Effect of cassava (Manihot esculenta Crantz) fermentation and cricket (Acheta domesticus) enrichment on protein quality, sensory properties, and shelf life of cassava-cricket biscuits

Abstract

Climate change and population growth, which have led to the subdivision of agricultural land, are threats to food security. Cassava (Manihot esculenta Crantz) and cricket (Acheta domesticus) are potential solutions to this threat. This study aimed to develop biscuits from fermented cassava enriched with cricket flour that meet the protein requirements of 5-13- year-olds. Cassava flour was fermented spontaneously and with Aspergi I I us oryzae, and mixed with cricket flour at three levels: 12%, 24%, and 36%. The blended flours were kneaded and baked at 180°C/7 minutes into biscuits then analysed for nutritional, microbial, shelf life, and sensory properties. Cricket flour was also analysed for amino acids and fatty acids. The results showed that cricket protein had significantly higher levels of all amino acids except threonine than the reference protein. It was richest in tyrosine, glutamic acid and histidine, with concentrations of 5.01, 4.76, and 4.01 g/100g, respectively. Cricket flour is a good source of retinol, with a concentration of 1.46 mg/100 g. The fat in cricket flour is richest in elaidic, palmitic, and stearic fatty acids, with concentrations of 43.13%, 21.83%, and 11.02%, respectively. Both method of fermentation and substitution level of cricket flour significantly improved the protein quality, sensory, microbial and shelf-life properties of the resultant biscuits. Biscuits made from spontaneous and Aspergillus oryzae fermented cassava flour had higher protein and ash content, and lower moisture and carbohydrate content than unfermented biscuits (p<0.05). Consumers rated the sensory attributes of biscuits lower as the cricket substitution level increased, regardless of the fermentation method used. Increasing the amount of cricket flour in biscuits significantly increased the intensity of colour, crumbliness, and bittemess, while significantly decreasing the intensity of consistency, density, baked aroma, sugary taste, and buttery flavour, irrespective of the fermentation method. Initial peroxide values of cassava-cricket biscuits were 2.9- 3.7 mEq of O2/kg. During storage the activation energy for oxidative rancidity in cassava-cricket biscuits was from -8.84 to 10.07 1.07 J/1QMol, enthalpy change was from -2462.71 to -2443.80 kJ/Mol, entropy change from -49.51 to -46.37 J/K/Mol and Gibbs free energy was from 1l.242.18 to 12,160.12 kJ/Mol. The thermodynamic properties of the biscuits showed that the environment was anaerobic and had low water activity hindering oxidative rancidity during storage, so peroxide value could not be solely relied on to predict shelf life. These findings show that cassava and cricket utilization can open up a new frontier in the incorporation of insects in baked foods as protein sources, and address food security challenges in Sub-Saharan Africa.