Antioxidant properties of garden strawberry leaf extract and its effect on fish oil oxidation

The present study characterises garden strawberry leaf extract and reports its effect on shelf life and quality characteristics of fish oil. Radical scavenging capacity of the extract in DPPH^? and ABTS^?+ assays was equivalent to 1207 and 1579 μmol g^?1 of trolox equivalents, respectively, total phenolic content was 257 mg g^?1 of gallic acid equivalents. Phenolic and volatile constituents were analysed by liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS). The extract was added to fish oil and its oxidation was followed during 42 days: peroxide, p‐anisidine values and hexanal concentration were lower in the samples with extract, particularly at the end of storage. The effect of extract on fatty acid composition was not significant, however the changes in the percentages of some individual acids were observed. Fish oil containing 5% of extract had lower levels of lipid oxidation in comparison to other samples. The results indicate that strawberry leaves could be a potential source of natural antioxidants.     

Phenolic compounds in germinated cereal and pulse seeds: Classification,transformation, and metabolic process

Abstract

Natural phenolic compounds are rich in cereal and pulse seeds and their dietary functions tend to improve dramatically during germination. This article reviews recent research on the transformation of phenolic compounds during seed germination. In particular, it highlights the classification of crude phenolic compounds that can be divided into extractable and non-extractable phenolic compounds based on the biosynthesis process and extraction method. It also recommends grouping resorcinol lipids in the category of extractable phenolic compounds as non-polar solvent extractable phenolic compounds. Moreover, it discusses the variation of the different form of phenolic compounds and proposes a possible metabolic model of these phenolic compounds for seeds germination. This article is crucial for phenolic compounds research, cereal and pulse seeds germination, and food ingredients industry.     

Phenolic compounds and antioxidant activity of tuberous root leaves

The antioxidant potential of five tuberous root leaves was evaluated. High performance liquid chromatography (HPLC/DAD) showed the presence of phenolic compounds in leaves, and the predominant ones were chlorogenic acids in carrot (458.79 mg.L^?1± 0.03): rosmarinic acid in sweet potato (222.05 mg.L^?1± 0.01) and quercetin in sweet potato (292.42 mg.L^?1± 0.01). Radish leaves showed a higher total in vitro antioxidant activity for all methods used in this study. The results indicated that these leaves were natural sources of antioxidants and, therefore, could be included in the health beneficial diet.     

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）。     

Phenolic Profiles and Antioxidant Properties of Apple Skin Extracts

ABSTRACT:  Lipid oxidation, especially the oxidation of polyunsaturated fatty acids, is a significant issue in the food industry impacting both food quality and health of consumers. Apple skin was investigated as a source of natural antioxidants. The phenolic compound composition and antioxidant properties of 21 selected apple genotypes were evaluated. The lipid stabilizing ability of the apple skin extracts was examined using an aqueous emulsion system of methyl linolenate. The total phenolic concentrations determined by high-performance liquid chromatography tandem mass spectrometry of methanolic extracts of skins of the apple genotypes varied from 150 to 700 mg/100 g DW. The antioxidant capacity measured by Folin–Ciocalteu (16.2 to 34.1 mg GAE/100 g DW), ferric reducing antioxidant power (1.3 to 3.3 g TE/100 g DW), oxygen radical absorbance capacity (5.2 to 14.2 g TE/100 g DW), and percent inhibition of oxidation of methyl linolenate (73.8% to 97.2%) varied among the apple genotypes. The apple skin extracts, specifically the crab apple varieties such as "Dolgo," were revealed to be effective inhibitors of oxidation of polyunsaturated fatty acid in a model system and thus can be considered as a potential source of natural food antioxidants.     

Syrah grape skin valorisation using ultrasound-assisted extraction: Phenolic compounds recovery,antioxidant capacity and phenolic profile

The influence of ultrasound power (1000–3000 W/L), citric acid concentration (0–3%) and solid:liquid ratio (1:5–1:15) on the phenolic compounds recovery and antioxidant capacity of Syrah grape skin extracts were evaluated. Total phenolic compounds varied from 6485 to 11732 mg gallic acid/100 g and monomeric anthocyanin content from 453 to 685 mg malvidin-3-glucoside/100 g. The antioxidant capacity measured by ORAC and ABTS methods ranged from 230 to 516 μmol Trolox/g and from 442 to 939 μmol Trolox/g, respectively. The most suitable conditions chosen for extraction, within the studied ranges, were 3000 W/L of power, 2.5% citric acid and solid:liquid ratio of 1:15. The extraction yield was satisfactory, with a recovery of 59% of the quantified phenolic compounds, with only 3 min of processing. Ultrasound was considered a suitable method as compared to the conventional extraction, improving the extraction of phenolic acids and facilitating their release.     

Analysis of volatile compounds and antioxidant activity in rice extracts (Oryza sativa L.) extracted by various conditions

This study focused on the analysis of the volatiles present in rice extracts (Oryza sativa L.) produced under various extraction conditions (i.e. the range of temperature was 50, 60 and 70 °C, and particle size was whole, 355, and 710 μm) The main volatiles identified were ethyl palmitate, benzenemethanol, nonanal, hexanal and 3-methyl-1-butanol. The highest levels of flavour compounds extracted from rice cultivated in Icheon and Cheorwon were recorded at an extraction temperature of 70 and 60 °C, respectively, and at a rice particle size of 355 μm. Non-volatile rice extracts were tested for antioxidant activity using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The antioxidant activity of Icheon rice extracts at a concentration of 2000 ppm was found to be 84.33 and 84.39% in the DPPH and ABTS assays, respectively.     

Phenolic compounds,lycopene and antioxidant activity in commercial varieties of tomato (Lycopersicum esculentum)

Nine commercial varieties of tomato (Rambo, Senior, Ramillete, Liso, Pera, Canario, Durina, Daniella and Remate) produced in Spain were analysed for their lycopene content, content of phenolic compounds and antioxidant capacity. The phenolic compounds were characterised as flavonoids (quercetin, kaempferol and naringenin) and hydroxycinnamic acids (caffeic, chlorogenic, ferulic and p‐coumaric acids). Antioxidant activity was measured using the DPPH and ABTS assays. The concentrations of lycopene and the various phenolic compounds as well as the antioxidant activity were significantly influenced by the tomato variety. Quercetin, the most abundant flavonoid, was found in concentrations ranging between 7.19 and 43.59 mg kg^?1 fresh weight, while naringenin levels were lower than 12.55 mg kg^?1. The most abundant hydroxycinnamic acid was chlorogenic acid, with values ranging from 14 to 32 mg kg^?1 fresh weight, followed by caffeic acid, while p‐coumaric and ferulic acids showed similar concentrations lower than 5 mg kg^?1. The highest content of lycopene was found in Ramillete, Pera and Durina (>50 mg kg^?1 fresh weight), while the concentration in the other varieties was between 50 and 30 mg kg^?1, with the exception of Liso (less than 20 mg kg^?1). The antioxidant activity of tomato extracts varied with the tomato variety and the assay method used. Individual compounds found to be significantly related to antioxidant capacity were lycopene and ferulic and caffeic acids, but not quercetin and chlorogenic acid. © 2002 Society of Chemical Industry     

Volatile composition of `grappa low wines' using different methods and conditions of storage on an industrial scale

This is a study on the volatile composition of grappa low-wines. Grappa low wines are the first distillation products, with about 15–20% v/v ethanol, when grappa is produced using continuous distillation. Different methods and conditions of marc and wine lees storage on an industrial scale have been considered. New technology for the storage of large amounts of grape marc, called the `Grappa system', was evaluated. By comparison with a traditional ensilage method, the low-wines obtained from the Grappa system resulted in higher concentrations of ethanol, lower levels of methanol, slightly different concentrations of fusel alcohols and higher concentrations of ethyl esters and terpenes. The use of phosphoric acid and sodium methabisulphate to achieve a partial control of marc fermentation had no effects using the Grappa system method. This could be the result of the mixing technique used which was spraying alone and was only slightly effective for the homogenous treatment of the mass. On the contrary, the lower content of methanol, 2-butanol and n-propanol confirmed the effectiveness of phosphoric acid addition to the wine lees.     

Phenolic and antioxidant potential of olive oil mill wastes

Olive oil mill waste was subjected to conventional liquid solvent extraction and supercritical fluid extraction using different solvents and carbon dioxide, respectively. The optimum solvent extraction conditions of phenols were 180 min using ethanol, at a solvent to sample ratio 5:1 v/w, and at pH 2. Solvent and SFE extracts were tested for their antioxidant activity by the DPPH radical scavenging method and by determination of peroxide value on virgin olive oil and sunflower oil. The ethanol extract exhibited the highest antiradical activity, and no correlation was found between antiradical activity and phenol content. The SFE extract exerted good antioxidant capacity although its phenolic yield was not quite high. Moreover, the ethanol extract appeared to be a stronger antioxidant than BHT, ascorbyl palmitate and vitamin E by the Rancimat method on sunflower oil. HPLC analysis of the extracts showed that the predominant phenolic compound was hydroxytyrosol. Various phenolic acids and flavonoids were also identified.     

黄参籽可溶性酯结合酚和糖苷结合酚的组成及其抗氧化活性

采用HPLC-MS对黄参籽可溶性酯结合酚和糖苷结合酚的组成进行了分析,并通过DPPH自由基清除活性、FRAP、TEAC、对羟基自由基介导的2-脱氧-D-核糖裂解的抑制作用以及对DNA氧化损伤的保护作用对黄参籽酚提取物的抗氧化能力进行了评价。结果显示,黄参籽可溶性酯结合酚中主要的酚类化合物为咖啡酸、木犀草素葡萄糖苷和儿茶酸葡萄糖苷,可溶性糖苷结合酚中主要的酚类化合物为儿茶酸葡萄糖苷;黄参籽可溶性酯结合酚的DPPH自由基清除活性、铁还原力和Trolox等量抗氧化活性均弱于可溶性糖苷结合酚;相反,对羟基自由基介导的2-脱氧-D-核糖裂解的抑制作用强于可溶性糖苷结合酚;测试浓度范围内,黄参籽酚提取物对DNA氧化损伤具有不同程度的保护作用,且可溶性酯结合酚提取物酚含量与保护作用之间存在显著（p<0.05）的正相关。      

Phenolic compounds and antioxidant activity are differentially affected by drying processes in celery,coriander and parsley leaves

Convective drying (CO) is the most common technique for drying herbs, although it may diminish phenolic compounds content. Microwave drying (MW) has been suggested as an alternative, although its effects on phenolic compounds remain to be explored. The aim of this study is to compare the effects of different convective temperatures (40, 80 and 120 °C) and microwave powers (100, 500 and 1000 W) on drying time, polyphenols classes (HPLC-DAD) and antioxidant capacity in celery, coriander and parsley leaves. Microwave procedure reduced drying time (MW: 3 h–7 min; CO: 25–1.5 h) resulting more effective than CO. Increasing temperatures led to an initial decrease in total phenolic content (TPC) and antioxidant activity followed by an increase, potentially by the release of bound phenolic acids. Regarding MW, the highest polyphenol content was generally observed at 500 W, probably due to the hydroxycinnamic acid's rise. Antioxidant capacity was similar at 500 and 1000 W. There was a good agreement between TPC and antioxidant capacity. Consequently, MW seems a good alternative to reduce drying time. However, the maintenance or improvement of phenolic activity depends on the food matrix. Indeed, the best drying system and conditions to preserve phenolic compounds were variable depending on the herb type: celery (CO at 40 °C), coriander (both CO at 40 °C and MW at 500 W) and parsley (MW at 100 W).     

Optimisation of microwave‐assisted extraction of phenolic compounds from broccoli and its antioxidant activity

The effect of independent variables of microwave‐assisted extraction (MAE), extraction temperature (50–90 °C), microwave power (100–200 W), solvent concentration (methanol/water, 50–90%, v/v) and extraction time (1–27 min) on total phenolics and flavonoids contents as well as antioxidant activity of broccoli extracts was investigated. Response surface methodology was successfully applied for optimisation and the high correlation of the mathematical model indicated that a quadratic polynomial model could be used for optimisation of investigated responses. Considering the maximum amount of extracted total phenolics, total flavonoids and antioxidant activity expressed as ORAC value, the optimal conditions for all three investigated responses were obtained (temperature ?71.11 °C; microwave power ?167.03 W; solvent concentration ?75.95%; and extraction time 16.34 min), which is in agreement with optimal conditions obtained for each investigated responses. The development of simultaneously MAE methods for total phenolics, total flavonoids and antioxidant activity of broccoli extracts might simplify assessment of broccoli as valuables source of antioxidants.     

酚类物质对红葡萄酒颜色影响的研究进展

颜色作为红葡萄酒的重要感官指标,提供了葡萄酒的品质、类型以及储存期的稳定性,也成为了消费者选购葡萄酒的重要因素。酚类物质作为红葡萄酒的"骨架结构",对葡萄酒的风味、口感以及颜色等都起着决定性的作用。因此,系统的对影响红葡萄酒颜色的酚类物质进行总结归纳,以及对其对红葡萄酒的颜色影响进行研究具有重要的参考意义。