Preparation method of yoghurt starter for prolonging shelf life of yoghurt

Abstract

The invention discloses a preparation method of a yoghurt starter for prolonging the shelf life of yoghurt, which belongs to the field of food preservation. The method comprises the following steps of: performing protoplast fusion on bacillus acidi lactici and lactic acid cocci which are separated out from homemade yoghurt lumps of Xinjiang herders; screening protoplasts after the fusion to obtain target strains; and using the strains as the yoghurt starter to prepare the yoghurt so as to prolong the shelf life of the yoghurt. The yoghurt prepared by using the starter provided by the invention has a long freshness date, and the yoghurt starter is favorable for increasing the yoghurt transport volume and reducing the cost to generate greater economic benefits.

Description

Technical field [0001] The invention belongs to the field of food preservation, and relates to a method for prolonging the storage period of yogurt. Specifically, it refers to a method for preparing a yogurt starter by using lactic acid bacteria isolated from homemade yogurt lumps of Xinjiang herders to prolong the storage period of yogurt. Background technique [0002] Yogurt (also called yogurt) is mostly fresh milk as raw material, a kind of moderately acidic agglomerated semi-solid milk product that is fermented and transformed by lactic acid bacteria. See reference: Chen Hui, Physical and chemical properties of yogurt during the process of fermenting curd And biological activity, "Journal of Wuxi University of Light Industry" 2000, 19(5). As one of the main products of lactic acid bacteria fermentation, yogurt is favored by more and more consumers due to its unique nutritional value and flavor, and has developed rapidly in terms of product quality, output and variety. Howev...

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Problems solved by technology

[0004] In the above method, by adjusting the ratio of Lactobacillus bulgaricus and Streptococcus thermophilus, and adding foreign substances, the degree of acidification can only be slightly weakened; while the method of changing cell membrane permeability and adding bacteriocin increases the production of Cost, not suitable for large-scale production; only the production of strains with weak acid production ability at low temperature and low pH through genetic engineering and mutation breeding can fundamentally solve the problem of acidification after yogurt

At present, although there are many reports on the genome of lactic acid bacteria at home and abroad, and great progress has been made, due to its complexity, the research on the gene regulation mechanism of lactic acid bacteria is not very thorough. The recombinant gene controls the acidification of yogurt. Research has rarely reported

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