Résumé:
To manage the seasonal production surplus of figs, some families and cooperatives resort to the traditional processing. The impact of these traditional processes has not been sufficiently addressed by the literature. An important challenge is therefore to determine how to effectively preserve the antioxidant content of fruits from harvesting until consumption. In this context, the objectives of this thesis are: (i) to know the traditional methods of drying figs in the sun and the preparation of jam based on figs; (ii) the physicochemical characterization of fresh and dried figs and fig jams; (iii) the study of the bioaccessibility of phenolic compounds and their antioxidant activity during in vitro gastrointestinal digestion, while taking into account the varietal effect and the effect of sun drying. The varieties treated in this study are Aberkane, Azanjar and Taamriwt. To achieve these objectives, initially a survey was carried out in the Bejaia, Jijel, Skikda and Guelmaa cities. The survey showed that traditional drying and artisanal preparation of jam are the most widely used methods for preserving figs. The determination of the levels of phenolic compounds (total polyphenols, total flavonoids and total anthocyanins) was carried out by colorimetric methods. The evaluation of the antioxidant and anti-free radical potential was estimated in vitro by four tests (ABTS, DPPH, CUPRAC and FRAP). High performance diode array detector liquid chromatography (HPLC-DAD) was used to determine the phenolic profile of the various fig samples. The results indicated that the sun drying of figs and the preparation of jam have had a different influence on the physicochemical characteristics of figs. The levels of some phenolic compounds are negatively influenced by sun drying and processing into jam. Very considerable losses vary from 52.02 to 61.58% for sun-dried figs and from 52.21 to 69.38% for figs processed into jam. The two traditional processes applied also seem to negatively influence the antioxidant capacity. Likewise, positive correlations have been noted between antioxidant activity and the levels of phenolic compounds in dried figs and prepared jams. The static model of Minekus et al. (2014) of in vitro gastrointestinal digestion is used to study the bioaccessibility of phenolic compounds and their antioxidant activity. The content of phenolic compounds and the antioxidant capacity of fresh and dried figs obtained before digestion are significantly (p < 0.05) higher than those obtained after digestion. A significant decrease (p < 0.05) in the levels of phenolic compounds and their antioxidant activity was observed during the different phases of digestion (oral phase > gastric phase > intestinal phase). During in vitro gastrointestinal digestion, the varietal and drying effects are not significant on the phenolic compounds and on their antioxidant activity. Likewise, fresh and dried figs retained a high content of these compounds after digestion.
