Phytochemicals and antioxidant activity of different fruit fractions (peel,pulp, aril and seed) of Thai gac (Momordica cochinchinensis Spreng)

Three fractions (peel, pulp and aril) of gac fruit (Momordica cochinchinensis Spreng) were investigated for their phytochemicals (lycopene, beta-carotene, lutein and phenolic compounds) and their antioxidant activity. The results showed that the aril had the highest contents for both lycopene and beta-carotene, whilst peel (yellow) contained the highest amount of lutein. Two major phenolic acid groups: hydroxybenzoic acids and hydroxycinnamic were identified and quantified. Gallic acid and p-hydroxybenzoic acid were found in all fractions. Ferulic acid and p-hydroxybenzoic acid were most evident in pulp. Myricetin was the only flavonoid found in all fractions. Apigenin was the most predominant flavonoid in pulp (red), whereas rutin and luteolin gave the highest content in aril. The extracts of different fractions exhibited different levels of antioxidant activity in the systems tested. The aril extract showed the highest FRAP value. The greatest antioxidant activities of peel and pulp extracts were at immature stage, whereas those in the seed extracts increased from mature stage to ripe stage. The contents of total phenolic and total flavonoid in peel and pulp decreased during the fruit development stage (immature > ripe fruit) and subsequently displayed lower antioxidant capacity, except for the seed.     

Antioxidant properties of various solvent extracts of potato peel,sugar beet pulp and sesame cake

BACKGROUND: Growing interest in the replacement of synthetic food antioxidants by natural ones has fostered research on vegetable sources and screening of raw materials to identify new antioxidants. The food‐processing industry generates substantial quantities of phenolic‐rich by‐products that could be valuable natural sources of antioxidants. In this study the antioxidant properties and total phenolic, flavonoid and flavonol contents of three industrial by‐products, sugar beet pulp, sesame cake and potato peel, extracted with various solvents were examined. Since different antioxidant compounds have different mechanisms of action, several methods were used to assess the antioxidant efficacy of extracts. RESULTS: Among the six solvents tested, methanol gave the highest extract yield of potato peel and sugar beet pulp, while diethyl ether gave the highest extract yield of sesame cake. Methanol exhibited the highest extraction ability for phenolic compounds, with total phenolics amounting to 2.91, 1.79 and 0.81 mg gallic acid equivalent g^?1 dry weight in potato peel, sugar beet pulp and sesame cake extracts respectively, and also showed the strongest antioxidant capacity in the three assays used. All three methods proved that potato peel extract had the highest antioxidant activity owing to its high content of phenolic compounds and flavonoids. CONCLUSION: On the basis of the results obtained, potato peel, sugar beet pulp and sesame cake extracts could serve as natural antioxidants owing to their significant antioxidant activity. Therefore they could be used as preservative ingredients in the food and/or pharmaceutical industries. Copyright © 2009 Society of Chemical Industry     

Effects of thermosonication and orange by‐products extracts on quality attributes of carrot (Daucus carota) juice during storage

Effect of thermosonication on carrot juice containing peel (CJPL) and pulp (CJPP) extracts from orange at different concentration (0.5, 2.0 and 4.0 mg GAE per g extracts) of total phenolic contents (TPC) was evaluated for quality attributes. Thermosonication of juice was done at 52 °C, 6 min for CJPL and 60 °C, 5 min for CJPP (values based on our preliminary optimisation results of ultrasound process conditions of the juice) at 40 kHz and 110W. Effect of thermosonication and addition of peel and pulp extracts at highest concentration increased the TPC and antioxidant activity of the juice (P < 0.05). Highest inactivation of microorganisms and better sensory attributes was achieved in thermosonicated CJPP for 21 days. Titratable acidity, pH, browning index and viscosity were improved by thermosonication and at highest extract concentration. °Brix and total carotenoid were not significantly affected by treatments. Therefore, thermosonication at 60 °C and 4.0 mg GAE per g extract concentration of peel and pulp may be used in formulation of functional carrot juice with improved health properties.     

Utilization of Jujube Fruit (Ziziphus mauritiana Lam.) Extracts as Natural Antioxidants in Stability of Frying Oil

The effects of ultrasound-assisted, supercritical CO₂ and solvent extraction methods on antioxidant activity of Ziziphus mauritiana (Lam.) extracts were investigated using 2,2-diphenyl-1-picrylhydrazyl and β-carotene assays. Ethanol-water extract of the jujube that was obtained with ultrasound-assisted extraction had the highest antioxidant activity. Ultrasound-assisted extraction was the most effective method on extraction of phenolic compounds. The effect of ultrasound extract in stability of soybean oil was compared to synthetic antioxidants by measuring total polar compounds, carbonyl value, peroxide value, free fatty acids, oxidative stability index, and conjugated dienes and trienes values. Results showed that ultrasound ethanol-water extract at 600 ppm had a higher stabilization efficiency than commercial antioxidants butylated hydroxyanisole, butylated hydroxytoluene, and tertiary butylhydroquinone.     

不同品种李子多酚组成及抗氧化活性

为研究不同品种李子果皮、果肉多酚组成及抗氧化活性,以9个不同品种的李子(芙蓉李、巫山李、玫瑰李、红布李、黑布李、西梅李、脆红李、江安李、青李)为原料,提取游离酚和结合酚,测定其1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基清除能力和抗氧化能力(oxygen radical absorbance capacity,ORAC)值,并通过高效液相色谱分析其多酚组成。结果显示:9种李子果皮总酚含量范围为111.52~775.88 mg GAE/100 g;果肉总酚含量范围为120.65~301.91 mg GAE/100 g,其中红布李果皮、果肉总酚含量均最高,西梅李总酚含量均最低。在多酚组成上,游离酚含量显著高于结合酚,且多酚组分主要为酚酸(原儿茶酸、绿原酸、咖啡酸)。体外抗氧化结果显示:9种李子果皮、果肉多酚均具有一定的抗氧化活性,DPPH自由基清除IC50值范围为4.38~46.46μg/m L,ORAC值范围为0.24~210.50μmol TE/g,其中巫山李果肉游离酚对DPPH自由基的清除能力最强,红布李果皮游离酚ORAC值最高。     

Antioxidant activity of 4 cultivars of persimmon fruit

In this study, the antioxidant activity of persimmon fruit of 4 different persimmon cultivars cultured at Korea was evaluated. There were 3 astringent persimmon cultivars [‘Bongok’ (BO), Japanese Hatchiya; ‘Cheongdobansi’ (CB); and ‘Dogeunjosaeng’ (DJ), Japanese Tonewase] a 1 non-astringent persimmon cultivar [‘Seochonjosaeng’ (SJ), Japanese Nishimurawase] fruits. After preparing extracts of fruits according to parts (calyx, pulp, and peel) with 4 different solvents (acetone, ethanol, methanol, and water), total phenolic contents (TPC) and antioxidant activity were determined. The extracts of calyx showed significantly higher TPC and antioxidant properties than those of the other persimmon parts. The highest 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀=43.36±1.78 μg/mL) and reducing power (IC₅₀=81.93±1.18 μg/mL) were found at acetone extract of SJ calyx, while SJ pulp extracts showed relatively lower antioxidant activities. Astringent persimmons showed relatively higher antioxidant activity than non-astringent persimmons in peel and pulp parts. These results indicated that persimmons have different antioxidant activity depending on cultivars and parts.     

Evaluation of antioxidant properties of pomegranate peel extract in comparison with pomegranate pulp extract

Pomegranate is an important source of bioactive compounds and has been used for folk medicine for many centuries. Pomegranate juice has been demonstrated to be high in antioxidant activity and is effective in the prevention of atherosclerosis. In a previous study, we found that pomegranate peel had the highest antioxidant activity among the peel, pulp and seed fractions of 28 kinds of fruits commonly consumed in China as determined by FRAP (ferric reducing antioxidant power) assay. In this study, we extracted antioxidants from pomegranate peel, using a mixture of ethanol, methanol and acetone, and the antioxidant properties of the extract were further investigated as compared with the pulp extract. The contents of total phenolics, flavonoids, proathocyanidins and ascorbic acid were also measured. The results showed that pomegranate peel extract had markedly higher antioxidant capacity than the pulp extract in scavenging or preventive capacity against superoxide anion, hydroxyl and peroxyl radicals as well as inhibiting CuSO₄-induced LDL oxidation. The contents of total phenolics, flavonoids and proathocyanidins were also higher in peel extract than in pulp extract. The large amount of phenolics contained in peel extract may cause its strong antioxidant ability. We concluded that pomegranate peel extract appeared to have more potential as a health supplement rich in natural antioxidants than the pulp extract and merits further intensive study.     

Evaluation of the Antioxidant Properties of the Brazilian Cerrado Fruit Annona crassiflora (Araticum)

Annona crassiflora, known commonly as araticum, is an exotic tropical fruit consumed mainly by native people of the Brazilian Cerrado (2nd biggest biome of Brazil). In this study, pulp, seed, and peel of slight ripe and overripe fruits were extracted using ethanol and water. The extracts showed high content of total phenols and were screening for their potential as antioxidants using the in vitro model 1,1‐ dipheniyl‐2‐picryl hydrazyl (DPPH). The ethanol extracts of peel and seeds showed IC50 of 48.82 μg/mL and 31.14 μg/mL, respectively, for the slightly ripe fruits. As the ethanolic fractions of araticum showed the highest antioxidant activity, they were selected for testing of its effect on lipid peroxidation. The ethanolic extracts of slightly ripe fruits showed IC₅₀ of 4.44 μg/mL, 1.72 μg/mL, and 8.62 μg/mL for the peel, seed, and pulp, respectively. This is the 1st report on the antioxidant properties of the extracts of araticum. Owing to these properties, the studies can be further extending to exploit them for their possible application as natural antioxidant for cosmetic, supplements, and functional ingredients for food products.     

Influence of Different Extraction Media on Phenolic Contents and Antioxidant Capacity of Defatted Dabai (<Emphasis Type="Italic">Canarium odontophyllum</Emphasis>) Fruit

Dabai (Canarium odontophyllum) is a potential “functional fruit”. Future commercialization of dabai fat as healthy oil may result in the accumulation of defatted dabai as a by-product. This study was carried out to determine the total phenolics and antioxidant capacity of defatted dabai parts as a new source of functional food and nutraceutical ingredient. In this study, defatted dabai parts were extracted using different extraction media (methanol, ethanol, ethyl acetate, acetone, and water) and analyzed for total phenolics, total flavonoids, total anthocyanins, and antioxidant capacity (ABTS⁺ radical scavenging and ferric-reducing antioxidant power assays) using spectrophotometric and high-performance liquid chromatography methods. Major phenolics in defatted dabai peel extracted using methanol were catechin and epigallocatechin while in water extract, major phenolic acid was ellagic acid. Defatted dabai peel also had higher anthocyanidin content than its pulp. The peel of a defatted dabai fruit extracted using methanol contained a high total phenolics and Trolox equivalent antioxidant capacity (TEAC). Ethyl acetate extract of defatted dabai parts had the least phenolics compared in ethanol and acetone extracts. Higher total phenolics and TEAC values were observed in water extract of a defatted dabai peel than ethanol, acetone, and ethyl acetate extracts. Hence, methanol extract of a defatted dabai peel could probably be used as a natural antioxidant.     

烹饪方式对红枣多酚抗氧化活性的影响

研究了不同烹饪方式(高压蒸、煮及常压蒸、煮)对红枣枣皮、枣肉中多酚粗提物及4种存在形式酚酸部分的总酚含量及抗氧化活性的影响。采用Folin-Ciocalteu比色法测定其总酚含量、DPPH法和FRAP法分别评价其抗氧化活性。结果表明:高压蒸煮较常压处理红枣中的总酚含量较高,尤其是枣肉;常压煮制红枣的枣皮和枣肉中酚酸类化合物的总酚含量均最高。常压蒸制处理的红枣枣皮的DPPH·清除能力和总抗氧化能力均较强,而高压蒸制处理的红枣枣肉的DPPH·清除能力较强,常压煮制的红枣枣肉总抗氧化能力较强。红枣中总酚尤其是酚酸类化合物对其抗氧化活性起了很大的作用。红枣若采用高压烹饪方式,蒸制处理能较好地保存红枣中的酚类化合物及抗氧化活性;若采用常压烹饪方式,则煮制较好。     

Evaluation of Irradiation and Heat Treatment on Antioxidant Properties of Fruit Peel Extracts and Its Potential Application During Preservation of Goat Fish <Emphasis Type="Italic">Parupenaeus indicus</Emphasis>

The quenching capacities of Vitus vinifera seed extract, Citrus limon peel extract, Punica granatum peel extract, and Citrus sinensis peel extract were studied together with their antioxidant activity in goat fish (Parupenaeus indicus). The functionality of the extracts was evaluated using β-carotene-linoleic acid model system, reducing power assay, DPPH, hydroxyl, and nitrite radical scavenging assay. V. vinifera and P. granatum extract demonstrated best radical scavenging potential in all multifunctional antioxidant assays. Radical scavenging activity measured by electron paramagnetic resonance against a stable radical 1,1,-diphenyl-2-picrylhydrazil revealed radical peaks of lower intensity in antioxidant-infused samples. Compounds possessing antioxidant properties were identified from purified fruit extracts by GC–MS analysis. Treatments with these extracts increased the stability of irradiated goat fish against lipid oxidation. TBARS values for irradiated control was 4.26 ± 0.10, whereas it was 2.44 ± 0.14, 2.97 ± 0.01, 2.93 ± 0.03, 3.89 ± 0.05, and 4 ± 0.01 mg of MDS per kilogram fish for BHA, P. granatum peel, V. vinifera seed, C. sinensis peel, and C. limon peel extract-treated samples, respectively. This study also elucidated the relationship between heating temperature and irradiation dose on the antioxidant activity of extracts. Maximum antioxidant activity was observed at 150 °C heated and 10-kGy irradiated extracts. These results suggest that fruit peels will be a potential material for extracting antioxidants.     

Bioactive compounds and antioxidant potential of mango peel extract

Bioactive compounds such as polyphenols, carotenoids and anthocyanins present in fruits and vegetables are receiving increased attention because of their potential antioxidant activity. Consumption of such antioxidants offers health benefits including protection against cardiovascular diseases and cancer. Mango peel is a major byproduct obtained during the processing of mango products such as mango pulp and amchur. In the present study, the antioxidant activity of mango peel extracts was examined. Polyphenol, anthocyanin and carotenoid contents in acetone extract of peels were determined. Ripe peels contained higher amount of anthocyanins and carotenoids compared to raw peels while raw mango peel had high polyphenol content. Antioxidant activity of ripe and raw mango peels extracted in acetone was determined using different antioxidant systems such as reducing power activity, DPPH free radical scavenging activity, iron induced lipid peroxidation of liver microsomes and soybean lipoxygenase inhibition. The IC₅₀ values were found to be in the range of 1.39–5.24 μg of gallic acid equivalents. Thus, the mango peel extract exhibited good antioxidant activity in different systems and thus may be used in nutraceutical and functional foods.     

油梨品种和部位间抗氧化及乙酰胆碱酯酶抑制活性比较

研究不同品种油梨之间的多酚含量及其抗氧化和乙酰胆碱酯酶抑制活性差异,以期为油梨高价值产品开发提供理论依据。测定热研1号、福尔特、哈斯、里德4种油梨的果皮、果肉、果核3个部位乙醇提取物的总酚含量、抗氧化及乙酰胆碱酯酶抑制活性。结果显示:4种油梨3个部位的总酚含量为9.6~27.8 mg GAE/g干物质。抗氧化及乙酰胆碱酯酶抑制活性均与样品质量浓度存在剂量关系。其中里德的果皮与果核对1,1-二苯基-2-三硝基苯肼自由基、2,2’-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基清除活性以及乙酰胆碱酯酶抑制活性均较强,热研1号与福尔特的果皮、果核对·OH清除活性最强。同一品种内,果皮与果核的活性较强,果肉的活性较差。因此,在产品开发过程中应尽可能地提高果皮、果核这些不可食用部位的利用率,达到变废为宝、提高产品附加值的目的。     

红枣不同部位的抗氧化活性

为了研究红枣的抗氧化活性,以体积分数为80%的甲醇为溶剂,测定了红枣不同部位(枣肉、枣核和枣皮)甲醇提取液中的总酚含量和总黄酮含量,采用体外法,评价了红枣甲醇提取物的总抗氧化能力及对DPPH.和羟基自由基(.OH)的清除能力。结果表明:红枣枣皮甲醇提取液的总酚和总黄酮含量显著高于枣肉和枣核,其总抗氧化能力、对DPPH.和.OH的清除率也较高,且红枣各甲醇提取液的总酚、总黄酮含量与其抗氧化活性具有一定的相关性。     

Antioxidant capacities of phenolic compounds and tocopherols from Tunisian pomegranate (Punica granatum) fruits

This article aims to determine the phenolic, tocopherol contents, and antioxidant capacities from fruits (juices, peels, and seed oils) of 6 Tunisian pomegranate ecotypes. Total anthocyanins were determined by a differential pH method. Hydrolyzable tannins were determined with potassium iodate. The tocopherol (α-tocopherol, γ-tocopherol, and δ-tocopherol) contents were, respectively, 165.77, 107.38, and 27.29 mg/100 g from dry seed. Four phenolic compounds were identified and quantified in pomegranate peel and pulp using the high-performance liquid chromatography/ultraviolet method: 2 hydroxybenzoic acids (gallic and ellagic acids) and 2 hydroxycinnamic acids (caffeic and p-coumaric acids). Juice, peel, and seed oil antioxidants were confirmed by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) methods. The highest values were recorded in peels with 25.63 mmol trolox equivalent/100 g and 22.08 mmol TE/100 g for FRAP and ORAC assay, respectively. Results showed that the antioxidant potency of pomegranate extracts was correlated with their phenolic compound content. In particular, the highest correlation was reported in peels. High correlations were also found between peel hydroxybenzoic acids and FRAP ORAC antioxidant capacities. Identified tocopherols seem to contribute in major part to the antioxidant activity of seed oil. The results implied that bioactive compounds from the peel might be potential resources for the development of antioxidant function dietary food.     

Total phenolic content and antioxidant capacity of extracts obtained from six important fruit residues

The extracts from kinnow peel, kinnow seeds, litchi pericarp, litchi seeds, grape seeds, and banana peel were screened for total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC), 1,1 diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, as well as reducing power. Kinnow peel extract exhibited the highest reducing power, TEAC, and DPPH free radical scavenging activity, whereas, the phenolic content of 37.4 mg GAE/g-dw was highest for grape seed extract. Banana peel extract with a low TPC showed the lowest reducing power, TEAC as well as DPPH free radical scavenging activity among the fruit residue extracts examined in the present study. Correlation analysis between the reducing power and DPPH radical scavenging ability; reducing power and ABTS radical scavenging activity; and ABTS and DPPH radical scavenging abilities showed a high degree of correlation (r² = 0.85-0.91). However, r² of 0.36, 0.66, and 0.49 between TPC and DPPH radical scavenging activity; TPC and reducing power; and TPC and ABTS radical scavenging ability, respectively, indicated that some non-phenolic compounds also contributed to the total antioxidant activity in fruit residue extracts examined in this study. To the best of our knowledge, this is the first paper presenting comprehensive data on TPC, reducing power, and antioxidant activity for the six fruit residues. This study demonstrated that kinnow peel, litchi pericarp, litchi seeds, and grape seeds, can serve as potential sources of antioxidants for use in food and pharmaceutical industry.     

Degradation kinetics of pigment,colour and stability of the antioxidant capacity in juice model systems from six anthocyanin sources

Coloured model juices with extracts from several species of commonly consumed vegetables rich in anthocyanins (eggplant peel, strawberry, grape, bilberry, red raspberry and plum peel) were studied in detail. The model juices prepared at pH 4.5 were stored in darkness for 17 weeks at 20 °C. The kinetics of anthocyanin degradation, colour and stability of the antioxidant capacity were measured during storage. The anthocyanins were determined identifying delphinidins, cyanidins, petunidins, pelargonidins, peonidins and malvidins. The extraction yields ranged from 2.3% to 13.3%. The level of anthocyanins in the model juices prepared with the extracts ranged between 4 and 158 mg L^–1. The results showed a good correlation between the anthocyanin concentration and the time of storage, with determination coefficients varying from R² = 0.9470 to R² = 0.9855. The eggplant peel, grape and plum peel anthocyanins showed the highest half‐life and D values that were higher than those of 12 and 17 weeks, respectively. The antioxidant capacity showed a high stability during the time of storage for all the model juices, showing the eggplant peel model juice the highest values.     

Antibacterial and antioxidant effects of five spice and herb extracts as natural preservatives of raw pork

BACKGROUND: The aim of this study was to find natural spice and herb extracts with antibacterial and antioxidant capacities that could be potentially used as natural preservatives in raw pork. RESULTS: The inhibitory effects of cinnamon stick, oregano, clove, pomegranate peel and grape seed extracts on Listeria monocytogenes, Staphylococcus aureus and Salmonella enterica were evaluated in raw pork at room temperature (～20 °C). The influences of these extracts on lipid oxidation in the meat were also investigated. The pH, colour parameters and TBARS (thiobarbituric acid‐reactive substances) values were tested periodically. The results showed that all five natural extracts, especially clove, were effective against the bacteria. During storage the colour parameters of the extract‐treated pork samples changed slightly, in comparison with significant changes in the control. Treatments with these extracts increased the stability of raw pork against lipid oxidation. Clove was the most effective for retarding lipid oxidation and presented the highest antioxidant activity in raw pork. CONCLUSION: This study suggests that the tested extracts, especially clove, have potential as natural preservatives to reduce numbers of pathogenic bacteria, colour degradation and lipid oxidation in raw pork. Copyright © 2009 Society of Chemical Industry     

Pilosocereus arrabidae (Byles & Rowley) of the Grumari sandbank,RJ, Brazil: Physical,chemical characterizations and antioxidant activities correlated to detection of flavonoids

The fruits of Pilosocereus arrabidae (Cactaceae) is found in the Grumari shoal, located in the Rio de Janeiro state, Brazil and, several studies have already highlighted the importance of consuming its fruits. This work aims to investigate the physical, mineral and physicochemical properties of its fruits as well as to establish the knowledge about their chemical constituents and antioxidant properties. The peel (Pe) and pulp (Pu) extracts were obtained by maceration with the following solvents: hexane (HX), dichloromethane (DCL), ethyl acetate (EAC) and ethanol 70% (ET). The extracts were analyzed by Gas Chromatography coupled to Mass Spectrometry (GC–MS) and, by High Performance Liquid Chromatography (HPLC–DAD and HPLC–MS) for its chemical investigation. For the antioxidant activity investigations the ORAC, DPPH and ferrous ion chelating capacity (FICC) tests were performed. As results, we found higher yields for peels (72%) compared to pulps (28%). By the physical–chemical analyses we point out the fruits as a good source of fiber (pulp: 6.01 mg/100 g; peel: 8.02 mg/100 g). The minerals were analyzed by the method of issuing flames and indicated high levels of selenium (DRI for pulp and peel: 147%) and manganese (DRI pulp: 97.69% and DRI peel: 269.56%). The total flavonoid contents of the fruits performed by HPLC–DAD presented 0.45 μg equiv. in quercetin/mL of peel EAC extract and 0.25 μg equiv. in rutin/mL of pulp EAC extract. The antioxidant activities by the ORAC, FICC and DPPH methods indicated that the ET extracts showed antioxidant activities above the standards adopted for the tests. Among these, we highlight the ET extract of the pulp with EC₅₀ of 17.57 ± 0.27 μg/mL, lower than Ginkgo biloba EGB761® (23.40 ± 0.04 mg/mL). By the FICC test the EAC extract of the peel and pulp showed 70.0% and 53.4% activity, respectively, at 500 mg/mL, higher than the standard quercetin (50.0%). By the HPLC–DAD and HPLC–MS methods there were detected, for the first time on this species, the presence of the following flavonoids on the EAC extracts: quercetin, rutin, catechin, dihydrokaempferol, quercetin 3 or 4′-O-glucoside, kaempferol and isorhamnetin. By the GC–MS analysis there were detected on the DCL extracts saturated fatty acids (palmitic and stearic) and, on the HX extracts, methylated sugars (peel) and menthol (pulp). To sum up, the fruits of P. arrabidae display antioxidant potential correlated to flavonoid presence, and, high levels of selenium, manganese and fibers, characteristics that can promote beneficial effects on human health.     

Antioxidant capacity of methanolic and water extracts prepared from food‐processing by‐products

This study aims to evaluate the antioxidant capacity of mango peel, roselle seed, okara (by‐product of soya milk industry), cocoa shell and pink guava (by‐product of pink guava industry) in comparison to 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid (Trolox). The β‐carotene bleaching, 1,1‐diphenyl‐2‐picrylhydrazyl and reducing power assays were used to determine the antioxidant capacity of selected by‐products by measuring the absorbance at 470, 520 and 700 nm, respectively. The results showed that methanolic extracts of pink guava and cocoa shell exhibited the highest antioxidant activity and free radical scavenging activity compared to other studied samples. Roselle seed water extract exhibited the highest antioxidant activity and free radical scavenging when extracted with water. Pink guava possessed the highest reducing power in methanolic extract at a concentration of 0.16 mg mL^?1. At the same concentration, mango peel exhibited the highest reducing power when extracted with water. The present study shows that pink guava, roselle seed and cocoa shell are potential sources of antioxidant components that can be exploited as food preservative agents or nutraceuticals. Copyright © 2006 Society of Chemical Industry