Combined effect of pulsed electric fields and drying method on the microbial load and protein properties of house crickets (Acheta domesticus)

Abstract

House crickets are already being consumed as food in many parts of the world. Pulsed electric fields (PEF) constitute a nonthermal food process capable of improving microbial stability, enhancing conventional processes, and altering protein structure. This study examined the impact of PEF pretreatment (4.4 kV/cm, 500 pulses) on cricket flour production, using oven-drying and freeze-drying. PEF reduced the energy consumption by 18.04 % in oven and 49.82 % in freeze-drying. Microbiological evaluation and assessment of protein properties were conducted on the produced flour. While PEF alone did not fully inactivate microorganisms, combining it with oven drying significantly reduced microbial levels (2.7 log/g, 1.6 log/g, and 2 log/g, for mesophilic bacteria, Enterobacteria, and molds, respectively). No reduction in spore count was noted. PEF influenced protein properties differently based on the drying method, increasing disulfide content by 34.18 % and hydrophobicity by 39.94 % in freeze-dried crickets and not influencing oxidation (33.44 and 17.63 nmol/g protein for oven and freeze-dried flours, respectively). Colloidal properties were primarily affected by the drying method. PEF also affected the secondary structure of oven-dried cricket proteins. PEF pretreatment and drying methods exhibit combined effect on the quality and stability of cricket flour.