Biochemical origin of browning during the processing of fresh yam (Dioscorea spp.) into dried product
Biochemical origin of browning during the processing of fresh yam (Dioscorea spp.) into dried product
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DOI：
10.1021/jf040265n
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发表时间：
2005-04-06
影响因子：
6.1
通讯作者：
Nago, M
中科院分区：
文献类型：
--
作者：
Akissoe, NL;Mestres, C;Nago, M
研究了山药在不同温度和干燥条件下烫漂过程中多酚氧化酶(PPO)、过氧化物酶(POD)和酚类化合物的动态变化，并用高效液相色谱法(HPLC)对山药制品中的主要酚类物质进行了鉴定。未经加工的冷冻干燥山药的PPO活性比未经加工的冷冻干燥山药高50%。在热烫过程中呈递减趋势。在60℃或65℃下漂烫50min后，PPO活性仍有45%，而POD活性在漂烫10min后急剧下降至初始活性的20%以下，无论漂烫温度如何。在520 nm波长处未加工的冻干山药中未检出花青素。黄烷醇的最大吸收波长为280 nm，肉桂酸化合物的最大吸收波长为320 nm。儿茶素是黄烷醇的主要成分，其含量因品种而异，变化范围为0.26~0.41亩Mg(-1)。在两个品种(0.03-0.04亩Mg(-1))中都鉴定和评估了一种肉桂化合物--阿魏酸。总酚、黄烷醇和肉桂酸的含量在漂白过程中下降，而不受温度的影响，而在干燥产品中有一些未分解的峰。后者可能是由于着色剂的消耗和聚合或复合有色产物的出现。
This study was undertaken to follow the kinetics of polyphenoloxidase (PPO), peroxidase (POD), and phenolic compounds during yam blanching at different temperatures and after drying and to identify by high-performance liquid chromatography (HPLC) the main phenolic compounds present in yam products. PPO activity was 50% higher in nonprocessed freeze-dried Florido (Dioscorea alata) than in nonprocessed freeze-dried Deba (Dioscorea rotundata). It decreased progressively during blanching. Forty-five percent of PPO activity remained after 50 min of blanching at 60 or 65 degrees C, whereas the POD activity dropped sharply to less than 20% of the initial activity after 10 min of blanching, whatever the blanching temperature. No anthocyanidins could be detected by HPLC at 520 nm in nonprocessed freeze-dried yam. Flavanols with a maximum absorption wavelength (lambda(max)) at 280 nm and cinnamic acid compounds with 320 nm lambda(max) were detected. Catechin was identified as the major flavanol with concentrations ranging from 0.26 to 0.41 mu M g(-1) depending on cultivar. One cinnamic compound, ferulic acid, was identified and assessed in both cultivars (0.03-0.04 mu M g(-1)). Total phenol, flavanol, and cinnamic contents decreased during blanching independently of temperature whereas some unresolved peaks were detected by HPLC in dried product. The latter was probably due to the consumption of coloring precursors and the appearance of polymerized or complex colored products.