大黄鱼腐败菌腐败能力分析与特定腐败菌鉴别

Analysis of microbial spoilage ability and characterization of specific spoilage organism for Pseudosciaena crocea

探讨了分别接种腐败希瓦氏菌和假单胞菌的无菌大黄鱼鱼块在5℃贮藏中的生长速率和腐败代谢产物的生成速率,以产生异臭味时的腐败菌数和腐败代谢产物的产量因子作为腐败菌腐败能力的定量指标。接种鱼块腐败时(产生明显异臭味)腐败希瓦氏菌与假单胞菌的菌数即最小腐败菌数(Ns)的对数值分别为9.14lg cfu/g和9.25lgcfu/g。由Gompertz方程得到腐败希瓦氏菌和假单胞菌的生长动力学参数:最大比生长速率(μmax)分别为0.0714和0.0700,最大菌数(Nmax)的对数值分别为9.45lg cfu/g和9.37lg cfu/g。结果表明,两种腐败菌在无菌大黄鱼鱼块中的μmax基本一致,且Nmax都超过Ns,这两种腐败菌都能引起大黄鱼的腐败。接种鱼块中腐败希瓦氏菌的腐败代谢产物(TVBN和TMA)的产量因子YTVBN/cfu和YTMA/cfu分别为1.38×10-10mg-N TVBN/cfu和1.31×10-10mg-N TMA/cfu,假单胞菌的腐败代谢产物(TVBN)的产量因子YTVBN/cfu为1.18×10-10mg-N TVBN/cfu,比较产量因子可得,两菌的腐败能力相当。因为大黄鱼低温贮藏中的优势腐败菌是腐败希瓦氏菌,其次是假单胞菌,根据特定腐败菌的概念,大黄鱼低温贮藏过程中的特定腐败菌是腐败希瓦氏菌,其次是假单胞菌。

The growth of spoilage bacteria and the rate of production of metabolite for sterile Pseudosciaena crocea tissue blocks inoculated Shewanella putrefaciens and Pseudomonas spp. stored aerobically at 5 ℃ were respectively assayed. The yield factor for production of metabolite and the cell concentration determined at the time of off-odour detection were used as quantitative measurements of microbial spoilage ability. At spoilage point,the logarithm counts of the N_s （minimum number of spoilage bacteria） of Shewanella putrefaciens and Pseudomonas spp. were 9.14 lg cfu/g and 9.25 lg cfu/g,respectively. Adopting Gompertz regression equation to describe the growth curve of Shewanella putrefaciens and Pseudomonas spp.,we gained growth kinetics model parameters of both spoilage bacteria. The μ_max （maximum specific growth rate） of Shewanella putrefaciens and Pseudomonas spp. were 0.071 4 and 0.070 0,the logarithm counts of the N_max （maximum number of bacteria） of them were 9.45 lg cfu/g and 9.37 lg cfu/g,respectively. The results showed that their μ_max were basically the same and both of N_max were more than N_s of them,suggesting both spoilage organisms could be responsible for spoilage of Pseudosciaena crocea. The Y_TVBN/cfu and Y_TMA/cfu of Shewanella putrefaciens were 1.38×10-10 mg-N TVBN/cfu and 1.31×10-10 mg-N TMA/cfu,respectively. The Y_TVBN/cfu of Pseudomonas spp. was 1.18×10-10 mg-N TVBN/cfu. The quantitative results indicated that the spoilage ability of both spoilage bacteria was equivalent. Because Shewanella putrefaciens and Pseudomonas spp. were the dominant spoilage bacteria when Pseudosciaena crocea was stored aerobically at low temperature,also based on the concept of SSO （Specific spoilage organism）,Shewanella putrefaciens was the most dominant spoilage bacterium in the specific spoilage organisms,followed by Pseudomonas spp.