Total energy consumption, i.e. the energy consumed by the vacuum system, the heating system, etc., was measured during blueberry processing. Energy consumption was measured with digital network analysers: (1) Series MPR-53/EPM-07, Model MPR-53S (ENTES Elektronik Cihazlar Imalatve Ticaret A.S., Istanbul, Turkey); (2) Model B65–6907C (BEMKO, Warsaw, Poland). Specific energy consumption of drying was determined by integrating energy use and calculating the amount of moisture removed from the material according to the following formula (Jokiniemi, Kautto, Kokin, & Ahokas, 2011):
equation(1)
View the MathML sourceESD=EDMW
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where ESD is specific energy consumption of drying, (kWh·kg of water removed−1); ED is energy consumption of drying (kWh); MW is the amount of water removed from the material during drying (kg).