Unlocking the potential of waxworm (Galleria mellonella) proteins: Extraction, fractionation, and protein quality assessment

Edible insects are increasingly recognized as an alternative and sustainable protein source to meet future protein demands. Owing to its significant protein content (33.43%), the edible insect Waxworm (Galleria mellonella) was characterized in this study for its protein extractability, structural properties, and protein quality. Protein extractability under various pH levels and ionic strengths was evaluated. Subsequently, Osborne fractionation was employed to characterize protein fractions based on their preferential solubilities. The extracted proteins and their respective fractions were visualized by SDS-PAGE, and the most intense bands were excised for proteomics data analysis. Secondary structure, pI, molecular mass, and denaturation temperature were also examined. The quality of waxworm protein was assessed by determining the IVPD, PDCAAS, and amino acid profile. Waxworm proteins exhibited greater stability in alkaline conditions compared to acidic environments. These might also be more sensitive to ionic strength than other alternative proteins, such as those derived from plants. The allergen tropomyosin was identified by SDS-PAGE with an approximate molecular weight of ∼32.5 kDa; however, it can be selectively removed by salt extraction. The secondary structures of waxworm proteins, extracted under various conditions, appeared stable, with α-helix and β-conformation being the predominant conformation. Among the protein fractions, prolamins displayed an α-helix conformation, while albumins, globulins, and glutelins predominantly adopted a β-sheet structure. It was observed that structural features could influence the overall quality of the protein. As for the protein quality, globulins are the protein fraction recommended as these showed the highest EAAI% (924.02), PDCAAS (0.84) and IVPD (76.33%) values.