The influence of freezing parameters and size on the drying process of apple pomace in a dryer with infrared heating

This article examines the impact of frozen apple pomace size on the intensification of the drying process. An analytical review of the literature revealed that short-term microwave heating (convective drying) is used to dry apple pomace at most industrial facilities. However, this method has several drawbacks when drying certain food products. Infrared radiation treatment, which has undeniable advantages over other methods, is now the most widely used method for drying plant materials. The authors used a dryer with infrared heating to dry the apple pomace. To intensify the process, the apple pomace was pre-frozen and ground. To confirm this hypothesis, an experiment was designed and conducted. The pomace was pre-crushed to sizes of 2–3 and 3–4 mm; uncrushed fractions measuring 6×6×6 mm were also used. The resulting raw material was dried on a laboratory bench at a temperature of 60 °C, taking measurements every 15 minutes. The experimental data showed that pre-freezing the apple pomace reduced the drying time by almost 30 %, and pre-crushing the frozen apple pomace reduced the drying time by almost 40 % under the same process parameters. The maximum drying rate was achieved using crushed apple pomace of the 2–3 mm size. The 3–4 mm fraction also demonstrated a significantly higher drying rate compared to the 2–3 mm size. This led to the conclusion that the crushing size of the apple pomace will determine the type of final product. The results obtained during the experiments can be applied in the design and determination of technological parameters for drying apple pomace.