## 3 Results and Discussion
### The Impact of PEF Pretreatment and Drying Methods on Microbiological Quality  
The microbiological quality of a product is one of the decisive factors determining whether a product is approved for consumption. The levels of permitted microbial contamination of yellow mealworm larvae are included in the European Union Regulation [59]. In conformity with this Regulation, the level of selected groups of microorganisms in dried larvae has been checked in our study. Table 2 shows the level of microbial contamination of dried yellow mealworm larvae as compared with larvae not subjected to heat treatment and PEF pretreatment. Fresh larvae were characterized by high levels of total viable count (TVC) and total yeast and mold count (TYMC) as well as aerobic spore-forming bacteria, which exceeded the levels of microorganisms allowed in the regulation (5 log CFU/g for TVC, 2 log CFU/g for TYMC and aerobic spore-forming bacteria) [59]. The samples did not contain any contamination with waterborne and foodborne pathogenic bacteria, e.g., _L. monocytogenes_, _E. coli_, and _S. aureus_, as well as anaerobic spore-forming bacteria. Due to the PEF pre-treatment and the drying process, the reduction in the count of microorganisms is noticeable. However, the method of drying has an impact on microorganism contamination, too. The infrared-convective dried samples were characterized by a lower microbial contamination than those dried only by means of the convective method. Figure 5: FTIR spectra of untreated and PEF-treated yellow mealworm larvae dried with convective (CD) and infrared-convective (IR-CD) methods. The use of infrared-convective drying allowed for the reduction in the count of yeasts and molds below the detection level, and the combination of this technique with the PEF pretreatment in higher doses, e.g., 20 and 40 kJ/kg, reduced the TVC above three log cycles (antimicrobial effect was demonstrated), as well as reducing aerobic spore-forming bacteria below the detection level. Convective drying did not result in such a high reduction in the total viable count (reduction by 1.6 log cycles was noticed for the highest dose of the PEF pretreatment). To sum up, the use of the PEF pretreatment followed by IR-CD drying can alleviate the microorganism count, ensuring yellow mealworm safety. Research on the microbiological safety of edible insect larvae is a frequent supplement to physical and chemical tests of those raw materials. It is stated that the microbiological quality of edible insects very often depends on the breeding conditions, so improving those conditions may significantly reduce the count of microorganisms in the final product. It has been shown that even slight contamination with _L. innocua_ causes the bacteria to enter the larvae's intestines, where they can multiply and pose a health risk to consumers that cannot be removed by washing, and it is necessary to look for other methods of treating edible insect larvae [60; 61]. In turn, contamination of feed with _Salmonella_ below two log cycles does not cause those bacteria to enter the intestines of the larvae. This indicates a lower risk of transmission of such type of bacteria by insect larvae, which may be due to the natural microflora of yellow mealworm larvae and the ability to compete with pathogenic bacteria [19]. Other studies did not show the presence of _Salmonella_ and _Listeria_ as pathogens of high risk to consumers in live insect larvae [62]. The research conducted by [PERSON] et al. [61] showed a total viable count of 7.7 log CFU/g, which indicated a slightly higher insect contamination than in our study. Furthermore, the authors did not detect the presence of _L. monocytogenes_, _E. coli_, and _S. aureus_, which was also found in our study. Similar results were obtained by [PERSON] et al. [63], in which the TVC was recorded at the level of 7.7-8.3 log CFU/g, and fungi at 5.2-5.7 log CFU/g.