Development of a shelf stable cricket flour for use as a food ingredient

Abstract

In many African cultures, insects are part of the human diet. Insects have also been associated with a low ecological foot print because fewer natural resources are required for their production. Therefore, the Food and Agriculture Organization of the United Nations promotes insects as an alternative source of protein to reduce environmental degradation caused by livestock production. However, processing and preservation of insects’ based-products are limited in most parts of the world. Processing technologies, as well as packaging and storage techniques that improve shelf-life are crucial. The aim of this thesis was to develop a shelf stable protein rich ingredient for use in food from the house cricket. Crickets were blanched for 6 minutes then dried in an air dryer at 60˚C. The moisture content (MC) of the samples was monitored during drying and recorded at different time intervals, namely; 1 h intervals for the first 4 hours, 15 minutes intervals between 4 and 7 hours, and 1-hour intervals from 7 hours and above. After drying, the samples with 17.5%, 11.6% and 5.9% MC were ground and each packed into two types of packaging material, namely: Low Density Polyethylene (LDPE) and high moisture barrier (HBM) bags made of 5-foil film, (code named VAX080200300, 80 MU) packaging bags, for further analysis. The effect of initial moisture content, packaging material and storage duration on shelf stability of the cricket flour was investigated over a period of 6 months. Results obtained showed that the suitable moisture content for cricket flour storage at room temperature was 5.9% in both LDPE packaging film and HBM packaging material. Cricket flour of 11.6% MC showed stability over the six months when packed in high moisture barrier HBM polyethylene bags, and for five months when in LDPE packaging film. Cricket flour of 17.5 MC was still stable after six months when packed in HBM bags, whereas the same flour displayed high microbial load after three weeks of storage when packed in LDPE packaging film. The appropriate packaging material for longer shelf life was therefore, the HBM bags. Regardless of the packaging material, cricket flour at 5.9% MC was stable over the six months storage period. The most stable cricket flour after six months was incorporated in a maize-millet composite instant flour for porridge. Incorporation of 5, 10.5 and 16% cricket flour in instant maize-millet flour composite improved the nutritional properties (protein, fat and fibre), but an incorporation at rate above 5% was rejected due to the bitterness observed with the higher cricket flour percentage. Further research should be done in order to identify the origin of the bitterness so as to increase cricket flour proportion without compromising the acceptability of the porridge.