葡萄牙牡蛎的净化及其低温贮藏研究

为保证生食葡萄牙牡蛎(Crassostrea angulata)的安全,在贝水比1∶10、水交换率3次/h、水温28℃、盐度28的条件下,采用流水式紫外线杀菌方法净化48 h,检测净化前后13个卫生指标的变化;净化后的牡蛎在冷藏(4℃)和冷冻(-18℃)两种条件下贮藏7 d以上;检测贮藏过程中菌落总数、大肠菌群和主要营养成分的变化。结果显示,经过48 h净化,菌落总数和大肠菌群含量均大幅下降,重金属、化学污染物等指标变化不大;两种贮藏条件下,菌落总数和大肠菌群都呈先下降再上升的变化,但始终处于安全水平内;蛋白质、脂肪、糖原含量缓慢下降,乳酸含量快速上升。研究表明,葡萄牙牡蛎在紫外线杀菌净化48 h后,至少在冷藏6 d或冷冻11 d内可以保证食品安全。

Depuration and low-temperature storage of Portuguese oyster (Crassostrea angulata)

In order to guarantee the safety of Portuguese oyster ( Crassostrea angulata) eaten raw,13 healthy indexes were examined before and after depuration for 48 h in a non-cyclical flow-through depuration system using ultraviolet light at ratio of oysters to water 1 ∶10,water exchange rate 3 times/h,temperature 28 ℃,and salinity 28.Then the total bacteria,coliform group and main nutritional components of depurated oysters stored respectively at 4 ℃and -18 ℃ for more than 7 days were detected. The results showed that, after 48 h of depuration,the total bacteria and coliform group sharply declined while other indexes changed little; during 4℃ and -18 ℃ storage,total bacteria and coliform group declined at the beginning and then rose up,but were within safety levels; protein, fat and glycogen decreased slowly whereas lactic acid increased rapidly. In summary,for Portuguese oyster that has been depurated for 48 h in UV system, its safety could at least be guaranteed within 6 days of refrigerated or 11 days of frozen storage.