摘要
本试验以MRS为培养基,对5株乳酸菌进行了生长性能和发酵性能研究。优选其中两株菌作为制备发酵剂的菌种,前期研究高密度细胞培养的条件、培养基成分,以培养过程中的pH值、活菌数为指标,后期研究制备发酵剂的最佳离心条件、筛选最适的冻干保护剂及浓度等进行了系统研究,研究表明,在接种量2%,培养温度30℃,初始pH6.6,装液量40ml(100ml三角瓶),振荡频率120r/min条件下培养,培养14h后补充营养物质继续培养,到20h时可使乳酸菌活菌数达到7.24×109CFU/ml。4℃、4000r/min离心30min为收集细胞的最佳条件,以10%的脱脂乳为冻干悬浮基质,对蔗糖、血清蛋白、甘油、海藻酸钠四种保护剂的保护效果进行了研究,结果表明,甘油的保护效果最佳,冻干后菌体的存活率最高,但甘油的吸湿强,给真空冷冻干燥后的活性菌种的分装带来困难,综合考虑选用10%的脱脂乳和血清蛋白作为冷冻保护剂。该研究旨在为直投式的乳酸菌发酵剂工业化生产提供理论依据。
Using MRS medium, the fermentative ability of five lactic acid bacteria was studied respectively, and two strains were affirmed as the primary fermentative species. Taking pH value and living cell count as indexes in the process of fermentation, the experiment studied strain ratios, cultural medium components, cultivation conditions, enrichment methods and cryoprotectant. The results indicated that the incubate volume 2%, the temperature 30℃, initial pH 6.6, cultural fluid amount 40ml, and shaking frequence 120r/min. After 14 hours, nutrient substance was added to the medium and after 20 hours of the total cells obtained are up to 7.24 - 109 CFU/ml. The optimum centrifugation conditions are： 4℃, 4000r/min, 30min. Using 10% nonfat milk as suspended substrate, the function of four protectors including sucrose, serum protein, glycerin and trehalose was studied respectively. The results suggested that all of them show some perfective effects on the living cell, while 10% nonfat milk and serum protein are among the best. The purpose of this study is to provide experimental basis for ready-to-use starters.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2006年第8期191-197,共7页
Food Science
基金
重庆市科委2002年重大攻关项目(7390)
关键词
发酵剂
高密度细胞培养
保护剂
冷冻干燥
culture starter
high cell concentration cultivation
cryoprotectant
freeze-drying
