Effect of Dairy Powders and Sorbitol-Based Encapsulation Systems on Functional, Thermal, and Microstructural Quality of Probiotic Ice Cream

This study investigated the effects of different microencapsulation wall materials on the physicochemical, textural, thermal, and microstructural properties of probiotic ice cream during frozen storage. Lactobacillus acidophilus ATCC 4356 was encapsulated using lyophilization with whole milk powder, skim milk powder, whey powder, or sorbitol, and added to the ice cream mix at 1% (w/w). Five formulations were produced (control and four encapsulated variants) and analyzed over 90–150 days of storage at −18 °C. The highest firmness (41.96 g) and consistency (58.65 g·s) values were observed in the skim milk powder group, whereas sorbitol decreased viscosity and increased overrun. Melting resistance improved during storage, particularly in skim milk powder samples, where the complete melting time increased to 87.35 min. DSC results showed significantly higher enthalpy in whey powder samples, while sorbitol reduced ice crystal growth. Cryo-SEM images confirmed smoother, denser microstructures in formulations with milk powders and sorbitol. Encapsulation markedly enhanced probiotic survival: while the control decreased from 5.04 to 2.18 log CFU/g, encapsulated samples maintained counts above the therapeutic threshold (≥6 log CFU/g) up to 150 days, with the highest viability in whole and skim milk powder. Overall, milk-based encapsulation systems provided both cryoprotection and quality enhancement, demonstrating that microencapsulation is an effective strategy to produce stable probiotic ice creams with improved structural and technological attributes.