果蔬中残留甲醛消解动态及其甲醛本底值的研究

Digestion Kinetics and Background Level of Formaldehyde in Fruits and Vegetables

摘要:

采用五氟苯肼衍生液相色谱法分析果蔬中残留甲醛在不同条件下的消解动态，同时对部分果蔬中甲醛本底值进行测定。研究表明：果蔬中残留甲醛的消解速度与贮藏介质有关，在水中浸泡消解速度明显比在空气中自然消解速度快。在空气中甲醛自然消解的主要影响因素是空气温度和果蔬基质，温度越高，消解速度越快。在水中浸泡消解速度与水温、pH和果蔬基质有关，50 ℃水中的消解速度要高于25 ℃水中的消解速度；pH=9时消解速度要高于pH=7和pH=5条件下。甲醛本底含量检测发现32种果蔬中有31种存在一定的甲醛本底，其中鱼腥草中未检出甲醛本底，柑橘类中桔子和橙子的甲醛本底含量较高，可达0.79~2.52 mg/kg，其他果蔬中甲醛含量均处于0.08~0.61 mg/kg之间，这为果蔬中甲醛含量的检测提供了参考数据。

Abstract:

Pentafluorophenylhydrazine derivatization liquid chromatography was performed to analyze the residual formaldehyde in fruits and vegetables under different digestion dynamics conditions, as well as to detect the background level of formaldehyde in various fruits and vegetables. Results showed that the digestion rate of formaldehyde in fruits and vegetables was associated with the storage medium. The digestion rate in water was significantly faster than that in air. The main factors affecting formaldehyde digestion in air were air temperature and the matrix of the fruits and vegetables; the higher the temperature, the faster the digestion. Digestion in water was related to water temperature, pH, and the matrix of the fruits and vegetables; the digestion speed in water at 50 ℃ was higher than that at 25 ℃; the digestion rate at pH 9 was higher than those at pH 7 and pH 5. Background levels of formaldehyde could be detected in 31 out of 32 types of fruits and vegetables. Among them, only Houttuynia cordata showed no detectable background level of formaldehyde. Relatively high background levels of formaldehyde could be detected in citrus fruits, such as mandarin and oranges, which reached 0.79 mg/kg~2.52 mg/kg, while formaldehyde contents in the other 30 kinds of fruits and vegetables were 0.08 mg/kg~0.61 mg/kg. These results provide reference data for the detection of formaldehyde content in fruits and vegetables.