电子鼻检测复合果汁饮料中的脂环酸芽孢杆菌

Detection of Alicyclobacillus acidoterrestris Spoilage of Mixed Fruit Juice Beverage by Electronic Nose

脂环酸芽孢杆菌是果汁加工中的一种重要腐败菌。因其具有嗜酸、耐热的特性,故巴斯灭菌不能除去此菌。该菌芽孢萌发、繁殖,产生类似药水的强烈异味,导致果汁腐败变质。本文从一种玉米蜜桃复合果汁饮料中分离筛选出1株嗜酸、耐热芽孢杆菌,经16S r DNA鉴定为脂环酸芽孢杆菌。采用FOX 4000电子鼻结合主成分分析(PCA),可快速、准确区分正常产品和异常样品(已污染脂环酸芽孢杆菌)。其中第一主成分累积方差贡献率为95.80%,异常样品与正常样品之间的模式判别指数大于79%。以正常产品为基础建立统计质量控制模型(SQC),被检异常产品位于置信区间之外。GC-MS分析结果表明,异常产品中3种挥发性物质含量高于正常产品,9种物质含量低于正常产品。结合挥发性物质的气味特征和活度分析,导致产品有异味的主要物质为邻乙氧基苯酚和愈创木酚,其含量高达51.79 mg/L和35.62 mg/L。本试验结果说明电子鼻技术可很好地用于检测果汁中的脂环酸芽孢杆菌。

Alicyclobacillus spp. have been a major problem to the fruit juice beverage industry worldwide as the thermo-acidophilic nature and highly risistant to the pasteurisation treatments normally applied to high-acid fruit products.Under certain conditions, endospores of Alicyclobacillus can germinate and multiply to a high number to produce offensive smelling ‘smoky＇ or ‘antiseptic＇ like flavour taints. In this study, a strain of Alicyclobacillus was isolated from a commercial fruit beverage mixed with peach and corn juice by BAT agar and was identified to Alicyclobacillus acidoterrestris using 16 S r DNA sequence. A FOX 4000 electronic nose was applied to diagnose the natrual contamination of Alicyclobacillus acidoterrestris in the mixed fruit juice products. The instrument was able to identify contaminated products accurately in a simple, rapid, and nondestructive manner. The acquired data were analyzed by principal component analysis（PCA） and the classification index was above 79%. Statistical quality control（SQC） analysis was also conducted. Uncontaminated samples were set as reference and all contaninated samples were mapped in a rejection region. These results were supported by the GC/MS measurements of specific chemical markers, such as guaiacol and 2-ethoxyphenol. This study strongly suggests the use of the electronic noses as screening tools in industrial quality control laboratories in the fruit juice beverage industry.