Preparation and optimal encapsulation of citral in proteins: effect of protein type, pH, and ratio

Citral is often used as a flavoring agent in food, beverages, and cosmetics. It deteriorates during storage due to its susceptibility to oxygen and acidic pH. In this work, we examined the influence of protein type, pH, and ratio on citral nanoencapsulation. To achieve this objective two protein types, whey protein concentrate (WPC) and skim milk (S), were used to nanoencapsulate citral via complex coacervation. Response surface methodology (RSM) using a Box-Behnken design optimized pH, protein type, and ratio. The maximum desirability was observed in 4% WPC and 1% carrageenan at pH 3. Different pH values (3, 6, and 9) were used for post-optimization characterization of the freeze-dried optimized formulation. The encapsulation efficiencies ranged from 64% to 35%, depending on pH. SEM results of citral-loaded nanocomplexes confirmed that the nanocapsules were spherical without holes under acidic conditions. These findings suggest that WPC-carrageenan complex coacervation is a promising approach for citral nanoencapsulation and may improve its applicability in food systems.