Changes in α-amylase activity in honey during the freeze-drying process
Latvia University of Life Sciences and Technologies, Faculty of Food Technology, Department of Chemistry, Liela Street 2, LV-3001 Jelgava, Latvia
*Correspondence: anete.keke@llu.lv
Abstract:
Honey is a natural product, which is appreciated for its sweetness, high nutritional value and health benefits all over the world. Despite all benefits, the usage of honey in food industry is limited due to its high viscosity. The use of dried honey could be an alternative to liquid honey, and would allow to use it as an additive in a range of many different food products such as sauces, beverages, yogurts etc. There are many parameters, which are used to determinate the quality of honey. α-amylase (diastase) activity is one of the most important criteria to determine the quality and freshness of honey. The aim of the present study was to investigate and compare α-amylase activity in liquid honey samples and freeze-dried honey samples. Overall, 18 honey samples were dehydrated using a freeze-drying method. Freeze-drying of the samples was carried out at – 50.6 °C and the pressure was 0.036 mbar for 72 hours. α-amylase activity in the honey samples was tested using Amylazyme test tablets. The obtained results showed variability in α-amylase activity after the freeze-drying process. As hydroxymethylfurfural (HMF) is another important quality parameter of honey, the content of HMF was determined in the samples by high performance liquid chromatography. In some samples the concentration of HMF after freeze-drying increased and was higher than it is allowed according to the International Honey Commission (for example, 55.75 mg kg-1).
Key words:
freeze-drying, HMF, honey, α-amylase activity