Antioxidant capacity, phenolic content and vitamin C in pulp, peel and seed from 24 exotic fruits from Colombia

Twenty-four exotic Colombian fruits were evaluated for antioxidant activity and total soluble phenolics (TP) (edible part, seed and peel) and ascorbic acid content (edible part). The antioxidant activities were evaluated by ABTS (free radical-scavenging capacity) and FRAP (ferric reducing antioxidant power) methods. The ABTS, FRAP, TP and ascorbic acid values in the edible part were 3.25 to 175 ??M Trolox equiv/g fresh weight (FW), 6.29 to 144 ??M Trolox equiv/g FW, 15.7 to 1018 mg gallic acid equiv/100 g FW, and 0.53 to 257 mg ascorbic acid/100 g FW respectively. There were positive correlations between antioxidant activity (assessed by both ABTS and FRAP) and TP and ascorbic acid with the FRAP and ABTS methods. The edible part of banana passion fruits (P. tarminiana and P. mollisima) exhibited the highest values of antioxidant activity and total phenolics, while the highest level of ascorbic acid was recorded in the edible part of guava apple and cashew. The seeds with the highest values of antioxidant activity and total phenols were cashew, algarrobo, arazá and coastal sapote, while the peel of coastal sapote and algarrobo had the highest values of antioxidant activity and total phenolics. To the best of our knowledge, this paper reports the first evaluation of pulp, seed and skin of Colombian tropical fruits with a view to their knowledge utilization for the development of novel functional food products.     

Preliminary characterisation of cornelian cherry (Cornusmas L.) genotypes for their physico-chemical properties

Fruit weight, antioxidant capacity, total anthocyanins, total phenolics, ascorbic acid, soluble solid content (SSC), reducing sugar and acidity of a number of selected cornelian cherry (Cornusmas L.) genotypes of varied pigmentation were investigated. Two methods, namely β-carotene bleaching and ferric reducing antioxidant power (FRAP) were used to determine total antioxidant capacity, while Folin–Ciocalteu reagent was used to determine total phenols. Fruit weight, SSC and ascorbic acid content of genotypes were 2.09–9.17; 12.53–21.17% and 29–112 mg/100 g, respectively. Antioxidant activity and total phenolic content varied among genotypes and 44-18 genotype had the highest antioxidant capacity using both methods. This genotype also had the highest total phenolic (74.8 mg GAE/g DW) and total anthocyanin (115 mg cyanidin-3-glucoside equivalents /100 g FW) content. There are linear relationships between antioxidant capacities and total phenols. The present study demonstrates the potential of certain cornelian cherry genotypes, notably 44-18, for improvement of nutritional value through germplasm enhancement programmes.     

Quantitative analysis and free-radical-scavenging activity of chlorophyll,phytic acid,and condensed tannins in canola

Seeds, meals and cakes of 27 canola (Brassica napus L.) varieties and one Indian mustard (Brassica juncea L.) sample were investigated for chlorophyll, phytic acid and condensed tannin content. The DPPH free-radical-scavenging potential of minor components was also investigated. Chlorophyll contents ranged from 2.57 to 16.95, 5.38 to 8.52 and 1.15 to 6.19 mg/kg for canola seeds, cakes and meals, respectively. A positive correlation (R² = 0.99) was found between the oil and chlorophyll contents. Phytic acid contents were 2.16–3.75, 3.15–3.28 and 2.07–3.62 g/100 g for canola seeds, cakes and meals, respectively. The corresponding values for condensed tannins were 0.46–1.53, 1.12–1.32 and 0.59–1.19 g/100 g. These components showed good DPPH-scavenging activity with phytic acid having the highest effect followed by condensed tannins and chlorophyll. This information will be helpful in selecting varieties with appropriate content of these components for further application.     

Optimization of phenolics and dietary fibre extraction from date seeds

This work was conducted to optimise extraction conditions of phenolics and dietary fibre from date seeds. The effects of solvent to sample ratio, temperature, extraction time, number of extractions and solvent type on phenolic extraction efficiency were studied. At two-stage extraction, each stage 1 h duration at 45 °C with a solvent to sample ratio of 60:1, is considered optimum. Acetone (50%), and butanone were the most efficient solvents for extraction and purification, increasing the yield and phenolic contents of seed concentrate to 18.10 and 36.26 g/100 g, respectively. The total dietary fibre of seeds (57.87 g/100 g) increased after water and acetone extractions to 83.50 and 82.17 g/100 g, respectively. Nine phenolic acids (free and liberated) were detected in seeds with p-hydroxybenzoic (9.89 mg/100 g), protocatechuic (8.84 mg/100 g), and m-coumaric (8.42 mg/100 g) acids found to be among the highest. After extraction and purification, total phenolic acid content increased significantly from 48.64 to 193.83 mg/100 g. Protocatechuic, caffeic and ferulic acids were the major phenolic acids found in the concentrates. Based on this study, we believe date seed concentrates could potentially be an inexpensive source of natural dietary fibre and antioxidants and possibly used as a functional food ingredient.     

Sugars,organic acids,phenolic composition and antioxidant activity of sweet cherry (Prunus avium L.)

Sugars, organic acids, phenolics and anthocyanins in fruits of 13 sweet cherry cultivars: Badascony, Burlat, Early Van Compact, Fercer, Fernier, Ferprime, Lala Star, Lapins, Noire de Meched, Sylvia, Vesseaux, Vigred (red-coloured) and Ferrador (bi-coloured) were quantified by HPLC. Sweet cherry cultivars of different pomological characteristics and different time of ripening were evaluated sensorily. Cultivars were evaluated for their total phenolic content and antioxidant activity. The sum of sugars (glucose, fructose, sucrose and sorbitol) ranged from 125 to 265 g/kg fresh weight (FW) and the sum of organic acids (malic, citric, shikimic and fumaric) ranged from 3.67 to 8.66 g/kg FW. Total phenolic content ranged from 44.3 to 87.9 mg gallic acid equivalents/100 g FW and antioxidant activity ranged from 8.0 to 17.2 mg ascorbic acid equivalent antioxidant capacity mg/100 g FW. The correlation of antioxidant activity with total phenolics content and content of anthocyanins was cultivar dependent.     

Chemical composition,anthocyanins, non-anthocyanin phenolics and antioxidant activity of wild bilberry (Vaccinium meridionale Swartz) from Colombia

Berries of Vaccinium meridionale Swartz native to Colombia were analysed for chemical composition, total phenolic content, anthocyanin content, and antioxidant activity. In addition, high-performance liquid chromatography with photodiode array detection (HPLC–DAD) and HPLC-electrospray ionisation tandem mass spectrometry (ESI–MS/MS) were used to determine anthocyanin and phenolic composition. Anthocyanin content was 329.0 ± 28.0 mg cyanidin 3-glucoside equivalents/100 g (fresh weight) FW and total phenolic content was 758.6 ± 62.3 mg gallic acid equivalent/100 g FW. Cyanidin 3-galactoside was the major anthocyanin while the most abundant non-anthocyanin phenolic was chlorogenic acid.     

Effect of semi-drying on the antioxidant components of tomatoes

Three tomato cultivars (Excell, Tradiro, and Flavourine) grown under hydroponic conditions in a commercial greenhouse in New Zealand were semi-dried at 42 °C. The semi-dried tomatoes contained low levels of 5-hydroxymethyl-2-furfural and were significantly (p < 0.05) darker (lower CIELAB L* values) and had a higher mean a*/b* value (1.6) than the fresh tomatoes (1.2). The mean total phenolics in the semi-dried samples of tomatoes (300 mg gallic acid equivalents, GAE/100 g dry matter (DM)) was significantly lower than that of fresh tomatoes (404 mg GAE/100 g DM). The mean total flavonoid, and lycopene contents in the fresh samples (206 mg rutin equivalents/100 g DM, 63 mg/100 g DM, respectively) also showed a significant decrease after semi-drying (179 mg rutin equivalents/100 g, 54 mg/100 g DM, respectively). Ascorbic acid content in fresh tomatoes (284 mg/100 g DM) decreased to 223 mg/100 g DM after drying. The total antioxidant activity of the semi-dried tomatoes (1783 μmole trolox equivalents antioxidant capacity (TEAC)/100 g DM) was significantly (p < 0.05) lower than that of the fresh samples (2730 μmole TEAC/100 g DM).     

Soybean seeds and its by-product okara as sources of dietary fibre. Measurement by AOAC and Englyst methods

The composition of soybean seeds and its by-product okara has been studied in this work. Dietary fibre was analysed by Englyst et al. method, by enzymatic–gravimetric methods of AOAC and by the quantification of the monomers obtained from the AOAC residues after acid hydrolysis (AOAC plus hydrolysis). Total dietary fibre by the enzymatic–gravimetric methods of AOAC in okara (55.48 g/100 g dry matter) is more than twice that of soybean seeds (24.37 g/100 g dry matter). The proportion IF/SF is 11 in okara and 6 in soybean seeds. Dietary fibre results from enzymatic–gravimetric AOAC methods are higher in okara and soybean seed samples than those from the Englyst method (okara: 41.14 g/100 g dry matter; soybean seeds: 15.05 g/100 g dry matter), and AOAC plus hydrolysis (okara: 44.91 g/100 g dry matter; soybean seeds: 16.38 g/100 g dry matter). In the case of the insoluble fibre from both samples, AOAC plus hydrolysis gives significantly (p < 0.001) higher values than the Englyst method, whilst for soluble fibre the opposite occurs (p < 0.001). The main monomers in soybean seeds and okara fibre are glucose, galactose, uronic acids, arabinose and xylose. The proportion of each monomer is similar in soybean seeds and okara, so the healthy properties of soybean seeds fibre are also claimed for okara.     

Determination of total phenolic and flavonoid contents in selected fruits and vegetables,as well as their stimulatory effects on mouse splenocyte proliferation

This study selected 13 fruits and vegetables to determine their total phenolic and flavonoid contents and their stimulatory effects on splenocyte proliferation from female BALB/c mice. The highest total phenolic content was observed in mulberry (1515.9 ± 5.7 mg gallic acid equivalents (GAE)/100 g fresh matter (FM)) among four selected fruit species. The highest total phenolic content was observed in a variety of red onions (310.8 ± 4.9 mg GAE/100 g FM) among nine selected vegetable species. The highest total flavonoid content was observed in mulberry (250.1 ± 6.3 mg quercetin equivalents (QE)/100 g FM) among the selected fruits. The highest total flavonoid content was observed in ceylon spinach (133.1 ± 26.2 mg QE/100 g FM) among the selected vegetables. The mulberry, strawberry and red onion demonstrated an immuno-modulatory potential via stimulating splenocyte proliferation. Bitter melon showed a significantly (P < 0.05) negative correlation with splenocyte proliferation. Their immuno-modulatory components are highly correlated with phenolics, including flavonoids. The total phenolic contents in all selected fruits and vegetables significantly correlated with splenocyte proliferation in vitro.     

Phenolics, betacyanins and antioxidant activity in Opuntia joconostle fruits

Sour prickly pears (xoconostles) are fruits from Opuntia joconostle cactus, which are cultivated in the central Mexico area. Phenolic and pigment content in various parts of O. joconostle fruits were analyzed. The antioxidant activity of a methanolic extraction and different semi-purified fractions were also evaluated by the DPPH⁺ method. Xoconostle fruits were obtained from a commercial orchard in Mexico State. Fruits were analyzed as whole fruit and each fruit part including pericarp, mesocarp and endocarp. Samples were homogenized and kept at 4 °C until sample preparation. Total phenolic content and total flavonoid content varied among the different parts of the fruit. The highest amount of phenolic compounds and total flavonoids content were found in pericarp 2.07 mg gallic acid equivalents (GAE)/g fresh weight (FW) and 0.46 mg(+)-catechin equivalents (CE)/g FW respectively. Seven phenolics were identified as protocatechuic, 4-hydroxybenzoic, caffeic, vanillic and syringic acids, rutin, and quercetin. The color of the fruit parts was mainly due to the presence of betacyanins. The betacyanin concentration was higher in the endocarp (23.03 mg betanin equivalents/100 g fresh weight) than in the pericarp and mesocarp. Betacyanins were identified by HPLC-PDA-MS as betanin, isobetanin, betanidin, isobetanidin, and phyllocactin. Methanolic extracts and semi-purified fractions A (phenolics and flavonols) and B (betacyanins) of xoconostle showed high antioxidant activity mainly in the pericarp. These results suggest that xoconostle is a rich source of antioxidant compounds such as phenolic compounds and betacyanins.     

Antioxidant activity and phenolic content of 16 raisin grape (Vitis vinifera L.) cultivars and selections

Six raisin grape cultivars and 10 new raisin grape selections were analyzed for antioxidant activity (ABTS assay) and for total and individual phenolic compounds. Samples were freeze–dried and values are reported on a dry weight basis. Antioxidant activity across the 16 samples ranged from 7.7 to 60.9 μmol Trolox/g DW, with A95-27 exhibiting the greatest activity. Total phenolic content, determined in gallic acid equivalents using the Folin–Ciocalteau assay, ranged from 316.3 to 1141.3 mg gallic acid/100 g DW and was strongly correlated (r = 0.990) with antioxidant results. Concentrations of individual phenolics were determined by HPLC. trans-Caftaric acid was the predominant compound in all samples. A95-15 contained the lowest concentration (153.5 μg/g DW) of caftaric acid, while Fiesta contained the highest concentration (598.7 μg/g DW). Selections A56-66, A95-15, and A95-27 had much higher levels of catechin (86.5–209.1 μg/g DW) and epicatechin (126.5–365.7 μg/g DW) than the other samples.     

Adding value to hard date (Phoenix dactylifera L.): Compositional,functional and sensory characteristics of date jam

Second-grade dates (with a hard texture) from three potential Tunisian cultivars (Deglet Nour, Allig and Kentichi) showed the same sugar (∼73.30–89.55 g/100 g dry matter), fibre (∼7.95–18.83 g/100 g dry matter) and total phenolics (∼280.6–681.8 mg of GAE/100 g) content as dates of high quality. Deglet Nour and Kentichi varieties were characterised by a high content of sucrose and low reducing sugar content; contrary to Allig and the majority of other date varieties tested. This work intended to add value to these raw materials by using them in jam production. The corresponding jams were characterised in terms of chemical composition, physical (texture and water retention capacities) and sensory properties. Results showed a significant effect of the date variety on the composition and physical characteristics of date jams. Indeed, Allig jam was richer in reducing sugars and was characterised by its higher firmness and water retention capacity. To test the acceptability of these new products, we compared them with quince jam (the most consumed in Tunisia). Results showed that Allig and Kentichi jams presented a higher overall acceptability. However, quince and Deglet Nour jams did not show any significant differences (P > 0.05). Results from this work revealed essential information that could promote the commercialization of dzate jam.     

Sacha inchi (Plukenetia volubilis): A seed source of polyunsaturated fatty acids,tocopherols, phytosterols,phenolic compounds and antioxidant capacity

Fatty acids (FA), phytosterols, tocopherols, phenolic compounds, total carotenoids and hydrophilic and lipophilic ORAC antioxidant capacities were evaluated in 16 cultivars of Sacha inchi (SI) seeds with the aim to valorise them and offer more information on the functional properties of SI seeds. A high α linolenic (α-Ln) fatty acid content was found in all cultivars (ω3, 12.8–16.0 g/100 g seed), followed by linoleic (L) fatty acid (ω6, 12.4–14.1 g/100 g seed). The ratio ω6/ω3 was within the 0.83–1.09 range. γ- and δ-tocopherols were the most important tocopherols, whereas the most representative phytosterols were β-sitosterol and stigmasterol. Contents of total phenolics, total carotenoids and hydrophilic and lipophilic antioxidant capacities ranged from 64.6 to 80 mg of gallic acid equivalent/100 g seed; from 0.07 to 0.09 mg of β-carotene equivalent/100 g of seed; from 4.3 to 7.3 and, from 1.0 to 2.8 μmol of Trolox equivalent/g of seed, respectively, among the evaluated SI cultivars. Results showed significant differences (p < 0.05) among the evaluated SI cultivars in the contents of ω3, ω6, antioxidant capacities and other evaluated phytochemicals. SI seeds should be considered as an important dietary source of health promoting phytochemicals.     

Carotenoid composition of Algerian date varieties (Phoenix dactylifera) at different edible maturation stages

The aim of this study was to investigate the carotenoid composition and the provitamin A value of three palm date (Phoenix dactylifera) varieties (Deglet-Nour, Hamraya and Tantebouchte) from Algeria at three different ripening stages (khallal, rutab and tamr). Chromatographic analysis showed that the major carotenoid pigment present in dates is lutein followed by β-carotene, with an evident carotenoid disappearance during ripening from the khallal to the tamr stage. The different date fruits present a total carotenoid content in the range of 61.7–167, 32.6–672, and 37.3–773 μg/100 g fresh weight (FW) in Deglet-nour, Tantebouchte and Hamraya varieties, respectively. The rutab stage of Tantebouchte showed the lowest carotenoid content of 32.6 μg/100 g FW, whereas the khallal stage of Hamraya presented the highest value, 773 μg/100 g FW, followed by Tantebouchte with 672 μg/100 g FW. Provitamin A value (due exclusively to β-carotene) increased from 0.4 to 0.5 RE/100 g in Deglet-Nour fruits, but decreased from 11.7 to 1.6 RE/100 g and from 3.9 to 0.5 RE/100 g in Tantebouchte and Hamraya fruits, respectively, during ripening. The lowest value was found at the tamr stage of the Deglet-Nour variety (0.5 RE/100 g) whereas the highest provitamin A content was found at the khallal stage of the Tantebouchte variety (11.7 RE/100 g).     

Antioxidant activity of white and black sesame seeds and their hull fractions

The total phenolic content (TPC), total antioxidant status (TAS), free radical scavenging capacity, inhibition of low density lipoprotein (LDL) cholesterol and metal chelating capacity of extracts of whole black and whole white sesame seeds and their hull fractions in 80% aqueous ethanol were investigated. The TPC of whole black sesame seeds and hull extracts were 29.9 ± 0.6 and 146.6 ± 0.6 mg catechin equivalents/g crude ethanolic extract, respectively. The corresponding values for white sesame were 10.6 ± 1.6 and 29.7 ± 0.9 mg catechin equivalents/g crude ethanolic extract. The TAS as determined by Trolox equivalent antioxidant capacity assay and expressed as Trolox equivalents was highest for black sesame hulls (65.9 ± 1.7) while white seeds showed the lowest (4.4 ± 0.6). Free radical scavenging capacity of sesame extracts (5–40 μg/mL) was measured using 2,2-diphenyl-1-picrylhydrazyl radical. The highest scavenging capacity was obtained at 40 μg/mL and was 94.9 ± 0.8, 25.1 ± 0.4, 14.4 ± 0.9 and 2.5 ± 0.4 for black sesame hulls, black sesame seeds, white sesame hulls and white sesame seeds, respectively. Inhibition of LDL oxidation at 100 ppm level was highest for black sesame hulls (96.7%) followed by those for white sesame hulls (84.6%), black sesame (78.4%) and white sesame seeds (57.3%). Sesame products displayed good ferrous ion chelating capacities, which ranged from 12% to 46% and 17% to 62% at 50 and 100 ppm levels, respectively. Results demonstrated considerable antioxidant activity of sesame products tested especially black sesame hulls.     

Study of polyphenol content in the seeds of red grape (Vitis vinifera L.) varieties cultivated in Turkey and their antiradical activity

The polyphenolic content and antioxidant capacity in the seeds of 11 red grape varieties (five international and six native) widely cultivated in Turkey were investigated. Total phenolic, total flavanol and total polymeric procyanidin content ranged from 79.2 to 154.6, 89.2 to 179.4, and 27.0 to 43.3 mg/g seed, respectively. While (+)-catechin (4.71–23.8 mg/g seed) was found as main flavanol, galloylated catechin monomer and dimeric procyanidin amounts varied between 2.89–17.2 and 0.97–2.97 mg/g seed, respectively. All seed extracts showed remarkable DPPH radical scavenging activity (EC₅₀) and oxygen radical scavenging capacity (ORAC) ranging from 2.71 to 4.62 μg/mL and 1425.9 to 3009.2 μmol Trolox equivalent/g seed, respectively. With high amount of total phenolic content and antioxidant activity, seeds of Okuzgozu, Papaz Karasi, Ada Karasi and Kalecik Karasi varieties could be evaluated as dietary supplement.     

Biological activity and chemical composition of different berry juices

Total phenolics, total anthocyanins, mineral content, radical scavenging activity and antiproliferative activity against human cancer cell lines were evaluated in fresh pressed juices of five different berries. Total phenolic content ranged from 133.0 to 260.3 mg of gallic acid equivalents/100 g of fresh weight, for red currant and black currant, respectively. Bilberry juice contained the highest amount of total anthocyanins (0.18%). Significant correlation between total phenolics content and radical scavenging activity was observed (r = −0.980; p < 0.01). All examined juices showed antiproliferative activity in dose-dependent manner with IC₅₀ ranging from 10.2 to 70.5 μl/ml. Black currant juice was the most effective inhibitor of proliferation in all cell lines tested (HeLa, Fem X, LS 174, MCF-7 and PC-3). Significant correlations of acidity and total anthocyanin content with antiproliferative activity of berry juices on HeLa cells, Fem X cells and MCF-7 cells were noticed. Berry juices are good sources of some minerals and contribute significantly to daily intake of these micronutrients.     

Antioxidant capacity,total phenolics,glucosinolates and colour parameters of rapeseed cultivars

The antioxidant capacity of twenty nine rapeseed varieties was determined by using ferric reducing antioxidant power (FRAP) and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) methods. Mean FRAP (3190–6326 μmol Trolox/100 g) and DPPH (3194–6346 μmol Trolox/100 g) values for methanolic extracts of rapeseed cultivars did not differ significantly. Moreover, the total content of phenolics (756–1324 mg sinapic acid/100 g), glucosinolates (4.2–87.5 μmol/g, respectively), erucic acid (0.0–56.1%) and colour parameters of the studied rapeseed cultivars were analysed. Antioxidant capacity determined by FRAP and DPPH methods correlated significantly with total phenolic content (TPC) in rapeseed cultivars (r = 0.9332, 0.9339, p < 0.001). Also, significant, inverse correlations were found between antioxidant capacity, total phenolics and luminosity (L^∗) or red colour intensity (a^∗) of rapeseed cultivars. Principal component analysis (PCA) allowed the rapeseed varieties to be differentiated based on their antioxidant capacities, total amounts of phenolics, glucosinolates, erucic acid and colour parameters.     

Extraction of phenolic compounds from grapes and their pomace using β-cyclodextrin

Use of aqueous cyclodextrins (CD) for recovery of selected bioactive phenolic compounds from grapes and their pomace was evaluated. When α, β and γ forms of CD were compared, β-CD was the most effective in recovering stilbenes, flavonols, and flavan-3-ols from grape pomace. The maximum quantified phenolics were obtained from the powder and the slurry of grape pomace when extracted with 2.5% (w/v) aqueous β-CD solutions at 60 °C for 12–24 h. With β-CD, total quantified phenolics obtained from the dry powder were 123 mg/100 g (DW) while from the slurry, they were 35.8 mg/100 g (FW). Incorporation of β-CD to grape mash prior to pressing for juice enhanced the recovery of phenolics in juice. Incorporation of β-CD was more effective in recovering flavan-3-ols than flavonols. Aqueous CD can effectively be used in recovering phenolics from by-products of fruit processing and therefore for functional foods and nutraceutical applications.