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     

果皮中酚类物质含量、抗氧化活性及在体外消化过程中成分的变化

从21 种果皮中筛选出总酚、总黄酮含量较高的果皮,并选择1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、2,2’-联氨-双-3-乙基苯并噻唑啉-6-磺酸（2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS）阳离子自由基清除力评价其抗氧化活性。对筛选出酚类物质含量高且抗氧化活性强的果皮进行体外模拟胃肠液消化,研究不同消化时间对总酚、总黄酮释放量的影响,并通过透析袋模拟肠道的吸收作用,考察其生物利用率,同时利用超高效液相色谱-二极管阵列检测器/电喷雾飞行时间质谱（ultra performance liquid chromatography-diode array detector/electrospray ionization-time of fight-mass spectrometry,UPLC-DAD/ESI-TOF-MS）研究模拟胃肠液消化前后酚类物质变化。结果表明：21 种果皮中石榴皮（总酚含量为（58.09±0.46）mg/g、总黄酮含量为（47.50±0.39）mg/g）和山竹皮（总酚含量为（52.09±1.52）mg/g、总黄酮含量为（36.07±0.46）mg/g）中酚类物质含量较高;石榴皮的抗氧化能力强于山竹皮;模拟胃液消化阶段,石榴皮中总酚和总黄酮释放量均增加,模拟肠液消化阶段总酚和总黄酮的释放量先增加后减少;与胃液消化阶段相比,肠液消化阶段总酚和总黄酮含量明显降低;生物利用率测定结果表明总酚的生物利用率在每个时间点均强于总黄酮;通过UPLC-DAD/ESI-TOF-MS从石榴皮提取物中共检测出的5 种酚类化合物（分别为α-安石榴苷、β-安石榴苷、鞣花酸己糖苷、鞣花酸脱氧己糖苷、鞣花酸）,其在胃液消化过程中损失率小于肠液消化,说明石榴皮中酚类物质在酸性环境中结构稳定。     

Antioxidant activity and total phenolic,organic acid and sugar content in commercial pomegranate juices

Pomegranate fruit and pomegranate juices (PJs) have taken great attention for their health benefits in the last years. The purpose of this study is to analyse the antioxidant activities, along with the organic acid and sugar contents of pomegranate juices sold in the Turkish markets. In the present study, we evaluated total phenolics (TPs), free radical scavenging capacity by 2,2-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing capacity of seven commercial PJs. Organic acid and sugar contents of juices were determined by capillary zone electrophoresis. The results showed that commercial pomegranate juices had markedly high total phenolic contents and antioxidant capacity. Fructose (F) and glucose (G) were found as the major sugars. The major acids were citric and malic. From the F/G ratio, organic acid profiles, TPs, and antioxidant capacity values, a possible adulteration was detected in one of the juices.     

Antioxidant capacity of different fractions of vegetables and correlation with the contents of ascorbic acid, phenolics, and flavonoids

The antioxidant capacity of different fractions of 17 vegetables were analyzed using ferric reducing antioxidant power assay (FRAP assay) after water and acetone extractions. The contents of ascorbic acid, phenolics, and flavonoids were determined and their correlations with FRAP value were investigated. The results showed that the peel or leaf fractions of vegetables were stronger than the pulp or stem fractions in antioxidant capacity based on total FRAP value. Lotus root peel was the highest and cucumber pulp the lowest in total FRAP value among the vegetable fractions analyzed. All water extracts were higher in FRAP value than the acetone extracts. The FRAP value was significantly correlated with the contents of ascorbic acid, phenolics, or flavonoids in water extracts, in which the phenolics contributed most based on multivariate regression analysis. We conclude that different vegetable fractions were remarkably different in antioxidant capacity. The phenolics are responsible mostly for the antioxidant capacity of vegetables in vitro.     

喀什甜石榴与会理青皮石榴品质及抗氧化 活性的比较

目的 比较新疆喀什甜石榴和四川会理青皮石榴两个品种的果实品质和抗氧化活性。方法 测定了这两个石榴品种的品质、糖酸含量、总花色素苷、总酚及其抗氧化能力。结果 新疆喀什甜石榴的可溶性固形物含量、籽粒色饱和度、苹果酸含量、总花色素苷含量和总酚含量均高于四川会理青皮石榴;而四川会理青皮石榴的葡萄糖含量和果糖含量则高于喀什甜石榴;喀什甜石榴和会理青皮石榴籽粒的总抗氧化能力分别为211.25 U和178.97 U;DPPH自由基清除率分别为0.87和0.82;石榴籽粒中抗氧化活性分别与总酚、总花色素苷成正相关。结论 两个石榴品种在果实品质和抗氧化活性方面各有特点,这为石榴品种的品质评价和果实加工利用提供了参考依据。     

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.     

石榴皮提取物对生猪肉饼品质的影响

研究石榴皮提取物的抗氧化性能及不同质量分数（0.01%、0.05%和0.10%）石榴皮提取物的添加对生猪肉 饼pH值、蒸煮损失、色差和冷藏过程中脂肪及蛋白氧化的影响。结果表明：石榴皮提取物富含多酚和黄酮,其总 抗氧化能力、自由基清除能力、Fe2＋螯合能力随石榴皮提取物质量分数增大而增强;石榴皮提取物的添加对生猪肉饼的 pH值和蒸煮损失率无显著影响,但对生猪肉饼的亮度值、红度值有一定的负面作用;石榴皮提取物能有效抑制生猪肉 饼冷藏过程中氢过氧化物、丙二醛及蛋白羰基生成,且质量分数越高抑制效果越好,整体效果优于丁基羟基茴香醚。     

Quality and antioxidant properties of a reduced-sugar pomegranate juice jelly with an aqueous extract of pomegranate peels

In the present study, the production of a reduced-sugar pomegranate juice jelly supplemented with an aqueous extract of pomegranate peel (PE) is described. Influence of different carbohydrate polymers (guar (G), xanthan (X) and tragacanth (T) gums) on rheological properties was studied. Combination GXT presented the most similar rheological behaviour to commercial jelly. Jelly (J) and jelly with PE (JE) were stored at 4 °C over an 8 week period for physical, chemical, antioxidant, microbiological and sensory analysis. J and JE showed similar values for °Brix, colour and Aw, though the pH of JE was lower than J. Thiol and phenolic compounds were higher in JE than in J. Antioxidant activity (radical scavenging activity and autoxidation of linoleic acid) was higher in JE than in J at 0 weeks, and were decreasing with time. Pomegranate juice with additives was generally less accepted than J and JE.     

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.     

刺葡萄皮醇提物和不同洗脱组分抗氧化成分及活性

以酸化甲醇为溶剂对刺葡萄皮进行超声波辅助提取,并用大孔树脂进行分离得到5 种不同洗脱组 分,研究刺葡萄皮醇提物和不同洗脱组分的活性成分及抗氧化能力。结果表明,刺葡萄皮含有较高含量的 多酚（1.836 mg/g mf）、黄酮（0.874 mg/ g mf）、VC（3.567 mg/g mf）、丹宁（3.578 mg/g mf）和花青素 （2.970 mg/g mf）,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、 2,2’-二氮-双（3-乙基苯并噻唑-6-磺酸）二铵盐自由基（2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) radical, ABTS＋·）清除能力、铁离子还原能力（ferric reducing antioxidant power,FRAP）分别为22.325、17.595、 26.487 μmol TE/g mf。在5 种组分中以水解吸组分活性成分含量最高,其多酚、黄酮、VC、丹宁和花青素含量分别 为0.876、0.116、1.577、1.576 mg/g mf和1.330 mg/g mf,其DPPH自由基、ABTS＋·清除能力和FRAP分别为3.636、10.109、 13.415 μmol TE/g mf,相关性分析表明抗氧化活性与活性成分花青素、丹宁、VC含量呈强相关关系,表明抗氧化活性可 能主要由这3 种活性物质贡献。本研究结果表明,刺葡萄皮有潜力作为膳食补充抗氧化物质的主要来源。     

Antioxidant and antimicrobial activity of pomegranate peel extract improves the shelf life of chicken products

The antioxidant and antimicrobial potential of pomegranate peel and seed extract was investigated. Pomegranate peel extract (PE) showed excellent antioxidant activity while the seed extract (PS) did not have any significant activity. The IC₅₀ value of PE for 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging was 4.9 μg mL^–1 while that of Butylated hydroxy toluene was 21.2 μg mL^–1, indicating that it was a stronger antioxidant. The efficacy of PE in scavenging hydroxyl and superoxide anion radical was also very high. It also had good reducing power and iron chelation capacity. PE showed good antimicrobial activity against Staphylococcus aureus and Bacillus cereus having minimum inhibitory concentration of 0.01%. Pseudomonas could be inhibited at a higher concentration of 0.1% while it was ineffective against Escherichia coli and S. typhimurium. Addition of PE to popular chicken meat products enhanced its shelf life by 2–3 weeks during chilled storage. PE was also effective in controlling oxidative rancidity in these chicken products.     

Comparison of thermal and non-thermal extraction methods on free and bound phenolics in pomegranate peel

Pomegranate peel is a valuable byproduct for phenolic extraction. However, comprehensive analysis on novel extraction methods is lacking. In this study, free and bound phenolics, extracted by thermal (heating) and non-thermal methods (conventional solvent, high pressure, and ultrasound), were systematically compared by UHPLC-QTOF-MS and UPLC-QQQ-MS. The total content of free phenolics, approximately 10 times to that of bound phenolics, showed no significant difference across different extraction methods. The highest yield of bound phenolics was obtained by heating and high-pressure methods and the composition was closely dependent on the degree of alkaline hydrolysis. Many of bound phenolics obtained by thermal extraction were small molecules. Meanwhile, a greater proportion of larger compounds were obtained by high-pressure extraction, indicating that high pressure was gentler than thermal extraction. Genistin, nicotiflorin and myricetin-3-galactoside were first reported in pomegranate peel. This study provides a solid foundation for purposeful extraction of phenolics from pomegranate peels for industry.     

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.     

Antioxidant properties and phytochemical composition of China-grown pomegranate seeds

Four cultivars of Shanxi-grown pomegranate seeds were investigated for their phytochemical composition and antioxidant properties. Pomegranate seed oils were extracted and analysed for their fatty acid profiles, and tocopherol and carotenoid contents. The defatted flours were extracted with 50% acetone or 80% methanol, and evaluated for levels of phenolics, flavonoids and proanthocyanidins, and scavenging capacities against DPPH and ABTS⁺ and their ferric ion reducing abilities. Pomegranate seed oil was rich in punicic acid (73.5-78.8 g/100 g oil) and total tocopherols (5.3-12.0 μmol/g). The 50% acetone and 80% methanol were appropriate solvents for extraction of total phenolic and total flavonoid, respectively. The four cultivars were significantly different in levels of phenolics, flavonoids, proanthocyanidins and their antioxidant properties (P < 0.05), generally flowing an order: Suanshiliu > Tianhongdan > Sanbaitian ≈ Jingpitian. This study will assist in the cultivar selection of the above pomegranate seeds for commercial production to meet the market demand.     

成熟期对冬枣多酚含量及其抗氧化活性的影响

研究了全绿、绿白、半红和全红四个成熟期冬枣果实的果皮和果肉中游离态、酯化态和结合态的酚含量以及其总抗氧化能力、清除DPPH自由基和铁还原能力的变化.结果表明,冬枣果实酚类物质主要以游离态和酯化态形式存在于果皮当中,全红期果皮以结合态为主.冬枣果皮中游离态和酯化态酚类物质对总抗氧化能力、清除DPPH自由基和铁还原能力起主要作用.半红期冬枣果实酚含量最多以及其抗氧化活性最为突出.     

火龙果不同部位发酵后活性成分含量和抗氧化活性

以红心火龙果和白心火龙果为原料,测定不同种类和部位火龙果(红心火龙果果肉,red flesh,RF;白心火龙果果肉,white flesh,WF;红心火龙果果皮,red peel,RP;白心火龙果果皮,white peel,WP)发酵液中总酚、总黄酮含量及抗氧化活性(总抗氧化能力、还原能力和羟自由基清除能力),考察酚类物质含量与抗氧化活性的相关性。结果表明:不同种类和部位火龙果发酵液中总酚、总黄酮含量及抗氧化活性存在显著性差异,且RP发酵液表现出最高的总酚(636.63 mg/L)、总黄酮含量(452.42 mg/L)及最强的总抗氧化能力(相当于V_C浓度169.32 mg/L)、还原能力(140.29 mg/L)和羟自由基清除能力(96.65%);总酚、总黄酮含量与总抗氧化能力、还原能力和羟自由基清除能力之间呈正相关,表明总酚类物质是火龙果中抗氧化成分。     

Extraction modeling and activities of antioxidants from pomegranate marc

To develop value-added antioxidants from the peel and seeds of pomegranate marc, a by-product after pomegranate juice processing, the effects of drying before extraction and processing parameters on the extraction kinetics and product properties were systematically studied using water as an environmental friendly solvent for the extraction. The results showed that the drying process did not significantly affect the yield, content, and activity of antioxidants from either the peel or seeds. The antioxidants extracted from the peel had higher yield and content than those from the seeds. The yield and content of antioxidants increased with reduced particle size and increased water/sample ratio and temperature, but antioxidant activity was low when extraction temperature was high. By considering the antioxidant activity and operation cost, the recommended extraction conditions were peel particle size of 0.2 mm, water/peel ratio of 50/1 (w/w), temperature of 25 °C, and extraction time of 2 min, which gave the high antioxidant yield (11.5%) and content (22.9%), and DPPH scavenging activity of 6.2 g/g. Kinetic models were successfully developed for describing the extraction processes with different processing parameters.     

Enrichment of Functional Properties of Ice Cream with Pomegranate By‐products

Pomegranate peel rich in phenolics, and pomegranate seed which contain a conjugated fatty acid namely punicic acid in lipid fraction remain as by‐products after processing the fruit into juice. Ice cream is poor in polyunsaturated fatty acids and phenolics, therefore, this study was conducted to improve the functional properties of ice cream by incorporating pomegranate peel phenolics and pomegranate seed oil. Incorporation of the peel phenolics into ice cream at the levels of 0.1% and 0.4% (w/w) resulted in significant changes in the pH, total acidity, and color of the samples. The most prominent outcomes of phenolic incorporation were sharp improvements in antioxidant and antidiabetic activities as well as the phenolic content of ice creams. Replacement of pomegranate seed oil by milk fat at the levels of 2.0% and 4.0% (w/w) increased the conjugated fatty acid content. However, perception of oxidized flavor increased with the additional seed oil. When one considers the functional and nutritional improvements in the enrichment of the ice cream together with overall acceptability results of the sensory analysis, then it follows from this study that ice creams enriched with pomegranate peel phenolics up to 0.4% (w/w) and pomegranate seed oil up to 2.0% (w/w) could be introduced to markets as functional ice cream. Enrichment of ice creams with pomegranate by‐products might provide consumers health benefits with striking functional properties of punicalagins in pomegranate peel, and punicic acid in pomegranate seed oil.     

Supplementation effects of pomegranate by-products on oxidative status,metabolic profile,and performance in transition dairy cows

Recent studies demonstrated a high antioxidant capacity for pomegranate components due to their rich bioactive compounds, such as conjugated fatty acids and phenolics. The objective of the present study was, therefore, to assess whether pomegranate seed or pomegranate seed pulp (peel + seed) supplementation could be effective to improve antioxidant status, and hence metabolic profile and performance in periparturient dairy cows. After a 1-wk pretreatment period, Holstein cows (primiparous n = 12, multiparous n = 18) were assigned to 3 dietary treatments from 25 d before expected calving through 25 d postcalving. The dietary treatments included (1) control (CON); (2) diet supplemented with pomegranate seeds (PS; 400 g/cow per day); and (3) diet supplemented with pomegranate seed pulp (PSP; 400 g of seeds/cow per day + 1200 g of peels/cow per day). Compared with CON, supplementation with either PS or PSP had no effects on dry matter intake, rumen fermentation, and plasma concentrations of cholesterol, total protein, globulin, and aspartate amino transferase, but enhanced plasma total antioxidant activity, and lowered triacylglycerol, free fatty acids (FFA), and β-hydroxybutyrate at both pre- and postpartum periods. Plasma concentration of glucose, albumin, malondialdehyde (MDA) and blood superoxide dismutase (SOD) activity were not affected by dietary treatments at prepartum, whereas SOD activity increased and glucose, albumin, MDA, and FFA-to-albumin ratio decreased by feeding both by-products at postpartum period. In contrast to PS, supplementing PSP resulted in a greater decrease in plasma glucose and triacylglycerol concentration and higher increase in SOD activity. Energy- and fat-corrected milk yields were higher in cows fed PSP diet compared with those fed CON or PS diets, but content of milk fat, protein, and lactose were similar across the dietary treatments. These findings indicated that dietary pomegranate by-products supplementation, in particular PSP, could improve antioxidant status, which was associated with a decline in lipid oxidation (FFA and β-hydroxybutyrate) and peroxidation (MDA) and an enhancement in glucose utilization as well as fat-corrected milk yield.