Acta Scientiarum Polonorum Technologia Alimentaria

Background. The growing population and the increase in protein hunger have highlighted a need to search for an alternative protein source. The European Food Safety Agency (EFSA) stated that yellow mealworm larvae (Tenebrio molitor L.) are a potential source of protein, fat, and fibre. Their processing involves different thermal treatments to ensure the quality and safety of the insect products. Therefore, the aim of this study was to explore the effect of four processing regimes.
Materials and methods. The applied regimes were: F.M. (fast frozen and microwave dried), S.M. (slow frozen and microwave dried), F.C. (fast frozen and conventionally dried), and S.C. (slow frozen and conventionally dried). The quality and safety of the flours from Tenebrio molitor L. were evaluated by the changes in proximate composition, technological properties, oxidative stability, fatty acids’ composition, and microbial status.
Results. The applied regimes had a slight effect on the proximate composition. Moisture and water activity (aw) were significantly affected by the applied regimes. The Saturated to Unsaturated fatty acids ratio was influenced by the type of drying. The microwave drying initiated hydrolytic and oxidative changes, but the limits for primary and secondary oxidation products were not exceeded. Higher survival rate of microorganisms was evaluated after fast freezing but low aW should guarantee microbial safety.
Conclusion. Both of the freezing and drying regimes tested slowly influence the proximate composition of mealworm flours. Summarizing the changes in lipid fraction of microwave dried flours it can be concluded that the induction period has passed and ongoing oxidation has been evaluated. Despite the positives of microwave drying as a faster and more energy efficient processing method, the decreased oxidative stability of the obtained flour could be a drawback. The results confirm the theory about the higher survival rate of microorganisms after fast freezing. At the same time, microbial safety could be ensured by a low moisture content and a_W.