*2.4. Degree of Hydrolysis*

Freeze-dried insect hydrolysates were rehydrated in deionized water at 5% (*w*/*w*) to determine the degree of hydrolysis. The degree of hydrolysis was determined by the o-phthaldialdehyde (OPA) method according to Church et al. [47]: Different concentrations (0.75–3 mM) of D-L-Leucine were used to obtain the standard curve [48]. The degree of hydrolysis was calculated according to the Equation (1) proposed by Hall et al. [3]:

$$DH\ \left(\%\right) = \left(\frac{h}{h\_{tot}}\right) \times 100\tag{1}$$

where *h* is the total peptide bonds cleaved and *htot* is the total peptide bonds. The *htot* of the equation was 8.64 milliequivalents (meq)/g for all samples [3]. Measurements of all samples were performed in triplicate.
