Partial substitution of soy protein isolates with cricket flour during extrusion affects firmness and in vitro protein digestibility

Kiiru, S.M.; Kinyuru, J.N.; Kiage, B.N.; Marel, A.K.

Partial substitution of soy protein isolates with cricket flour during extrusion affects firmness and in vitro protein digestibility

2020

Kiiru, S.M. | Kinyuru, J.N. | Kiage, B.N. | Marel, A.K.

The rapid increase in global population and the unsustainable conventional meat production have created demand for alternative animal-derived protein. Traditionally, soy has been utilised in structuring meat analogues. Currently, edible insects are researched as a potential alternative source of proteins and a valuable ingredient in development of meat analogues. High moisture extrusion was applied to a mixture of soy protein isolate (SPI) and full or low-fat cricket flour (CF) and the impact of cricket inclusion levels as well as extruder barrel temperature on the firmness and in vitro protein digestibility was evaluated. The SPI flour was substituted at 0 (control), 15, 30 and 45% and extruded on a laboratory co-rotating twin-screw extruder with a throughput of 1 kg/h at 150 rpm screw speed. Cooking temperature was varied at 120, 140 and 160 °C and water flowrate set to 10 ml/min. Texture as evaluated on all the treatments by texture profile analysis while the in vitro crude protein digestibility (CPD) was done on raw flours and extrudates with 15 and 45% CF inclusion and at 120 and 160 °C. The extrusion temperature had a negative correlation (r=-0.49) with the CPD but the CF inclusion had a correlation; r=0.71 (120 °C) and -0.28 (160 °C). The highest CPD (50%) was recorded from 45% full-fat CF extruded blend at 120 °C. Firmness was positively influenced (r=0.56) by temperature but negatively influenced (r≈-0.57) by CF inclusions at selected temperatures. Overall the low-fat CF blends had lower firmness values compared to their full-fat counterparts and control samples. The findings from this research demonstrated to be relevant for processing of high-protein and insect-based meat alternatives for food dependencies.

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