engleski

Antioxidant and antimicrobial potential of by-products from berry juice production

The transition towards the sustainability of food sector includes, among others, the full exploitation of the raw materials and by-products. The aim of this study was to valorize the by-products from traditional berry juice production (blackberry, cherry, aronia) and rosehip extract that are usually wasted from these industries. All samples were collected from the local producers and shade-dried. The extractions were done in 50% EtOH (50 mg dry sample/250 mL) using the microwave-assisted extraction (600 W, 5 minutes). After the extraction, the EtOH was evaporated and the extracts freeze dried. The extracts were described for chemical profiles and total phenolic content (TPC). Besides, they were analyzed for antioxidant activity (FRAP, DPPH, ORAC) and antimicrobial activity against common foodborne pathogens (Staphylococcus aureus, Listeria innocua, Escherichia coli, Salmonella Typhimurium, Campylobacter jejuni) and spoilage bacteria (Shewanella baltica, S. putrefaciens, S. xiamenensis, Pseudomonas fragi) using minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) assays. The dominant phenolic components in the samples were rutin in blackberry by-product extracts, gallic, protocatechuic, chlorogenic acid, and astringnin in aronia extracts, and gallic acid and quercetin in rosehip extracts. The TPC of the by-product extracts ranged from 30.10 to 159.31 mg gallic acid equivalents/g dry extract, being the highest in aronia and blackberry by-product extracts. The highest FRAP results (mM Trolox equivalent) and DPPH (% inhibition) was observed for blackberry by-product extracts and rosehip extracts, while ORAC values were the highest in aronia by- product extracts. The strongest antimicrobial effect was observed for blackberry juice and rosehip by- products against C. jejuni (MIC 0.125 and 0.25 mg/mL respectively) and for blackberry juice by-product against P. fragi (MIC 0.5 mg/mL). Among studied by- products, blackberry extracts were found to be the most effective, especially against spoilage bacteria belonging to the genera Pseudomonas and Shewanella.

by-products ; MAE ; phenolic components ; antioxidant capacity ; antimicrobial activity

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