Appraising Blueberry Residues as a Natural Source of Bioactive Compounds ^†

Abstract

The main solid byproduct of blueberry juice processing is peel, representing up to 20% of the initial fruit weight. Blueberries are considered as a particularly interesting fruit for their well-known antioxidant and antimicrobial properties [1]. It is expected that blueberry peel retains some compounds with interesting properties. However, its excessive accumulation causes a seasonal management and environmental problem. These byproducts could be reused to reduce the environmental impact of the industrial activity and obtain, in parallel, an economical profit. The main objective of this work was to perform a deep characterization of blueberry peel residues and their derived extracts. To obtain extracts that are rich in bioactive compounds and ready-to-use in other sectors, environmentally-friendly procedures, namely matrix solid-phase dispersion (MSPD) and medium-scale ambient temperature systems (MSATs) [2,3], were employed. Physical, mechanical, and chemical characteristics of the raw material (blueberry), as well as the total polyphenolic content (TPC), antioxidant capacity, and sugar content of corresponding byproducts and their derived extracts were assessed, obtaining high values. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) was employed to quantify individual phenolic compounds. The results revealed that anthocyanins were the most abundant polyphenolic group of compounds in the blueberry peel extracts reaching concentrations of up to 6899 µg g⁻¹ dw, followed by flavonols, especially quercetin and its derivatives (quercetin-3-glucoside, quercetin-3-rutinoside). Moreover, other non-flavonoids, such as hydroxycinnamic acids, including caffeic and chlorogenic, were found at high concentration levels (1226 µg g⁻¹ dw) in the obtained extracts. The ultimate conclusion of this work is the investigation of the utility of food processing wastes as raw materials, in order to obtain extracts with added value for use in new products with beneficial health properties.