Stability and Color of Unreported Wine Anthocyanin-derived Pigments

Grape anthocyanin-3-glucosides and unreported natural pigments characterized as vinylphenol anthocyanin-3-glucoside adducts were studied. Our investigations were undertaken to compare color and stabilities when processed and stored under identical conditions. Studies of molecular concentration, color density and Hunter color values were done at pH levels. Grape anthocyanin-3-glucosides were less stable than their 4-vinylphenol derivatives and the color stability of the unreported pigments was higher than that of anthocyanin-3-glucosides. Moreover, the compounds were resistant to SO₂ discoloration whereas anthocyanins were completely bleached.     

外源添加物质对黑莓清汁花色苷稳定性和抗氧化活性的影响

本文研究了咖啡酸、阿魏酸、单宁酸、黄芩素、茶多酚、没食子酸、原儿茶酸、芦丁等8种外源辅色素对黑莓清汁花色苷辅色效果、热稳定性、光稳定性和体外抗氧化活性的影响。结果表明:咖啡酸、原儿茶酸、茶多酚、没食子酸、单宁酸对黑莓清汁花色苷的辅色效果影响较显著(p<0.05),最适浓度为0.1 mmol/L,而芦丁的最佳辅色浓度为0.4 mmol/L;实验所选辅色素能够在一定程度上提高黑莓清汁花色苷的热稳定性,其中没食子酸、阿魏酸、咖啡酸对其影响效果显著(p<0.05),分别使黑莓清汁花色苷的热降解半衰期延长了6.06、2.07和1.39倍。此外,原儿茶酸、阿魏酸、芦丁能够显著提高黑莓清汁花色苷的光稳定性、DPPH自由基清除能力和总还原力(p<0.05);没食子酸和单宁酸的辅色作用降低了黑莓清汁花色苷的光稳定性。黄芩素、阿魏酸、咖啡酸、芦丁等外源物质可作为黑莓清汁花色苷有效的辅色素。     

花色苷基于分子辅色机制的稳态化制备与应用技术研究进展

源于天然植物的花色苷是集着色、增香和保健作用于一体的新一代功能性食品配料,但在食品加工过程中易受多种外界因素的影响而发生水解或去糖基开环反应,导致产品褪色、风味品质劣变及生物活性丧失。而研究发现在自然生化条件下,植物花色苷通过其内部的多种化学成分(多酚、生物碱、核苷酸和金属离子等)的分子辅色作用而维持稳定性,从而实现花色苷食品的色泽、风味和营养的稳态化。目前通过模拟植物花色苷的分子辅色作用也成为研究功能性色素的重要内容之一。本文在分析花色苷分子辅色作用机制基础上,重点综述了近年来的天然植物花色苷基于分子辅色技术的稳态化制备工艺及相关应用技术取得的最新进展,为植物花色苷食品的稳态化加工技术研究提供依据和参考。     

Detection and Partial Characterisation of New Anthocyanin-Derived Pigments in Wine

New anthocyanin-derived red–orange pigments were detected in wine in the course of cross-flow microfiltration experiments. Analysis of the sugar and organic acid released respectively by acid and alkaline hydrolysis showed that the two major products were respectively a glucoside and the corresponding p-coumaroylglucoside. Mass spectrometry indicated molecular masses of 755·5 for the p-coumaroylglucoside and of 447·5 for its aglycone. Therefore, the new pigments are likely to result from condensation reaction between grape anthocyanins (possibly the 3-glucoside and 3-p-coumaroylglucoside of malvidin) and another wine component, which is not a flavanol. This reaction may partici-pate in the mechanism of colour change during ageing of red wines.     

红毛丹果皮色素及其稳定性的研究

红毛丹(Nephelium lappaceum L.)果皮含有较高的色素。为综合利用植物色素资源,对红毛丹果皮色素进行提取与纯化,并从光照、温度、pH 值、氧化与还原介质、防腐剂、酸味剂、糖类、VC 和金属离子方面对该色素的稳定性进行研究。结果表明：红毛丹色素属花色苷类;对自然光、高温、H2O2 和Na2SO3 的耐受性较差,在pH3 以下色泽较稳定;低浓度防腐剂苯甲酸钠对色素稳定性影响较小,柠檬酸具有一定的增色作用;乳酸、葡萄糖和蔗糖、VC 对色素的稳定性无明显的影响,但Fe3+、Fe2+、Pb2+、Sn2+ 对该色素稳定性起不利的作用。该研究为开发植物新的天然色素产品提供理论参考。     

Ascorbic acid improves the antioxidant activity of European grape juices by improving the juices' ability to inhibit lipid peroxidation of human LDL in vitro

Antioxidant activities of red and white European grape juices towards copper induced lipid oxidation of human low-density lipoproteins (LDL) were examined in vitro . LDL lipid peroxidation was assessed spectrophotometrically by monitoring the development of conjugated lipid hydroperoxides at 234 nm. Red grape juice concentrate inhibited lipid peroxidation of LDL by prolonging the lag phase by 2.7 times relative to a control when evaluated at a total phenolic concentration of 10 μM gallic acid equivalents (GAE). Both red grape juices tested blocked lipid peroxidation of LDL at 20 μM GAE. White grape juice exerted prooxidant activity at 5–20 μM GAE. The antioxidant activity, inhibition of lipid peroxidation of LDL in vitro , was correlated with the juices' levels of total phenols ( r  > 0.98, P  < 0.01), anthocyanins ( r  > 0.99, P  < 0.01), flavan-3-ols ( r  > 0.97, P  < 0.05), and hydroxybenzoates ( r  > 0.96, P  < 0.05) when the phenolic composition of each grape juices was analysed by HPLC. 5 μM ascorbic acid alone did not exert antioxidant activity towards LDL, but combinations of 5 μM ascorbic acid with 5 μM GAE juice phenols eliminated the prooxidant activity of white grape juice, and significantly improved the antioxidant activities of red grape juices.     

花青素加工贮藏稳定性的改善及应用研究进展

花青素是一类广泛存在于果品蔬菜等植物性食品中的水溶性类黄酮色素,不仅为食品提供了丰富的颜色, 而且其呈现的抗氧化、抗炎、抗肿瘤等生理活性使其成为功能性食品研究开发的热点。由于花青素不稳定,其在食 品饮料和膳食补充剂中的应用受到限制。本文在广泛查阅文献的基础上,综述了近年来改善花青素加工贮藏稳定性 的方法和技术,重点论述了共色作用、复合作用及载体包埋等技术方法在提升花青素加工贮藏稳定性方面的进展, 以期为花青素的深入研究和工业化利用提供参考。     

Antioxidant properties of domesticated and wild Rubus species

The antioxidative capacities of a number of Rubus species of varied pigmentation have been investigated. In addition, total phenol, anthocyanin and ascorbic acid contents have been determined. Two methods to assess the antioxidant potential of fruit juices have been used. The antioxidant capacities of the fruit ranged from 0 to 25.3 µmol Trolox equivalents g⁻¹ (TEAC) or from 190 to 66 000 µmol l⁻¹ ferric reducing antioxidant power (FRAP). Ascorbic acid contributes only minimally to the antioxidant potential of Rubus juices (<10%, TEAC). There are apparent linear relationships between antioxidant capacity (assessed as both TEAC and FRAP) and total phenols (r_xy = 0.6713 and 0.9646 respectively). Also, anthocyanin content has a minor influence on antioxidant capacity (r_xy = 0.3774, TEAC; r_xy = 0.5883, FRAP). The sample with the highest antioxidant capacity (Rubus caucasicus) had the highest phenol content, but only a low percentage was represented by anthocyanins. The present study demonstrates the potential of certain wild Rubus species, notably R caucasicus, for improvement of nutritional value through germplasm enhancement programmes. © 2000 Society of Chemical Industry     

Strawberry juice colour: The effect of some processing variables on the stability of anthocyanins

The colour stability of juice and purées made from a mixture of two strawberry varieties, stored at + 20°C or at –20°C under aerobic and anaerobic conditions, was studied. High-performance liquid chromatography and spectrophotometric analysis were used to monitor the changes in colour during storage. Pelargonidin 3-glucoside comprised 80% of the total anthocyanin content. Four other pelargonidin-based peaks were found, being 10.4%, 3.5%, 0.7% and 0.3% of the total and two cyanidin peaks were present, being 3.3% and 0.4% of the total. Clarification before storage caused considerable losses in the initial anthocyanin concentrations. Storage conditions (air versus nitrogen) did not influence the rate of loss of anthocyanins during storage or the formation of polymeric pigments. There were no losses in anthocyanins and no increase in the amount of colour measured at 510 nm due to polymers in samples stored at–20°C. Polymerisation occurred in the samples stored at + 20°C, especially in the clarified samples.