GAMMA IRRADIATION EFFECTS ON THE PHYSICOCHEMICAL AND TECHNO-FUNCTIONAL PROPERTIES OF ETHANOL-DEFATTED TENEBRIO MOLITOR FLOUR

 Defatting is an important strategy to increase protein concentration and improve the potential use of edible insect flours as functional food ingredients. However, gamma irradiation may induce physicochemical modifications that influence their technological performance. This study aimed to evaluate the effects of gamma irradiation on the proximate composition, instrumental color, water-holding capacity (WHC), and oil-holding capacity (OHC) of ethanol-defatted Tenebrio molitor flour. Tenebrio molitor flours were previously subjected to gamma irradiation at 0 (control), 5, 7.5, and 10 kGy and subsequently defatted using an adapted sequential extraction procedure with cereal ethanol (93.8%). Three successive extraction cycles were performed at 40 °C for 45 min under continuous agitation, using a flour-to-solvent ratio of 1:5 (w/v). Solid–liquid separation was performed by filtration and mechanical pressing, followed by drying at 50–55 °C. The resulting flours were evaluated for proximate composition, instrumental color (L*, a*, and b*), WHC, and OHC. All defatted flours had protein contents above 70%, with no significant differences among irradiation treatments, indicating that irradiation did not substantially affect measured protein concentration. Moisture content was highest at 10 kGy, differing from the control, whereas the 5 and 7.5 kGy treatments showed similar values. Residual lipid content was highest at 5 kGy (7.76%), while the control had the lowest value and did not differ significantly from the 10 kGy treatment. These variations may reflect irradiation-induced changes in matrix organization and lipid accessibility during solvent extraction. Ash content was highest in the control flour. WHC was significantly higher at 10 kGy, potentially reflecting structural modifications that increased access to hydrophilic groups. Conversely, OHC was highest at 7.5 kGy, suggesting possible changes in the availability of hydrophobic binding sites. Irradiation also affected instrumental color. The 5 kGy treatment exhibited significantly higher lightness (L*) than the remaining treatments, which did not differ from one another. The highest yellowness (b*) was observed at 10 kGy, whereas redness (a*) remained statistically unchanged. These variations may reflect changes in pigment-associated compounds and irradiation-induced oxidative reactions. Sequential ethanol extraction produced protein-rich T. molitor flours, while gamma irradiation influenced their residual lipid content, instrumental color, and techno-functional properties. The findings highlight the potential of irradiation dose selection to modulate the functional characteristics of defatted insect flours for food applications.