Introduction. The fruit types such as raspberries (Rubus idaeus), cherries (Prunus cerasus), blackberries (Rubus fructicosus), blackthorns (Prunus spinosa) and aronia (Aronia melanocarpa) are very common in Serbia. These fruit species are a valuable source of antioxidants. The goal of our work was to evaluate the antioxidant activities of ethyl acetate extracts of these five berries and to establish possible correlation between the content of anthocyanin and the antioxidant activity. Materials and methods. To determine antioxidant activity of the selected fruits, the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, the ABTS (2,2-azinobis-3 ethyl benzothiazoline-6-sulfonic acid) cation decolorization activity, the FRAP (ferric reducing antioxidant power), and the TRP (total reducing power) were measured. Results. The four methods selected for our assays showed strong antioxidant properties for blackberry samples. The total anthocyanin content was estimated using the pH differential method. The highest amount of anthocyanin was found in blackberry samples [(1063.53 ± 0.01) mg·kg–1 fresh fruit], while the lowest was in raspberry samples [(180.84 ± 0.02) mg·kg–1 fresh fruit]. The correlation between the content of anthocyanin and antioxidant activity was established using regression analysis. The highest correlation was found between total reducing power and total anthocyanin (r = 0.97, p < 0.05). Hierarchical cluster analysis divided selected fruit species into two statistically significant clusters. Conclusion. Our results confirmed that analyzed berries are rich in anthocyanins. A strong correlation among different assays as well as with anthocyanin content was observed. Cluster analysis can be used in food science, to classify different food types into groups, based on similarity among the results.

Introduction. Many underutilized wild fruits have great nutritional and functional potential, providing chemical compounds with biological properties. Materials and methods. In the present work we quantified bioactive compounds such as vitamin C (ascorbic and dehydroascorbic acids), and total phenolic compounds composed mainly of phenolic acids, flavonols and anthocyanins, as well as evaluating the antioxidant capacity through different in vitro tests (Folin-Ciocalteu, ABTS·+, DPPH· and FRAP) in wild blackthorn (P. spinosa L.) and hawthorn (C. monogyna Jacq.) fruits of Spanish origin, including samples from different seasons and locations. Results and discussion. As expected, wide variability was found in the composition of fruits of the same species, which justifies the necessity of analyzing several batches of wild fruits, in order to have representative results taking into account the natural variability. Fruits of P. spinosa showed vitamin C content ranging between (5.14 and 15.35) mg·100 g–1 fw (mainly dehydroascorbic acid); total phenolic compounds ranged from (1851 to 3825) mg·100 g–1 fw, characterized by a high content of anthocyanins and phenolic acids. Fruits of C. monogyna presented (16 to 39) mg vitamin C·100 g–1 fw and (449 to 1438) mg total phenolic compounds·100 g–1 fw, characterized by a high content of phenolic acids and flavonols. Antioxidant capacity was higher for P. spinosa fruits than for C. monogyna fruits; DPPH· values showed a strong correlation with vitamin C, while phenolic compounds were a major contributor to the antioxidant activity of these fruit extracts. Fruits of P. spinosa and C. monogyna should be reconsidered as new valuable sources of safe and inexpensive antioxidants.

Introduction.Strawberry is rich in health as well as bioactive compounds, andbenefits resulting from the use of natural products rich in bioactivesubstances are receiving increased interest from the pharmaceutical,food and cosmetic industries. Materials and methods.Twenty-two cultivars of strawberry (Fragaria × ananassa Duch.) grown under a temperate ecosystemwere screened for ascorbic acid, phenolic compounds, flavonoids,anthocyanins and antioxidant activities (DPPH and FRAP assays).The phenolic content was measured by Folin-Ciocalteu reagent usinggallic acid as the standard. Antioxidant activity was determinedin terms of DPPH and FRAP assays and expressed as ascorbic acidequivalent. Total anthocyanins and total flavonoid content weredetermined using a colorimetric method. Titratable acidity (citricacid) was determined by the titration method. The average data oftwo years was analyzed using SAS 9.2 software. Results and discussion.Significant differences in the health and bioactive compounds weredetected among the cultivars. The range of ascorbic acid of thetested samples was (51.03 to 89.40) mg·100 g–1 fresh weight. Titratableacidity varied between 0.73% and 1.44%; however, total anthocyanins rangedbetween (28.24 and 43.32) mg cyanidin-3-glucoside Eq·100 g–1 freshweight. Total phenols varied from (380.10 to 888.10) mg gallic acidEq·100 g–1 and total flavonoids from (31.26 to 55.16) mg catechinEq·100 g–1. The total antioxidant activity ranged between (203.13 and471.10) mg ascorbic acid Eq·100 g–1 fresh weight for DPPH, and between (326.06and 701.13) mg ascorbic acid Eq·100 g–1 fresh weight for FRAP. Totalphenols, DPPH and FRAP showed close association; however, PCA clearlycategorized the selected cultivars intotwo broad groups.All of the diverse cultivars were clustered into two clusters which couldbe exploited for future qualitative breeding programs based on average clusterdistance and can act as gene sources for making health foods. Conclusion.The importance of our findings would be significant for farmers,breeders, consumers and industries concerning food quality, diseaseprevention and healthcare.

Introduction. Red and black currants are a valuable component of a healthy diet because they are an excellent source of ascorbic acid, anthocyanins and minerals. Materials and methods. Three red currant cultivars and eight black currant cultivars were evaluated in terms of fruit quality. Some selected physicochemical characteristics such as berry weight, dry matter, soluble solids, total sugars, titratable acidity and total anthocyanins were investigated. Total anthocyanin content was measured with the pH differential absorbance method while citric, malic, tartaric and ascorbic acid were quantified by a reversed-phase HPLC method. Sodium, calcium, magnesium, iron, manganese, chromium and zinc were determined by ICP-MS following a microwave digestion, while potassium content was determined by FAAS. Results. Significant differences in the physicochemical and mineral content were detected among the cultivars. The range of total anthocyanins of the tested samples was 12.14–22.06 mg·100 g-1 (red currants) and 116.17–287.78 mg·100 g-1 (black currants). Ascorbic acid content varied between 23.23–44.62 mg·100 g-1 (red currants) and 161.58–284.46 mg·100 g-1 (black currants). Citric acid was predominant in all studied black and red currant cultivars, followed by malic and tartaric acids. Black and red currants have rich mineral composition, especially potassium, calcium and magnesium. Black currant fruits were superior to red currants with regard to calcium and magnesium content.

Introduction 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 (Ea) 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 Ea 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

Introduction. Hibiscus sabdariffa L. est une plante herbacée, vivace, localisée dans les zones tropicales et subtropicales des deux hémisphères. L’espèce est exploitée pour sa fibre et principalement pour ses calices qui sont de trois types : vert, rouge et rouge foncé. Composition. Les calices de type rouge sont les plus utilisés et se caractérisent par leur concentration élevée en anthocyanes qui peut atteindre 1,5 g·kg–1. La delphinidine 3-sambubioside et la cyanidine 3-sambubioside sont les anthocyanes majoritaires avec, respectivement, (71 et 29) % des anthocyanes totaux. Les acides organiques, minéraux et acides aminés sont présents dans les calices, feuilles et graines d’H. sabdariffa à des teneurs variables suivant la variété et la zone géographique. Utilisations. Les utilisations des différentes parties de l’H. sabdariffa sont nombreuses et variées aussi bien dans l’alimentation que dans la médecine traditionnelle. Les calices, du fait de leur concentration élevée en acides, vitamine C et surtout en anthocyanes, constituent la partie de la plante la plus valorisée. Ils sont surtout utilisés pour la production de boissons désaltérantes et tonifiantes sans alcool. Les graines d’H. sabdariffa de par leur richesse en protéine (26 %), lipides (20 %) et sucres totaux (40 %) sont très utilisées dans l’alimentation dans de nombreux pays africains. Les feuilles constituent une bonne source de nutriments et sont utilisées en Afrique pour la préparation de sauces.

Introduction. After harvest, litchi fruits (Litchi chinensis Sonn.) rapidly lose their bright red skin color. Peel browning of harvested litchi fruit has largely been attributed to rapid degradation of red anthocyanin pigments associated with the oxidation of phenolic compounds by polyphenol oxidase (PPO) and/or peroxidase (POD). An anthocyanase has been also identified in litchi peel. Our work aimed at characterizing two specific litchi varieties that differ greatly in their color and browning behavior. Materials and methods. The anthocyanins, polyphenol oxidase (PPO), peroxidase (POD) and anthocyanase in the pericarp of two litchi cultivars, Kwai May and Wai Chee, grown in Reunion Island and Spain, respectively, were studied. Results and discussion. The qualitative composition of major anthocyanins (cyanidin-3-rutinoside and cyanidin-3-glucoside) was identical for the two cultivars studied, but, quantitatively, the variety Kwai May had a lower concentration than Wai Chee (64% less) of cyanidin-3-rutinoside. This component represented more than 90% of total anthocyanins in both cultivars. The activity of PPO was 6 times greater in the variety Kwai May than in Wai Chee and the activity of POD 30 times greater. The activity of POD was greater than that of PPO in both varieties. These differences help to explain the different behaviors of the cultivars during subsequent postharvest studies.

Introduction. The peel of lychee fruit turns from its attractive bright red color to a dull brown color when the fruit starts to age. This study reports how the color change of lychee pericarp from red to brown is associated with several factors and may be reversed depending on its pH, anthocyanin content and brown pigments. Materials and methods. After transport by air transit from China to Canada, arriving 4 d after harvest, the anthocyanin, brown pigment concentrations and the pH values in the lychee (Litchi chinensis Sonn.) pericarp were determined over a period of 5 d at 25 °C and 65% RH. The macromolecular sizes of the brown pigment extract were measured in solutions between a pH of 4 and 6. Results and discussion. The acidity in the lychee pericarp decreased from a pH of 4.3 to 5.3, at the end of the 5-day period. The anthocyanins in the lychee pericarp decreased and the brown pigment increased. Polyphenol oxidase in the pericarp was active when its pH was between 4.1 and 4.6, and became less active when its pH was above 4.6. The diameter of the brown pigment molecules in the solutions increased when the pH of the solutions was increased and maintained for 5 d. The anthocyanins returned to their original redness and concentrations if they were placed in solutions with a pH value ranging between 4 and 6 for 10 min or they were placed in solutions with a pH value of 4 for 5 d. However, the anthocyanins did not return to their original redness and concentration if they were placed in solutions with a pH value ranging between 5 and 6 for 5 d. Conclusion. This study suggests that the bright red color of lychee peel could be maintained if its pericarp pH could be maintained at a pH of 4. If the pericarp pH is above 4, the reversibility of its bright red color from brown pigments is dependent on storage time.