Effects of salting-in/out-assisted extractions on structural, physicochemical and functional properties of Tenebrio molitor larvae protein isolates

Tenebrio molitor larvae protein isolates (TPIs) were extracted using the alkaline extraction and acid precipitation methods (AEAP) assisted by NaCl (salting-in) and (NH4)2SO4 (salting-out) procedures. The structural, physicochemical, and functional properties of TPIs were investigated. It was found that the salt-assisted treatments did not affect the total amino acid content but altered specific amino acid compositions. The salting-in-AEAP extraction resulted in non-significant (P > 0.05) differences in zeta potential, hydrophobicity, thermal stability, solubility and foaming capacity compared with the AEAP extraction. Salting-out-AEAP extraction significantly (P < 0.05) increased overall protein solubility, emulsion activity, foaming capacity and stability that were associated with lower hydrophobicity, higher zeta potential, α-helix and disulfide bond contents. The salting-in-AEAP-out extraction generated the greatest protein yield (39.54%), emulsion activity index (55.5 m2/g), foaming capacity (205%) as well as foaming stability (65.59%).