Chemical composition and physical properties of extruded snacks containing crab-processing by-product

The crab-processing industries generate millions of pounds of by-product annually, which results in a loss of edible product and presents a considerable waste disposal problem. The purpose of this research was to investigate the use of crab-processing by-product (CB) in the development of a calcium-rich expanded snack. The specific objectives were to examine the effects of type of CB (wet or dry), feed composition and screw speed (150 or 250 rpm) on selected properties of extruded snacks. Product formulations consisting of 0-400 g kg^-1 CB combined with corn meal and potato flakes were processed in a twin-screw extruder. The resulting extrudates were analysed for proximate and mineral (calcium, sodium) composition, pH, water activity (aw), total plate count, bulk density, expansion ratio and colour. Both CB type and level of incorporation had significant effects (P < 0.05) on the calcium content, expansion ratio, bulk density and pH of the extrudates. Increasing the CB level resulted in increased calcium content (from 5.1 to 52.4 mg g^-1) and pH (from 6.1 to 8.8). Screw speed had no significant effects (P > 0.05) on expansion ratio and bulk density. A high processing temperature (157 °C) and low aw resulted in undetectable microbial growth on the extrudates. This research demonstrates that ground crab-processing by-product can be successfully incorporated into an expanded snack product. Further research will evaluate consumer response to this novel value-added product.