Ready-to-eat foods such as soups are in great demand by consumers, owing to the changes in lifestyle over the last half-century. In this context, the addition of new health-promoting active ingredients such as polyphenols could represent an important way to increase the intake of these compounds. Three different by-products from artichoke, lettuce and cauliflower handling and commercialisation have been use to obtain enriched polyphenol extract using a water extraction protocol. The artichoke by-products extract was composed of caffeic acid derivatives while the lettuce and the cauliflower by-products extract were composed of both caffeic acid derivatives and flavonols. The amounts of these compounds were evaluated with HPLC-DAD; it transpired that the artichoke by-products extract had the highest levels of polyphenols (100 mg of polyphenols/g of dry extract), followed by lettuce by-products extract (46 mg of polyphenols/g of dry extract) and cauliflower by-products extract (34 mg of polyphenols/g of dry extract). A sensory panel with four trained judges evaluated the addition of different amounts of extracts. Both artichoke and lettuce by-products extract could be added to the soup to a maximum amount of 10 mg of extract/mL of soup and cauliflower with 5 mg of extract/mL of soup, while still improving the grade of acceptability of the soup with respect to the original soup. In addition, antioxidant capacity was evaluated as free radical scavenging activity (ABTS·+ assay) and the ability to reduce the 2,4,6-tripyridyl-s-triazine (TPTZ)-Fe(III) complex to TPTZ-Fe(II) (FRAP assay). The antioxidative capacity increased with addition of the extracts between 3.5 times and 13 times (ABTS·+ assay) as well as between 23 times and 85 times (FRAP assay). The results obtained indicate that these by-products could provide the extracts with antioxidant phenolics that could be used to functionalise foods. Obviously, before incorporating these by-product extracts as dietary complements, it is necessary to carry out further studies about their toxicity (i.e. possible residual presence of pesticides), in vivo activity, and bioavailability.

6 pages, 2 tables.-- Printed version published 2005.

Peer reviewed