Effect of microwave‐assisted extraction on the release of polyphenols from ginger (Zingiber officinale)

The significance of different variables viz. temperature, time and solvent at constant power in microwave‐assisted extraction (MAE) process of ginger was studied and compared with conventional method. Aqueous ethanol (50%) provided higher yields of extract as well as the highest release of total polyphenols (TPP) than alcoholic solvents. The reason could be the high dielectric constant of aqueous ethanol as compared to alcohols. Microwave heating being a volumetric process, an exposure time of 1 min was found to be sufficient. The better penetration of microwaves and greater solubility at higher temperature resulted in higher yield of TPP and [6]‐gingerol. The resultant extract showed higher radical scavenging activity (RSA) values. Thus, MAE allowed higher recoveries compared to conventional extraction process, with improvement in the quantity and quality of extract in very short period of time.     

酶法辅助提取生姜姜辣素及其对山茶油抗氧化作用研究

油脂氧化是山茶油变质和品质降低的主要原因。姜辣素具有良好的抗氧化活性,提取的关键在于破坏生姜细胞结构。本研究采用单因素实验和正交实验研究了酶用量、酶解温度、酶解pH和酶解时间对姜辣素提取率的影响,并采用Schaal烘箱法研究了姜辣素提取物对山茶油的抗氧化作用。结果显示,淀粉酶和纤维素酶复合酶处理对姜辣素提取具有协同增效作用,最佳配比为3:2;单因素实验和正交实验优化后的最佳工艺条件为：酶用量15 mg/g干姜粉,酶解温度55 ℃,酶解pH为5.5,酶解时间1.25 h。在此条件下,姜辣素提取率为4.75±0.07%。姜辣素提取物对山茶油具有较好的抗氧化作用,其效果随提取物姜辣素浓度提高而增强,但与BHT仍有一定差距;8-姜酚、10-姜酚和6-姜烯酚与姜辣素提取物复配,均对山茶油抗氧化具有协同增效作用,其抗氧化效果接近BHT。研究结果对姜辣素的提取和山茶油抗氧化具有重要的理论指导意义和实际应用价值。     

Microwave drying of mango ginger (Curcuma amada Roxb): prediction of drying kinetics by mathematical modelling and artificial neural network

Curcuma amada (Mango ginger) was dried at four different power levels ranging 315–800 W to determine the effect of microwave power on moisture content, moisture ratio, drying rate, drying time and effective diffusivity. Among the fifteen thin layer drying models considered for evaluating the drying behaviour, the semi‐empirical Midilli et al., model described the drying kinetics very well with R² > 0.999. Drying rate and effective diffusivity increased as the microwave power output increased. Activation energy was estimated by a modified Arrhenius type equation and found to be 21.6 kW kg^?1. A feed‐forward artificial neural network using back‐propagation algorithm was also employed to predict the moisture content during MW drying and found adequate to predict the drying kinetics with R² of 0.985.     

Influence of heating on the polyphenolic content and antioxidant activity of grape seed flour

Abstract: The production of grape seed flour (GSF) from a waste product generated during winemaking, is of interest in product development applications due to its potential health benefits. However, before GSF can used in baking as a source of additional antioxidants, research on its heat stability is required. The overall objective of this study was to assess changes in phenolic content and antioxidant activity of GSF during heating. Merlot GSF was heated at 5 temperatures (120 to 240 °C) for 0 to 90 min. At each time/temperature combination, total phenolic content (TPC), total flavanoid content (TFC), Trolox equivalent antioxidant capacity (TEAC), 2,2 diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, and ferric ion reducing antioxidant power (FRAP) of the extracts were determined. Specific polyphenolic compounds, including catechin, gallocatechin, epicatechin, and gallic acid were also measured. Results showed that when Merlot GSF was heated to ≥180 °C, significant decreases in the TPC and antioxidant activity, measured using FRAP, DPPH, and TEAC, were observed. Longer heating times also caused a reduction in antioxidant capability. Catechin and epicatechin content decreased with increasing heating temperature while gallocatechin and gallic acid content increased. Both catechin and epicatechin content had strong positive correlations (r > 0.91) with TPC and TFC, as well with FRAP and TEAC, suggesting that the GSF antioxidant activity is related to the presence of these particular compounds. Overall, while a decrease in antioxidant content was observed during heating, this occurred at higher baking temperatures. Thus GSF may be suitable for use as an ingredient in baked goods to bolster antioxidant content. Practical Application: In order for Merlot grape seed flour (GSF) to be used in baking as a source of additional antioxidant compounds, the impact of heating on the polyphenolic compounds in the GSF needed to be examined. Thermal treatment of Merlot GSF caused significant decreases in the TPC, antioxidant power, and specific polyphenolic compounds when heated ≥180 °C. Thus while antioxidant content decreased with higher heating temperatures, this occurred at higher baking temperatures. Thus, GSF may be suitable for use as an ingredient in baked goods to bolster antioxidant content.     

Effects of drying on flavour compounds in Australian‐grown ginger (Zingiber officinale)

The volatile compounds responsible for the flavour of Australian‐grown ginger have been extracted using supercritical carbon dioxide. Both fresh and dried ginger samples have been examined and the major effects of the drying process are a reduction in gingerol content, an increase in terpene hydrocarbons and the conversion of some monoterpene alcohols to their corresponding acetates. © 2000 Society of Chemical Industry     

基于气味检测的生姜微波干燥特性研究

分别在50,60,70,80~℃4个恒定干燥温度下,通过采集干燥过程中及干燥后的样品挥发性气味,分析不同温度下气味图谱变化过程及风味散发强度与干燥特性关系,并对比干后生姜的品质。结果表明:过低的温度避免了焦糊但是由于干燥时间过长气味散发比较多。相反,高温干燥时干燥时间比较短但由于产生焦糊气味导致产品品质过差。水分蒸发会伴随着挥发性风味的散失,为达到气味保留与抑制焦糊性能最佳,同时保证干后品质,60~℃原始风味保留与抑制焦糊性能较佳,同时色泽保留效果与复水性均最好。     

Effect of drying temperature on polyphenolic content and antioxidant activity of apricots

This study was carried out in order to check for the influence of drying parameters on the phenolic compounds and antioxidant activity on two apricot cultivars (Pelese and Cafona) using two sets of air drying temperatures: (1) air temperature at 55 °C; (2) air temperature at 75 °C. Whole fresh and dried fruits were assessed for: phenolics, ascorbic acid, antioxidant activity and redox potential (all parameters were calculated on a dry matter basis). Analysis of data shows that the decrease in chlorogenic and neochlorogenic acid in Cafona cultivar is higher at the lower drying temperature. Catechin showed the same behaviour of hydroxycinnamic acids in both cultivars, while the decrease in the other compounds was significantly more marked in the sample dried at 75 °C. The antioxidant activity increased significantly in Cafona fruits and this increase was confirmed by a diminution of the redox potential.     

生姜不同切割后的抗氧化成分及其活性的变化

对生姜进行不同程度的切割伤害处理(分别切成片状、块状及末状),并在4℃的贮藏温度下于不同的放置时间(0,3,6,12h)测定其抗氧化物质含量,包括黄酮类物质、还原型谷胱甘肽和抗坏血酸含量,并且测定超氧化物歧化酶(SOD)活性,以及测定脂溶性物质抗氧化能力和水溶性物质抗氧化能力。实验结果表明,不同程度的切割伤害处理均使生姜的黄酮类物质含量、还原型谷胱甘肽含量、SOD活性以及水溶性和脂溶性物质的抗氧化能力上升,但切割处理却使VC含量降低,切割伤害程度越大,VC含量下降的速率越快。生姜的脂溶性物质抗氧化能力远远高于水溶性物质的抗氧化能力,总体来说,切割伤害提高了生姜的抗氧化能力,且3种不同的切割伤害处理以伤害程度中等的块状切割最有利于生姜抗氧化能力的提高。      

生姜多糖类物质的提取及抗氧化活性研究

目的以生姜为原料,采用超声波辅助法和热水浸提法提取生姜多糖类物质并进行抗氧化活性对比研究。方法经单因素试验结合响应面优化设计考察最优提取工艺参数,同时对2种方法提取的生姜多糖抗氧化活性进行对比分析。结果超声波辅助法提取生姜多糖最佳提取条件为:超声温度48℃,超声功率340W,超声时间21 min,液固比50:1(m L/g),在此条件下多糖得率为6.87%;热水浸提法的最佳提取条件为:温度72℃,时间164 min,液固比40:1(m L/g),在此条件下多糖得率为3.13%。抗氧化活性测定结果表明,超声波辅助法和热水浸提法提取生姜多糖的DPPH自由基清除能力的IC_(50)值分别为0.21 mg/m L和0.42 mg/m L,还原能力分别相当于维生素C的3.14%和0.5%,铁离子螯合能力的IC_(50)值分别为2.17 mg/m L和4.18 mg/m L,超声波辅助法提取的生姜多糖的DPPH自由基清除能力、还原力和金属螯合能力分别是热水浸提法提取的生姜多糖的2倍、6倍和1.9倍。结论生姜多糖具有一定的抗氧化活性,本研究可为生姜多糖的提取提供参考。     

Effect of drying conditions on bioactive compounds and antioxidant activity of broccoli (Brassica oleracea L.)

The effect of air‐drying parameters on antioxidant activity and changes in antioxidant compounds of broccoli (Brassica oleracea L.) were studied. Broccoli samples were dried to 70 g kg^?1 moisture content using temperatures ranging from 50 to 100 °C and air flow‐rates from 1.20 to 2.25 m s^?1, resulting in drying times from 25 to 90 min. Temperature, owing to its positive effect on the oxidation kinetics, was negatively correlated with ascorbic acid and free and total polyphenol contents but not with kaempferol, even though the sample dried at the highest temperature showed the lowest kaempferol content. The air flow‐rate was positively correlated with the total (TPP) and free (FPP) polyphenol contents because it led to a reduction in the drying time. No correlation was found between air flow‐rate and kaempferol content. Air flow‐rate and temperature positively affected the antioxidant activity by reducing the drying time. High‐temperature, short‐time processes maximised the antioxidant activity of broccoli owing to the negative effect of drying time on antioxidant activity. The antioxidant activity of broccoli was positively and significantly correlated with the FPP content but not with TPP and kaempferol. The evaluation of hydroxymethylfurfural content as an indicator of the occurrence of a Maillard reaction in dried broccoli did not support the hypothesis of a contribution of MRPs to the antioxidant activity of dried broccoli. Copyright © 2006 Society of Chemical Industry     

姜辣素的超声波辅助提取及其抗氧化活性研究

研究通过单因素及正交试验探讨乙醇体积分数、料液比、超声波处理时间对姜辣素提取效果的影响,确定姜辣素的优化工艺,并探讨了姜辣素提取物对花生油的抗氧化作用,为其进一步开发研究提供参考。结果表明,姜辣素的最佳提取工艺是乙醇体积分数65%vol、功率300W超声提取20min、料液比1∶12（g∶mL）,姜辣素在适宜条件下的提取率达2.78%,该提取物具有抗花生油氧化的作用。     

干燥方法对杏肉全粉品质及抗氧化活性的影响

采用微波干燥(MD)、热风干燥(HAD)、微波真空干燥(MVD)、微波对流干燥(MCD)4种干燥方法制备纯天然杏肉全粉,比较了干燥方法对杏肉全粉营养成分、物理特性、感官品质和抗氧化能力的影响。结果表明,干燥方法对杏肉全粉品质的影响显著(P0.05),MVD和MCD 2种方法干燥的杏肉全粉总糖和还原糖保留较好,并且MCD法干燥的产品总酚和VC损失最少,而HAD法对总酸的保留最好;MD法制备的产品吸湿性和结块度最低,MCD法制备的产品堆积密度和休止角最小,且获得的感官评价分值最高(95.2分);制备的杏肉全粉还原力及清除DPPH、超氧阴离子和羟自由基的能力呈显著的量效依赖性且存在显著差异,MVD法制备的产品对DPPH自由基清除能力最强,而MCD对羟自由基、超氧阴离子自由基的清除能力最强,还原力也最大,分别为88.5%,85.1%,1.98。     

姜精油的超临界CO2提取及其抗氧化性研究

采用正交试验的方法,确定了超临界CO2萃取姜精油的最佳工艺条件萃取温度40℃,萃取压力20MPa,萃取时间90min;研究了姜精油在植物油和动物油中的抗氧化性能,结果表明,生姜的超临界CO2提取物是一种良好的天然抗氧化剂,柠檬酸、BHT、TBHQ对其增效显著.     

沙蒿籽总黄酮和总多酚及其抗氧化活性

本文测定了沙蒿籽的四种不同极性溶剂提取物中总黄酮和总多酚的含量、化学成分及其体外抗氧化活性。结果显示:沙蒿籽总黄酮和总多酚的提取含量与溶剂的极性相关,甲醇提取物的总黄酮(33.30±0.11)mg/g和总多酚(80.1±0.16)mg/g含量最高,其次是丙酮和乙酸乙酯提取物,氯仿提取物含量较低。相对应的是,甲醇提取物的DPPH和ABTS自由基清除能力最强,其IC50分别是19.09、26.30μg/m L,其铁离子还原能力也明显高于其它三种提取物。通过HPLC法检出槲皮素和儿茶素两种黄酮,均在甲醇提取物中含量最高,分别为5.15、28.24 mg/g。这表明,甲醇更适宜于沙蒿籽中总多酚和总黄酮的提取,这为沙蒿籽作为抗氧剂的开发利用提供了理论依据。      

喷雾干燥法制备生姜微胶囊的研究

以生姜为原料,经乙醇提取而得的姜油树脂为心材,以阿拉伯胶和麦芽糊精为壁材,用喷雾干燥法来制取姜油树脂微胶囊。通过正交试验分析,以油树脂包埋率为指标,确定了生姜喷雾干燥法微胶囊化的最佳工艺条件:心材与壁材比为1∶5、进风温度190℃、阿拉伯胶与麦芽糊精比为1∶7。     

生姜糖蛋白提取工艺优化及抗氧化活性研究

以生姜为原料,在单因素实验基础上采用三元二次回归正交组合设计优化生姜糖蛋白的提取工艺,采用红外光谱初步分析了生姜糖蛋白的结构特征。同时,考察了生姜糖蛋白的抗氧化活性和凝集素芯片的荧光强度。结果表明,生姜糖蛋白的最优提取条件:提取温度为90℃,液固比为35.5∶1,p H为7.5,在此条件下提取3 h,蛋白质得率为2.437 mg/g,糖得率为117.126 mg/g;经分离纯化获得的生姜糖蛋白,采用红外光谱分析表明其存在多糖和蛋白质的特征吸收峰。抗氧化实验与凝集素芯片实验结果表明,生姜糖蛋白在蛋白表面具有糖链结构,且可以螯和金属离子,具备一定的还原能力与重要的生理功能。