Effect of disaccharides on survival during storage of freeze dried probiotics

Abstract

-The aim of this study was to investigate the effects of protective media and different relative vapour pressures (RVPs) on the survival of probiotics during freeze drying and subsequent storage, to determine the optimal conditions for the production of freeze dried probiotics at industrial scale, ensuring a high survival rate. The effect of protective media i.e. reconstituted skimmed milk (RSM) or either of the cryoprotective disaccharides lactose, trehalose, sucrose, maltose, lactose + maltose and lactose + trehalose on the survival of a probiotic culture was assessed at five different RVP environments (0.0%, 11.4%, 33.2%, 44.1% and 76.1%) at room temperature in freeze-dried systems. RVP was shown to have a significant effect on the survival rates of the probiotic cultures Lactobacillus paracasei NFBC 338 and Lactobacillus rhamnosus GG following freeze drying in RSM. Interestingly, retention of cell viability was greatest for cells stored at 11.4% RVP, but was compromised at all other RVPs tested. However, an increased tolerance to freeze drying was observed for L. rhamnosus GG when dried in the presence of disaccharides in the order of trehalose = lactose + maltose lactose + trehalose maltose > lactose > sucrose. Survival studies over a 38-40 day storage period indicated that trehalose and lactose + maltose were the most effective cryoprotective additives, especially notable at 0.0 and 11.4% RVP. At all other RVPs tested, viability was compromised. Crystallisation of the disaccharides was observed to be a detrimental factor affecting the survival of Lactobacillus during storage at high RVP, where an inverse relationship was shown to exist between the % RVP and the glass transition temperature (T g ) of the disaccharides.probiotics / storage / viability / relative vapour pressure / disaccharides Résumé -Effet des disaccharides sur la survie de probiotiques lyophilisés au cours du stockage. Le but de cette étude était de rechercher les effets de milieux protecteurs et de différentes pressions de vapeur relatives (PVR) sur la survie de probiotiques au cours de la lyophilisation et du stockage ultérieur, afin de déterminer les conditions optimales pour la production de probiotiques lyophilisés à l'échelle industrielle assurant un taux de survie élevé. L'effet de milieux de protection, i.e. lait écrémé reconstitué ou l'un des disaccharides cryoprotecteurs suivants : lactose, tréhalose, saccharose, maltose, lactose + maltose ou lactose + tréhalose, sur la survie d'une culture de probiotiques a été étudié dans 5 environnements de PVR différents (0 ; 11,4 ; 33,2 ; 44,1 et 76,1 %) à température ambiante dans des systèmes lyophilisés. On a montré que la PVR avait un effet significatif sur les taux de survie des cultures de probiotiques Lactobacillus paracasei NFBC 338 et Lactobacillus rhamnosus GG après lyophilisation dans le lait écrémé reconstitué : le maintien de la viabilité cellulaire était plus élevé pour des cellules conservées à une PVR de 11,4 %, alors qu'il était compromis à toutes les autres PVR étu...

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