Extraction of proteins from Tenebrio molitor and Gryllodes sigillatus and evaluation of their potential as future protein source
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Plain language summary
In this work, Tenebrio molitor and Gryllodes sigillatus were evaluated for their potential as future protein source. A factorial design (pH: 7, 8.5 and 10; temperature: 22°C and 50°C) was carried to extract the proteins. Resulting extracts were freeze dried and analyzed for protein and fat contents, and protein recovery was estimated. Extracts with the highest protein recovery were then characterized for their functional properties (solubility; fat adsorption capacity (FAC)), and bread making potential. Protein content (NX4.76) of the extracts ranged between 21.99-31.56%, for T. molitor and between 36.19-40.28%, for G. sigillatus, while their corresponding fat content ranged between 41.49-49.72%, and 13.01-15.25%. Protein recovery was found to be the highest at pH 10; 22°C for T. molitor (16.61±0.59) and at pH 10; 50°C for G. sigillatus (19.20±3.47). Solubility profiles of insects extracts showed minimum solubility for pH between 4 and 5 (T. molitor: 35%; G. sigillatus: 40%). For all pH range, solubility of insects extracts was found to be lower than for whey and pea proteins. On the other hand, T. molitor and G. sigillatus extracts showed a FAC of 214.3±5.9% and 328.6±12.2%, respectively, compared to 138.3±8.9% and 204.1±5.0%, for whey and pea proteins. Substitution of wheat flour with 10% of insects extracts induced a decrease in the loaf specific volume (cm3/g) compared to unsubstituted flour (Control: 4.74; T. molitor: 3.94; G. sigillatus: 3.80). However, this should still be considered as satisfactory by consumers. In conclusion, both insect species studied have potential to be used as future functional protein source.