Synergistic effects of encapsulated phycocyanin and phycoerythrin on probiotic ice cream quality

The limited stability of Saccharomyces boulardii and sensitive phycobiliproteins during frozen storage, together with the growing demand for natural antioxidant ingredients, represents a challenge for developing functional probiotic ice cream. This study aimed to evaluate whether chitosan encapsulation of phycocyanin (PC) and phycoerythrin (PE) could improve pigment stability and probiotic survival while maintaining the physicochemical, antioxidant, color, textural, and sensory quality of ice cream during 8 weeks of frozen storage. PC and PE were encapsulated using 2% ( w / v ) chitosan and ionic gelation, followed by lyophilization. FTIR spectroscopy (4000–400 cm −1 , ATR mode) was used to identify and compare functional group changes in control (C) and S. boulardii -inoculated coated-pigment (T2) ice cream samples. The coated pigments showed a particle size of 149.8 nm, zeta potential of +66.5 mV, and encapsulation efficiency of 83.37%. Among the five formulations, T2, containing S. boulardii inoculated before aging with chitosan-coated PC + PE, showed the most favorable performance. At week 8, T2 exhibited the highest total phenolic content (143 mg GAE g −1 DW vs. 86.8 mg GAE g −1 DW in the control), the lowest color change (ΔE = 6.32 vs. 12.67; ∼50% reduction), and the highest probiotic viability (8.08 log CFU g −1 ). T2 also showed approximately 12% lower melting rate than the control, while maintaining acceptable sensory properties. FTIR showed T4 differs from the control mainly through two new bands (1701.9 cm −1 , C=O; 1622.7 cm −1 , C C), confirming pigment retention, plus an O H shift linked to S. boulardii activity, while the core lipid/carbohydrate matrix stayed unchanged. These findings indicate that chitosan-encapsulated PC + PE with pre-aging probiotic inoculation improves bioactive stability, probiotic survival, antioxidant capacity, and color stability, supporting its potential for functional probiotic ice cream.