The in -vitro digestion behaviors of milk proteins acting as wall materials in spray-dried microparticles: Effects on the release of loaded blueberry anthocyanins

Studies have shown that microencapsulation can protect blueberry anthocyanins (ACNs) from degradation. Naturally derived micellar casein and whey protein isolate (WPI) are commonly employed as wall materials owing to their unique digestion properties, which are believed to significantly influence the stability and release of core materials in the gastrointestinal tract. Micellar casein and WPI were used to prepare spray-dried microparticles to load ACNs. The dynamic release of ACNs was investigated during in vitro digestion from the perspective of structural changes in wall materials, which were mainly identified by scanning electron microscopy and confocal laser scanning microscopy. ACN-loaded micellar casein microparticles dissolved slowly and coagulated into oversized curds during digestion, which significantly improved the retention of ACNs in the harsh gastrointestinal tract. In contrast, ACN-loaded WPI microparticles dissolved quickly, but liquid microparticles subsequently formed and hindered the release and degradation of ACNs. This study provides a reference for the design of spray-dried microparticles and should help in understanding the release behaviors of loaded bioactive compounds in other delivery systems containing such proteins during in vitro digestion.