl) on the gel properties of gelatin, the triple helix content, texture properties, water-holding capacity, water distribution, microstructure and stress relaxation characteristics of gels of 10% (m/m) pig skin gelatin solution containing different concentrations (0.0, 0.5 and 1.0 mol/L) of sodium chloride were analyzed. The results showed that with the increase in sodium chloride concentration, gumminess and chewiness was significantly reduced; the hardness of gelatin gel with 1.0 mol/L NaCl was 2.24 kg, lower than that (3.15 kg) of the control group. The increase in NaCl concentration limited the formation of triple helices in the gelatin solution; gelatine gels showed a looser network structure with increasing NaCl concentration, with reduced network density, increased pore size and a significant decrease in water-holding capacity. The stress relaxation behavior of gelatin gels with different salt concentrations was quite different. When the three-element Maxwell model was used to fit the stress relaxation test results, the equilibrium elastic modulus of gelatin gel with 1.0 mol/L NaCl was 53% lower than that of the control group. However, when the CONTIN model was used to fit the stress relaxation test results, the reproducibility of relaxation peak distribution of the gel was poor. In conclusion, the increase in NaCl reduced the formation of triple helix in gelatin gel, resulting in a loose network structure and ultimately weakening the mechanical properties and water retention capacity of gelatin gel. The decrease in mechanical properties of gelatin was consistent with the results of the stress relaxation test.