养殖大黄鱼加工和冰藏过程中鲜度和细菌类型的变化

通过对养殖海水以及捕获、加工、流通和冰藏等整个供应链过程养殖大黄鱼的温度履历、感官、化学、微生物的品质监测,评估养殖海水、碎冰和加工过程中大黄鱼细菌卫生状况,分析其在整个过程鲜度和细菌相变化。结果表明,养殖海水和碎冰的菌落总数分别为4.99±0.41 lg cfu/g和3.90±0.32 lg cfu/g,大肠菌群数分别为30~450 MNP/100 g和低于30 MNP/100 g;新捕获养殖大黄鱼的菌落总数为3.82±0.38 lg cfu/g,假单胞菌数为3.13±0.58 lg cfu/g,嗜冷菌数为2.82±0.60 lg cfu/g,大肠菌群数为低于30 MPN/100 g;冰藏第18天时TVBN含量为28.62±0.51 mg/100 g,菌落总数、假单胞菌数、嗜冷菌数和大肠菌群数分别为6.24±0.06lg cfu/g、6.01±0.25 lg cfu/g、5.68±0.21 lg cfu/g和30 MPN/100 g。养殖海水和新捕获鱼中细菌种类繁多,革兰氏阴性菌分别占其总菌株数的64.9%和56.8%;革兰氏阳性菌分别占其总菌株数的27.0%和42.0%;优势菌群为黏性威克斯菌、腐败希瓦氏菌和假单胞菌属。加工结束后,假单胞菌(34.9%)、玫瑰小球菌(32.6%)和缺陷短波单胞菌(14.0%)成为主要菌群。冰藏第4天时仅分离出4种不同类型的细菌,腐败希瓦氏菌比例上升明显,冰藏第10天和第18天时,所占比例分别为63.5%和69.1%,是冷却链养殖大黄鱼产品的优势腐败菌。

Changes on the freshness and the bacterial typology of cultured large yellow croaker (Larimichthys crocea) during processing steps and iced storage

Present paper deals with the changes on the freshness and microbiological typology of cultured large yellow croaker Larimichthys crocea during processing steps and iced storage.In order to understand the changes of the freshness and bacterial flora of the fish,Larimichthys crocea artificially cultured in the sea-water,during the chilling supply chain from catching,processing,distributing steps and iced storage,the temperature antecedents,sense,chemical and bacterial quality in the sea-water have been monitored.The bacterial sanitation of the sea-water for culturing,crushed ice and the fish in processing steps were also assessed.The results showed that the total viable counts(TVC) were 4.99±0.41 lg cfu/g and 3.90±0.32 lg cfu/g in cultured sea-water and crushed ice,and Coliform bacteria were from 30 to 450 MNP/100 g and below 30 MPN/100 g respectively.The TVC,Pseudomonas,Psychrophiles bacterial counts and Coliform bacteria in the fish to be just caught Larimichthys crocea were 3.82±0.38 lg cfu/g,3.13±0.58 lg cfu/g,2.82±0.60 lg cfu/g and less than 30 MPN /100 g,respectively.The cultured Larimichthys crocea ice-stored for 18 days was refused by sensory group when TVBN reached 28.62 ± 0.51 mg/100 g,while the TVC,Pseudomonas,Psychrophiles counts and Coliform bacteria were 6.24±0.06 lg cfu/g,6.01±0.25 lg cfu/g,5.68±0.21 lg cfu/g and 30 MPN/100 g,respectively.Bacterial flora was much complex in the sea-water used for culturing and the fish to be just caught,among them the gram negative bacteria respectively occupied 64.9% and 58.1%,while the gram positive bacterial respectively occupied 27.0% and 42.0%.The dominated bacteria in cultured sea-water and the fish to be just caught consisted of micro-organisms belonging to the Pseudomonas spp.,Weeksella virosa and Shewanella putrefaciens.After processing,Pseudomonas spp.(34.9%),Micrococcus roseus(32.6%) and Brevundimonas diminuta(14.0%) became main bacterial species.The composition of bacterial flora gradually became simple,and the percentage of Shewanella putrefaciens increased significantly during iced storage.Four species were isolated from Pseudosciaena crocea ice-stored for 4 days,the dominated bacteria of Shewanella putrefaciens isolated from Pseudosciaena crocea ice-stored for 10 days and 18 days reached 63.5% and 69.1%,respectively.