兰考泡桐木材成分的变色行为及其变色过程

从兰考泡桐（ＰａｕｌｏｗｎｉａｅｌｏｎｇａｔａＳ．Ｙ．Ｈｕ）木材的含水甲醇浸提物分离出梓醇、泡桐素和芝麻素三种成分，在不同条件下进行模拟变色试验。结果显示，ｐＨ值是影响梓醇变色的主要因素，光照和氧气同时作用可导致泡桐素和芝麻素变色。温度和湿度变化对兰考泡桐木材成分变色也有显著影响。泡桐木材变色是多种因素共同作用的结果。根据对实验事实的分析，提出了这些成分在变色过程中可能发生的一系列反应。

Impacts of different drying strategies on drying characteristics,the retention of bio-active ingredient and colour changes of dried Roselle

The drying kinetics of Roselle （Hibiscus sabdariffa L） of variety Terengganu （UMKL-1） and the quality attribution of Roselle were studied. The experiments were conducted using four different drying methods, including solar greenhouse drying （SD）, solar greenhouse with intermittent heat pump drying （SIHP）, hot air drying （HA） and heat pump drying （HP）. Among the four drying methods, HP achieved the highest drying rate at a range from 0.054 g H20-（g DM）-1. rain-1 to 0.212 g H20-（g DM）-1. rain 1 while SD had the lowest drying rate, measured at 0.042 g H2O. （g DM） 1.min- 1. The analysis on colour kinetics revealed that there is no significant colour loss （p 〉 0.05） observed from HP＇s dried Roselle. Greater amount of flavonoid compounds i.e. protocatechuic acid was found in SD and SIHP dried finished product whereas HP＇s dried Roselle contains higher percentage of catechin as compared to other drying methods.