LAUSR

Three types of honey including lime (Tilia spp.), buckwheat (Fagopyrum spp.) and acacia (Robinia pseudoacacia) honeys were analyzed. Honeys were subjected to conventional heating at a temperature of 60°C and heated in a microwave field. Depending on the type of honey, the temperature obtained in the microwaves was in the range of 48 and 69°C. After processing, honeys were stored for 3 months in uniform condition (ambient temperature, darkness, constant humidity) and subsequently reanalyzed. Oversized decrease in the value of diastase number was found in only two cases of honeys exposed to microwave field (after storage). Under the experiment conditions, there was no clear changes in the HMF concentration The largest increase was found in the case of acacia (A-CD) and buckwheat (B-B) honeys. For these types of honeys, increase in HMF concentration was of 2 mg/kg and 3 mg/kg, respectively. The biggest impact of the microwave irradiation was observed on the invertase activity. All the tested honeys, especially those subjected to microwave irradiation, showed a statistically significant decrease (five times the initial value) in the activity of this enzyme. Decrease in the diastase activity in microwaved honeys was from 6.8 to 3.7° Schade in case of acacia honey (A-B) from 27.0 to 11.6°Schade in case of buckwheat (B-OSP) honey. Practical Applications The research is valuable for preserving quality of natural products, i.e., honey. The use of thermal treatment of honey is particularly important in countries with tropical climates. This is due to the danger of spontaneous fermentation of honey. Thermal processing of honey is also used for other practical reasons (filling and packaging, preventing crystallization). From practical point of view, it is worth to point out that the use of microwave irradiation, despite advantages such as shorter heat exposure time appears to be unacceptable in the case of honey processing due to its destructive effect on the enzymes present in the product.