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从市售异味玉米果汁饮料中分离、筛选嗜酸耐热菌,对其进行分子生物学鉴定,并研究分离菌株对玉米果汁饮料挥发性成分和色度的影响。结果表明,市售异味玉米果汁饮料中分离筛选出一株嗜酸耐热芽孢杆菌,该菌最适生长温度为45~50℃,最适pH为3.5~4.0,16S rDNA测序鉴定为酸土脂环酸芽孢杆菌。将分离菌株接种于正常样品于45℃培养30 d,气相色谱-质谱联用技术(Gas Chromatograph-Mass Spectrometer,GC-MS)分析表明,正常样品和接种样品挥发性成分的种类相似,但在关键性气味物质的含量上有显著差异。接种样品中14种挥发性物质含量极显著高于正常样品,其中愈创木酚和邻乙氧基苯酚具有类似草药、消毒水等异味,且两种物质在接种样品中气味活度分别高达1696.58和398.40,为酸土脂环酸芽孢杆菌污染该饮料产生的特征性异味物质。色差分析表明接种样品L值显著高于正常样品,表明污染饮料产生异味的同时产品白度增加。
Isolation and screening of acidophilic heat-resistant bacteria from commercially available off-flavor corn juice beverages were carried out to identify their molecular biology and to study the effects of the isolated strains on the volatile components and color of corn juice drinks. The results showed that a strain of Escherichia acidophilus was isolated and screened from the commercial malt juice beverage. The optimal temperature for growth was 45 ~ 50 ℃ and the optimum pH was 3.5 ~ 4.0. The sequence of 16S rDNA was identified as acid earth Bacillus acidophilus. The isolated strains were inoculated into normal samples and cultured at 45 ℃ for 30 days. Gas Chromatograph-Mass Spectrometer (GC-MS) analysis showed that the volatile components of normal samples and inoculated samples were similar, Odor substances have significant differences in content. The contents of 14 volatile compounds in inoculated samples were significantly higher than those in normal samples, of which guaiacol and o-ethoxyphenol had odor like herbs and disinfecting water, and the odor activity of the two samples in inoculated samples were as high as 1696.58 And 398.40, contaminating the beverage with the characteristic off-flavor substances produced by B. acidocaldarius. Chromatic aberration analysis showed that the L value of the inoculated sample was significantly higher than that of the normal sample, indicating that the whiteness of the product was increased while contaminating the beverage with odor.