Agent selection and protective effects during single droplet drying of bacteria

• Published in: Food chemistry Vol. 166; pp. 206 - 214
• Main Authors: Khem, Sarim, Woo, Meng Wai, Small, Darryl M., Chen, Xiao Dong, May, Bee K.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2015
• Subjects: Lactobacillus plantarum; Lactobacillus plantarum - chemistry; Lactose; Lactose - chemistry; Protective mechanism; Single droplet drying; Trehalose; Trehalose - chemistry; Whey protein isolate; Single droplet drying; Lactose; Protective mechanism; Lactobacillus plantarum; Trehalose; Whey protein isolate
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2014.06.010

•Skim milk and WPI provided the highest protection during the middle drying stage.•Reduction in the rate of temperature rise reduces stress and preserves bacteria.•Whey protein isolate offers different protective behaviour in the dry form. The protective mechanisms of whey protein isolate (WPI), trehalose, lactose, and skim milk on Lactobacillus plantarum A17 during convective droplet drying has been explored. A single droplet drying technique was used to monitor cell survival, droplet temperature and corresponding changes in mass. WPI and skim milk provided the highest protection amongst the materials tested. In situ analysis of the intermediate stage of drying revealed that for WPI and skim milk, crust formation reduces the rate of sudden temperature increase thereby imparting less stress on the cells. Irreversible denaturation of the WPI components might have also contributed to the protection of the cells. Skim milk, however, ‘loses’ the protective behaviour towards the latter stages of drying. This indicates that the concentration of the WPI components could be another possible factor determining the sustained protective behaviour during the later stages of drying when the moisture content is low.