Astaxanthin encapsulation in multilayer emulsions stabilized by complex coacervates of whey protein isolate and Persian gum and its use as a natural colorant in a model beverage

Crustacean byproducts are valuable sources of astaxanthin. In this study, an astaxanthin-rich lipid phase was extracted from shrimp waste and encapsulated in multilayer emulsions. Stabilized by electrostatic complexes of whey protein isolate (WPI) and Persian gum (PG), the multilayer emulsions were created by different WPI:PG mixing ratios (1:2–1:4). The resultant emulsions were then exposed to lyophilization. The encapsulation efficiency of astaxanthin in lyophilized powders was 42.9–49.8 (g astaxanthin/100 g astaxanthin). The moisture content and water activity of the powders decreased significantly (p < 0.05), but their solubility and hygroscopicity increased significantly (p < 0.05) in response to an increase in the PG content of the mixture (or by reducing the WPI:PG ratio). Morphological characterizations revealed the formation of smaller and more uniform microcapsules when higher amounts of PG were used. Water dispersibility was higher than 94 (g powder/100 g powder). The results of an accelerated stability test showed an improvement in astaxanthin chemical stability in the multilayer emulsions, particularly when the WPI:PG ratio was 1:4. A model beverage consisting of water (89 g/100 g), sugar (10 g/100 g) and citric acid (1 g/100 g) was prepared and the potential application of astaxanthin microcapsules as a natural colorant was studied and compared with a synthetic colorant (E110) under the effect of light/darkness, temperature (4 and 25 °C) and time (0–60 d). The encapsulated lipid extract imparted a highly stable color to the product which was comparable to the effect of the synthetic colorant. However, the astaxanthin concentration was highly affected by time and partially affected by light and temperature.