Assessing the quality, safety and shelf stability of refined house cricket (Acheta domesticus) powder and its oil fraction

Abstract

Incorporation of whole house cricket (Acheta domesticus) powder into staple flours such as maize, cassava, millet, and bean has led to an increase in protein levels (> 50%) of its composites. However, the incorporation levels have remained low due to reduced sensory acceptability. The maximum incorporation level is between 5% and 6% as attributes such as aroma and color are affected, causing the flours to become darker and aroma becoming less appealing with higher incorporation levels. To increase levels of incorporation, design expert software was used to generate different house cricket powder refining protocols, that were tested for consumer acceptability. Refined house cricket powder with the highest preference was produced through defatting roasted house cricket powder using petroleum ether and bleaching the powder using two methods. 1. Using a mixture of sodium hypochlorite and hydrogen peroxide; 2. using chloroform. This prompted an investigation into how refinement impacts the quality, safety, and shelf stability of the refined house cricket powder and its oil fraction. To achieve this objective, proximate analysis, functional properties and sensory evaluation of refined house cricket powders and controls were studied using standard and developed methods. The microbial (pour plate and spread plate methods) and chemical (chromatography, mass spectrometry, Kjeldahl) assays were conducted to determine the safety and stability together with sensory stability of the cricket powders and oil. Refined house cricket powder had a higher consumer acceptability than controls. The study also observed improvement in the protein levels of the cricket powder with refinement from 50% to 58.4% (p<0.05) in control and in refined powder, respectively. Refined house cricket powders possessed greater oil absorption capacities; solubility (20%) and dispersibility (72%) compared to the controls that had around 11% and 63% (p<0.05), respectively. Chemical analysis confirmed the absence of pesticide residues, aflatoxins, and toxic chemicals, except for lead, which was detected in control samples (0.48 and 0.83 mg/kg) and refined cricket powder bleached using chloroform (0.98mg/kg). Cricket powder bleached with chloroform also contained aflatoxin B1 (1.27 pbb). Microbiological assays showed absence of Escherichia coli, Salmonella spp, Listeria spp, Entero bacteriacae, total coliforms and Staphylococcus aureus in the powders. In terms of shelf stability, all the cricket powders remained stable for microbial, chemical and sensory stabilities over the 24-weeks of storage. SV, PV and IV of oil stayed within standard acceptable of 154 mg KOH/g, 8.3 meq O2/kg and 7.60 g iodine/100g respectively. However, the acid value, moisture and paranisidine value were higher than acceptable limits and the house cricket oil exhibited color changes, becoming darker after 15 weeks of storage. Refining house cricket powder improved sensory acceptability and protein content which increased by 8.4%. Refining did not affect safety and stability of the house cricket powders (met Uganda's edible insect safety standard US 2146:2020). Incorporating refined cricket powder into staple flours may improve protein content, and ongoing investigations should prioritize improving the stability of house cricket oil.