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.