Comparative study on chemical composition,polyphenols, flavonoids,carotenoids and antioxidant activities of various cultivars of sweet potato

Chemical composition, polyphenols, flavonoids, carotenoids and antioxidant activities of twenty-five cultivars of sweet potato were investigated. Starch, crude protein, crude fat, total dietary fibre, reducing sugar and ash contents ranged between 51.88–69.21, 2.36–7.79, 0.24–1.11, 5.02–14.35, 1.07–9.78 and 1.95–4.29 g per 100 g dry weight (DW), respectively. Cultivars of Longshu, Pushu 32 and Qinshu No.7 (Shanxi province) displayed the highest values in total polyphenol contents (9.38, 9.11 and 8.76 mg GAE per g DW, respectively), Huangmeigui showed higher flavonoids content (2.54 mg RE per g DW), Xiangshu presented higher anthocyanin content (1.02 mg per g DW), whereas Pushu 32 had the highest β-carotene content (208.11 μg per g DW). Strong significant positive correlations were presented between antioxidant activities and total polyphenol and flavonoid contents, indicating that polyphenols and flavonoids are essential antioxidants in sweet potatoes. Among all cultivars, Pushu 32 presented the highest grey relational grade (GRG) value (0.7811), suggesting its importance as a healthy diet.     

粗毛纤孔菌(Inonotus hispidus)的鉴定及其子实体不同溶剂提取物的抗氧化活性与抑菌活性研究

采用rDNA ITS序列分析对一株野生桑黄菌(SH)进行鉴定,研究了其子实体不同溶剂(70%乙醇、甲醇、乙酸乙酯、氯仿)提取物中的总黄酮、总多酚与抗氧化活性的相关性以及4种提取物的抑菌活性。结果表明:该野生桑黄菌为粗毛纤孔菌(Inonotus hispidus),其子实体不同溶剂提取物的总黄酮、总多酚、抗氧化活性和抑菌活性存在显著差异,其中甲醇提取物中的总黄酮和总多酚含量最高,分别为(14.78±0.16)mg芦丁/g和(67.42±1.41)mg没食子酸/g;70%乙醇提取物的和DPPH·清除能力ABTS+·清除能力最强,分别为(43.83±0.03)和(116.08±0.24)mg Trolox/g,甲醇提取物的铁离子还原能力最强,为(126.24±3.02)mg Trolox/g;总多酚和总黄酮含量与FRAP法之间呈极显著正相关(p<0.01),总多酚与ABTS+·清除能力和DPPH·清除能力之间呈显著相关(p<0.05),而总黄酮与ABTS+·清除能力和DPPH·清除能力不相关;70%乙醇提取物和甲醇提取物的抑菌效果最好,其中对草莓灰葡萄孢霉的抑菌效果最好(抑菌圈直径>30 mm),其次是对金黄色葡萄球菌(抑菌圈直径>15 mm),对大肠杆菌的抑菌效果最差(抑菌圈直径>10 mm)。研究发现粗毛纤孔菌甲醇提取物的总多酚、总黄酮含量最高,抗氧化活性和抑菌活性最强,是天然抗氧化剂的良好来源。     

荔枝果实不同部位提取物的总黄酮含量及其稳定性、抗氧化、美白活性分析

目的 探究荔枝果实不同部位多酚提取物（果肉、鲜干果核、鲜干果壳）中总黄酮含量及其稳定性、抗氧化及美白活性。方法 通过亚硝酸钠显色法测定荔枝果实不同部位多酚提取物中的黄酮类物质含量,并以紫外分光光度法测定其对1,1-二苯基-2-苦基肼(1,1-diphenyl-2-picrylhydrazyl, DPPH)自由基的清除能力、稳定性（温度、pH及光照）及对酪氨酸酶的抑制活性。 结果 荔枝果实不同部位多酚提取物中均有较高的总黄酮含量,其中荔枝果肉多酚中黄酮占比最高为93.24%;其DPPH抗氧化活性顺序是荔枝果肉＞鲜荔枝核＞干荔枝核＞鲜荔枝壳＞干荔枝壳;对酪氨酸酶抑制能力分别是：荔枝果肉＞干荔枝核＞鲜荔枝核＞鲜荔枝壳＞干荔枝壳,其中荔枝果肉与干荔枝核的半抑制浓度(half maximal inhibitory concentration, IC50) 分别为0.197与0.241,均优于熊果苷(IC50为0.343)。在同等温度、pH、自然光条件下,荔枝果实总黄酮稳定性顺序分别是干荔枝壳＞干荔枝核＞鲜荔枝壳＞鲜荔枝核＞荔枝果肉;结论 荔枝果实不同部位多酚提取物均具有一定DPPH抗氧化活性、稳定性与酪氨酸酶抑制活性,且其DPPH抗氧化活性和酪氨酸酶抑制活性均与其总黄酮含量和成分相关。荔枝果肉和荔枝壳、荔枝核等废弃物均可成为天然抗氧化剂与美白成分的原料来源,为拓展荔枝果实在食品及日化行业的应用提供参考。     

Fracture Resistance of Cashew Nuts as Influenced by Pre-Shelling Treatment

The fracture resistance of raw and pre-treated cashew nuts during uni-axial compressive loading was investigated. Cashew nut samples were subjected to two pre-shelling treatments, namely: steam boiling and roasting in hot cashew nut shell liquid. Two loading rates of 2.5 and 50 mm/min and two loading orientations (longitudinal and transverse) were considered for fracture resistance of pre-treated cashew nuts using a 50 kN capacity Instron testing machine. The data obtained were subjected to analysis of variance. The average values at 2.5 mm/min were 342 and 318 N for raw nuts, 321 and 242 N for roasted nuts, and 341 and 309 N for steam boiled nuts during longitudinal and transverse loading, respectively; whereas corresponding values at 50 mm/min were 784 and 763 N for raw nuts, 517 and 464 N for roasted nuts, and 436 and 398 N for steam boiled nuts, respectively. In each of the pre-treatment methods and loading rates, more force was required to crack cashew nuts during longitudinal loading than transverse loading; and for each loading rate, pre-treated nuts generally required less force than raw nuts.     

14 种海棠果实多酚种类及体外抗氧化活性分析

目的：评价14 种海棠果实多酚、黄酮的组成及体外抗氧化活性。方法：取14 种海棠果实,用清除1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-（2,4,6-trinitrophenyl）hydrazyl,DPPH）自由基、2,2’-联氮-双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azinobis-（3-ethylbenzthiazoline-6-sulphonate））自由基（ABTS+•）和铁还原能力（ferric ion reducing antioxidant power,FRAP）法分析其体外抗氧化活性,Folin-Ciocalteau法测其多酚含量,高效液相色谱（high performance liquid chromatography,HPLC）分析其酚类物质的组成与含量,相关系数法分析多酚、黄酮与抗氧化活性间的相关性,并对14 种海棠的检测结果进行主成分分析和聚类分析。结果：14 种海棠果实的多酚含量为62.96～287.86 mg GAE/100 g鲜质量,黄酮含量为83.77～604.11 mg RE/100 g鲜质量。其中,贴梗海棠的多酚和黄酮含量最高,抗氧化活性也最高,垂丝海棠次之。HPLC检测出绿原酸、表儿茶素、芦丁和根皮苷等13 种成分。多酚、黄酮含量与抗氧化活性呈显著正相关。以酚类物质 种类和含量为依据,可将这14 种海棠聚为3 类,A类中绿原酸含量较高,B类中儿茶素、芦丁、根皮苷含量较高,C类中表儿茶素、金丝桃苷含量较高;含香草酸的海棠也被划分在C类中。结论：14 种海棠中多酚类物质含量丰富,贴梗海棠多酚含量和抗氧化活性最高,垂丝海棠次之,是较好的开发功能性食品的资源。     

Walnuts and almonds as model systems of foods constituted by oxidisable,pro-oxidant and antioxidant factors

Walnuts and almonds were selected as complex model systems in order to study possible interactions among oxidisable substances, pro-oxidant species and antioxidants. Lipoxygenase activities in a direct-micelle system were determined for these nuts according their globulin contents in their soluble protein fraction. Walnut lipoxygenase activity was 1.5 times higher than that of almonds. Among antioxidant compounds, hydrophilic contents were analysed in these nuts, hence, extractable, hydrolysable and condensed phenolic compound fractions were determined as well as lipophilic phenolic concentration corresponding to tocopherol fraction. Extracts of brown skins and whole walnuts have significantly higher phenolic contents than those of almonds. Radical scavenging activities of phenolic extracts were measured. Besides, the experiments demonstrated the ability of all nut extracts to inhibit the coupled oxidation of linoleic acid with β-carotene induced by lipoxygenase. The antioxidant substances were mainly found in nut brown skins. Walnut extracts showed higher antioxidant activity than those of almonds. Lipoxygenase pro-oxidant activity was also measured in AOT reverse micelles in conditions that model these nuts.     

Antioxidative potential of cashew phenolics in food and biological model systems as affected by roasting

The effect of different roasting conditions on antioxidant capacity of phenolics of cashew nuts and their testa was evaluated using several food and biological model systems. Total phenolic content (TPC) of cashew extracts was determined and accelerated oxidative stability of stripped corn oil in the presence of cashew extracts evaluated. In addition, the antioxidant activity of the extracts was assessed in a β-carotene-linoleate and a cooked comminuted pork model system. Inhibition of oxidation of human low density lipoprotein (LDL) cholesterol and stand breaking of supercoiled deoxyribonucleic acid (DNA) was also investigated. The TPC ranged from 5 to 791 mg gallic acid equivalents/g crude extract. In general, whole cashew nuts and testa extracts demonstrated stronger antioxidant activity than that of the cashew kernel. The inhibition percentage of LDL cholesterol oxidation, as evaluated by conjugated dines formation, of cashew kernels was higher than that of testa and was 69% at the end of 24 h incubation. Extracts of roasted cashew nut showed considerable antioxidative efficiency in model systems employed in this study, however, the effect was not significantly (P ? 0.05) different from that of their raw counterparts, except for the accelerated oxidative stability assay. The results suggest that whole cashew nut and testa extracts could be used as a potential source of natural antioxidants in certain food applications and for disease risk reduction.     

Antioxidant Potential and Polyphenol Content of Beverages,Chocolates, Nuts,and Seeds

Polyphenols present in plant foods as natural antioxidants may inhibit the pathogenesis of many diseases, which involve oxidative reactions. This study aimed to measure the total antioxidant potential with the ferric reducing antioxidant power method and the total polyphenol contents of 15 kinds of beverages, 4 types of chocolates, and 6 sorts of nuts and seeds commonly consumed. The antioxidant potential and polyphenol content ranged (respectively): in beverages 0.216–2.940 mmol/100 ml and 31–241 mg/100 ml, in chocolates 0.550–14.67 mmol/100 g and 222–1617 mg/100 g, in nuts and seeds 0.851–55.91 mmol/100 g and 125–3521 mg/100 g. The antioxidant potential of the foods tested was related to the total polyphenol contents.     

Macromolecular antioxidants or non-extractable polyphenols in fruit and vegetables: Intake in four European countries

Macromolecular antioxidants or non-extractable polyphenols are an emerging and ignored fraction of dietary antioxidants that present differential structural and physiological features as compared with the well-known extractable polyphenols. In this study, the macromolecular antioxidant content and profile were determined by the first time for the 24 most consumed fruit and vegetables in four European countries (France, Germany, The Netherlands and Spain). Results showed that macromolecular antioxidants, made up of hydolysable polyphenols and polymeric proanthocyanidins, are major contributors (mean value 57%) to the total polyphenol content of fruit and vegetables. Macromolecular antioxidant intake from fruit and vegetable determined in the four countries selected was about 200 mg. Spain had the highest daily per capita macromolecular antioxidant intake from fruit, while The Netherlands had the highest intake derived from vegetables. Future studies of plant food macromolecular antioxidant analysis and of dietary intakes in different populations are needed to elucidate the contribution of these macromolecular antioxidants to the health effects associated with fruit and vegetable consumption, and with dietary antioxidant intake.     

西藏野生卷叶黄精多酚的提取及其抗氧化活性分析

以西藏野生卷叶黄精为原料,用乙醇提取其中的多酚类物质,通过单因素试验和正交试验,探讨提取温度、料液比、乙醇溶液体积分数和提取时间对多酚提取效果的影响并确定最佳提取工艺。利用DPPH自由基、超氧阴离子自由基、羟自由基活性检测法,研究其抗氧化活性。结果表明:提取温度70℃、料液比1∶25(g/m L)、乙醇溶液体积分数70%、提取时间2.5 h时,多酚提取量最大,达到19.8?mg/g;以VC为对照,在最优工艺条件下测定多酚提取物清除能力,多酚提取物具有较强的抗氧化活性,是一种极具潜力的天然抗氧化剂。     

Pomegranate (Punica granatum) supplements: Authenticity,antioxidant and polyphenol composition

Pomegranates contain a complex mixture of gallotannins, ellagitannins, ellagic acid and anthocyanins. However, label claims on pomegranate supplements (PS) may not correlate with actual content of antioxidants, polyphenols or tannins. Nineteen PS were evaluated for their authenticity by determining ellagitannin composition by RP-HPLC and studying the relationship between total polyphenols as measured by the Folin–Ciocalteau assay and antioxidant capacity by oxygen radical absorbing capacity (ORAC), free radical scavenging properties by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and ferric reducing antioxidant power (FRAP). Only a limited number of pomegranate supplements were authentic. Product labels were inconsistent with polyphenol composition and antioxidant content. A majority of the samples (n = 13) contained disproportionately high amounts of ellagic acid and low or no detectable pomegranate tannins. Only six products had tannin composition that resembled pomegranates (punicalagin, punicalin, ellagitannins and gallotannins). PS-01 (natural pomegranate extract) was the most representative of pomegranate fruit polyphenols with 99% total pomegranate polyphenol and the highest antioxidant capacity across all measures. Correlations between total polyphenols and antioxidant content were high (R² > 0.87) in products that had polyphenol composition resembling pomegranates. Products that contained high amounts of ellagic acid and low or no detectable pomegranate tannins had poor correlations between total polyphenols and antioxidant content. The results indicate that reliable labeling information, better standardization, improved manufacturing practices and regulation of the market is required to assure consumers of the quality of pomegranate supplements.     

客家炒青绿茶加工过程中品质成分的动态变化

为了研究客家炒青绿茶加工过程中的主要品质成分动态变化规律，以广东客家小叶群体种-仙湖茶为原料，按摊青、杀青、揉捻、炒青、辉干等工艺制作炒青绿茶，对加工过程中的主要内含物成分及香气组成进行测定分析。结果显示，随着加工的进程，茶叶在制品含水率呈下降趋势，以“炒青”工序最为显著，含水率降至4.74%，降幅达91.63%；在“炒青”工序，茶叶生化成分含量变化最大：可溶性糖含量达到最大值5.71%，水浸出物含量达到最小值35.85%，氨基酸含量达到最小值2.71%。加工过程中，水浸出物、氨基酸、茶多酚及咖啡碱呈下降趋势，儿茶素总量及酯型儿茶素含量的变化趋势与茶多酚一致。香气组分以醇类物质为主，其中香叶醇、芳樟醇、二十八烷醇及叶绿醇等化合物在炒青绿茶不同阶段加工过程中占比较高且变化幅度较大。该研究揭示了客家炒青绿茶加工过程中的主要风味物质变化过程，可为优化客家炒青绿茶加工工艺与品质良好风味的形成提供数据参考。     

挤压膨化对青稞中不同形态多酚组成及抗氧化活性的影响

以独立花青稞为材料,探究挤压膨化对青稞中不同形态多酚组分及抗氧化活性的影响。采用福林酚法测定膨化前后青稞样品的多酚含量;采用高效液相色谱法测定醇提物中的7种多酚单体含量;采用1,1-二苯基-2-三硝基苯肼自由基清除法测定抗氧化能力的变化。结果表明,经挤压膨化处理后,总多酚、游离型多酚和结合型多酚分别降低了52.7%,89.3%,23.7%,酯化型多酚含量较低,略微增加了2.49 mg/100 g;游离型多酚中检测出的多酚种类增加了3种,7种多酚单体在结合型多酚中均有测出;其中阿魏酸含量最高且主要以结合态存在,其含量处理后显著增加;此外,两种条件下青稞提取物抗氧化活性分别为1.76,0.93 mg/g,多酚含量与抗氧活性呈极显著正相关。表明挤压膨化技术运用于青稞加工之中,在改变青稞质构和口感的同时会降低多酚含量及抗氧化活性。     

Total antioxidant capacity of spices, dried fruits, nuts, pulses, cereals and sweets consumed in Italy assessed by three different in vitro assays

With the aim to expand the Italian total antioxidant capacity (TAC) database, the TAC values of 11 spices, 5 dried fruits, 7 sweets, 18 cereal products, 5 pulses, and 6 nuts were determined using three different assays and considering the contribution of bound antioxidant compounds in fiber-rich foods (i. e. cereals, legumes, and nuts). Among spices, saffron displayed the highest antioxidant capacity, whereas among dried fruits, prune exhibited the highest value. The TAC values of all the chocolates analyzed were far higher than the other sweet extracts measured. Among cereal products, whole meal buckwheat and wheat bran had the greatest TAC. Among pulses and nuts, broad bean, lentil and walnuts had the highest antioxidant capacity, whereas chickpeas, pine nuts and peanuts were less effective. The contribution of bound phytochemicals to the overall TAC was relevant in cereals as well as in nuts and pulses. The complete TAC database could be utilized to properly investigate the role of dietary antioxidants in disease prevention.     

Control of antioxidant beer activity by the mashing process

Beer is considered to be a good source of antioxidants. The composition and the quantity of the antioxidant compounds depend not only on the qualities of the raw materials, but also on the technology processes. Barley and malt represent the main source of antioxidant compounds in beer and the contribution of the hop antioxidants is lower. The influence of the mashing process on the antioxidant activity and polyphenol concentration is crucial. The antioxidant state of the sweet wort and the hopped wort are dependent on the technology processes and the raw materials used. The spontaneous sorption of polyphenols onto wort dregs and the polymerization of catechin and epicatechin lead to decreasing concentrations of individual polyphenols in the final beer. Two methods, based on electron spin resonance were used to determine antioxidant activity. These were the DPPH (2,2‐diphenyl‐1‐picryl‐hydrazyl) assay and the ‘lag time’ assay using free radical spin‐trapping agent PBN (N‐tert‐butyl‐α‐phenylnitrone). HPLC with CoulArray detection was used to measure the concentration of the individual polyphenols. This study focused on the antioxidant compounds and on the correlation of their concentrations with the values of total antioxidant activity depending on the mashing process. A good correlation was found between the decline in the concentrations of DPPH (expressed as ARA2) and concentrations of catechin and epicatechin (in sweet wort samples R² = 0.970, R² = 0.961, respectively, and in hopped wort samples R² = 0.949, R² = 0.956 respectively). Copyright © 2012 The Institute of Brewing & Distilling     

Toxicity of Selenium in Brazil Nuts to Rats

Nuts from Bertholletia excelsa, commonly known as Brazil nuts, were analyzed for selenium. Of 529 nuts from one commercial source, 6% were found to contain 100 ppm selenium or more. The mean value for all nuts was 29.6 ppm and the median value was 13.4 ppm. Hexane extracted high-selenium Brazil nut meal in a corn-based diet fed to rats produced toxicity similar to that obtained from seleniferous corn, selenomethionine or sodium selenite as assessed by weight gain, visually scored liver damage, and liver, kidney, and spleen weights. Selenium contents of liver, kidney, spleen, and blood were also determined. It is suggested that the selenium in Brazil nuts is as biologically potent as that from other sources.     

Almond Polyphenols: Methods of Analysis,Contribution to Food Quality,and Health Promotion

Almond is a nutrient‐dense tree nut recognized for its favorable lipid profile, vitamin E content, and polyphenols. The objectives of this review were to determine the polyphenols reported in almond, summarize the methods of analysis, and determine the polyphenol contribution to almond quality and health‐promoting activity. Approximately 130 different polyphenols have been identified in almond, although not all of these have been quantitated. The mean and 25% to 75% percentile contents reported in literature were 162 mg (67.1 to 257) proanthocyanidins (dimers or larger), 82.1 mg (72.9 to 91.5) hydrolysable tannins, 61.2 mg (13.0 to 93.8) flavonoids (non‐isoflavone), 5.5 mg (5.2 to 12) phenolic acids and aldehydes, and 0.7 mg (0.5 to 0.9) isoflavones, stilbenes, and lignans per 100 g almond. Following solvent extraction of almond, hydrolysis of the residue liberates additional proanthocyanidins, phenolic acids and aldehydes, and total phenols. Blanching and skin removal consistently reduces almond polyphenol content, but blanch water and almond skins retain enough polyphenols to be used as antimicrobial and antioxidant ingredients. Roasting and pasteurization have inconsistent effects on almond polyphenols. Almond polyphenols contribute to shelf life by inhibiting lipid oxidation and providing pigmentation, flavor, astringency, and antimicrobial activity. The health‐promoting activity of whole almonds has been widely investigated, but few have considered the contribution of polyphenols. Preclinical studies of polyphenol‐rich almond skin or almond extracts suggest putative effects on antioxidant function, detoxification, antiviral activity, anti‐inflammatory function, and topical use for inhibiting ultraviolet A damage. Therefore, almond has a diverse polyphenol profile contributing to both its food quality and health‐promoting actions.     

The effects of solvents on the phenolic contents and antioxidant activity of Stypocaulon scoparium algae extracts

Water, water/methanol (1/1), methanol and ethanol crude extracts from a brown alga Stypocaulon scoparium were examined for total phenolic contents (TPC) using Folin–Ciocalteu method. DPPH scavenging assay was performed to measure the radical scavenging activities (RSA) of the extracts. Results showed a significant association between the antioxidant potency and the TPC. The aqueous extract showed both, the highest antioxidant activity and highest phenolic contents. The identification and quantification of phenolic antioxidants were carried out with a rapid and simple method of reverse phase high performance liquid chromatography (RP-HPLC). This method was developed for the simultaneous analysis of 14 polyphenols, namely gallic acid, catechin, epicatechin, rutin, p-coumaric acid, myricetin, quercetin and protocatechuic, vanillic, caffeic, ferulic, chlorogenic, syringic and gentisic acids. The chromatographic separation of 14 polyphenols was achieved in less than 40 min by RP-HPLC (Varian, Pursuit XRs C18 column, 5 μm, 250 mm × 4.6 mm) using linear gradient elution of methanol and water (0.1% formic acid) with a flow rate of 1 ml/min. Gallic acid was by far the predominant polyphenol.     

Total phenolic contents,radical scavenging and cyclic voltammetry of seaweeds from Brittany

The role of polyphenols as antioxidants in our daily nutrition has been extensively investigated, but information on composition of tannins from marine sources on nutrient utilisation is limited. This study will be focused on the determination of the polyphenol quantities in brown seaweeds from Brittany coast in France; the extracts were delivered from algae centre for valorisation (CEVA), and the fidelity of the method was examined intraday and interlaboratories. The seaweed’s extracts are divided into three categories: Fucus Vesiculosus, Ascophyllum nodosum and Fucus Serratus. Consequently, the total polyphenol contents (TPC) of these extracts will be measured using Folin–Glombitza spectrophotometric method. Thereafter, the antioxidant properties of these polyphenols were determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. All polyphenols extracted were tested using cyclic voltammetry (CV) in aprotic media. The CV is realised to compare the results from spectroscopic method and to electrochemically characterise the seaweed’s polyphenols.     

3种天然抗氧化剂对腊肉理化性质的影响

目的 比较儿茶素、迷迭香酸、茶多酚三种天然抗氧化剂的不同添加量(0.075g/kg、0.15 g/kg、0.3 g/kg)对腊肉过氧化值、菌落总数、pH、水分含量、质构、色泽等理化性质的影响。结果 0.15 g/kg迷迭香酸、0.3 g/kg迷迭香酸和0.15 g/kg儿茶素处理组的抗氧化性能最佳,0.075 g/kg茶多酚处理组的抑菌效果最佳;0.075 g/kg儿茶素处理组的水分含量最高;0.075 g/kg儿茶素处理组的L*值和a*值最大。结论 三种天然抗氧化剂的添加能效减缓腊肉脂肪的氧化、具有明显的抑菌作用,且对腊肉的水分含量、色泽和质构有着积极的影响,从而在一定程度上改善了产品品质。