一种新型开菲尔风味复合发酵剂的研制

Preparation of A Novel Kefir Flavor Compound Fermentation Starter

摘要:

为研制一款新型的风味突出、理化性质稳定的开菲尔风味复合发酵剂，该研究从源自中国新疆的10种开菲粒中分离获得51株乳酸菌、22株酵母菌。51株乳酸菌中，3株乳酸菌的产香能力和蛋白分解能力突出，单菌发酵乳的全质构特性最稳定。其中，开菲尔乳杆菌MLK5的乙醛质量浓度为15.82 mg/L、双乙酰质量浓度为3.99 mg/L、氨基氮质量浓度为597.09 mg/L，干酪乳杆菌SLC1的乙醛质量浓度为20.02 mg/L、双乙酰质量浓度为4.69 mg/L、氨基氮质量浓度为684.92 mg/L，肠膜明串珠菌NLM2的乙醛质量浓度为18.01 mg/L、双乙酰质量浓度为4.44 mg/L、氨基氮质量浓度为600.58 mg/L。22株酵母菌中，马克思克鲁维酵母菌菌株FY1的乙醇产量适宜，遗传稳定性好，乳糖利用率最高为56.56%。最终确定，发酵剂中最佳比例为乳酸菌:酵母菌=5:1，3株乳酸菌间最优例为肠膜明串珠菌:开菲尔乳杆菌:干酪乳杆菌为1:2:1。复合发酵乳的凝乳时间为6.0 h、酸度为84.65 ºT、持水力为62.31%、乙醇体积分数为0.53%、乳酸菌活菌数为3.89×109 CFU/mL、酵母菌活菌数为4.61×106 CFU/mL、感官评分为89.21，与开菲尔粒发酵乳的各项指标类似。而复合发酵乳中的挥发性风味物质间构成和谐，更易于消费者接受。上述研究结果，有助于稳定和简化开菲尔的工业生产，为开发不同风味酸乳产品提供参考。

Abstract:

To develop a compound starter with excellent flavor and stable physical and chemical properties, 51 strains of lactic acid bacteria (LAB) and 22 strains of yeasts were isolated from ten types of kefir grains collected from Xinjiang, China. Among the LAB strains, three exhibited outstanding incense production and proteolytic ability. The textural characteristics of single-bacteria-fermented milk were the most stable. The acetaldehyde, diacetyl, and amino nitrogen concentrations for Lactobacillus kefir MLK5 were 15.82, 3.99, and 597.09 mg/L, respectively, and those for Lactobacillus casei SLC1 and Leuconostoc membranae NLM2 were 20.02, 4.69, and 684.92 mg/L and 18.01, 4.44, and 600.58 mg/L, respectively. The yeast, Kluyveromyces marxianus FY1, exhibited a suitable ethanol yield, good genetic stability, and the highest lactose utilization rate (56.56%). The optimal ratio of LAB to yeast in the starter was 5:1, and the optimal proportion of the 3 LAB strains was Leuconostoc mesenteroides: L. kefir: L. casei = 1:2:1. The curd time of compound fermented milk, acidity, water holding capacity, ethanol content, viable count of LAB, viable count of yeasts, and sensory score were 6.0 h, 84.65 °T, 62.31%, 0.53%, 3.89×109 CFU/mL, 4.61×106 CFU/mL, and 89.21. These indexes are similar to those of kefir grain fermented milk. The volatile flavor compounds in compound fermented milk were found to be harmonious and more acceptable to consumers. These results will help stabilize and simplify the industrial production of kefir and provide a reference for the development of different flavored yogurt products.