Effect of heat processing on the nutrient composition, colour, and volatile odour compounds of the long-horned grasshopper Ruspolia differens serville.

Heat processing is commonly used to prepare edible insects for consumption. This study aimed at determining the effect of boiling and subsequent oven roasting on Ruspolia differens' nutrient composition, colour and odor compounds. Boiling leads to: a significant increase in protein and decrease in fat content on a dry matter basis; a minimal influence on its amino and fatty acids profile; a significant reduction in its ash content due to leaching of phosphorus, potassium and sodium; a significant increase in iron, zinc, copper, manganese and calcium content; and a fivefold reduction in the amount of vitamin B12. Roasting leads to a relative increase in the amount of calcium and trace mineral elements but doesn't affect other nutrients. Roasting results into a more uniform colour intensity when green and brown polymorphs are roasted together. Lipid oxidation is responsible for the colour and aroma of heat processed R. differens.