Disaccharide incorporation to improve survival during storage of spray dried Lactobacillus rhamnosus in whey protein-maltodextrin carriers

Abstract The viability of encapsulated L. rhamnosus by spray drying, using carriers based on whey protein isolate-WPI and maltodextrins-MD, with and without sucrose or trehalose as protective agents, was studied as a function of the storage time and the equilibrium water activity (a w ) at 20 °C. The water sorption and water plasticization behaviour of the dried products were also analysed. Although all the formulations were physically stable at a w below 0.43, the formulations stored at a w of 0.11 exhibited the best cell counts. No cell survival was observed after 84 days in WPI:MD formulations, but the partial replacement of maltodextrin by trehalose or sucrose allows for viable cells after 196 days. Cold storage of formulations enhanced cell preservation, although after 7 storage months only formulations containing disaccharide had viable cells. So, the incorporation of sucrose or trehalose to WPI:MD carriers is a good strategy to extend the shelf-life of L. rhamnosus probiotic products.