Myofibrillar protein composite gels: effect of esterified potato starch, lard and peanut oil on the gel properties.

BACKGROUND: Heat-induced composite gels were prepared with 20 g kg-1 myofibrillar protein (MP) sol, 20 g kg-1 modified starch and 100 g kg-1 lipid pre-emulsified by MP in 0.6 mol L-1 NaCl, at pH 6.2. The effects of esterified potato starch (EPS) and emulsified lipid (lard or peanut oil) on the rheology, texture properties and nuclear magnetic resonance characterization of MP gel were evaluated. RESULTS: The addition of starch and lipid significantly improved the gel strength and water holding capacity (WHC) of the MP gel. Analysis of the relaxation time compared with the WHC tests showed that the variation range of the transverse T22 relaxation time of a gel was positively proportional to changes in WHC of the composite gel, and the lower the T22 relaxation time, the better the WHC of composite gel. Moreover, MP gel with starch and emulsified lard added at the same time has the lowest T2 relaxation time, and also the best WHC of the gel. Environmental scanning electron microscopy showed that emulsified oil droplets embedded the gaps in the protein network, and the gelatinized starch contributed to restrict the oil droplet size, resulting in thicker MP gel. CONCLUSION: Emulsified lipid and modified starch have an important influence on the rheology and microstructure of MP gels, indicating the subtle interaction between starch, lipid and protein. The results suggest the potential feasibility of modified starch and vegetable oil to improve the textural properties in comminuted meat products. © 2021 Society of Chemical Industry.

Antioxidant activity of Lactobacillus plantarum NJAU-01 in an animal model of aging.

BACKGROUND: Excessive reactive oxygen species (ROS) can cause serious damage to the human body and may cause various chronic diseases. Studies have found that lactic acid bacteria (LAB) have antioxidant and anti-aging effects, and are important resources for the development of microbial antioxidants. This paper was to explore the potential role of an antioxidant strain, Lactobacillus plantarum NJAU-01 screened from traditional dry-cured meat product Jinhua Ham in regulating D-galactose-induced subacute senescence of mice. A total of 48 specific pathogen free Kun Ming mice (SPF KM mice) were randomly allocated into 6 groups: control group with sterile saline injection, aging group with subcutaneously injection of D-galactose, treatments groups with injection of D-galactose and intragastric administration of 107, 108, and 109 CFU/mL L. plantarum NJAU-01, and positive control group with injection of D-galactose and intragastric administration of 1 mg/mL Vitamin C. RESULTS: The results showed that the treatment group of L. plantarum NJAU-01 at 109 CFU/mL showed higher total antioxidant capacity (T-AOC) and the antioxidant enzymatic activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) than those of the other groups in serum, heart and liver. In contrast, the content of the oxidative stress marker malondialdehyde (MDA) showed lower levels than the other groups (P < 0.05). The antioxidant capacity was improved with the supplement of the increasing concentration of L. plantarum NJAU-01. CONCLUSIONS: Thus, this study demonstrates that L. plantarum NJAU-01 can alleviate oxidative stress by increasing the activities of enzymes involved in oxidation resistance and decreasing level of lipid oxidation in mice.

Effect of konjac glucomannan/carrageenan-based edible emulsion coatings with camellia oil on quality and shelf-life of chicken meat.

The quality and safety of chicken meat are prone to deteriorate due to bacteria reproduction and oxidation reaction. In this study, the antimicrobial and antioxidant effects of KGM-KC coatings incorporated camellia oil were evaluated to extend the shelf-life of chicken meat. The result showed that the KGM/KC-CO coating significantly (P < 0.05) decreased weight loss, pH, thiobarbituric acid reactive substance (TBARS), total volatile nitrogen (TVN) and microbial counts when compared to uncoated samples. The obtained results revealed that KGM/KC-based coating incorporated with CO significantly extended the shelf-life of chicken meat by restraining the oxidation of lipid and protein, and retarding the microbial growth. The sensory evaluation showed that the addition of CO did not affect the odor of chicken meat, maintained the overall acceptability of coated samples. The shelf-life of chicken meat was extended up to 10 days using KGM/KC-based coating containing 3.5% CO at refrigeration (4 °C) compared to control samples. These results indicated CO could be used as an active agent to be dispersed in KGM/KC matrix by emulsification method, and the prepared emulsion coating had positive effects on extending the shelf-life of chicken meat.

Antimicrobial and Preservative Effects of the Combinations of Nisin, Tea Polyphenols, Rosemary Extract, and Chitosan on Pasteurized Chicken Sausage.

ABSTRACT: This study was conducted to evaluate the antimicrobial and preservative effects of the combinations of nisin (NS), tea polyphenols (TP), rosemary extract (RE), and chitosan (CS) on pasteurized chicken sausage. An orthogonal test revealed that the most effective preservative was a mixture of 0.05% NS plus 0.05% TP plus 0.03% RE plus 0.55% CS (weight by sausage weight). This mixture had antimicrobial and antioxidant effects in pasteurized chicken sausage and extended the shelf life to >30 days at 4°C. The inhibitory effects of NS, TP, RE, and CS were also evaluated against Pseudomonas aeruginosa, lactic acid bacteria (LAB), and Staphylococcus aureus, the dominant spoilage and pathogenic bacteria in pasteurized chicken sausage. NS had the greatest inhibitory effect on LAB and S. aureus, with inhibitory zone diameters of 19.7 and 17.8 mm, respectively. TP had the largest inhibitory effect on P. aeruginosa, with a clear zone diameter of 18.2 mm. These results indicate that the combination of NS, TP, RE, and CS could be used as a natural preservative to efficiently inhibit the growth of microorganisms in pasteurized chicken sausage and improve its safety and shelf life.

Effect of typical starch on the rheological properties and NMR characterization of myofibrillar protein gel.

BACKGROUND: Composite gels were individually prepared from 20 g kg-1 myofibrillar protein (MP) imbedded with typical native starch (potato, tapioca, rice or corn starch) in 0.6 mol L-1 NaCl at pH 6.2. The gel strength, water holding capacity, rheological properties and microstructure of the obtained myofibrillar protein-starch composite gels were evaluated. RESULTS: Tapioca starch improved (P < 0.05) gel strength and water holding capacity of MP composite gel at 80 °C. Rheological properties of MP-starch composites differed significantly with the addition of different types of native starch. Additionally, the promoting effect of starch on the storage modulus of the composite gels positively correlated with the gelatinization properties of different typical starch. Environmental scanning electron microscopy showed that the filling effect of starch on the composite gel was related to the pasting temperature and particle size of typical starch, with almost no particles forming at 80 °C. Moreover, the addition of starch changed the relaxation peak area and increased the relaxation time in nuclear magnetic resonance tests, which suggested that starch could improve the water holding capacity of MP-starch composite gels. CONCLUSION: Different typical native starch has varied impacts on the gel strength, water holding capacity, rheological properties and microstructure of MP gels, indicating the potential and feasibility of these typical native starches as an addition agent to modify the textural properties in comminuted meat products. © 2019 Society of Chemical Industry.