# Current Status and Economic Prospects of Alternative Protein Sources for the Food Industry
## 2 Alternative Protein Sources
### Edible Insects  
Insects have been historically consumed as part of the human diet for centuries, especially by African and Asian cultures ([PERSON] et al., 2018) [50]. Insect proteins have recently received increasing attention from an environmental perspective, especially for their efficient energy conversion to biomass that exceeds many livestock, which makes them produce protein more efficiently ([PERSON] et al., 2016; [PERSON] et al., 2013) [51; 52]. Currently, over 2000 insect species have been identified as edible ([PERSON] et al., 2021) [53] and commonly studied edible insects include mealworms (_Tenebrio molitor_), superworm (_Zophobas morio_), lesser mealworms (_Alphitobius diaperinus_), house crickets (_Acheta domesticus_), dubia roaches (_Blamtica dubia_), black soldier flies (_Hermetia ilucens_) and western honey bees (_Apis mellifera_). Edible insects show high protein content with suitable amino acid profiles and studies confirm that their nutritional profile is suitable according to FAO standards (FAO/WHO/UNU, 2007) [54]. On average, they have 40-75% protein by weight, on a dry basis ([PERSON] et al., 2007) [55], including _A. domesticus_ (32.6%), _T. molitor_ (38.3%), beetles (42.2%) ([PERSON] et al., 2019) [56], grasshoppers (61-77%) and butterflies (15-60%) ([PERSON] et al., 2007) [55]. _H. ilucens_ has a high content of essential aromatic amino acids (phenyl-alanine and tyrosine) and sulfur essential amino acids (methionine and cysteine). On the other hand, _T. molitor_, _Z. morio_, _A. diaperrius_, _A. domesticus_ and _B. dubia_ were reported to be deficient in tryptophan, valine, isoleucine and threonine, three of which are essential amino acids ([PERSON] et al., 2013) [52]. Industrial processing of edible insects mostly follows three main steps: pre-treatment, drying and formulation ([PERSON] et al., 2024) [57]. Following harvest, pre-treatments generally intend to decrease microbial contamination and enzyme activity for the purpose of ensuring food safety and avoiding possible lipid oxidation ([PERSON] et al., 2019) [58]. Blanching and freezing are the most cited pre-treatment options applied to common insect protein sources (_Hermetia illucens_, _Tenebrio molitor_, _Acheta domesticus_), with blanching being featured as the most cost-effective ([PERSON] et al., 2020; [PERSON] et al., 2020) [59; 60]. Drying is an important step for increasing the shelf-life of edible insects. Traditional solar drying has been replaced by industrially preferred convection oven drying. Freeze drying and microwave drying have also been investigated, but the high costs associated with equipment and operation hinder their wide implementation ([PERSON] et al., 2024) [57]. Finally, the formulation step varies with the intended application of the insect-based product and it goes from simple grinding and bleaching, for the production of protein-rich insect flours, to alkaline protein extraction (protein-rich ingredients) or solvent-based solid-liquid extraction (inset oil or chitin production) ([PERSON] et al., 2024) [57]. Reports on functionality of insect proteins vary with species and are scattered. Defatting is a common pre-treatment, and the choice of defatting solvent, as well as the choice of extraction procedure affect the solubility and functionality of insect protein ([PERSON] et al., 2023) [61]. [PERSON] et al. (2021) [53] demonstrated that protein concentrates of mealworm (_T. molitor_), cricket (_Gryllodes sigillatus_), and locust (_Schistocerca gregaria_) had water-holding capacity and oil-holding capacity up to 300% greater than their respective raw flours. _H. ilucens_ was reported to have a great foaming capacity, increasing up to 1080% after thermal treatment ([PERSON] et al., 2023) [61], while _A. mellifera_ ([PERSON] et al., 2019) [62], _A. domesticus_, _T. molitor_, _Z. morio_, _A. diaperinus_, _B. dubia_ exhibited poor foaming properties ([PERSON] et al., 2013) [52]. On the other hand, _A. domesticus_ exhibited far better gelling properties than other insects ([PERSON] et al., 2023) [61].