Changes in the catechin and epicatechin content of grape seeds on storage under different water activity (aw) conditions

Storage effect on antioxidant content and capacity of grape seeds under different a_w conditions (a_w 0.33; 0.53; 0.75/50 days, 25 °C) was examined. Total phenol content (determined by the Folin–Ciocalteu method) decreased during storage though changes were trivial for samples stored at 33% or 53% RH. High level of humidity (75%) accelerated degradation and resulted in a ∼50% reduction of total phenol content. Minor loss of the DPPH radical scavenging activity (%RSA) of the extracts was observed. Catechin and epicatechin content monitored by RP-HPLC was reduced during storage, particularly at 75% RH. Epicatechin content proved to be less sensitive to water activity conditions than catechin content. Results of various in vitro assays (Folin–Ciocalteu, FRAP, DPPH, ABTS, CBA, ORAC and copper induced liposome oxidation) did not support difference in terms of resistance to oxidation. Based on the continuous release of gallic acid, our finding was related to hydrolytic reactions. Control of a_w of grape seeds can be of practical importance for the wine industry.     

The antioxidant capacity of complex mixtures by kinetic analysis of crocin bleaching inhibition

The capability of a compound or of a mixture of compounds to quench peroxyl radicals was measured by analyzing the kinetics of the competition of a parallel reaction where peroxyl radicals bleach the carotenoid crocin. This kinetic approach, originally described for the analysis of antioxidants reacting with hydroxyl radicals in water, was modified by both decreasing the polarity of the solvent, thus allowing the analysis of lipophilic compounds, and by substituting a source of peroxyl radicals for the hydroxyl radical generating system. Single compounds as well as complex mixtures were analyzed by kinetic data processing. Overall antioxidant capacity, relative to that of α-tocopherol or of its soluble analog Trolox C, was calculated. As examples of the use of this test, the antioxidant capacities of a crude rosemary extract, Maillard reaction products, and virgin olive oils were measured.     

Changes in Pigments and Volatiles of Saffron ( Crocus sativusL) During Processing and Storage

Significant variations were observed in the concentration of pigments (10·0–17·0%, moisture-free basis) and flavour components during different post-harvest processing conditions of saffron (stigmas ex Crocus sativus L). The crocin pigments concentration was highest (15–17%) in the saffron samples dried between 35°C and 50°C either in a solar dryer or in an oven dryer and this also resulted in considerable reduction of normal drying time. Under these conditions the main flavouring component, safranal, was at its peak value of 60% in the oil in almost all the samples except the vacuum oven dried samples which interestingly contained 4-β-hydroxysafranal in major amounts. Studies indicated that 4-β-hydroxysafranal may be an intermediate in the formation of safranal. It was observed that prolonged storage affected the pigments and flavour concentration to a great extent, but proper packaging and storage with 5% moisture in the saffron reduced the deterioration, thereby increasing the shelflife of the product.     

栀子黄色素稳定性研究

以提纯的栀子黄色素为材料,研究了酸碱度,温度,光照等因素对其稳定性的影响,考察了栀子黄色素在多种条件下的变化规律,其结果为栀子黄色素的加工,贮运,开发应用提供了参考依据。     

利用大孔吸附树脂吸附分离藏红花细胞培养液中藏红花素和藏红花苦素

目的:研究大孔树脂提取藏红花细胞培养液中藏红花素和藏红花苦素的工艺。方法:对4种大孔树脂提取藏红花素和藏红花苦素的效果进行比较,考察HPD-100A大孔树脂提取藏红花素和藏红花苦素的最佳工艺条件。结果:HPD-100A树脂提取藏红花素和藏红花苦素效果最佳,其最适工艺条件为25℃、色素液pH6、藏红花素和藏红花苦素上样质量浓度分别为1.0mg/mL和24.6mg/mL、溶液处理量1.5BV、吸附流速1.5mL/min、洗脱剂为体积分数40%乙醇溶液、洗脱剂体积1.7BV、洗脱流速1.0mL/min。藏红花素和藏红花苦素的吸附率分别达到94.4%和75.5%,解吸率分别为99.9%和87.5%。结论:采用大孔吸附树脂吸附分离藏红花培养液中藏红花素和藏红花苦素方法可行,前景广阔。     

Stability of Saffron Pigments in Aqueous Extracts

The effect of pH, light, temperature and oxygen on the stability of saffron pigments in aqueous extracts has been studied. First-order kinetics for the degradation of saffron pigments was observed for all experimental conditions. Kinetic data were calculated from the values of the coloring power of saffron aqueous extracts.