Antioxidant activity and typical ageing compounds: their evolutions and relationships during the storage of lager beers

Five commercial lager beers were used to investigate the evolution of antioxidant activity and ageing compounds during storage. The relationships between antioxidant activity and ageing compounds were clarified by principal component analysis (PCA). Results showed that total phenolic content (TPC) and antioxidant activities of beers evaluated by different assays gradually decreased by 16.08–22.71% (average of 18.56%) and 1.99–78.79% (averages of 24.44–70.50%), which was accompanied by 100.50–269.35% (average of 178.77%) and 11.11–57.14% (average of 28.73%) of increases in total ageing compounds and thiobarbituric acid (TBA) value, respectively, during 6 months of storage at 25 °C. Results from PCA elucidated that there were negative correlations between antioxidant activities and ageing compounds of beers during storage, and satisfactory discrimination among beers with different storage time could be achieved on the basis of antioxidant activities and typical ageing compounds selected.     

Assessment of endogenous antioxidative compounds and antioxidant activities of lager beers

BACKGROUND: Flavour stability is increasingly becoming the limiting factor in the shelf life of beer. Increasing the antioxidant activity of beer itself could suppress the rate of oxidative reaction and improve the flavour stability of beer. This report describes the levels of phenolic compounds, melanoidins and sulfur dioxide, and antioxidant activities of 40 lager beers. The relationships between antioxidative compounds and antioxidant activity were elucidated by multivariate analysis techniques. RESULTS: The results showed that the total phenolic content and the melanoidins content correlated well (P < 0.05) with antioxidant activity, while there was no significant correlation (P > 0.05) between total sulfur dioxide content and antioxidant activity. Satisfactory discrimination among beer samples with significantly different antioxidant activity was achieved by principal component analysis. Results from stepwise linear regression further demonstrated that different antioxidative components responsible for antioxidant activity were dependent on the assay used. The phenolic compound group is by far the most antioxidative compounds in beer and total phenolic content, melanoidins and sulfur dioxide together made a 22–68% contribution to the antioxidant activities of beers. CONCLUSION: Therefore, it might be an efficient means for brewers to increase total phenolic content during brewing for improvement in flavour stability of the final beer. © 2012 Society of Chemical Industry     

Assessing the association between phenolic compounds and the antioxidant activity of Brazilian red wines using chemometrics

The objective of this study was to evaluate the association among chemical parameters, the commercial value, and the antioxidant activity of Brazilian red wines using chemometric techniques. Twenty-nine samples from five different varieties were assessed. Samples were separated into three groups using hierarchical cluster analysis: cluster 1 presented the highest antioxidant activity towards DPPH (68.51% of inhibition) and ORAC (30,918.64 μmol Trolox Equivalents/L), followed by cluster 3 (DPPH = 59.36% of inhibition; ORAC = 25,255.02 μmol Trolox Equivalents/L) and then cluster 2 (DPPH = 46.67% of inhibition; ORAC = 19,395.74 μmol Trolox Equivalents/L). Although the correlation between the commercial value and the antioxidant activity on DPPH and ORAC was not statistically significant (P = 0.13 and P = 0.06, respectively), cluster 1 grouped the samples with higher commercial values. Cluster analysis applied to the variables suggested that non-anthocyanin flavonoids were the main phenolic class exerting antioxidant activity on Brazilian red wines.     

压榨对酿酒葡萄皮渣酚类物质提取及抗氧化活性的影响

酿酒葡萄皮渣（皮和籽）生物活性物质含量丰富,具有很高的再加工利用价值。对鲜葡萄皮渣进行压榨处理后再干燥,研究压榨对皮渣的酚类物质提取及抗氧化活性的影响。结果表明：压榨处理可以快速降低葡萄皮渣水分含量,缩短干燥时间、提高可溶性膳食纤维提取率。压榨葡萄皮总酚、原花青素的提取量均有所增加,其含量分别为19.56 mg/g和22.64 mg/g。压榨葡萄皮的抗氧化能力高于未压榨葡萄皮,其DPPH、ABTS及羟自由基清除率分别为62.90%、70.18%和41.09%,铁氰化钾还原能力及金属离子螯合能力分别为0.23%和21.33%。压榨籽和皮籽混合物的酚类物质和抗氧化活性则明显降低。抗氧化活性与总酚、原花青素存在显著的相关关系（P＜0.01）。     

微波加热对食品中酚类物质的含量及抗氧化活性的影响

酚类物质具有预防疾病和抗氧化等功效,在食品中应用广泛,但是食品烹调手段可能会影响酚类物质的组成和特性,微波加热是新兴的食品烹调加工方法,本文对微波引起食品中酚类物质和食品抗氧化活性的影响进行了综述,展望了酚类提取物的应用情况。      

Bioactive compounds of 44 traditional and exotic Brazilian fruit pulps: phenolic compounds and antioxidant activity

Bioactive compounds and antioxidant activity from 44 fruit were evaluated. The data were statistically evaluated by analysis of common components and specific weights (CCSWA). Panã, acerola, açaí, and jabuticaba showed higher values of total phenolic compounds (TPCs) and antioxidant activity. The analysis of CCSWA was able to explain almost 100% of the variance of the data and established the correlation between TPC and antioxidant capacity, being the most influential variables in the classification of samples. This statistical method is ideal for quickly analyzing a large amount of data, as obtained in this research, which facilitates routines of industrial analysis.     

热水提取胡柚果皮中矿物质、酚类物质及其水提液抗氧化性研究

目的:研究热水提取胡柚果皮矿物质、酚类物质的效率及其提取液的抗氧化能力。方法:原子吸收光谱法测定七种主要矿物质;高效液相法测定胡柚皮中七种主要酚酸和六种黄酮;福林酚法、FRAP、DPPH法测定提取液的抗氧化能力。结果:热水提取可以有效提取胡柚果皮中的酚类物质与部分矿物质。抗氧化能力分析表明,热水提取液具有与甲醇提取液相近的抗氧化能力。结论:传统中药煎煮条件(100℃,30min)可以有效提取柑橘类中药的酚类物质与部分矿物质。      

Stability and antioxidant activity of phenolic compounds during in vitro digestion

The impact of phenolic compounds on the human body depended on the type, content, bioavailability, and antioxidant activity. After digestion, different phenolic compounds had different changes of bioavailability and antioxidant activity, which needed to be considered in the application. In this experiment, the structural stability and antioxidant activity of 27 phenolic compounds (phenolic acids, flavonols, flavonoids, and flavanones) were investigated during the in vitro simulated digestion. This experiment eliminated the influence of food matrix, provide a basis for regularity for the changes of phenolic substances in different materials. Results showed that the bioaccessibility of phenolic compounds with different structures varied, and there was a conformational relationship between the structure and stability. After oral digestion, most of the phenolic compounds underwent degradation and the cellular antioxidant activity (CAA) values decreased to a large extent (p < 0.05). After gastric digestion, the content (p > 0.05) and CAA values (p < 0.05) of most phenolic compounds increased. However, after intestinal digestion, the phenolic compounds were degraded to a greater extent, and different structures of phenolic compounds had different changes in CAA values (p < 0.05). In general, the CAA values of most phenolic compounds after in vitro digestion were lower than the initial value. The 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ehylbenzthiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP) values of phenolic acids and flavonols decreased after in vitro simulated digestion (p < 0.05), while the values of DPPH, ABTS, and FRAP of most flavonoids (p < 0.05) increased. The increased oxygen radical absorption capacity (ORAC) values were found in most phenolic acids, flavonols, and flavonoids (p < 0.05), and most flavanones showed unremarkable changes in ORAC values (p > 0.05). In general, the changing trend of chemical-based antioxidant activity was consistent with the content of phenolic compounds.     

Changes of phenolic compounds and antioxidant capacity in cocoa beans processing

A number of studies have shown that the consumption of cocoa and chocolate products has positive health effects on humans. The object of this research was to monitor changes of total and individual phenolics and antioxidant capacity during the cocoa bean manufacturing. The loss of cocoa phenolics and their antioxidant activity vary with the degree of technological process. The process of roasting and cocoa nib alkalisation had the major influence on phenolic compounds as well as on antioxidant capacity. The roasting treatment resulted in 14% loss of the total phenolics content, while alkalisation resulted in 64% loss of total phenolics content. Procyanidins B1 and B2 as well as (?)‐epigallocatechin were the unstable components, while caffeic acid derivate showed the greatest stability in all technological process. Furthermore, PCA showed that phenolic contents, antioxidant capacity and non‐fat cocoa solids parts of the samples were classified in groups according technological conditions.     

莲房多酚提取工艺优化及其抗氧化活性研究

在单因素实验的基础上,通过正交实验优化了热回流提取莲房多酚的工艺,并通过测定其清除ABTS+自由基、DPPH自由基、OH自由基的能力,还原力,亚铁离子螯合活性及对大鼠脑匀浆脂质过氧化的影响,对莲房多酚的抗氧化活性进行综合研究。结果表明,热回流提取莲房多酚的最佳工艺参数为:乙醇浓度50%,料液比1∶25,提取温度80℃,提取时间为2h,最优条件下的得率是5.23%。莲房多酚的体外抗氧化实验表明莲房多酚对DPPH自由基、ABTS+自由基、OH自由基有很强的清除能力,对亚铁离子的螯合活性和还原力均较强,并能显著抑制大鼠脑匀浆脂质过氧化。本研究表明在该优化工艺下提取的莲房多酚具有较强的抗氧化活性。      

Comparative study of phenolic compounds and antioxidant activity in different species of cherries

A new spectrometric method ultra performance liquid chromatography-tandem mass spectrometric with high precision and rapid analysis was developed to separate 17 phenolic compounds. Different species of cherries, including 10 sweet cherry (Prunus avium L.) cultivars, a tart cherry (P. cerasus L.) rootstock (CAB), and a hybrid rootstock 'Colt' (P. avium × P. pseudocerasus), were analyzed for phenolics contents by this method. The results showed that significant differences were observed among the phenolic compound contents in different cherry species. In 10 sweet cherry cultivars, the contents of neochlorogenic acid and cyanidin-3O-rutinoside were much higher in red-colored fruits (for example, 64.60 and 44.50 mg/100 g fresh weight in Burlat, respectively) than those in bicolored ones. Principal component analysis revealed that cyanidin-3O-rutinoside was an effective index for grouping the cultivars with similar species and fruit colors. Moreover, there were strong positive correlations between phenolics content and antioxidant activity, which was higher in red-colored cherries.     

The influence of ripening stage and cultivation system on the total antioxidant activity and total phenolic compounds of yellow passion fruit pulp

BACKGROUND: This work aimed to investigate the influence of both ripening stage and cultivation system on the total phenolic compounds (TPC) and total antioxidant activity (TAA) of passion fruit pulp. TPC extraction was optimized using a 2³ central composed design. The variables were fruit pulp volume, methanol volume and extraction solution volume. TPC was determined using the Folin–Ciocalteu reaction, and TAA using the ABTS radical reaction. RESULTS: The conditions to extract TPC were 2 mL passion fruit pulp and 9 mL extraction solution containing 40% methanol:water (v/v). TPC values increased in the passion fruit pulp during ripening for both cultivation systems, ranging from 281.8 to 361.9 mg gallic acid L^?1 (P?0.05) for the organic pulp and from 291.0 to 338.6 mg gallic acid L^?1 (P?0.05) for the conventional pulp. CONCLUSION: TPC values increased during ripening for both organic and conventional passion fruit. The same was true for TAA values for conventional passion fruit. For organic passion fruit, however, TAA values were highest at the initial ripening stages. These results suggest that antioxidant compounds exert strong influence on the initial ripening stages for organic passion fruit, when TPC still did not reach its maximum level. Copyright © 2012 Society of Chemical Industry     

Oil content,phenolic profiling and antioxidant potential of Tunisian olive drupes

BACKGROUND: The aim of this work was to investigate the effect of the maturation process of the olive fruit on oil content, phenolic profile and antioxidant activity of four Tunisian cultivars (Zelmati, Chemchali, Chemlali and Chétoui). RESULTS: The average oil content of the studied varieties ranged between 17.50% and 20.25% at the first stage of maturation and from 30.20% to 35% in the last harvest. Qualitative and quantitative analysis of phenolic compounds were carried out using HPLC and LC‐MS/MS. Twenty‐six biophenolic compounds were identified. In all samples, hydroxytyrosol and oleuropein were the major compounds identified while rutin and luteolin 7‐O‐glucoside were the two main flavonoids. The total phenolic content varied from 3.46 to 4.30 g kg^?1 at the first stage of maturation and from 8.71 to 11.52 g kg^?1 of fruit fresh weight at the last maturation phase. Total flavonoid content reached 432.80 mg kg^?1. The antioxidant activity of the extract was evaluated by DPPH and ABTS assays. The IC₅₀ values of the olive extracts ranged from 2.69 to 10.96 µg L^?1 and from 2.15 to 3.03 mmol L^?1 trolox equivalent at the last stage of maturation. CONCLUSION: A relationship between the changes in phenolic content and the physicochemical changes in Tunisian olive fruit during maturation was established. These findings could be used for controlling the production processes and correlating the oil sensorial characteristics to the polyphenolic pattern. Copyright © 2010 Society of Chemical Industry     

不同发酵时间对沙米甜醅营养、感官品质及其酚类物质抗氧化活性的影响

为促进沙米作为食品原料的开发利用,对其进行甜醅发酵处理,探究不同处理时间对沙米营养、食用品质及其酚类物质抗氧化活性的影响。结果表明,不超过12 h的短时发酵处理对沙米成分没有显著性（P＞0.05）影响;处理时间大于12 h后,沙米甜醅的总酸、还原糖含量随处理时间延长显著增大（P＜0.05）,两者均在48 h后出现下降趋势,而游离氨基酸、总酚含量及其DPPH清除率一直呈现显著（P＜0.05）升高趋势;36 h及以上的发酵处理可使沙米淀粉中抗性淀粉含量相比对照显著（P＜0.05）增大,快速消化淀粉显著（P＜0.05）降低;发酵处理使得沙米色泽偏红偏黄,饱和度增高;感官评价表明发酵48 h的沙米甜醅食用品质最佳。本研究将为沙米发酵食品的研发提供科学指导。