2.3. Preparation of Hydrogels

Gelatin-based hydrogels were obtained by microwave assisted method using gelatin, glycerol, whey hydrolysates or WPI and CuSO₄ * 5H₂O. The gelatin was mixed with glycerol and water, then the sample was kept at room temperature for 10 min, followed by the addition of WPI or WPH solutions. The mixtures were subjected to irradiation in a household microwave system at 480 W for 25 s until homogenous and clear solutions were obtained.

To determine the influence of the cross-linking agent, hydrogels with different concentration of Cu²⁺ were synthesized from 0.5 g gelatin, 0.4 g glycerol, 4 mL hydrolysates or 5% WPI solutions, 2 mL water adding various quantities of 30% CuSO₄ × 5H₂O solutions. The samples were poured in Petri dishes and dried at room temperature for 2 days. For comparison, control hydrogel samples were prepared using 5% whey protein isolate solutions.

Table 1 presents the conditions for the obtaining of gelatin-whey hydrogels.

The conditions for the obtaining of gelatin-whey hydrogels.

¹ Concentration CuSO₄ * 5H₂O [%] reported to sample without water.