Microencapsulation Quality and Efficiency of Lactobacillus casei by Spray Drying Using Maltodextrin and Vegetable Extracts

<p>Survival and quality efficiency of <em>Lactobacillus casei </em>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 <em>L. casei</em>. 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 <em>L. casei</em> was evaluated after the spray drying process and after 60 days of storage at 25 °C. The quality efficiency of the microencapsulated <em>L. casei</em> 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 <em>L. casei</em> after the spray drying process was of one log cycle and significantly different (p &lt; 0.05) with the presence of maltodextrin when using orange or grapefruit peel. A microbial population over 10⁷ cfu/g of <em>L. casei</em> microencapsulated was maintained after 60 days of storage which guarantees its use to develop functional food.</p>