Microencapsulation of grape skin phenolics for pH controlled release of antiglycation agents

Grape skin (GS) phenolics can prevent structural damage of proteins due to reducing sugars or dicarbonyl compounds, which is the leading cause of hyperglycaemia damage and is involved in inflammatory diseases. In this study, alginate hydrogel was used to encapsulate GS phenolics as a pH dependent releasing system. Microbeads were obtained by a vibrating nozzle method using calcium chloride as hardening agent. Encapsulation efficiency for total phenolics was 68%. At pH 1.4, the alginate microbeads remained intact and only 13% of total phenolic compounds of the microbeads was released. The percent release depended on the compound: procyanidin B1 release was 74%, catechin and epicatechin release was ~ 50%, while anthocyanin and flavonol release was less than 11%. At pH 7.4, the microbeads were dissolved and formed a viscous solution that showed ability to protect bovine serum albumin from glycation induced by both fructose and methylglyoxal. The antiglycation activity was 246 mmol catechin equivalents (CE)/kg of dry microbeads in the fructose model system and 78 mmol CE/kg of dry microbeads in the methylglyoxal model system. These values corresponded to 68% and 62% of the expected activity, probably due to interaction between phenolics and the alginate carrier. Despite the recovery of antiglycation activity was incomplete, results of this study confirmed the efficiency of alginate to act as a pH controlled released system for GS phenolics. This functionalized polymer could be applied in the prevention of advanced-glycation-endproducts related diseases.