藏灵菇菌发酵性能以及抑菌特性研究

Fermentation and antibacterial properties of Tibetan kefir

以复原乳为原料,将藏灵菇菌作为发酵剂以10%的接种量在30℃、37℃、42℃培养至凝乳,4℃冷藏。考察了凝乳期间和后酸化过程中藏灵菇菌产酸能力以及藏灵菇菌发酵乳的保水率、黏度;以大肠杆菌为指示菌,采用滤纸片法研究了藏灵菇菌块、发酵乳上清液对大肠杆菌的抑菌活性。在42℃下藏灵菇菌发酵乳产酸快,9h达到81°T,37℃下发酵12h达到83°T。发酵乳冷藏1d后的测定的黏度值(表观黏度η′)由大到小依次为:η′37℃>η′42℃>η′30℃,三者保水率相近。综合考虑藏灵菇菌发酵乳较优发酵温度为37℃,发酵12h;藏灵菇菌块对大肠杆菌有一定抑菌作用,且产生这种抑菌作用的物质对热敏感,发酵乳上清液对大肠杆菌起抑菌作用主要由酸度降低引起。

Using reconstituted milk as raw material and Tibetan kefir as the starter,a kind of milk curd was fermented by adding 10% inoculum of starter culture under different temperatures（30℃,37℃,42℃）.The acidity variation in curd forming and postacidification period were investigated,fermentation properties of Tibetan kefir such as the water-holding capacity rate,viscosity were studied in this paper.Taking E.coli as the indicator bacteria,antibacterial properties of Tibetan kefir and fermented milk supernatant were studied by using filter paper method.The results shown that acid were produced quickly,and the titratable acidity reached 81°T after 9h fermentation under 42℃,while 83°T after12h fermentation under 37℃.The apparent viscosity η′ values under different temperatures were determined after fermented milk had been refrigerated for 1d,which followed the order： η′（37℃）η′（42℃）η′（30℃）.The water-holding capacity rate of fermented milk under different temperatures were similar.The optimum fermentation conditions were obtained as： fermentation temperature 37℃ and fermentation temperature 12h.Tibetan kefir had a certain antibacterial substance which was sensitive to temperatures,the antibacterial effect of fermented milk supernatant on E.coli bacteria mainly caused by lower acidity.