Micellar Casein and Whey Protein as Encapsulating Agents of Natural Extracts: Antioxidant Capacity and Phenolic Compounds

Resumo

Dairy proteins can be used as encapsulating agents for natural compounds during spray drying. This
enhances the health benefits of both ingredients. This study aimed to determine the best encapsulating
agent for three different natural extracts, considering their trolox equivalent antioxidant capacity (TEAC)
and phenolic contents. The experimental strategy was based on three different natural extracts (passion
fruit, avocado seed, and green coffee) encapsulated in two types of proteins (whey protein [WPC] and
micellar casein [MC]). The particle size, morphology, Raman spectroscopy, TEAC, phenolic compounds,
moisture, and water activity were measured during the experiment. The results indicated that only the
green coffee extract modified the spectra of WPC and MC in the dry powders, which could be attributed
to chlorogenic acid. MC promoted greater retention of phenolic compounds (226.30 mg GAE/100 g for
passion fruit; 245.20 mg GAE/100 g for avocado seed; 331.05 mg GAE/100 g for green coffee in) and
trolox equivalent antioxidant capacity (28.03 μmol TE/g for passion fruit; 27.29 μmol TE/g for avocado
seed; 13.31 μmol TE/g for green coffee) compared to those of WPC. Passion fruit and avocado seed
extracts encapsulated in MC showed the highest trolox equivalent antioxidant capacity. In conclusion,
the encapsulating agent exerted different effects on the encapsulation of natural extracts, depending on
the TEAC and phenolic content.