Polyphenolic-rich products made with Georgia-grown rabbiteye blueberries

Abstract

Blueberries contain fiber and bioactives, and therefore are a possible avenue for value-added products. One product, blueberry wine, is produced worldwide and associated with considerable anthocyanin and phenolics contents. However, these compounds may change during bottle storage. Total monomeric anthocyanin (TMA) content, total phenolics content (TPC), antioxidant activity, and color qualities of blueberry wine were investigated during six months of bottle storage. After 6 months storage, monomeric anthocyanins were almost complete gone, antioxidant activity slightly decreased, and phenolics content slightly rose at two months. Color density reduced and percent polymeric pigment increased. Monomeric anthocyanins likely polymerized with other compounds to create stable pigments. Blueberry juice processing, like wine-making, produces large amounts of waste (pomace) that contains fiber and polyphenols. Powder would be a more preferred form of bluberry pomace as a nutritional ingredient. Powders were produced using vacuum belt drying (VBD) and the effect of deseeding was investigated. VBD powders had similar TMA and TPC as freeze-dried control powder when process at temperatures below 120°C but in much less time. Likely, this is because VBD allows drying at temperatures below 100°C. For both VBD and freeze-dried powders, deseeding decreased TMA and TPC. This is likely due to the loss of larger blueberry skin particles during the deseeding process. VBD pomace powder with seeds can be added into other products, such as baked goods, cereals and snacks, to improve the dietary profile. Extruded sorghum and pomace powder snacks were darker and more purple compared to the lighter, yellow control snack. The color is due to the anthocyanins naturally found within the pomace powder. Extruded sorghum and blueberry pomace snacks were less expanded, more dense, and harder than sorghum control, but still equally preferred by consumers. The snack with pomace powder had more total dietary fiber, anothcyanins, phenolics and radical scavenging capabilities when compared with control. The control snack had very little phenolics content and contained no anthocyanins. Overall, VBD can produce blueberry nutraecutical ingredients from wine and juice processing waste that can be used to improve the nutrition of food products.