STUDY OF THE INFLUENCE OF PLUM DRYING PARAMETERS ON THE CONTENT OF POLYPHENOLIC SUBSTANCES AND ANTIOXIDANT ACTIVITY IN PRUNES

Contemporary prune production is largely driven by industry and market demands. Uniform dimensions and color, balanced taste and attractive flavor are appreciated by consumers . In addition, dried plum is considered a rich source of the essential phytochemicals, mainly polyphenolic compounds. Drying is an effective method of fruit preservation. Drying can maintain the quality of the finished product, but the decisive factor in this process is the method chosen, the equipment and the parameters of the thermal agent. In this work, drying in an infrared cabinet was used as an effective and progressive method that reduces the drying time while preserving the bioactive substances of the initial raw material. To produce a prune authors used the plum species (Prunus domestica L. – domestic plum) of the genus Prunus, the variety «Vengerka domashnya», cultivated in the south of Kazakhstan and as the most suitable variety for obtaining prunes. The results of the study showed that despite the shorter drying time at higher temperature (80°C), drying carried out at 60°C for 10 hours was more effective in terms of polyphenol preservation. Although drying fresh plums causes significant chemical changes, prunes dried in an infrared dryer at temperature 60°C can be considered a functional food due to the high levels of antioxidants: polyphenolic substances in amount 169.51±0.58 mg GAE/100 g DW and Total Antioxidant Capacity (TAC) in amount 64.27±0.65 mg equivalents of α-tocopherol/ g extract.