酸奶中益生菌多样性检测及其货架寿命预测模型的建立
发布时间：2018-11-24 13:41
【摘要】：酸奶因健康味美日益受到广大消费者的喜爱,其中所含乳酸菌对促进人体健康起到重要作用。但酸奶中所含乳酸菌种类与标签标识菌种是否一致还是有待探讨的问题,本论文首先利用Illumina深度测序技术对酸奶中乳酸菌多样性进行定性研究。另外活性乳酸菌的加入使酸奶具有很短的货架寿命,如何精准确定酸奶货架期是酸奶制造中另一个重要问题,本研究后期采用加速破坏性和温度波动性实验对酸奶在不同储藏温度下各评价指标的实时变化进行监测,然后利用阿仑尼乌斯模型建立酸奶货架期的动力学预测模型。结果表明:(1)虽然市售酸奶标签标示乳酸菌种类丰富,但结果显示各品牌酸奶中益生菌含量同质化程度较高,部分品牌标示菌种(双歧杆菌)未被检出,部分品牌检出了未标示菌种(肠球菌属、乳球菌属)。各品牌酸奶中乳酸菌种类从属的分类水平来看主要包括链球菌属(Streptococcus、87.1%)、乳杆菌属(Lactobacillus、10.3%)、乳酸乳球菌属(Lactococcus、0.3%),对比可以看出链球菌属在酸奶中乳酸菌菌群中占有绝对优势。(2)在储藏过程中,乳酸菌总量、双乙酰含量随时间的增加呈现先升高后降低的趋势,酸度随时间增加呈现逐渐升高的趋势,pH、粘度、感官评分都呈现逐渐降低的趋势,并且温度的升高对以上六个指标变化产生了很大影响。温度波动性试验显示了储藏期间内即使短暂的温度波动也会对酸奶品质造成较大影响。(3)根据不同储藏温度下各评价参数随时间的变化规律,建立了三种酸奶样品的货架期预测模型,其中一号样品预测模型为A=A_0e~(-0.03127),5℃储藏温度下预测期为15.5天;二号样品的预测模型为A=A_0e~(-0.01515),5℃储藏温度下预测期为19天;三号样品预测模型为A=A_0e~(-0.00995),5℃储藏温度下预测值为16.5天,与标示货架期对比显示预测结果可靠有效。
[Abstract]:Yogurt is more and more popular by consumers because of its healthy taste, among which lactic acid bacteria play an important role in promoting human health. However, whether the type of lactic acid bacteria contained in yoghurt is consistent with that of labeled bacteria is still a question to be discussed. In this paper, the diversity of lactic acid bacteria in yoghurt is studied qualitatively by Illumina deep sequencing technique. In addition, the addition of active lactic acid bacteria makes yoghurt have a very short shelf life. How to accurately determine the shelf life of yogurt is another important problem in yoghurt manufacture. In the later stage of this study, accelerated destructiveness and temperature fluctuation experiments were used to monitor the real time change of each evaluation index of yoghurt at different storage temperatures, and then the alenius model was used to establish the dynamic prediction model of the shelf life of yoghurt. The results showed that: (1) although there were abundant kinds of lactic acid bacteria labeled on the market, the results showed that the content of probiotic bacteria was high and some of the brand labeled bacteria (Bifidobacterium) were not detected. Some brands detected unlabeled bacteria (Enterococcus, Lactococcus). The taxonomic levels of lactic acid bacteria in various brands of yoghurt include Streptococcus (Streptococcus,87.1%), Lactobacillus (Lactobacillus,10.3%), Lactococcus (Lactococcus,0.3%). The comparison shows that Streptococcus has an absolute advantage in the lactic acid bacteria community in yogurt. (2) during storage, the total amount of lactic acid bacteria and the content of diacetyl increased first and then decreased with the increase of time. The acidity increased gradually with the increase of time, and the viscosity and sensory score of pH, decreased gradually, and the increase of temperature had a great influence on the changes of the above six indexes. The temperature fluctuation test shows that even the transient temperature fluctuation during storage period will have a great impact on the quality of yogurt. (3) according to the variation of evaluation parameters with time under different storage temperature, The shelf-life prediction models of three kinds of yoghurt samples were established. The prediction model of No. 1 sample was Agna _ 0e ~ (- 0.03127), and the prediction period was 15.5 days at 5 鈩，
本文编号：2353936
[Abstract]:Yogurt is more and more popular by consumers because of its healthy taste, among which lactic acid bacteria play an important role in promoting human health. However, whether the type of lactic acid bacteria contained in yoghurt is consistent with that of labeled bacteria is still a question to be discussed. In this paper, the diversity of lactic acid bacteria in yoghurt is studied qualitatively by Illumina deep sequencing technique. In addition, the addition of active lactic acid bacteria makes yoghurt have a very short shelf life. How to accurately determine the shelf life of yogurt is another important problem in yoghurt manufacture. In the later stage of this study, accelerated destructiveness and temperature fluctuation experiments were used to monitor the real time change of each evaluation index of yoghurt at different storage temperatures, and then the alenius model was used to establish the dynamic prediction model of the shelf life of yoghurt. The results showed that: (1) although there were abundant kinds of lactic acid bacteria labeled on the market, the results showed that the content of probiotic bacteria was high and some of the brand labeled bacteria (Bifidobacterium) were not detected. Some brands detected unlabeled bacteria (Enterococcus, Lactococcus). The taxonomic levels of lactic acid bacteria in various brands of yoghurt include Streptococcus (Streptococcus,87.1%), Lactobacillus (Lactobacillus,10.3%), Lactococcus (Lactococcus,0.3%). The comparison shows that Streptococcus has an absolute advantage in the lactic acid bacteria community in yogurt. (2) during storage, the total amount of lactic acid bacteria and the content of diacetyl increased first and then decreased with the increase of time. The acidity increased gradually with the increase of time, and the viscosity and sensory score of pH, decreased gradually, and the increase of temperature had a great influence on the changes of the above six indexes. The temperature fluctuation test shows that even the transient temperature fluctuation during storage period will have a great impact on the quality of yogurt. (3) according to the variation of evaluation parameters with time under different storage temperature, The shelf-life prediction models of three kinds of yoghurt samples were established. The prediction model of No. 1 sample was Agna _ 0e ~ (- 0.03127), and the prediction period was 15.5 days at 5 鈩，
本文编号：2353936
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