Thermodynamic and Phase Separation Characteristics of Maltodextrin and Gelatin Aqueous Solutions: A New Approach

Gelatin and maltodextrin are biopolymers widely utilized in the food and pharmaceutical industries due to their functional properties. Gelatin (Mw ≈ 122,300 Da) and maltodextrin (Mw ≈ 1,400 Da) were analyzed using multiple experimental methods. To investigate the impact of temperature on phase separation, binodal curves have been established at 37°C and 45°C using ternary compositions of maltodextrin and gelatin (5–12% w/w). The tie-line compositions and refractive indices were determined using binodal curves, which demonstrated that miscibility was improved as the temperature increased. Two methodologies were employed to independently estimate the Flory–Huggins parameters (\({\chi }_{FH}\)). Initially, water activity measurements were conducted for gelatin (0.05–4% w/w), maltodextrin (1–40% w/w), and their mixtures (0.5–4% gelatin and 1–6% maltodextrin). The results indicated a strong and medium interaction between gelatin and water (\({\chi }_{FH}\) = –0.68) and maltodextrin and water (\({\chi }_{FH}\)= 0.48), respectively, as well as a strong repulsion in the ternary system (\({\chi }_{FH}\)= 15.5). Secondly, intrinsic viscosity measurements were used to estimate Hansen solubility parameters (HSP) for mixtures of maltodextrin and gelatin separately in seven specific solvents (0–10 g/dl). The total solubility parameters (δt) for maltodextrin and gelatin were 39.6 MPa½ and 43.4 MPa½, respectively. Finally, the values of \({\chi }_{FH}\) that were derived from HSP were 0.368 for gelatin and 0.205 for maltodextrin (α = 1). This integrated methodology offers a distinctive thermodynamic perspective on the incompatibility of biopolymers in aqueous mixtures.