Evaluation of anthocyanin stability during storage of a coloured drink made from extracts of the Andean blacberry (Rubus glaucus Benth.), açai (Euterpe oleracea Mart.) and black carrot (Daucus carota L.)

The effect of temperature on the stability of three purified anthocyanin sources in a soft drink (pH 3, 10 °Brix) stored at (4, 20, 30 and 50) °C for 60 days was investigated. Materials and methods. Anthocyanins from Andean blackberries ( Rubus glaucus Benth.), açai (Euterpe oleracea Mart.) and black carrot ( Daucus carota L.) were purified and concentrated on a laboratory scale by adsorption to a styrene divinylbenzene copolymer. Two classical empirical approaches (Arrhenius and Ball models) were used to describe the thermal degradation kinetic of these three anthocyanins. Results. No degradation was detected during the refrigerated storage (4 °C). At all temperatures, the degradation rate constant ( k ) for black carrot anthocyanins was less than those in açai and blackberry (0.42 × 10 –2 , 0.77 × 10 –2 and 1.08 × 10 –2 )·d –1 , respectively, at 30 °C). Anthocyanins in black carrot degraded less rapidly than those in açai and Andean blackberry. The activation energy ( E a ) for degradation of black carrot anthocyanins was (63.2 ± 4.3) kJ·mol –1 , and (66.3 ± 2.7) kJ·mol –1 and (91.2 ± 0.4) kJ·mol –1 for açai and blackberry anthocyanins, respectively, at 20–50 °C. These higher E a of blackberry anthocyanins as compared with those of black carrot and açai imply that a small temperature increase is sufficient to degrade them more rapidly. Conclusion. Our results clearly showed that anthocyanins from black carrot have a good stability during thermal storage (4 °C to 50 °C) with regard to blackberry and açai anthocyanins. Acylation of black carrot anthocyanins probably explains their greater stability. Acylated anthocyanins have shown to be promising alternatives to the use of synthetic dyes in drink systems. (Résumé d'auteur

Physicochemical and biochemical characterization of ripening injujube (#Ziziphus mauritiana# Lamk) fruits from two accessions grown in Guadeloupe

International audienceJujube fruits (Ziziphus mauritiana Lamk) from two accessions grown in Guadeloupe were harvested andsampled at five ripening stages, from green to reddish-brown in colour. Their physiological character-istics were then investigated. Ascorbic acid increased with ripening until stage 4, to 463 mg/100 g and168 mg/100 g dry weight, for cultivars P3 and P5, respectively. Likewise, ethylene production increaseduntil stage 4, to 121 \ₗ/kg/h and 116 \ₗ/kg/h, for cultivars P3 and P5, respectively. High and transientsucrose accumulation was observed during ripening of P3 fruits, concomitantly with low and constantglucose and fructose contents. P5 fruits also accumulated sucrose transiently but at a lower level than P3fruits, with a marked decrease at the end of ripening. In contrast to P3 fruit, glucose and fructose accu-mulated continuously to high levels during P5 fruit ripening. These data suggested differential sucrosemetabolism during ripening of these fruits. Postharvest treatments with 1-MCP and acetylene were alsoperformed on the three first ripening stages of both cultivars P3 and P5. On the basis of the findings, wediscuss the climacteric behaviour of the P3 and P5 ripening process. (Résumé d'auteur) AD -; CIRAD-PERSYST-UMR Qualisud (FRA); CIRAD-PERSYST-UMR Qualisud (GLP); Université de la Réunion (REU); CIRAD-PERSYST-UMR Qualisud (FRA); CIRAD-PERSYST-UMR Qualisud (GLP

Changes in antioxidant activity during the ripening of jujube (Ziziphus mauritiana Lamk)

International audiencePhenolic compounds from jujube fruits and related antioxidant activities were investigated during the ripening stages. Three different antioxidant assays, including ORAC, FRAP and DPPH, were monitored on crude jujube extract (CJE). Jujube fruits were additionally fractionated into three selective fractions F1, F2, and F3. However, only the FRAP assay gave the relative antioxidant activity for the three fractions. Furthermore, HPLC–ESI-MSMS (Q-Tof) and GC–MS were used to identify the compounds in each purified fraction. Using FRAP, F1 mainly composed of lipids, exhibited the lowest antioxidant activity (≈0.080 ± 0.015 mmol trolox/100 g, p < 0.05). F2, rich in flavanols and flavonols, displayed 50-fold higher activity (4.27 ± 0.11 mmol trolox/100 g). Remarkably, F3 with an elevated content of condensed tannins (polymeric proanthodelphinidins), exhibited the highest antioxidant activity (25.4 ± 0.35 mmol trolox/100 g). The presented results showed that the phenolic profiles of the fruits were influenced by their developmental stage. Furthermore, during ripening, the antioxidant activity may be more impacted by the flavanols and condensed tannins. The purified condensed tannins of jujube fruits may be used as natural antioxidant extracts

Processed Z. Mauritiana Lamk in the Formula of High Nutritional Value Cake

International audienceThe nutritional value of jujube fruits Ziziphus mauritiana Lamk was processed through an optimized traditional cake procedure. The characteristics of jujube fruit polysaccharides from an accession known as P3 were determined for each of the 5 ripening stages. Therefore, the content of the Alcohol Insoluble Materials, Water Soluble Polysaccharide and Galacturonic Acid was determined at each ripening stage. The degree of methylation (DM) of jujube pectins was less than 50% therefore was classified as low methoxylated pectin (LM). Using the 3 rd and the 5 th ripening stage, the impact of the drying and cooking was evaluated on selected nutritional characteristics, including vitamin C, total phenolics content and antioxidant capacity. Remarkably, using the fruits from the 3 rd stage, the drying process decreased the vitamin C content (74.5%, p<0.05) whereas an increase of 20% (p<0.05) was observed for the cake. Interestingly, the antioxidant activity was unchanged during the drying process. In contrast, after the cooking process the phenolics content and the antioxidant capacity had both increased, by 64% and 30% (p<0.05) respectively. Overall, our results indicated that stage 3 fruits would exhibit higher nutritional qualities than stage 5 fruits. We strongly recommend stage 3 fruits of accession P3 for food applications, including jujube cake processing