Enquête sur les procédés traditionnels (séchage et préparation de confiture) et étude de leurs effets sur la teneur, le profil et l’activité antioxydante des composés phénoliques de raisins.

Abstract

Among seasonal fruits, grapes are the main fruits flooding the shelves of various Algerian fruit and vegetable markets. However, the lack of processing and preservation industries for these fruits, particularly rapidly perishable fruits and those with low market value, have encouraged producers to preserve them in a traditional way. For grapes, the two most widely used traditional processes are sun-drying and homemaking jam. The main objectives of this study are to establish traditional diagrams: sun-drying of grapes and homemaking grape (Var. Cardinal and Var. Sabel) jam by domestic cooking. In addition, we aim to study the effect of these two traditional processes on phenolic compounds content, profile as well as their total antioxidant capacity, before and after simulated digestion in vitro. In order to achieve these objectives, a survey was established and conducted among individuals and families from the agricultural sector, including farmers and winegrowers. Samples of fresh grapes, dried grapes and homemade grape jams (Var. Cardinal and Var. Sabel) were subjected to series of spectrophotometric analyzes to determine total polyphenols, total flavonoids, total monomeric anthocyanins and total antioxidant capacity, along with the determination of phenolic profiles by HPLC-DAD-MS-QTOF. Additionally, an in vitro gastrointestinal digestion was applied to assess the bioaccessibility of phenolic compounds from fresh grapes and their traditional derivatives. The results showed that the two traditional processes led to considerable losses in the contents of certain phenolic compounds (phenolic acids and flavonoids) as well as in their antioxidant capacity. However, an increase in the content of certain phenolic acids was observed. The bioaccessibility coefficients of phenolic compounds and total antioxidant capacity obtained from the dialyzable fractions of dried grapes and grape jam digested in vitro were relatively improved.