Summary The influence of ultrasound power (1000–3000 W/L), citric acid concentration (0–3%) and solid:liquid ratio (1:5–1:15) on the phenolic compounds recovery and antioxidant capacity of Syrah grape skin extracts were evaluated. Total phenolic compounds varied from 6485 to 11732 mg gallic acid/100 g and monomeric anthocyanin content from 453 to 685 mg malvidin‐3‐glucoside/100 g. The antioxidant capacity measured by ORAC and ABTS methods ranged from 230 to 516 μmol Trolox/g and from 442 to 939 μmol Trolox/g, respectively. The most suitable conditions chosen for extraction, within the studied ranges, were 3000 W/L of power, 2.5% citric acid and solid:liquid ratio of 1:15. The extraction yield was satisfactory, with a recovery of 59% of the quantified phenolic compounds, with only 3 min of processing. Ultrasound was considered a suitable method as compared to the conventional extraction, improving the extraction of phenolic acids and facilitating their release.

This study aimed to recover bioactive compounds by solid-liquid extraction from the agro-industrial residue obtained during juçara fruits processing into pulp. A preliminary study using different solvents (methanol, ethanol and water) indicated ethanol in aqueous solution as the best solvent for antioxidants recovery. Then, a Box-Behnken design was applied considering as independent variables the solvent composition (30-70% ethanol in water), temperature (30-70 °C) and time (30-60 min), in order to evaluate the effects of these factors on antioxidant activity in juçara extract. Results showed that the extracts with higher antioxidant activity were obtained using 30% ethanol at 70 °C for 60 min; measurements included ABTS and DPPH assays, determination of total phenolic content and total monomeric anthocyanins. Furthermore, the effect of pH in antioxidants recovery was evaluated. For this purpose, the 30% ethanol solution was acidified to pH 1 and 2 with HCl. Principal component analysis showed the formation of three distinct groups: one characterized by high bioactive compounds content (pH 1.0), another with superior antioxidant activity (pH 5.75, non-acidified), and finally the group at pH 2 presenting the worst concentrations in the evaluated responses. HPLC analysis showed the presence of cyanidin-3-O-rutinoside and cyanidin-3-O-glucoside in the extracts. Therefore, the conventional solid-liquid extraction using renewable solvent can be successfully applied to recover bioactive compounds from juçara residue, which can be used by different food industries.

Introduction. Tropical fruit have a good commercial potential as natural colorants; however, they are underexploited. Anthocyanins from jamelão (Syzygium cumini) fruit peel have been shown to be an alternative source of natural pigments for the food industry. Due to the toxicity of some synthetic colorants to the environment and human health, these artificial colorants are being replaced by natural pigments. This study was carried out to evaluate the properties and the technological feasibility of using the peel powder of the jamelão fruit as a colorant. Materials and methods. Over a 5 month period the anthocyanins from the jamelão fruit peel powder were tested for stability by HPLC every 30 days. Results and discussion. A loss of 36% of the total monomeric anthocyanins was noted at the end of the study. Despite this loss, the final product maintained its quality as a colorant, due to the initial high concentration of anthocyanin. Conclusion. Besides its intense and attractive color, the peel powder of jamelão also proved to be rich in dietary fibers and thus a good ingredient for low-calorie diets as well as having low lipid content. Keywords: Brazil / jambolão / jamun / Syzygium cumini / antioxidant / natural colorant Résumé-Caractérisation de la poudre de la peau des fruits du jamelonier (Syzygium cumini L. Skeels) pour une utilisation comme colorant naturel. Introduction. Les fruits tropicaux présentent en général un bon potentiel commercial comme colorants naturels ; et pourtant, peu d'entre eux sont exploités. Les anthocyanes de la peau du fruit du jamelonier (Syzygium cumini) passent pour être une source alternative de pigments naturels pour l'industrie alimentaire. En raison de la toxicité de certains colorants synthétiques pour l'environnement et la santé humaine, ceux-ci sont remplacés par des pigments naturels. La présente étude évalue les propriétés et la faisabilité technique de l'utilisation de la poudre de zeste du fruit du jamelonier comme colorant. Matériels et méthodes. Sur une période de 5 mois, la stabilité des anthocyanes de pelure en poudre des fruits du jamelonier a été testée par HPLC tous les 30 jours. Résultats et discussion. Une perte de 36 % du total des anthocyanes monomères a été notée à la fin de l'étude. Malgré cette perte, le produit final a maintenu sa qualité de colorant, en raison de la forte concentration initiale en anthocyanines. Conclusion. Outre sa couleur intense et attrayante, la poudre de pelure de fruit du jamelonier s'est également avérée être riche en fibres alimentaires, et donc un bon ingrédient pour les régimes hypocaloriques, d'autant plus qu'elle présente une faible teneur en lipides.

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