Investigation of flowability and extrusion behavior of black soldier fly (Hermetia illucens L.) prepupal protein powder for 3D food printing applications

Timilehin Martins Oyinloye, Jirawat Yongsawatdigul, Sununta Chumee, Yupa Hanboonsong, Won Byong Yoon

Black soldier fly (Hermetia illucens L.) prepupae (BSFP) are a sustainable protein source, but the use of full-fat prepupal protein powder in extrusion-based three-dimensional food printing is limited by poor structure and flow control. This study developed black soldier fly prepupal protein-based pastes and evaluated the effects of tapioca starch concentration and thermal treatment on rheology, die swell, and printing stability. Pastes were formulated at 80% moisture content using 0.5% gellan gum, tapioca starch at 0, 2.5, or 5%, and corresponding BSFP powder contents of 24.87, 21.98, and 19.09%, respectively. Thermal treatment significantly strengthened the paste structure, increasing the initial storage modulus to 3998.56, 6248.78, and 8891.23 Pa for 0%, 2.5%, and 5% starch, respectively. Steady shear analysis showed shear-thinning behavior, while model-estimated yield stress after heating increased from 363.58 to 636.06 Pa with starch addition. Large-amplitude oscillatory shear and Chebyshev coefficient analysis showed that starch increased nonlinear elastic resistance and strain stiffening. However, 5% starch caused the high die swell ratio of 1.96 and edge roughness of 0.074 mm. The 2.5% starch formulation showed the lowest edge roughness of 0.049 mm and thickness variation of 8.1%, producing the most stable printed structure. Overall, moderate starch addition improved printability by balancing flow, recovery, and shape retention.