*2.6. Protein Solubility*

Protein solubility was determined at different concentrations (3.0, 1.0 and 0.5% (*w*/*v*)) of hydrolysates and meals, and at different pHs (4.0, 5.5 and 7.0) by using the methodology described by Morr et al. [49]. Briefly, samples of meals and hydrolysates were dispersed in 50 mL McIlvaine buffer and stirred at 20 ◦C for 2 h. The dispersion was then centrifuged at 2000× *g* for 30 min at 20 ◦C. The Kjeldahl method was used to determine the nitrogen content of the supernatants. Protein solubility was calculated using the Equation (2) proposed by Hall et al. [3] and expressed as a percentage:

$$\text{Solubility} \left( \% \right) = \left( \frac{\text{protein content in supernatant}}{\text{protein content in sample}} \right) \times 100 \tag{2}$$
