Insights into changes of anthocyanins-rich blueberry extracts concentrated by different nanofiltrations and their storage stability

Abstract Anthocyanins-rich blueberry extracts, which commonly used as food additive, are good for human health, but they are unstable during concentration processes. In this study, five flat-sheet nanofiltration (NF) membranes were used to concentrate the blueberry aqueous extracts. Effects of different membranes on physicochemical characteristics of concentrates (total phenolics, total anthocyanins, total sugars, total pectin, etc.), properties of membrane fouling, and stability of concentrates in cold storage were investigated. Among different NF membranes, NF3, made from polyamide and molecular weight cut off of 400 Da was the best to concentrate the extracts with the highest content of anthocyanins (147.59 mg/L) and polyphenols (434.70 mg/L). In the storage at 4 °C for 4 weeks, concentrates were more stable than the original extracts. Total polyphenols in concentrates decreased about 13.9% only, and total anthocyanins reduced more slowly. Accordingly, NF is a promising technology to promote the stability of active compounds, especially anthocyanins in blueberry extracts during concentrations and their storages.