Agriculture & Food, Volume 9, 2021

Abstract: Blueberries have been hailed as excellent source of health-promoting and restoring bioactive compounds: vitamins, phenolic compounds, minerals and sugars. The blueberries could be eaten fresh and raw or processed into jams, syrups, smoothies, yoghurts, beverages or other products. The aim of the present study was to evaluate the content of phenolic compounds, antioxidant properties, water content, acidity, pH and sugar content of blueberry (Vaccinium corymbosum L.) fruits and jam. The antioxidant activities were evaluated using seven different antioxidant assays. It was observed that thermal processing of fruits led to statistical significant alterations for most of monitored parameters. The fresh fruits contains higher water content (86.903%) compared to jam (41.943%). Blueberry jam had higher content of total phenolics, total tannins and total flavonoids compared to fruits and manifested higher antioxidant capacity measured by ABTS (2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)), FRAP (ferric reducing antioxidant power), total reduction capacity and total antioxidant activity assays. The values of pH, acidity, total anthocyanins and DPPH (2,2-diphenyl-1-picrylhydrazyl radical) assay showed not statistical significant alterations after thermal processing. Methanol extracts of fresh blueberry fruits and jam posses similar scavenging capacities for O2·- and ·NO free radicals. Hence, the obtained results demonstrated that, besides fresh blueberry fruits, the blueberry jams also possess noticeable amount of phenolic bioactive compounds with considerable antioxidant capacity.