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Microencapsulation of probiotic bacteria in alginate, maltodextrin or other matrices helps to reduce the impact of heating process as spray drying, yielding a more stable presentation of the desired microorganism. Despite this protective effect, the microbial viability in final products is reduced up to 4 log cycles, making thus necessary the development of more efficient strategies to retain a higher rate of survival. Protein isolates on the other hand, are increasingly popular as a source of nutrients because of the perception that proteins increase energy levels and support overall health. The development of microparticles with a carbohydrate scaffold, prebiotics as inulin and proteins as thermal-protective agents of probiotic bacteria has not been fully explored and only some reports about the use of whey protein are found in literature. The objective of this work was to determine the thermo-protective effect of soybean, whey and peanut protein isolates on microencapsulation of <i>Lactobacillus plantarum</i> 299v in terms of final viability. The experiments were made using an aqueous mix with alginate (1%), inulin (5%), maltodextrine (5%) and 2.5% of each tested proteins. Mixes were inoculated with <i>L. plantarum</i> (4x109 CFU/ml) before a spray drying stage at 130°C. Dry product was collected and diluted in PBS solution, inoculated on MRS agar plates and colony forming units were counted after incubation (48h at 37°C in aerobic conditions). Results show that after spray drying, the reduction of viable cells was roughly 2.5% (not even a log cycle: 1x109 CFU/mL final in the case of whey protein treatment). This study suggests that microencapsulation with 2.5% of protein isolates has a positive effect, making <i>Lactobacillus </i>more resistant to the harsh conditions of spray drying, an operation thoroughly used in food industry to produce ingredients at large-scale.