Processing affects the oxidative and nutritional quality of yellow mealworm (Tenebrio molitor) before and after in vitro gastrointestinal digestion

This study investigated how processing influences the nutritional composition and oxidative quality of yellow mealworm-derived (Tenebrio molitor) ingredients. Mealworms were killed by blanching or blast-freezing, dried by freeze- or oven-drying, and processed into full-fat and defatted flours and protein extracts. Lipid oxidation (propanal, hexanal, 4-hydroxy-2-nonenal), protein oxidation (free thiols, protein carbonyl compounds, α-aminoadipic semialdehyde, γ-glutamic semialdehyde) and glyc(oxid)ation (pentosidine, Maillard reaction products) were measured before and after in vitro gastrointestinal digestion. The type and extent of oxidative damage depended on the processing method, involving interactions between lipid-, protein- and glyc(oxid)ation pathways. Freeze-drying promoted, whereas defatting reduced lipid oxidation. Blast-frozen and oven-dried samples showed pronounced glyc(oxid)ation. Protein extraction of blast-frozen samples led to an increase of pentosidine whilst reducing α-aminoadipic semialdehyde levels. These findings show the high susceptibility of insect-based food ingredients to oxidative processes, with potential implications for nutritional quality and consumer health.