Abstract

Survival and quality efficiency of Lactobacillus casei microencapsulated by spray drying using different vegetable extracts (asparagus, artichoke, orange or grapefruit peel) were evaluated. Aqueous suspensions of the vegetable extracts with or without maltodextrin (adjusting to 25% w/w) were prepared for the microencapsulation of L. casei. The evaluated spray drying conditions were at a fixed air inlet temperature (Tin) of 145 °C and varying the aqueous suspensions flux (Q) of 10 or 15 g/min. Survival of L. casei was evaluated after the spray drying process and after 60 days of storage at 25 °C. The quality efficiency of the microencapsulated L. casei was evaluated by measuring in the product, physicochemical properties (moisture content, a_w), determining moisture gain and modeling adsorption isotherms, besides analyzing micrographs. Results demonstrated that moisture content of the different spray drying powders was less than 2% wb and less than 0.30 of a_w. It was evidently that the use of maltodextrin reduced 50% the powders moisture gain (hygroscopicity) therefore reducing stickiness problems during storage. The Scanning Electron Microscopy (SEM) confirmed individual particles formation with a homogeneous coat when using vegetable extracts+maltodextrin and hence better powder quality than without it. The microbial reduction of L. casei after the spray drying process was of one log cycle and significantly different (p < 0.05) with the presence of maltodextrin when using orange or grapefruit peel. A microbial population over 10⁷ cfu/g of L. casei microencapsulated was maintained after 60 days of storage which guarantees its use to develop functional food.

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