A multimethodological approach to study chemistry and safety of digested Locusta migratoria

In this study, a multimethodological approach was proposed as model to better define chemical changes and cell compatibility properties of digested Locusta migratoria, thus enhancing the definition of this less studied edible insect nutritional value. INFOGEST protocol was applied on a commercial sample of L. migratoria, observing the chemical changes during simulated digestion, as well as amino acids bioaccessibility and bioavailability, cell safety and biocompatibility. A chitin content of 13.19±1.25 g/kg was measured in raw sample. For targeted RP-HPLC-DAD amino acids analysis, optimization of microwave-assisted protein hydrolysis was carried out. A total amino acids content of 49.57±0.80 g/100 g was measured in raw sample. During in vitro digestion, amino acids release was observed in gastric and duodenal phases. Cysteine, serine, lysine, leucine, and phenylalanine had good absorption and bioavailability. Differently, histidine, threonine, valine, proline, alanine, and glutamate showed a limited bioavailability. NMR metabolomics also observed protein hydrolysis phenomena. Moreover, the behavior of organic acids, nitrogen-bases and derivatives, and other metabolites was observed. For instance, acetate, succinate and phosphorylcholine increased in duodenal phase. Cell viability on Caco-2 and Raw 264.7 murine macrophages was evaluated before and after digestion phases. Good cytocompatibility with Caco-2 and Raw 264.7 was observed for both undigested and digested phase, mainly in Caco-2 cells for duodenal phase. In addition, barrier integrity was evaluated for duodenal phase, reporting no significant changes in TEER values. Moreover, cell morphology was assessed by CLSM and SEM, confirming that no alterations of the epithelial barrier or monolayer integrity occurred.