In vitro Protein Digestibility and Textural Properties of High Moisture Extruded Cricket-Soy Meat Analogues

Abstract

The rapid increase in global population and the unsustainable conventional meat production have created demand for alternative animal-derived protein. Partial replacement of meat with soy protein-based meat analogues have been traditionally done through high moisture extrusion cooking and presently, edible insects such as house crickets which are a sustainable alternative source of proteins has been suggested. However, the composition and amount of insect content is a challenge to effective texturisation as well as protein digestibility of the meat analogues. This research was aimed at developing meat analogues from a mixture of soy protein isolate (SPI) substituted with full or low- fat cricket flour at 0, 15, 30 and 45%. A laboratory co-rotating twin-screw extruder with a throughput of 1 kg/h and 150 rpm screw speed was used while, the cooking temperature was varied at 120, 140 and 160 °C and water flow rate (WFR) set to 9 or 10 ml/min. The impact of cricket flour (CF) inclusion on in vitro protein digestibility (IVPD), firmness, parallel (L) and perpendicular (V) tensile stress and anisotropy index (AI) was evaluated. IVPD analysis was conducted on 15 and 45% CFs blends at 120 and 160°C while, texture profile analysis was analysed on all treatments. The results showed that, full and low-fat CFs addition had a significant (P<0.05) increase in IVPD (r=0.93 and 0.88) at 120°C and a decrease (r= -0.36 and -0.49) at 160°C. The highest IVPD (50.21%) was obtained from 45% full-fat CF inclusion at 120°C. Textural properties significantly correlated and were affected (P<0.01) by all treatments. At WFR of 10 and 9ml/min, the samples firmness increased (r= 0.56, 0.57) with process temperatures but reduced (r≈ -0.47, -0.72) with CF inclusions, respectively. Correspondingly, defatting of CF negatively influenced firmness (r= -0.62 and -0.5921). Comparatively, all blends exhibited stronger tensile stress L than V at all treatments. At WFR of 10 and 9 ml/min, defatting CF, inclusion of full and low- fat reduced (r= -0.50, -0.24, -0.54) and (r= -0.48, -0.47, -0.57) tensile L, and (r= -0.49, -0.16, -0.56) and (r= - 0.53, - 0.47, -0.55) tensile V. On the same however, process temperature increased (r= 0.69, 0.60) tensile stress L and (r= 0.65, 0.57) tensile V. Increasing WFR reduced (r= -0.17) tensile stress L and (-0.20) tensile V. From SEM and AI analysis, CFs inclusion up to 30% CF and high water flow rate and process temperatures improved fibrousness. Inclusion of 30% low-fat CF and extruded at 160°C and WFR of 10ml/min had most pronounceable anisotropic structure with highest AI of 2.8. These findings showed that, CF can be utilized to structure meat-like products with superior textural and protein digestibility thus a valuable ingredient for manufacturing animal-derived meat analogues.