几种淡水商品鱼背、腹肉一般成分的季节变化

本文研究了鲢、鳙、草鱼、团头鲂、鲫背、腹肉蛋白质、脂肪等的季节变化及其有关营养、风味特点，发现5种鱼背肉脂肪含量12个月平均值均低于1％；蛋白质含量平均值在17．3—18．5％之间．不存在季节变化；是一种典型的高蛋白、低脂肪食物。反之，腹肉脂肪含量在2．2—9．7％之间．具有较多的脂肪和较好的风味。针对这种特点．鲢、鳙、草鱼等大型鱼采取背部、腹部分别加工是可取的。此外还测定证实鲢肌肉中含有较多的EPA和DHA。

SEASONAL VARIATION IN PROXIMATE COMPOSITION OF DORSAL AND BELLY MUSCLES OF FRESHWATER FISHES

The proximate compositions of dorsal and belly muscles of silver carp, grass carp, bighead carp, blunt snout bream and crucian carp were analyzed. Also, their seasonal differences in nutritional peculiarity and flavor were observed. It was found that the fat content in dorsal muscle of these fish was less than 1% in annual average, somewhat equivalent to that in lean fish muscles. However, the fat content in dorsal muscle of these fish reared in the months from September to Deecember was more than that in the rest months of a year. The protein content of dorsal muscle in these fishes ranged from 17. 3% to 18. 5% which showed some variation in species. In contrast with dorsal muscle, the fat content in belly muscle of these fish was in a range of 2. 2% to 9. 7% in annual average,somewhat equivalent to that in medium fat fish or fat fish. It showed that there was a big variation in fat content in belly muscle of these fishes. The fat content in belly muscle was higher than that in dorsal muscle, whereas the protein and moisture contents in belly muscle decreased accordingly. Based on the variation of fat and protein contents in belly and dorsal muscles of these five species, the belly part has the peculiarity of high fat and good flavor and the dorsal part is considered to be a kind of typical health food with high protein and low fat and low value of calorie. From such differences in protein and fat contents in these two parts of fish body, it is suggested to process these muscles separately, in which the dorsal part is appropriate to be processed to surimi products due to its high content in protein and the belly part for fillets, steaks, etc, due to its good flavor. Especially for grass carp, silver carp or bighead carp it seems either reasonable or important to process dorsal and belly part separately because of their big body size and high annual productvity in several million metric tons in China. Besides, the data obtained by gas chromatography verified that a higher contents of EPA and DHA were presented in the belly muscle of silver carp.