Study On The Effect Factors Of Hydroxymethylfurfural During Honey Thermal Treatment

The effects of temperature and time on the HMF content of honey thermal treatment were studied, during the isothermal heating process at mild temperatures of five fresh unifloral Chinese honeys (Rape, Loquat, Osmanthus yunnanensis, Leechee and Longan). According to the results, the kinetics of HMF formation was also investigated. The influence of physicochemical characteristics of Rape honey on the HMF formation was studied, which were the moisture content, pH, reducing sugars content, proline content, initial HMF content and metal ions. The effects of maillard reaction inhibitor on HMF content during honey thermal treatment were researched. Changes of HMF content in honey during ultrasonic thermal treatment were also investigated. The results were summarized as follows:(1) The rate of HMF formation in honeys during thermal treatment:Loquat> Osmanthus yunnanensis> Longan> Rape> Leechee. The kinetics of HMF formation [HMF]=a· eb·T· t2+c· ed·T· t+[HMF]0[HMF]t and [HMF]0are the HMF contents of honey at t and0minutes. T and t are thermal treatment temperature and time.(2) The physicochemical properties of honey showed significant correlation with HMF content. The results revealed that heating was not the only factor influencing HMF formation in honey, but also honey composition could contribute to these variations, such as the moisture content, pH, reducing sugars content and proline content and so on. The metal ions could enhance the formation of HMF. The higher moisture content and proline content in honey, the lower HMF content were tested after thermal treatment. The lower pH in honey, the higher HMF content appeared. The higher reducing sugar content, the HMF content increased and then decreased. The higher HMF initial content in honey, the greater HMF incremental content was measured after thermal treatment.(3) Only two maillard reaction inhibitors (Na2SO3and Na2HPO4) could inhibit the HMF formation during honey thermal treatment. Others have no inhibition on the HMF.(4) Ultrasonic thermal treatment improve the rate of HMF formation at60℃and70℃, but improve indistinctively at80℃.