Abstract—In this study, 3 different drying methods (hot-air drying, freeze drying, microwave vacuum drying) were compared by aroma composition of dried hops and the required electrical energy for each technology. From the total volatile fraction, 3 main compounds were detected: ß-myrcene, α-caryophyllene and ß-caryophyllene. According to the results, the 3 drying technologies did not cause significant change in aroma compound composition in dried hop. ß-myrcene was preserved in the largest amount by freeze drying, followed by microwave vacuum drying and hot-air drying, respectively. Freeze drying had by far the highest energy consumption, followed by microwave vacuum drying. Hot-air drying used the less energy, which is 5.96% of freeze drying. Microwave vacuum drying could be a promising alternative to widely used hot-air drying for hop, because of better aroma retention and slightly higher required electric energy.
 

Index Terms—drying, microwave vacuum drying, freeze drying, hot-air drying, hop drying

Cite: Sándor Ferenczi, Helga Molnár, Nóra Adányi, and Zsuzsanna Cserhalmi, "Comparison of Microwave Vacuum-, Freeze- and Hot-Air Drying by Energy Efficiency and Aroma Composition of Dried Hop (Humulus lupulus)," International Journal of Food Engineering, Vol. 4, No. 2, pp. 136-139, June 2018. doi: 10.18178/ijfe.4.2.136-139