No abstract

Twenty-four Eastern Zhejiang White Geese were slaughtered, dry-cured by 2 different kinds of salt contents (12 geese with 4% low salt level [LS]; 12 geese with 8% high salt level [HS]) for one d, marinated in brine for one d, and air dry-ripened at 16 °C for 7 d. The effect of dry-curing salt contents on the changes in myofibril proteins, potential proteolysis activities, and total free amino acid (TFAA) in dry-cured goose was investigated. Compared to the raw, cathepsin B+L and calpains activities decreased at the end of dry-curing and the third d of dry-ripening. At the final products, the activities of cathepsin B+L and calpains were about half of those in raw meat. There was no difference in proteolysis activities except for the end of dry-curing (P < 0.05) and the 3 d of dry-ripening (P < 0.05) for cathepsin B+L, and the end of dry-curing (P < 0.05) for calpains (P < 0.05) between groups. Myosin light chain (MLC) and troponin-I were cleaved. Compared to the raw, TFAA increased by 36.64 and 31.82% in the final products for HS (P < 0.001) and LS (P < 0.01), respectively. The increase of TFAA could be attributed to the proteolysis of myofibril proteins and retained proteolysis activities. No significant difference on TFAA and MLC and troponin-I bands was observed between groups in final products. This means that different proteolysis activities during processing did not cause the difference in quality of final products between groups, and that 4% low salt can be used in future applications.

No abstract

An 8‐week feeding trial was conducted to estimate the optimum dietary manganese (Mn) requirement for juvenile hybrid grouper, Epinephelus lanceolatus × E. fuscoguttatus. The basal diet was formulated to contain 520 g/kg crude protein from casein and fishmeal. Manganese methionine was added to the basal diet at 0 (control group), 2.5, 5, 10, 20 and 40 mg Mn/kg diet providing 7.48, 10.34, 13.76, 19.72, 31.00 and 53.91 mg Mn/kg diet, respectively. Each diet was randomly fed to triplicate groups of juveniles, and each tank was stocked with 20 fish (initial weight, 60.06 ± 0.68 g). The manganese content in rearing water was monitored and kept below 0.01 mg/L. Results showed that the weight gain ratio (WGR), protein efficiency ratio (PER), specific growth rate (SGR), Mn contents in whole body, liver and vertebra, and activities of hepatic Mn superoxide dismutase (Mn‐SOD), total SOD (T‐SOD) and glutathione peroxidase (GSH‐PX) were significantly improved by dietary Mn supplementation (p < .05). However, dietary Mn did not affect arginase (DArg) activity. The highest feed conversion ratio (FCR) was observed in fish fed the basal diet (p < .05). No significant differences were found on the Cu and Zn contents in whole body by supplementing dietary Mn. Supplemented Mn in diets had significantly effect on liver and vertebral trace element deposition (p < .05). Fish fed the basal diet had the highest Fe and Zn contents in vertebra (p < .05). There were no significant differences on hepatic pyruvate decarboxylase (PDC) activity with supplemented Mn levels below 13.76 mg/kg. As biomarker of oxidative stress, malondialdehyde (MDA) content in liver was significantly higher in fish fed the basal diet (p < .05). Using the broken‐line models based on SGR, dietary Mn requirement of the juvenile hybrid grouper was estimated to be 12.70 mg/kg diet.

To study the activation of caspase-9 and its potential influence in conditioning, longissimus thoracis (LT), semitendinosus (STN) and psoas minor (PMi) muscles were used to analyze the ratio of pro-apoptotic bax to anti-apoptotic bcl-2 in fresh tissues and observe the changes in ATP, cytosolic cytochrome c and caspase-9 activity levels during storage at 4°C. Caspase-9 activity at 5 h is higher than the activity at 0 and 24 h in the muscles ( P < 0.001). The ATP content decreased between 0 and 3 h, between 8 and 14 h in the PMi and LT muscles ( P < 0.0001), whereas between 0 and 5 h, between 8 and 14 h in the STN muscle ( P < 0.0001). There is 60.2%, 55.3% and 43.1% available ATP in the STN, LT and PMi muscles at 5 h, respectively. The cytosolic cytochrome c level increased during 5 and 24 h storage in the LT and PMi muscles ( P < 0.0001), during 5 and 96 h in the STN muscle ( P < 0.0001). The cytosolic cytochrome c at 24 h ( P < 0.001) and ratio of bax to bcl-2 ( P < 0.05) was higher in the PMi than in other muscles. We concluded that the increase in cytosolic cytochrome c and available intracellular ATP should be responsible for the increase in caspase-9 activity; the activation of caspase-9 could be limited by the subsequent depletion of ATP; the postmortem release level of cytochrome c could be determined by the ratio of bax to bcl-2 in fresh tissues.

An analytical method is presented to investigate the scale effect on the shrinkage rate and the healing history of a spherical cavity in a stressed grain. The results show that the scale effect on the shrinkage rate of a spherical cavity in a stressed grain gradually increases as the spherical cavity shrinks. Because of the influence of a small-scale parameter from the nonlocal elastic theory, a spherical cavity in stressed grain does not eliminate completely through only lattice diffusion. The result may give a reference to reveal the healing mechanism of the damage defects in grains under hydrostatic pressures.

a b s t r a c tThis paper reports the result of an investigation into the effect of electric and mechanical loads on the morphological evolution of a void in piezoelectric materials based on a model for the morphological evolution of a void, the thermodynamics potential and energy principle. Thus, the path and the bifurcation condition of the morphological evolution of the void in piezoelectric materials are described, which gives some insight into the reliability of piezoelectric films under electric and mechanical loads.

Silicone rubber (SR) is widely used in the food processing industry due to its excellent physical and chemical properties. However, due to the differences in SR product production formulas and processes, the quality of commercially available SR products varies greatly, with chemical and biological hazard potentials.Residual chemicals in SR, such as siloxane oligomers and 2,4-dichlorobenzoic acid, are non-intentionally added substances, which may migrate into food during processing so the safe use of SR must be guaranteed. Simultaneously, SR in contact with food is susceptible to pathogenic bacteria growing and biofilm formation, like Cronobacter sakazakii, Staphylococcus aureus, Salmonella enteritidis, and Listeria monocytogenes, posing a food safety risk. Under severe usage scenarios such as high-temperature, high-pressure, microwave, and freezing environments with long-term use, SR products are more prone to aging, and their degradation products may pose potential food safety hazards. Based on the goal of ensuring food quality and safety to the greatest extent possible, this review suggests that enterprises need to prepare high-quality food-contact SR products by optimizing the manufacturing formula and production process, and developing products with antibacterial and antiaging properties. The government departments should establish quality standards for food-contact SR products and conduct effective supervision. Besides, the reusable SR products should be cleaned by consumers immediately after use, and the deteriorated products should be replaced as soon as possible.