单花蜜中羟甲基糠醛生成反应动力学研究

Study on Kinetics of HMF Formation In Unifloral Honey

羟甲基糠醛含量是评价蜂蜜质量的重要指标,研究羟甲基糠醛(HMF)生成反应的影响因素显得尤为重要。本论文在不同温度下对金银花蜜、枸杞蜜、椴树蜜恒温热处理2～10h,采用紫外分光光度计法测定这三种单花蜜中HMF含量随热处理时间的变化。结果表明:这三种单花蜜中HMF的生成反应表观上皆遵循一级反应动力学模型[HMF]t=[HMF]0exp(kt),其反应速度常数与热处理温度之间的关系表观上皆符合阿累尼乌斯方程k=kfexp(-Ea/RT)。结论:在蜂蜜热处理过程中,HMF的生成是必然的,蜂蜜质量的降低程度取决于HMF生成反应进行的速度和时间,温度越高,质量下降越快;但由于品种的不同,蜂蜜质量下降的速度与温度的关系并不相同。

Usually, 5-Hydroxymethylfurfural （HMF） comes into being during thermal treatment, and not presents in fresh honey. The content of HMF is used to evaluate the quality of honey. Because it is poisonous for people＇ s health, the content of HMF must be confined. In this paper, honeysuckle honey, bass honey and medlar honey were isothermally treated at different temperatures for 2 and 10h, respectively, the relationship between the content of HMF and the time of thermal treatment was detected by Ultraviolet Spectrophotometry, and the data were regressed by Modify Partial Least Squares （MPLS）. The results indicated that the content of HMF increased with the increase of the time of thermal treatment and the increase rate quickened with the increase of the temperature of thermal treatment, the HMF formation followed first order kinetics, its expression was： [HMF]=[HMF0]exp（kt）. The relationship between the rate constant k and the temperature of thermal treatment followed the Arrhenius equation, its expression was： k=Kfexp（- Ea/RT）. The HMF initial concentrations （[HMF]0） of these unifloral honeys were 2.84, 6.20 and 5.24mg/kg, respectively, their kf were 4.659 ×10^14h^-1, 8.525 × 10^12h^-1 and 8.790 × 10^14 h^-1, respectively, and their Ea were： 102.104, 91.603 and 84.420kJ/mol, respectively.