Effects of different carrier materials on physicochemical properties of microencapsulated grape skin extract

The goal of this study was to investigate the characteristics of grape skin extract (GSE) spray dried with different carriers: maltodextrin (MD), gum Arabic (GA) and skim milk powder (SMP). The grape skin extract was obtained from winery by-product of red grape variety Prokupac (Vitis vinifera L.). The morphology of the powders, their thermal, chemical and physical properties (water activity, bulk and tapped densities, solubility), as well as release studies in different pH conditions were analyzed. Total anthocyanin content and total phenolic content were determined by spectrophotometric methods. MD and GA-based microparticles were non-porous and spherical, while SMP-based ones were irregularly shaped. The process of spray drying Prokupac GSE using these three carriers produced powders with low water activity (0.24-0.28), good powder characteristics, high yields, and solubility higher than 90%. The obtained dissolution/release profiles indicated prolonged release of anthocyanins and phenolic compounds in different mediums, especially from GSE/GA microparticles. These results have shown that grape skin as the main by-product of wine production could be used as a source of natural colorants and bioactive compounds, and microencapsulation as a promising technique for the protection of these compounds, their stabilization in longer periods and prolonged release

Releasing characteristics of anthocyanins extract in pectin–whey protein complex microcapsules coated with zein

This study investigated pectin-based capsules as delivery systems for purple rice bran anthocyanin extract (AE) during exposure to simulated gastrointestinal conditions. Four different capsules loaded with AE were prepared by ionotropic gelation/extrusion, including (1) pectin capsules (PE), (2) pectin capsules coated with zein (PE/ZE), (3) pectin-whey protein isolate complex capsules (PE + WP), and (4) pectin-whey protein isolate complex capsules coated with zein (PE + WP/ZE). CaCl in an ethanol solution with or without zein was used as a crosslinking solution. Swelling and release characteristics of all capsules under simulated gastric fluid at pH 1.2 (SGF) and simulated intestinal fluid at pH 6.8 (SIF) for 120 and 180 min, respectively, were examined. PE + WP, PE + WP/ZE, and PE/ZE capsules had higher encapsulation efficiency than PE capsules. After incubation, PE + WP/ZE and PE capsules had the lowest swelling ratio in SGF and SIF, respectively. PE + WP/ZE capsules had the lowest AE release in SGF, while PE capsules had the highest. Both PE + WP and PE + WP/ZE capsules had significantly lower AE release in SIF than PE and PE/ZE capsules. The study demonstrated that PE + WP and PE + WP/ZE capsules have potential to function as a slow release delivery system for AE