Shelf life of the preheated and ready-to-eat long-horned grasshopper Ruspolia differens Serville

Abstract

Ruspolia differens is an edible insect delicacy in sub-Saharan Africa, majorly harvested from the wild, with a very short shelf life (24 hours depending on the handling conditions). Combinations of preheating, roasting and drying, and storage at refrigerated and room temperature were used to prolong its shelf life. Product quality was evaluated using sensory, microbial and chemical analyses. To allow transportation from the harvesting areas to the market, preservation up to 9 hours at room temperature was possible using only preheating (boiling at 100 °C for 6 minutes). Combinations of preheating and roasting (for 25 and 35 minutes at 165 °C) resulted in moisture contents of 21.3 and 10.4% with shelf life at refrigeration temperature of 25 and 54 days, respectively. Aroma was the main factor determining the shelf life. Further drying of preheated and roasted grasshoppers resulted in a product with 4.5% moisture. In combination with vacuum packaging, storage at room temperature was possible for at least 20 weeks. This research therefore contributes to long term storage of the surplus harvested R. differens, and thus to increased food security.