title: Optimization of a protective medium for enhancing the viability of freeze-dried Lactobacillus delbrueckii subsp. bulgaricus based on response surface methodology.
abstract: Response surface methodology (RSM) was used to optimize a protective medium for enhancing the cell viability of Lactobacillus delbrueckii subsp. bulgaricus LB14 during freeze-drying. Using a previous Plackett-Burman design, it was found that sucrose, glycerol, sorbitol and skim milk were the most effective freeze-drying protective agents for L. bulgaricus LB14. A full factorial central composite design was applied to determine the optimum levels of these four protective agents. The experimental data allowed the development of an empirical model (P<0.0001) describing the inter-relationships between the independent and dependent variables. By solving the regression equation, and analyzing the response surface contour and surface plots, the optimal concentrations of the agents were determined as: sucrose 66.40 g/L, glycerol 101.20 g/L, sorbitol 113.00 g/L, and skim milk 130.00 g/L. L. bulgaricus LB14 freeze-dried in this medium obtained a cell viability of up to 86.53%.
authors.affiliation: College of Food Science and Technology, Key Laboratory of Food Processing and Quality Control of Ministry of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, Peoples Republic of China. fmb@njau.edu.cn
authors.forename: Lijin
authors.initials: L
authors.lastname: Huang
authors.forename: Zhaoxin
authors.initials: Z
authors.lastname: Lu
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Yuan
authors.forename: Fengxia
authors.initials: F
authors.lastname: Lü
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Bie
mesh_terms: D018929:Cell Culture Techniques / Q000379:methods; D003451:Cryoprotective Agents / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry*; D005612:Freeze Drying / Q000379:methods*; D048668:Lactobacillus delbrueckii / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D008954:Models, Biological
chemical_list: D003451:Cryoprotective Agents; D003470:Culture Media