Comparative evaluation of greenhouse gas emissions and specific energy consumption of different drying techniques in pear slices

Abstract

AbstractIn recent years, global warming, climate change, and carbon emissions have emerged due to the uncontrolled use of fossil fuels and the lack of widespread use of renewable energy sources on a global scale. This research investigated specific energy consumption (SEC) and greenhouse gases (GHG) emissions (carbon dioxide [CO2] and nitrogen oxides [NOX]) during the drying of pear samples by five different types of dryers, namely, convective (CV), infrared (IR), microwave (MW), combined IR/CV, and MW/CV. Moreover, the quality properties of dried pears, such as shrinkage, rehydration (RR), and color change were determined. The results showed that the highest shrinkage (72.53%) and color change (ΔE = 33.41) values were obtained in CV drying at 50 °C and thickness of 2 mm and IR dryer 1000 W and thickness of 6 mm, respectively. The greatest rehydration rate (4.25) was also determined in MW/CV drying at 450 W and an air temperature of 60 °C. The lowest SEC was observed for the MW/CV dryer with a power of 630 W and air temperature 70 °C (20.25 MJ/kg), while the highest SEC (267.61 MJ/kg) was obtained in the CV drying (50 °C, sample thickness of 6 mm). The highest CO2 and NOX emissions (GT-GO power plant) were 280.45 and 1.55 kg/kg water in the CV dryer at 50 °C and a thickness of 6 mm. In conclusion, the increases in IR and MW power and temperatures led to reduced CO2 and NOX emissions, while the increases in sample thickness led to increase CO2 and NOX emissions.