The Effect of Unconventional Technologies on Carbon Emissions During the Convective Drying of Yellow Mealworm (Tenebrio molitor L.) Larvae and the Selected Physical Properties Thereof

The drying of insects is an important step in their processing. This research aimed to investigate the impact of a pulsed electric field (PEF), immersion in ethanol (EtOH), and combined (immersion in EtOH followed by PEF) treatment on the convective drying process, the emission of CO2, and the quality of the dried insects with regard to such elements as water content and activity, rehydration and hygroscopic properties, optical properties, internal structure, and microbiological quality. In applying a PEF, the drying time was made longer (up to 21%), but the rehydration and hygroscopic properties were improved (about 15–16.5% and 8.3–21.7%, respectively) compared to the untreated sample. Using a PEF prior to EtOH treatment improved the rehydration properties (about 3.9–5.9%), while the hygroscopicity was slightly lower compared to the PEF-treated samples. Furthermore, immersion in ethanol (both alone and after PEF) provided a lighter color of dried insects and more outstanding microbiological quality, e.g., the absence of water-borne and food-borne pathogens and anaerobic spore-forming bacteria. This study revealed that combined pretreatment seems to be the most promising method for insects as regards obtaining better rehydration and comparable hygroscopic properties, as well as an attractive color compared to untreated insects, and, above all, in ensuring suitable microbiological quality.