engleski

Antioxidant potential of by-products extracts from traditional Mediterranean productions

Recently, research has focused on the reuse of by-products from the food industry to achieve sustainable production and reduce waste generation. The aim of this study was to investigate the potential utilisation of by-products from selected traditional Mediterranean productions as antioxidant agents. Samples of blackberries, cherries and aronia fruits were collected from local Dalmatian juice and tea producers. The samples were shade-dried and extracted in a green solvent (ethanol-water mixture) to ensure that the extracts were safe for food use. The extracts were obtained in an advanced microwave extraction system at 600 W for 5 minutes. Ethanol was evaporated from the extracts, and the remaining water was freeze-dried. Total phenolic content (TPC) and chemical profile were determined as well as antioxidant potential. The profile was analysed by high-performance liquid chromatography (HPLC), and for antioxidant potential, 2.2 of the extracts, namely, diphenyl-1-picrylhydrazyl radical scavenging capacity (DPPH), ferric reducing capacity (FRAP), and oxygen radical absorbing capacity (ORAC) were used. The highest TPC results of the samples ranged from 601.9 ± 13.9 to 3186.1 ± 96.6 mg gallic acid equivalents/L, with the highest concentration found in aronia by-products. All extracts had high inhibition of DPPH radicals, ranging from 80.1 to 84.0%. The highest reducing activity was found for the extract from blackberry by-products. The extracts were diluted 1000-fold before ORAC analysis. The results ranged from 36.1 ± 1.1 to 9.5 ± 0.7 μM Trolox equivalents, with the highest result for aronia by-products. A correlation was observed between the TPC and ORAC results. The predominant constituents of the extracts were rutin, protocatechuic acid, chlorogenic acid, and gallic acid, all phenolic acids known to be potent antioxidants, with protocatechuic acid dominating in aronia by-product extracts. The composition of phenolic acids was most diverse in the extract of aronia berries, which exhibited high antioxidant activity. Blackberry by-product extract was rich in rutin, while gallic acid and protocatechuic acid were detected in lower amounts. Cherry by-product extract showed the lowest antioxidant potential, and rutin was the only phenolic compound identified in the sample. These results show that by- products from traditional Mediterranean fruit juice/ tea production could be used for the production of extracts with high antioxidant activity that can be reused in the food industry. This research is supported by the PRIMA programme under project BioProMedFood (Project ID 1467). The PRIMA programme is supported by the European Union.

valorisation of by-products ; green solvent ; microwave-assisted extraction

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