Karadeniz F, Durst R W, Wrolstad R E
Department of Food Engineering, Faculty of Agriculture, Ankara University, Ankara, Turkey.
J Agric Food Chem. 2000 Nov;48(11):5343-50. doi: 10.1021/jf0009753.
The polyphenolics of raisins were extracted, separated by HPLC, and characterized by their UV-vis spectra, and their concentrations measured. Color measurements and browning indices were also determined. Samples (n = 20) included sun-dried, dipped, and golden raisins. Comparisons were also made with fresh and frozen Thompson Seedless grapes. Golden raisins (which are treated with SO(2)) had the highest amount of hydroxycinnamic acids and the highest lightness values. In comparison with fresh grapes, percent losses of the two major hydroxycinnamics (caftaric and coutaric acids) in sun-dried, dipped, and golden raisins were on the order of 90%. Flavonols were not influenced by processing as much as hydroxycinnamics, while procyanidins and flavan-3-ols were completely degraded in all raisin samples. Formation of hydroxymethylfurfural and loss of amino acids in sun-dried and dipped raisins are ascribed to Maillard browning reactions.
提取葡萄干中的多酚类物质，通过高效液相色谱法（HPLC）进行分离，利用紫外可见光谱对其进行表征，并测定其浓度。还测定了颜色参数和褐变指数。样本（n = 20）包括晒干葡萄干、浸渍葡萄干和金色葡萄干。同时也与新鲜和冷冻的汤普森无核葡萄进行了比较。金色葡萄干（用二氧化硫处理）含有最高量的羟基肉桂酸和最高的亮度值。与新鲜葡萄相比，晒干葡萄干、浸渍葡萄干和金色葡萄干中两种主要羟基肉桂酸（咖啡酸和对香豆酸）的损失率约为90%。黄酮醇受加工的影响不如羟基肉桂酸大，而原花青素和黄烷-3-醇在所有葡萄干样本中均完全降解。晒干葡萄干和浸渍葡萄干中羟甲基糠醛的形成和氨基酸的损失归因于美拉德褐变反应。
