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Characterization of freeze-dried Lactobacillus acidophilus in goat milk powder and tablet: Optimization of the composite cryoprotectants and evaluation of storage stability at different temperature

Shu, Guowei, Wang, Zhuo, Chen, Li, Wan, Hongchang, Chen, He
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2018 v.90 pp. 70-76
Lactobacillus acidophilus, cell viability, cryoprotectants, dried skim milk, food industry, freeze drying, goat milk, lactose, manufacturing, milk production, probiotics, protective effect, response surface methodology, sodium phosphate, storage quality, storage temperature, storage time, survival rate, trehalose
Probiotic application in food industry remains a challenge in decades because of bacterial loss in viability during powder manufacture and storage. Well-designed cryoprotectants and storage condition are crucial for successful probiotic application. In this study, survival of Lactobacillus acidophilus with composite cryoprotectants was investigated during freeze-drying and subsequent storage at different temperature (−18 °C, 4 °C and room temperature- 25 °C). The composite cryoprotectants were optimized to be trehalose of 13%, Na2HPO4 of 0.33%, lactose of 7.5% and skim milk powder of 21% with the aid of response surface method. The survival rate of freeze-dried L. acidophilus increased to (93.9 ± 0.12) % in comparison to control (36.6 ± 0.08) %. Furthermore, freeze-dried L. acidophilus powder was applied in two dairy forms (goat milk powder and tablets) and cell viability was monitored during 180 days of storage. The freeze-dried powder exhibited better stability in goat milk powder than that in tablets. The cell survival in goat milk powder and tablets was higher at low temperature (−18 °C and 4 °C) during storage. Our finding provided a formulation of composite cryoprotectant with great protective effect to probiotic cells during freeze-drying. The freeze-dried powder showed potential application to functional dairy production in relative food industry.