Development of state diagram of bovine gelatin by measuring thermal characteristics using differential scanning calorimetry (DSC) and cooling curve method

A state diagram of bovine gelatin was developed by measuring the freezing curve, glass transition, unfolding, solids-melting lines, and ultimate maximum-freeze-concentration conditions. The freezing point decreased with the increase of solids; whereas glass transition, unfolding, and solids-melting decreased with the decrease of solids up to solids content 0.84 g/g gelatin and then remained constant. The freezing point, glass transition and solids-melting were modeled by Chen's model based on the Clausius-Clapeyron equation, modified Gordon-Taylor model, and Flory's equation, respectively. The ultimate maximum-freeze-concentration conditions were found as (T(m)')(u) equal to -11.9 degrees C and (T(g)''') to -14.9 degrees C, and the characteristic solids content, X(s)' as 0.80 g/g sample (i.e. un-freezable water, X(w)' = 0.20), respectively. Similarly the value of T(g)(iv) (i.e. intersection of vertical line passing through T(m)' and glass transition line) was estimated as 34 degrees C. (C) 2010 Elsevier B.V. All rights reserved.