Quality assessment of low-sugar jams enriched with plant raw materials exhibiting health-promoting properties.

Low-sugar gooseberry jams enriched by the addition of black chokeberry, elderberry, Japanese quince, flax seeds and wheat germs were examined for the content of total polyphenols, total flavonoids, and total anthocyanins as well as their antioxidant activity (DPPH, ABTS, and FRAP) and individual phenolic compounds. The jams were evaluated immediately after production and after 6 and 12 months of storage. Samples were stored at chilled temperature (10 °C) and room temperature (20 °C). A significant increase in the level of the analyzed components and antioxidant activity were determined in jams with the addition of chokeberry, elderberry and Japanese quince, while in the case of other plant ingredients the differences were not always significant. Immediately after production, the highest levels of total polyphenols (330 mg/100 g), total flavonoids (160 mg/100 g) and total anthocyanins (35 mg/100 g) were recorded in the gooseberry jam with a 15% addition of chokeberry fruit. In the examined jams, p-cumaric acid, ferulic acid, caffeic acid, (+)-catechin and rutin were identified and (+)-catechin were determined in the greatest quantities (1.874-5.660 mg/100 g). The storage conditions of jams determined the level of the examined constituents. Storage temperature generally had significant effect on the level of compounds with antioxidant properties, lower in the products which were chill-stored compared to those stored at room temperature. Anthocyanins were found to be the most sensitive components during storage.