Resumen de Foam‐Mat Freeze‐Drying of Bifidobacterium longumRO175: Viability and Refrigerated Storage Stability
Danilo Izquierdo‐López, Jacques Goulet, Cristina Ratti
Foaming as a pretreatment was used prior to freeze‐drying of Bifidobacterium longumRO175 to investigate the potential acceleration of the drying rate and increase in microorganism viability after the process. A study on storage of foamed and nonfoamed freeze‐dried products at 4 °C completed this study. B. longumRO175 in foamed medium could be freeze‐dried in 1/7 to 1/4 of the time required for nonfoamed suspensions. In addition, foamed suspensions presented higher viability immediately after freeze‐drying (13.6% compared to 12.81 % or 11.46%, depending on the cryoprotective media). Refrigerated storage led to a reduction in B. longumRO175 viability for all tested protective agents (foamed and nonfoamed). No correlation between glass transition temperature and stability of probiotic powders was observed during storage. In addition, lower viability after 56 d of storage was observed for foamed materials, probably due to foam porous structure and higher hygroscopicity, and oxygen presence and moisture pickup during storage. Foaming pretreatment prior to freeze‐drying can be used to preserve Bifidobacterium longumRO175 cultures, greatly reducing the freeze‐drying times, having higher viability after freeze‐drying and maintaining the number of viable microorganisms offered in commercial probiotics supplements (>109CFU/g) after 56 d storage period at 4 °C.
