The inclusion of probiotic bacteria in food formulations to provide beneficial effects to health, is now a growing interest for the food industry. However, the stability of probiotics during processing of the product is not always optimal, due to some methods used. Microencapsulation can be used to maintain the viability of probiotic bacteria during food processing and storage of the product. The aim of this study was to use new sources of wall materials, such as starches and acetylated succinatados amaranth and maltodextrins for microencapsulation of Lactobacillus casei. The acetylated starch was modified directly by thermoplastic extrusion using acetic anhydride. Succinylated starch was obtained hydrolyzing with hydrochloric acid prior to esterification with n-octenilsucccinate, using the conventional method in suspension and subsequently extruded. According to the experimental design it was selected the blend offering a better survival to the microorganism after spray drying. The survival L. casei was evaluated in microcapsules and at room temperature for 35 days to three water activity (aw) (0314, 0515 and 0743). Microencapsulation by spray drying using modified amaranth starch blends with maltodextrins as wall material showed good survival of L. casei. The higer survival (6.8 CFU/g) was obtained at low aw (0.314) at the end of storage. The survival of L. casei microcapsules in milk powder formulations was 6 CFU/g. The acetylated amaranth starch and succinylated amaranth starch showed good protection properties of L. casei during storage and in a food system.