*2.5. Color Evaluation*

The color parameters of protein-resveratrol solutions before and after storage at 45 ◦C for 30 days were measured using a ColorQuest XE colorimeter (ColorQuest XE, Hunter Lab, Reston, VA, USA) and calculated using the Hunter Lab color scale (L\*a\*b\*). L\* represents the lightness (black = 0 to white = 100), a\* varies from red (positive) to green (negative), and b\* varies from yellow (positive) to blue (negative). The total color difference (ΔE) was calculated from the tristimulus color coordinates using the following equation:

$$
\Delta \mathbf{E} = \left[ (\mathbf{L}^\* - \mathbf{L}\_i^\*)^2 + (\mathbf{a}^\* - \mathbf{a}\_i^\*)^2 + (\mathbf{b}^\* - \mathbf{b}\_i^\*)^2 \right]^{1/2} \tag{1}
$$

where, Li\*, ai\*, bi\* are the initial values of the CIE L\*a\*b\* color coordinates of freshlyprepared samples, and L\*, a\*, b\* are the color coordinates of samples after 30 days. Additionally, the difference in chroma (ΔC\*) value, which represents the color intensity of samples, was analyzed by the following equation [22]:

$$
\Delta \mathbf{C}^\* = \left[ \left( \mathbf{a}^\* - \mathbf{a}\_i^\* \right)^2 + \left( \mathbf{b}^\* - \mathbf{b}\_i^\* \right)^2 \right]^{1/2} \tag{2}
$$
