Oil characteristics and influence of heat processing on fatty acid profile of wild harvested termite (Macrotermes subhylanus) and long-horned grasshopper (Ruspolia differens)

The aim of this study was to assess the physico-chemical characteristics and fatty acid profile of oil from termite ( Macrotermes subhylanus) , green and brown long-horned grasshopper ( Ruspolia differens). The insects were harvested in Siaya county of Western Kenya from the wild during swarming seasons. Physico-chemical characteristics of insects oil and the effect of two traditional heat processing methods (frying and solar drying) on the fatty acid profile were determined using standard methods. The insects oil was a clear, golden or light yellow colored liquid at room temperature, with a low solidification temperature (8–12 °C) for M. subhylanus and10–15 °C for R. differens . M. subhylanus showed an iodine value of 83.51 g iodine/100 g oil, peroxide value 0.19 mEq/Kg, saponification value 160.61 mg KOH/Kg and 38.77 mg/100 ml of total cholesterol. R. differens showed an iodine value of 86.97 g iodine/100 g oil, peroxide value 0.13–0.14 mEq/Kg, saponification value 229.67–234.40 mg KOH/Kg and 27.51–31.40 mg/100 ml of total cholesterol. Oleic acid was the major fatty acid in all the fresh insect samples ( M. subylanus 52.1%, green R. differens 43.2%, brown R. differens 37.1%) while palmitic acid was the second most abundant fatty acid. Total unsaturated fatty acids were proportionately more than the total saturated fatty acids. The level of saturated fatty acids increased from fresh insect samples to heat processed samples (fried, fresh-dried and fried-dried), while the level of unsaturated fatty acids decreased with processing though insignificantly. The insects have high quality oil that maybe exploited in processing of nutritional food products and they may therefore be heat processed domestically without adversely affecting the quality of the oils.