Pyropia columbina phycocolloids as microencapsulating material improve bioaccessibility of brewers' spent grain peptides with ACE-I inhibitory activity

The effects of wall hydrocolloids on delivery and bioaccessibility of encapsulated brewers' spent grain ACE-I inhibitory peptides after simulated gastrointestinal digestion were assessed. Microencapsulation of peptides was carried out by spray drying using locust bean gum, P. columbina phycocolloids, or its mixtures as wall materials. Microcapsules presented round external surfaces with some concavities, negative surface charge and encapsulation efficiencies higher than 90%. The incorporation of phycocolloids to formulations increased the encapsulation efficiency, negative surface charge and resistance against digestive enzymes of microcapsules. Encapsulated peptides with P. columbina phycocolloids showed lower IC50 value of ACE-I inhibition than un-encapsulated peptides (2.4 +/- 0.2 vs. 7.2 +/- 0.3 mg mL(-1) protein), but higher than that obtained for hydrolysate (1.5 +/- 0.2 mg mL(-1) protein), indicating a 75% protection of bioactivity. Electrostatic and hydrophobic interactions between P. columbina phycocolloids and brewers' spent grain peptides could be implicated in the protection of peptides during gastrointestinal digestion.