Soy extract and maltodextrin as microencapsulating agents for Lactobacillus acidophilus: a model approach.

The present study aimed to optimize the microencapsulation of Lactobacillus acidophilus La-05 by spray drying, using soy extract and maltodextrin as encapsulants. Air inlet temperature, maltodextrin/soy extract ratio and feed flow rate were investigated through Central Composite Rotational Design (CCRD). Probiotic viability increased with increasing the proportion of soy extract. Temperature and feed flow rate had a negative effect. Particle diameter ranged from 4.97 to 8.82 μm, water actvity from 0.25 to 0.52 and moisture from 2.30 to 7.01 g.100g-1 . Particles produced following the optimized conditions (air temperature of 87 °C, maltodextrin/soy extract ratio of 2: 3 w.w-1 , feed flow rate of 0.54 L.h-1 ) reached Encapsulation yield (EY) of 83%. Thermogravimetry and FTIR analysis suggested that microcapsules could protect L. acidophilus cells against dehydration and heating. During storage, microencapsulated probiotic had high cell viability (reductions ranged between 0.12 and 1.72 log cycles). Soy extract/maltodextrin presented good encapsulating properties of Lactobacillus acidophilus La-05.