發(fā)布時間：2018-11-24 13:41

【摘要】：酸奶因健康味美日益受到廣大消費者的喜愛,其中所含乳酸菌對促進(jìn)人體健康起到重要作用。但酸奶中所含乳酸菌種類與標(biāo)簽標(biāo)識菌種是否一致還是有待探討的問題,本論文首先利用Illumina深度測序技術(shù)對酸奶中乳酸菌多樣性進(jìn)行定性研究。另外活性乳酸菌的加入使酸奶具有很短的貨架壽命,如何精準(zhǔn)確定酸奶貨架期是酸奶制造中另一個重要問題,本研究后期采用加速破壞性和溫度波動性實驗對酸奶在不同儲藏溫度下各評價指標(biāo)的實時變化進(jìn)行監(jiān)測,然后利用阿侖尼烏斯模型建立酸奶貨架期的動力學(xué)預(yù)測模型。結(jié)果表明:(1)雖然市售酸奶標(biāo)簽標(biāo)示乳酸菌種類豐富,但結(jié)果顯示各品牌酸奶中益生菌含量同質(zhì)化程度較高,部分品牌標(biāo)示菌種(雙歧桿菌)未被檢出,部分品牌檢出了未標(biāo)示菌種(腸球菌屬、乳球菌屬)。各品牌酸奶中乳酸菌種類從屬的分類水平來看主要包括鏈球菌屬(Streptococcus、87.1%)、乳桿菌屬(Lactobacillus、10.3%)、乳酸乳球菌屬(Lactococcus、0.3%),對比可以看出鏈球菌屬在酸奶中乳酸菌菌群中占有絕對優(yōu)勢。(2)在儲藏過程中,乳酸菌總量、雙乙酰含量隨時間的增加呈現(xiàn)先升高后降低的趨勢,酸度隨時間增加呈現(xiàn)逐漸升高的趨勢,pH、粘度、感官評分都呈現(xiàn)逐漸降低的趨勢,并且溫度的升高對以上六個指標(biāo)變化產(chǎn)生了很大影響。溫度波動性試驗顯示了儲藏期間內(nèi)即使短暫的溫度波動也會對酸奶品質(zhì)造成較大影響。(3)根據(jù)不同儲藏溫度下各評價參數(shù)隨時間的變化規(guī)律,建立了三種酸奶樣品的貨架期預(yù)測模型,其中一號樣品預(yù)測模型為A=A_0e~(-0.03127),5℃儲藏溫度下預(yù)測期為15.5天;二號樣品的預(yù)測模型為A=A_0e~(-0.01515),5℃儲藏溫度下預(yù)測期為19天;三號樣品預(yù)測模型為A=A_0e~(-0.00995),5℃儲藏溫度下預(yù)測值為16.5天,與標(biāo)示貨架期對比顯示預(yù)測結(jié)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，

本文編號：2353936