Spray-drying encapsulation of probiotics for ice-cream application

Ice-cream is generally considered as a nutritive food, representing an interesting vehicle for delivering beneficial microorganisms to consumers. Many ice-cream makers use industrial dry bases for its preparation. The aim of this study was to investigate the possibility of producing spray-dried probiotic formulations to be used for partial substitution of the commercial ice-cream bases. A commercial cream base was selected for the study and, according to its composition and literature, two different formulations (FA and FB) were investigated. FA consisted in 46 % commercial skim milk powder, 24 % anhydrous glucose, 28 % maltodextrin (Maltrin® 40) and 2 % sodium alginate. FB contained prebiotic inulin fiber (Fibruline® instant) instead of Maltrin®. Powders were obtained with a lab-scale spray dryer dissolving each formulation in water at a 10 % w/v, with a 6 mL/min flow rate, 150 °C inlet temperature and increasing feed volume (100, 200, 300, 400 mL). The process gave a total dry solids yield ranging from 62.07 % (with 100 mL feed volume) to 58.14 % (with 400 mL) for FA, and from 65.55 % to 59.46 % for FB. Powder aw was always < 0.3. Probiotic-enriched bases were obtained using FA and FB for encapsulation of a strain of Lactobacillus paracasei. Considering a recommended probiotics minimum daily intake of 109 CFU, a 100 g ice-cream serving, a 5 % substitution of the commercial base with the probiotic-enriched base and supposing no vital loss during the process, the cellular feed concentration for the spray-drying trials was calculated. However, in the presence of probiotics, FA could not be spray dried, while encapsulation with FB gave a 50.89 % yield, 0.42 aw and 82 % cell mortality. Ice-cream was finally prepared in a domestic ice-cream maker using the probiotic-enriched FB after the pasteurization step and before the 12 h maturation step which caused limited additional mortality.