Antioxidant capacity and total reducing power of balsamic and traditional balsamic vinegar from Modena and Reggio Emilia by conventional chemical assays

Antioxidant capacity of a number of balsamic vinegar (BV) and traditional balsamic (TBV) vinegars from the districts of Modena and Reggio Emilia (Italy) have been assessed using two chemical assays, the Briggs–Rauscher oscillating reaction method and the Trolox equivalent antioxidant capacity (TEAC) method. The total reducing power was also evaluated using the Folin–Ciocalteu reagent. The results show that the antioxidant parameters of TBV are significantly better than those of the BV, in agreement with the different manufacturing procedures and product ageing. A good correlation was found between the methods used. Suggestion for an approximate evaluation of ageing based on antioxidant parameters values is also given.     

Antioxidant properties of traditional balsamic vinegar and boiled must model systems

Traditional balsamic vinegar (TBV) is a natural product prepared with cooked and concentrated locally grown grape must. It has been demonstrated that TBV contains phenols and shows antioxidant activity. In this study we investigated the antioxidant properties of TBV in relation to its content of phenolic compounds, polymeric tannins and Maillard reaction products (MRPs). Results show that TBV has a high antioxidant activity measured with both FRAP and ABTS assays, which is higher or equal to those obtained in some red wines. About 45% of the antioxidant activity of TBV is due to the total polyphenolic fraction. Among polyphenols, tannins contribute to about 50% of the antioxidant activity of the total polyphenolic fraction. The residual antioxidant activity of TBV is due to the melanoidins (about 45%) synthesized during the boiling of the must and the ageing of TBV and to other compounds such as low molecular weight MRPs. When we investigated the effect of heating on the browning and on the formation of antioxidant MRPs in must model systems, we observed a major formation of antioxidant MRPs for the model system containing both amino acids and sugars with respect to the model system containing only sugars. We also tested the effect of some representative phenolic compounds present in must. Only polyphenols were stable in the model solution; however, at our experimental conditions they did not influence the browning and the formation of MRPs. Independent of their bioavailability, dietary antioxidants play an important role in protecting the gastrointestinal tract from oxidative damage and also possibly against a buildup of peroxides and their assimilitation in the digestive tract.     

Application of denaturing gradient gel electrophoresis (DGGE) analysis to evaluate acetic acid bacteria in traditional balsamic vinegar

Acetic acid bacteria (AAB) are fastidious micro-organisms to isolate and cultivate despite of the great number of growth media available. Moreover, conventional techniques used to study AAB populations are time consuming and not completely reliable. In this study, we tested the usefulness of the polymerase chain reaction-denaturing gradient gel electophoresis (PCR-DGGE) as a rapid and cost effective method for the screening of AAB in traditional balsamic vinegar (TBV). DGGE analysis was applied to 19 AAB strains isolated by agar plating from three different samples of TBV. DGGE was also used for the analysis of PCR products obtained from DNA extracted directly from the TBV samples. A tentative species identification was achieved comparing the PCR-DGGE patterns of the isolated strains and the TBV samples to those of 15 AAB reference strains. The results support that DGGE is functional to monitor vinegar's AAB population.     

Evaluation of antioxidant capacity and total phenolic content of different fractions of selected microalgae

In order to identify new sources of safe and inexpensive antioxidants, the antioxidant capacity and total phenolic content of different fractions of 23 microalgae were evaluated, using Trolox equivalent antioxidant capacity assay and the Folin–Ciocalteu method, respectively. The microalgae were extracted using hexane, ethyl acetate and water by a three-step sequential extraction procedure. Most of these microalgae were evaluated for the first time for their antioxidant activities. It was found that the microalgae Synechococcus sp. FACHB 283, Chlamydomonas nivalis and Nostoc ellipsosporum CCAP 1453/17 possessed the highest antioxidant capacities and thus could be potential rich sources of natural antioxidants. In addition, the correlation coefficients between the antioxidant capacities and the phenolic contents were very small in hexane (R² = 0.0075), ethyl acetate (R² = 0.5851) and water (R² = 0.3599) fractions. Thus, phenolic compounds were not a major contributor to the antioxidant capacities of these microalgae. This was very different from many other plant species like fruits, vegetables and medicinal plants. The microalgae could contain different antioxidant compounds from other plants.     

Formation of glucose and fructose acetates during maturation and ageing of balsamic vinegars

We report for the first time the detection of glucose acetates in balsamic vinegars. It is well known that during traditional balsamic vinegar (TBV) ageing several modifications occur. In this paper it was experimentally determined that some modifications take also place during the short maturation time of balsamic vinegar of Modena (BVM), with an increase of the esters content due to the reaction between acetic acid and sugars, in particular glucose. The formation of esters was observed both on reference solutions containing glucose and acetic acid, subjected to an accelerated ageing by heating at 50 °C, and on real balsamic vinegar samples. Glucose esters were mainly detected as α- and β-glucopyranose acetates. The formation of fructose acetates in reference solutions, was also studied, recording a more complex pattern of products. The structures of the esters were determined by GC/MS analyses and NMR spectroscopy.     

Fluctuations in the phenolic content and antioxidant capacity of dark fruit juices in refrigerated storage

The changes in total phenol content and antioxidant capacity were monitored in six industrial dark fruit juices during 29-day refrigerated storage. The initial total phenol values ranged from 1302.1 mg/L GAE (strawberry) to 1919.8 mg/L GAE (black currant) with a mean of 1573.3 mg/L GAE. All juices exhibited fluctuations in TP values with a marked increase after 48 hours in refrigerated storage, and a greater overall TP content in 5/6 studied juices after 29 days. Antioxidant capacity was evaluated using the DPPH radical scavenging assay and cyclic voltammetry (CV) and expressed as Trolox equivalent antioxidant capacity (TEAC). Black currant juice exhibited the highest TEAC values according to both CV (2.42 mM Trolox) and the DPPH assay (5.68 mM Trolox), while cranberry juice antioxidants exhibited the greatest storage stability and the smallest antioxidant capacity decrease on day 29, 20% (CV) and 15% (DPPH assay). At the end of 29-day storage 5/6 juices exhibited a significant loss in antiradical activity and all 6 juices exhibited a significant loss in TEAC derived from CV measurements. Significant linear correlation was observed between the results of CV measurements and the DPPH antiradical activity (r² = 0.62).     

三种食醋中酚类物质及抗氧化能力的比较研究

通过光谱和高效液相色谱技术对苹果醋、山西老陈醋及恒顺香醋中酚类物质以及抗氧化能力进行分析研究,评价三种醋的营养价值。结果表明:三种醋都具有较高的总酚,且粮食醋大于苹果醋。同时总酚与抗氧化能力呈显著正相关。在色谱条件下,以没食子酸等十六种单体酚作为标准品,苹果醋中能被定量的单体酚有8种,其中绿原酸(6.56mg/L)、咖啡酸(3.03mg/L)和根皮苷(1.76mg/L)含量最为丰富,是苹果醋相对粮食醋的特征单体酚;粮食醋(山西老陈醋和镇江香醋)中能被定量的单体酚有5种,其中没食子酸含量最高(在山西老陈醋中含量为60.56mg/L,恒顺香醋中为241.96mg/L),山西老陈醋和恒顺香醋中多酚物质结构比例差距较大。      

Effects of genotype, location and baking on the phenolic content and some antioxidant properties of cereal species

In order to assess the effect of genotype, location and their interaction on total phenolic content (TPC) of chemical extracts, the whole grains of durum and soft wheat, oat, barley and triticale were evaluated. Data showed differences in phenolic content of chemical extracts among cereal species and the analysis of variance confirmed the key role of location. Besides TPC and trolox equivalent antioxidant capacity (TEAC) values assessed by chemical extraction were compared with those obtained with an in vitro digestive enzymatic extraction. Differences were found between methanolic and enzymatic extracts, and data confirmed that enzymatic technique enhanced extraction of antioxidants but pointed out lesser differences among cereal types. The breads obtained by flours enriched with different levels of bran were also evaluated. Chemical extracts highlighted the increasing levels of antioxidants according to bran enrichments, without pointing out changes caused by baking. The enzymatic extraction instead did not show differences regarding to bran enrichments, but documented a loss in antioxidant properties of breads in respect to corresponding flours. On the other hand the scarce differences between flours and corresponding breads did not allow asserting that baking modified the TPC and TEAC, independently of the extraction methods used. Indeed, during baking process, also the observed phenolic acids profile variations did not vary the antioxidant properties of breads.     

梁汾醋对小鼠免疫增强作用及体外抗氧化活性

目的 以梁汾醋为研究对象,测定其中的主要成分及其含量并研究对小鼠的免疫增强作用和体外抗氧化活性。方法 通过比较研究低剂量与高剂量梁汾醋对小鼠免疫器官的脏器指数、NK细胞活性、淋巴细胞转化功能、迟发型变态反应和细胞因子变化等的影响,评价梁汾醋对小鼠免疫功能的作用。通过1,1-二苯基-2-苦肼基(1,1-diphenyl-2-picrylhydrazyl, DPPH)自由基、2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)(2, 2''-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS)自由基和羟基自由基清除实验,观察梁汾醋的体外抗氧化活性。结果 两个剂量的梁汾醋对小鼠的体重、脾脏指数和胸腺指数均无显著影响,但高剂量组能够显著提高小鼠的NK细胞活性、脾淋巴细胞的转化能力,有效缓解迟发型变态反应,促进细胞因子IL-10、 IL-12的释放,增加免疫球蛋白(IgA)的水平;梁汾醋表现出显著的清除DPPH自由基以及羟基自由基的能力,在一定浓度下清除率可达到100%,对于ABTS自由基也有较好的清除率,在浓度为120μg/mL时清除率达到76.73% ± 3.28%,并与浓度呈现量效关系。结论 摄入一定量的梁汾醋具有增强小鼠免疫功能的作用,且具有良好的抗氧化效果。     

Antioxidant properties of phenolic compounds occurring in edible mushrooms

Total phenolic and flavonoid contents occurring in eight types of edible mushrooms (Agaricus bisporus, Boletus edulis, Calocybe gambosa, Cantharellus cibarius, Craterellus cornucopioides, Hygrophorus marzuolus, Lactarius deliciosus and Pleurotus ostreatus) have been respectively evaluated by the Folin–Ciocalteau assay and by the colorimetric reaction with NaNO₂ and AlCl₃ in a basic media. Generally, the assayed mushrooms contained between 1 and 6 mg of phenolics per gram of dried mushroom, depending on the species, while the flavonoid concentrations ranged between 0.9 and 3.0 mg per gram of dried matter. The profile and concentration of individual phenolics was determined by means of high performance liquid chromatography. Homogentisic acid was the free phenolic acid significantly present in all mushrooms although the content varied considerably among the analysed species. Flavonoids, such as myricetin and catechin were also detected in the mushrooms studied. The antioxidant properties of the methanolic extracts from mushrooms were evaluated by monitoring the linoleic acid autoxidation, and all the mushrooms species showed inhibition, with C. cibarius being the most effective against lipid oxidation (74% of inhibition) and A. bisporus the species with lowest antioxidant activity (10% of inhibition).     

Total phenolic compounds and antioxidant capacities of major fruits from Ecuador

Seventeen fruits from Ecuador were analysed for total soluble phenolic compounds content and for antioxidant capacity, using three different methods (DPPH, FRAP and ABTS⁺). For the total phenolic content measured by the Folin–Ciocalteu method, three groups, having <100, 200–500 and >1000 mg GAE/100 g FW, were clearly distinguishable. Andean blackberry, capulí cherry peel and banana passion fruit were classified in the third group, with concentrations of 2167, 1494 and 1010 mg of GAE/100 g FW, respectively. Antioxidant capacity analyses revealed the same classes. FRAP and ABTS⁺ gave comparable results and were highly correlated (y = 0.691x + 6.78; r² = 0.908). Spectrophotometric measurements showed that the Andean blackberry and capulí peel but not banana passion fruit contained high levels of anthocyanins (λ_max = 520 nm).     

Evaluation of the phenolic content,antioxidant activity and colour of Slovenian honey

Honey samples from the seven most common honey types in Slovenia were screened for total phenolic content by the modified Folin–Ciocalteu method, for potential antioxidant activity using the ferric reducing antioxidant power (FRAP) assay and by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method for antiradical activity. In addition the colour characteristics of honey samples were analysed. The results of the study showed that total phenolic content, antioxidant activity and colour parameters differ widely among different honey types. Phenolic content expressed as gallic acid equivalent ranged from 44.8 mg/kg in acacia honey to 241.4 mg/kg in fir honey. Antioxidant activity was the lowest in the brightest acacia and lime honeys and the highest in darker honeys, namely fir, spruce and forest. The colour of the Slovenian honeys, analysed in this study was very variable and ranged from pale yellow to dark brown. Correlations between the parameters analysed were found to be statistically significant (p < 0.05).     

The effect of adding sour cherry pulp into yoghurt on the physicochemical properties,phenolic content and antioxidant activity during storage

This study investigated the effect of adding sour cherry pulp into yoghurt on its physicochemical properties, phenolic content, antioxidant activity and sensory characteristics. Sour cherry pulp was added at 0%, 8%, 12% and 16% into the yoghurt, and measures were checked through 14 days cold storage. The increasing sour cherry pulp concentration in yoghurt resulted in increasing pH and whey separation, whereas the values of the other parameters, total solid, fat, protein, ash, titratable acidity and viscosity decreased. During storage, total phenolic contents and antioxidant activity in yoghurts ranged from 20 to 81 μg gallic acid equivalent per mg of sample and from 48% to 86%, respectively.     

提取溶剂对青稞提取物总酚、黄酮含量及其抗氧化活性的影响

以3种不同的青稞为原料,采用不同的提取溶剂(水、60%乙醇、60%甲醇、60%丙酮、95%乙醇、100%甲醇、100%丙酮)对青稞进行提取。对各提取物的总酚、总黄酮进行测定,同时采用3种抗氧化方法:二苯代苦味酰自由基(DPPH)、2,2’-联氨-双(3-乙基苯并噻唑啉-6-磺酸)二胺盐自由基(ABTS)和总抗氧化能力(FARP)评价青稞提取物的抗氧化活性。结果表明,95%乙醇和60%丙酮更有利于青稞多酚的提取。藏青2000的各溶剂提取物的总酚、总黄酮及抗氧化活性普遍高于相应溶剂的循化蓝青稞和香格里拉绿青稞。藏青2000的60%丙酮提取物含有最高的总酚含量,达到211.92mg GAE/100g DW;在60%乙醇提取时具有最高的总黄酮含量,达到60.11mg RT/100g DW;在60%乙醇提取时具有最强的DPPH清除能力,达到80.08%;而用60%丙酮提取时,具有最强的ABTS清除能力和总抗氧化能力,分别达到了1.85,9.28 mmol TEAC/100g DW。总酚含量与抗氧化活性均具有显著的相关性,FRAP法与DPPH、ABTS法具有极显著的相关性。综上表明,青稞富含总酚成分,是一种潜在的天然抗氧化剂资源。     

The flavone,flavonol and flavan-3-ol content of the Greek traditional diet

Flavonoids are an important category of plant antioxidants and evidence is accumulating on their favorable effects against the development of heart disease and certain forms of cancer. We analytically determined the flavonol (quercetin, kaempferol, myricetin, isorhamnetin), flavone (luteolin, apigenin) and flavan-3-ol (catechin, epicatechin, epigallocatechin, epigallocatechin gallate, epicatechin gallate) content of a weekly menu representative of the Greek traditional diet. The overall daily average content was found 79.01 mg of which flavonols contribute 47% (37.17 mg/day), flavan-3-ols 40% (31.67 mg/day) and flavones 13% (10.17 mg/day). The levels of agreement between the analytical results and the respective theoretical flavonoid calculations conducted previously on the same weekly menu ranged widely, indicating that caution should be taken when calculated flavonoid values are to be used in epidemiological studies. Compared to northern European and American diets, the traditional Greek diet has a higher flavonoid content, at least with respect to flavones, flavonols and flavan-3-ols.     

山西老陈醋中总黄酮含量的测定

采用亚硝酸钠-硝酸铝-氢氧化钠显色法在510nm处测定山西老陈醋中的总黄酮,结果显示,该方法在20min内测定稳定,在中性条件下山西老陈醋中总黄酮的提取量最大,其含量为1525.30mg/L,相对标准偏差(RSD)为0.95％(n=6),加标回收率在93.60％～97.65％之间.该方法操作简单、重现性良好、准确度较高,可作为山西老陈醋中总黄酮含量测定的参考方法.     

微分电位溶出法直接测定食醋中铅的含量

采用微分电位溶出法对食醋中铅的含量进行直接测定,确定最佳条件为:介质采用0.1mol/L的盐酸,富集电位为-1.1 V,清洗电位为-0.05 V,电位上限-0.8 V,电位下限-0.2 V,富集时间为100 s.此法的应用测试结果令人满意.     

高效液相色谱-二极管阵列联用技术同时检测苹果醋和甘蔗醋中11种酚类物质

利用高效液相色谱联合二极管阵列技术（HPLC-DAD）建立一种可以同时检测不同苹果醋和甘蔗醋中11种酚类物质的分析方法。使用OMNI Hubble C₁₈色谱柱（250 mm×4.6 mm,5μm）,流动相A为甲醇-甲酸（100∶2,v/v）,B为10 mmol/L磷酸氢二钾-磷酸水溶液（200∶1,v/v）,流速为1.0 m L/min,进样量为20μL,梯度洗脱,柱温为35℃,二极管阵列扫描波长范围210⁴00 nm。应用本方法可以检测出不同苹果醋和甘蔗果醋中香草醛、香豆素、绿原酸、咖啡酸、阿魏酸、对香豆酸、芹菜素、木犀草素、肉桂酸、山奈酚、芒柄花黄素等11种酚类物质,其中甘蔗醋中富含绿原酸等10种酚类物质成分。本方法回收率在84.1%¹18.2%之间,结果准确可靠,简单易行,适合用于各类果醋中酚类物质的分析检测。