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.
Supplementary Materials
The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/Foods2021-10931/s1, Poster: Appraising blueberry residues as a natural source of bioactive compounds.
Author Contributions
Conceptualization, M.L. and C.G.-J.; methodology, M.C., A.C. and A.R.; validation, A.C. and A.R.; formal analysis, M.C.; investigation, M.C., A.C. and A.R.; resources, C.G.-J. and M.L; writing-original draft preparation, M.C.; writing-review and editing, C.G.-J. and M.L.; supervision, M.L.; project administration, C.G.-J. and M.L.; funding acquisition, C.G.-J. and M.L. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by project ED431, 2020/06 (Galician Competitive Research Groups Xunta de Galicia). Several of the authors belong to the National Network for the Innovation in miniaturized sample preparation techniques, RED2018-102522-T (Ministry of Science, Innovation and Universities, Spain). This study is based upon work from the Sample Preparation Study Group and Network, supported by the Division of Analytical Chemistry of the European Chemical Society. All of these programs are co-funded by FEDER (EU).
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
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