Onion high-pressure processing: Flavonol content and antioxidant activity

Onion flavonol content and antioxidant activity have been related to human health promoting effects. Quercetin and quercetin glucosides (quercetin-4′-glucoside and quercetin-3,4′-diglucoside) have been reported the main onion flavonols in recent literature. Impact of combined treatments of high-pressure processing (HPP) and temperature on onion nutritional attributes has been scarcely studied.Our study aimed to investigate the impact of HPP technology combined with temperature on onion (Allium cepa L. var. cepa, ‘Grano de Oro’) total phenol content, flavonol content, and antioxidant capacity. The experimental design comprised a response surface methodology according to a central composite face-centred design. The variable ranges were 100-400 MPa (pressure) and 5-50 °C (temperature), time was set up constant to 5 min.Response surfaces of onion total quercetin, quercetin-4′-glucoside, and quercetin-3,4′-diglucoside content showed a similar pattern. The application of low temperature (5 °C) combined with pressures of 100 and 400 MPa triggered to a better extraction of these flavonols among the treatments analysed. Response surface of the EC₅₀ antioxidant parameter as a function of pressure and temperature showed a clear trend towards an increase in onion antioxidant activity when applying pressures from 100 to 400 MPa. Four hundred megapascals/5 °C-processed onion showed an approximately 33% higher quercetin-4′-glucoside content compared with the untreated onion, and maintained the antioxidant activity of the untreated onion.     

不同品系食用红甜菜的红色素提取

分别利用水萃取法和0.1mol/L稀盐酸浸提法对北京红和食甜一品红块根中的红色素进行提取测定。结果表明:北京红和食甜一品红块根中红色素含量存在差异,且差异达到极显著水平,在块根中北京红的红色素含量较高;两种提取方法间也存在极显著差异,其中水萃取法的提取率高,经济实用,且安全性好。     

Impact of germination on phenolic content and antioxidant activity of 13 edible seed species

The aim of this work was to test 13 edible seeds for the levels of phenolic compounds and the antioxidant activity (TAC) at different germination states (dormant, imbibed and 7d sprouts). Selected seeds included mungbean, alfalfa, fava, fenugreek, mustard, wheat, broccoli, sunflower, soybean, radish, kale, lentil and onion. Accumulated phenolics (mg chlorogenic acid equivalent, CAE) and TAC (μg Trolox equivalent) on dry basis (DB) showed the general trend distribution of 7d sprouts > dormant seeds > imbibed seeds. In addition, the specific TAC (μg Trolox mg⁻¹ CAE) increased only for imbibed seeds indicating a possible protection effect of the phenolic antioxidants to the emerging sprouts. Phenolic contents of 7d sprouts (DB) ranged from 490 (lentil) to 5676 (mustard) mg CAE 100 g⁻¹. Seven day sunflower sprouts had higher TAC on a DB (40202 μg Trolox g⁻¹) compared to other seeds (1456–25991) and a blueberry reference (35232). Increases in phenolics (DB) from dormant seed to 7d sprout differ among seeds, ranging from 2010% (mungbean) to −11% (kale), while increases in TAC (DB) ranged from 1928% (mungbean) to 0% (lentil). This study shows that germinated edible seeds are an excellent source of dietary phenolic antioxidants.     

苦荞挂面加工过程中黄酮含量及抗氧化活性变化研究

以30%的苦荞粉添加到小麦粉中制作苦荞挂面,探讨挂面加工过程中以及不同的面团醒发时间时苦荞黄酮与芦丁含量、存在形式和抗氧化活性的变化规律,并分析了黄酮、芦丁含量与抗氧化能力之间的相关性。结果表明:苦荞与小麦混合粉和面成面团时游离态黄酮、游离态芦丁与总黄酮、总芦丁含量明显增加,游离黄酮提取液的DPPH自由基清除能力,ABTS⁺·清除能力明显增强;结合态黄酮、结合态芦丁含量及结合态黄酮提取液的抗氧化活性则显著下降;醒发、制作湿面条与烘干加工过程对苦荞中不同存在形式黄酮、芦丁含量及其抗氧化活性均影响较小;苦荞中黄酮、芦丁含量与DPPH自由基清除能力,ABTS⁺·清除能力受醒发时间的影响不显著,总抗氧化能力则随醒发时间的延长而增强。苦荞挂面加工过程中黄酮、芦丁含量与DPPH自由基清除能力,ABTS⁺·清除能力之间具有良好的相关性（p<0.01）,与总抗氧化能力的相关性较差。      

Effect of processing on buckwheat phenolics and antioxidant activity

The effect of processing on functional compounds in buckwheat was investigated. Extractions of buckwheat flour were carried out before and after roasting or extrusion. Folin–Ciocalteu assays indicated that processing did not cause any change in total phenolic content in buckwheat flour. Roasted (200 °C, 10 min) dark buckwheat flour exhibited an increase in non-polar compounds as well as polar compounds whereas extrusion exhibited increase only in polar compounds. Antioxidant activity test (DPPH) showed that roasting at 200 °C for 10 min decreased the antioxidant activity slightly whereas extrusion (170 °C) did not cause any change. The results suggest that processing conditions can be optimized to retain the health promoting compounds in buckwheat products.     

Effects of high pressure processing on antioxidant activity, and total carotenoid content and availability, in vegetables

High pressure processing (HPP) is a relatively new food preservation processing technology that enhances food safety and shelf-life without compromising organoleptic qualities. There has been little research on the impact of HPP on the nutritional and health-promoting properties of foods to date and most of it has focused on juices and purees of fruit such as oranges and tomatoes. The objective of this study was to determine the effects of HPP treatment at two pressure levels (400 MPa; 600 MPa) on antioxidant activity, total carotenoid content and carotenoid availability in vitro, of three commonly consumed vegetables. Antioxidant capacity and total carotenoid content differed between vegetables but were unaffected by HPP treatment. In vitro availability of specific carotenoids also varied greatly between vegetables (3–35%). HPP altered availability of carotenoids according to the type of vegetable treated and processing pressure applied, however the magnitude of the responses was minor.

Industrial relevance

This study provides further scientific evidence of the benefits of high pressure processing in retaining the nutritional attributes of fresh foods. Antioxidant activity and levels of carotenoids before and after exposure to high pressures (up to 600 MPa for 2 min) were essentially no different. Also, the data suggest that micronutrients and phytochemicals in certain vegetables may be made more bioavailable by high pressure treatment. From a nutritional perspective, high pressure processing is an attractive food preservation technology and clearly offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier food products.     

不同处理工艺对玫瑰花中抗氧化物质含量及抗氧化活性的影响

目的 研究不同处理工艺对平阴玫瑰中总黄酮、芦丁、总多酚含量及抗氧化活性的影响。方法 对干花直接提取、干花超微粉碎提取以及鲜花冷冻干燥提取3种不同处理工艺的平阴玫瑰进行水提,采用分光光度法测定水提液中总黄酮、总多酚的含量,高效液相色谱法测定水提液中芦丁含量,并对3种不同处理工艺的水提液进行1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl, DPPH)自由基清除、羟自由基清除以及超氧阴离子清除能力的研究。结果 3种不同工艺处理的玫瑰花总黄酮含量、芦丁含量、总多酚含量及抗氧化活性均为：鲜花冷冻干燥>干花超微粉碎>干花直接提取。结论 经冷冻干燥处理后的平阴玫瑰抗氧化性物质含量及抗氧化活性均有升高,为玫瑰花抗氧化应用提供依据。     

茄子皮红色素抗氧化活性研究

目的:研究茄子皮天然红色素体外抗氧化活性;方法:以抗坏血酸为对照,以Fenton反应产生羟自由基(·OH),肾上腺素自氧化反应产生超氧阴离子自由基(O-2·)为试验模型,采用紫外分光光度法和荧光分析法,测定茄子皮红色素对羟自由基、超氧阴离子自由基、过氧化氢的清除作用;结果:茄子皮红色素对上述自由基均有清除作用,时羟自由基和超氧阴离子自由基清除效果比抗坏血酸好,清除过氧化氢能力弱于抗坏血酸;结论:茄子皮红色素具有明显清除自由基的作用.     

Effect of grape processing on selected antioxidant phenolics in red wine

Wine, particularly red wine, is an important source of polyphenols and several studies have shown that moderate wine consumption is associated with a reduced risk of coronary heart disease. It has been hypothesized that these antioxidant compounds may be responsible for the potential beneficial effects of wine. The influence of different vinification techniques (fermentation on skin [A], mash heating [B], and the combination of both [C]) on the antioxidant capacity and the phenolic composition of red wines (Spätburgunder [Pinot Noir], Lemberger, and Cabernet Franc) were tested in the present study. The highest concentrations of anthocyanins, flavan-3-ols, flavonols, stilbenes, and antioxidant capacity were found in the red wines which were produced under the conditions of C, followed by B and A.     

Impact of limited drying on Momordica cochinchinensis Spreng. aril carotenoids content and antioxidant activity

Food product based on gac fruit (Momordica cochinchinensis Spreng.) arils have a high potential due to the high carotenoids content of this fruit. Drying is a key preparation step for carotenoids extraction from gac fruit in a economically viable process. The impact of different drying technics, temperature, final product moisture content on the carotenoid content, hydrophilic and lipophilic antioxidant activity (evaluated with three methods) and color of the gac arils is discussed based on laboratory scale experimental tests. The results highlight an optimal temperature between 50 °C and 60 °C to conserve the color, the carotenoid content and the antioxidant activity. Also, these properties are better preserved by limiting the drying to dry based moisture content between 15% and 18% while the advantages of drying for further processing and for refrigerated conservation for a few months are achieved.     

Changes in the content of health-promoting compounds and antioxidant activity of broccoli after domestic processing.

The effect of water- and steam-cooking on the content of vitamin C, polyphenols, carotenoids, tocopherols and glucosinolates, as well as on the antioxidant activity of broccoli, are reported. Flavonoids, phenolic acids, vitamins C and E, beta-carotene, lutein, and glucosinolates in domestically processed broccoli were quantified using high-performance liquid chromatography (HPLC) methods; total polyphenols were determined with Folin-Ciocalteu reagent. The antioxidant capacities of broccoli extracts were evaluated using the Trolox equivalent antioxidant capacity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods. The results indicated that steam-cooking of broccoli results in an increase in polyphenols, as well as the main glucosinolates and their total content as compared with fresh broccoli, whereas cooking in water has the opposite effect. Steam-cooking of broccoli has no influence on vitamin C, whereas cooking in water significantly lowers its content. Both, water- and steam-cooking of broccoli results in an increase in beta-carotene, lutein, and alpha- and gamma-tocopherols as compared with fresh broccoli. Similar effects of steaming and water-cooking of broccoli on their antioxidant activity were observed.     

甜菜红色素的稳定性探讨

采用紫外可见光谱法对甜菜红色素的稳定性进行研究,探讨了pH、温度、时间和金属离子对甜菜红色素吸收光谱的影响,分析了甜菜红色素降解的原因。结果表明：甜菜红色素的稳定性较差,随着pH的增加、温度的升高、时间的延长,甜菜红色素的降解程度均逐渐增大。     

Phenolic content and antioxidant activity of olive extracts

The phenolic component of freeze-dried olive fruit was fractionated by high-performance liquid chromatography using ultraviolet, atmospheric pressure chemical ionisation (APCI) and electrospray ionisation (ESI) detection. The fractions together with several standards were tested for antioxidant activity in an aqueous and a lipid system. The negative ion mode of APCI and ESI showed less fragmentation than positive ion mode. The latter was generally more useful in obtaining fragmentation data and hence structural information. Some olive phenolics notably tyrosol exhibited a low ionisation efficiency in both APCI and ESI. There was no simple relationship between antioxidant activity and chemical structure. The ranking of antioxidant activity was strongly dependent on both the test system and on the substrate demonstrating the need to examine activity in both aqueous and lipid systems. Significant antioxidant activity was seen in most olive fractions and this was related to phenolic content. The kinetics of the oxidation process are complex and suggest that multiple pathways may be involved at different antioxidant concentrations.     

桑椹红色素的纯化及其抗氧化活性研究

研究了从桑椹(桑树721)果浆中提取的桑椹红色素在D101大孔树脂上的动态吸附和洗脱工艺参数,并通过还原能力、清除·OH能力及鳌合Fe2 能力三种抗氧化体系的测定比较纯化前后桑椹红色素的抗氧化性.结果表明,较好的动态吸附和洗脱条件为吸附流速2mL/min,洗脱流速2mL/min,洗脱荆用量3BV.纯化色素的色价是未纯化的4.39倍.纯化色素的还原性、·OH清除率及Fe2 整合力普遍高于未纯化色素,且抗氧化能力的大小与色素浓度高低相一致.     

Effect of nitrapyrin on nitrapyrin residues and nitrate content in red beet roots fertilised with urea

The effect of nitrapyrin [2-chloro-6-(trichloromethyl)pyridine] application on nitrapyrin residues and nitrate content in red beet (Beta vulgaris L. var. conditiva) roots and in soil fertilised with urea was studied during the 1977 growing season. The nitrapyrin residues in roots were on 15 August between 0.00–1.19 μg g^?1 and on 1 October between 0.00–0.45 μg g^?1 (dry weight basis) correlating significantly r = 0.99, P<0.01) to the rates of nitrapyrin applied on 8 June (0–34 kg ha^?1). The content of nitrapyrin in roots decreased in autumn having in August-September a ‘biological half-life’ of 3 weeks. In soil the same parameter was in July-September more than 4 months. The ratio of nitrapyrin to its main breakdown product varied in soil between 3.5–24.8 and in red beets between 0.6–1.4. Neither of these compounds were found in processed canned red beets. Nitrapyrin treatment decreased the nitrate content in both soil and beets. The inhibitor application of 18 kg ha^?1 caused the highest reduction of the NO₃-nitrogen content in beets, the average values on dry weight basis being 0.51–0.34 mg g^?1 for 0–18 kg ha^?1 nitrapyrin application, respectively. The reduction of NO₃-nitrogen in beets from its level of 15 August to its September level was 44%. After 5 September the reduction of the nitrate level in beets was not significant.     

红心与白心火龙果总糖、还原糖含量及其抗氧化活性的对比分析

以红心与白心火龙果为原料,采用热水浸提法提取果肉中的糖分。分析比较2种火龙果总糖、还原糖含量及其抗氧化活性。试验表明,温度对糖分提取具有显著影响。在80℃时,红心火龙果总糖(28.68%)及还原糖(8.85%)含量均显著高于白心火龙果总糖(18.46%)及还原糖(7.09%)含量。抗氧化活性测试结果显示,其抗氧化活性随多糖浓度的升高而增强,其中红心火龙果多糖的抗氧化活性强于白心火龙果。当多糖浓度为2.0 mg/mL时,红心火龙果多糖对·OH、DPPH、NO2-的清除率可达73.44%、48.39%、47.59%,总抗氧化力为0.79,总还原力为0.65。     

山楂红色素抗氧化作用的研究

以山楂果实的综合加工利用为目的,用有机溶剂和水提取山楂果粉中的脂溶性和水溶性色素(HP1～HP5),对其色素的抗氧化性进行考察的结果表明,各山楂色素对超氧阴离子自由基、羟自由基和DPPH自由基均具有显著的清除效果。此实验结果也预示着山楂果实红色素在食品抗氧化剂或抗氧化功能食品的开发领域可期待很好的应用前景。     

In vitro antioxidant activity of red grape skins

Phenolic antioxidants seem to be partly responsible for the protective effects against cardiovascular diseases attributed to moderate wine consumption. Grape skins greatly contribute to the phenolic composition of red wine. In this paper, the in vitro antioxidant activity of red grape (Vitis vinifera) skins is determined. We show that the radical scavenging activity (C ₅₀ values) against 2,2-diphenyl-1-picrylhydrazyl (DPPH^·) of grape skin extracts is relatively high (3.2–11.1 mg dried skin/mg DPPH^·) in relation to other foodstuffs and, as expected, is influenced by grape variety, stage of grape ripening and vintage. The antioxidant potential of grape skins seems to be transferred into wine since grape varieties with skins exhibiting high antioxidant potential also resulted in wines with high antioxidant activity. Statistically significant correlations were found between antioxidant activity and phenolic content (total polyphenols, proanthocyanins, catechins and anthocyanins) for both grape skins and wines.     

Effect of processing on the antioxidant activity of millet grains

Millets are generally dehulled and subjected to a hydrothermal treatment before consumption, thus the hulls can be used as a potential source of antioxidants. Several millet grains, namely kodo, finger (Ravi), finger (local), proso, foxtail, little and pearl millet were studied. Antioxidant activities of phenolic extracts obtained from whole grains, as well as their corresponding dehulled and cooked grains and hulls were studied for their total phenolic content (TPC), radical scavenging capacity, and antioxidant activity in a β-carotene/linoleate emulsion. The phenolics present in whole grains were identified and quantified using HPLC and HPLC/MS and results were expressed as total for each of the phenolic groups. The TPC ranged from 2 to 112 μmol ferulic acid equivalents/g defatted meal. All varieties exhibited effective inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, peroxyl and superoxide radicals. Dehulling and cooking affected the TPC and radical scavenging and antioxidant activities of the grains, depending on the variety. In general, the antioxidant activity of phenolic extracts was in the order of hull > whole grain > dehulled grain > cooked dehulled grain With the exception of the two finger millet varieties, hulls of other millet grains had high TPC, thus demonstrating their superior antioxidant activity. Hydroxybenzoic acids, hydroxycinnamic acids and flavonoids in whole grains were identified as contributors to the observed effects. Therefore, dehulling of grain and hydrothermal treatments affect the phenolic content and antioxidant potential of millet grains.