Insect oil and protein: Biochemistry, food and other uses: Review

In searching for new sources of oil, protein and gelatin researchers have investigated many wild plants, but our research group took a different approach: We looked at insects as oil, protein and gelatin source for both nutritional and industrial applications. According to Sudanese indigenous knowledge, many insects have food and medicinal uses. We targeted two of these insects for our research: Aspongopus vidiuatus (melon bug) and Agonoscelis pubescens (sorghum bug). The two insects showed 27.0% and 28.2% crude protein, 45% and 60% oil, respectively. The oils contained 46.5% and 40.9% oleic acid, 3.4% and 34.5% linoleic acid, 44.2% and 12.1% palmitic acid and traces of linolenic acid, respectively. The tocopherol content of these oils amounted to 0.3 and 34.0 mg/100g oil, respectively. The total content of sterols in the two oils was 17 and 450 mg/100g oil, respectively, whereas β-sitosterol was determined as the main compound in all oils with about 60% of the total sterol. The oxidative stability of the oils, as measured by the Rancimat test at 120 ̊C, was 38 and 5.1 h, respectively. Edible gelatin was extracted from the two insect using hot water and mild acid and distilled water. SDS-PAGE patterns of the insect gelatins had very low molecular weight chains, and the two gelatins contained 40 kDa as main component, differential scanning calorimetry results confirmed the difference between extraction methods concerning the extracted gelatin quality. FTIR spectra of melon and sorghum bug gelatins were similar and the absorption bands were situated in more than 6 bands in melon bug gelatin and only 6 bands in sorghum bug gelatin. Microstructures of the insect gelatin examined with the scanning electron microscope showed that melon bug exhibited the finest gelatin network with very small voids. Melon bug gelatin showed the finer structure with smaller protein strands and voids than sorghum bug gelatin. Ice cream was made by using 0.5% insect’s gelatine and compared with that made using 0.5% commercial gelatine as stabilizing agent. The properties of the obtained ice cream produced using insects gelatine were found to be acceptable for the panelists, and no significant differences between ice cream made using insect gelatine when compared with that made using commercial gelatine in their general preferences The behavior of the crude Sorghum bug oil during deep-frying of par-fried potatoes was studied with regard to chemical, physical, and sensory parameters, such as the content of FFA, tocopherols, polar compounds, oligomer TG, volatile compounds, oxidative stability, and total oxidation (TOTOX) value. The results showed that the oil was suitable for deep-frying of potatoes. The oxidative stability of sunflower kernel oil was improved by blending with melon bug oil, the oxidative stability in the Rancimat test was improved from 5% to 68% compared to the control, with increasing parts of MBO, respectively. The insect oils were transesterified using methanol or ethanol in the presence of sulfuric acid to obtain biodiesel. The obtained insect biodiesel characteristics were studied in accordance with the DIN EN 14214 specifications for biodiesel. It was possible to prepare the methyl and ethyl esters catalyzed by H2SO4 from the two insect oils.