title: Absolute determination of the gelling point of gelatin under quasi-thermodynamic equilibrium.
abstract: Thermodynamic studies on phase transformation of biopolymers in solution are useful to understand their nature and to evaluate their technological potentials. Thermodynamic studies should be conducted avoiding time-related phenomena. This condition is not easily achieved in hydrophilic biopolymers. In this contribution, the simultaneous effects of pH, salt concentration, and cooling rate (Cr) on the folding from random coil to triple helical collagen-like structures of gelatin were systematically studied. The phase transformation temperature at the absolute invariant condition of Cr = 0 °C/min (T(T)Cr=0) ) is introduced as a conceptual parameter to study phase transformations in biopolymers under quasi-thermodynamic equilibrium and avoiding interferences coming from time-related phenomena. Experimental phase diagrams obtained at different Cr are presented. The T(T)(Cr=0) compared with pH and TT(Cr=0) compared with [NaCl] diagram allowed to explore the transformation process at Cr = 0 °C/min. The results were explained by electrostatic interactions between the biopolymers and its solvation milieu.
authors.affiliation: Inst. de Desarrollo Tecnológico para la Industria Química, Univ. Nacional del Litoral - Consejo Nacional de Investigaciones Científicas y Técnicas, CP-3000, Santa Fe, Argentina.
authors.forename: Franco
authors.initials: F
authors.lastname: Bellini
authors.affiliation: Inst. de Desarrollo Tecnológico para la Industria Química, Univ. Nacional del Litoral - Consejo Nacional de Investigaciones Científicas y Técnicas, CP-3000, Santa Fe, Argentina.
authors.forename: Ivana
authors.initials: I
authors.lastname: Alberini
authors.affiliation: Inst. de Desarrollo Tecnológico para la Industria Química, Univ. Nacional del Litoral - Consejo Nacional de Investigaciones Científicas y Técnicas, CP-3000, Santa Fe, Argentina.
authors.forename: María G
authors.initials: MG
authors.lastname: Ferreyra
authors.affiliation: Inst. de Desarrollo Tecnológico para la Industria Química, Univ. Nacional del Litoral - Consejo Nacional de Investigaciones Científicas y Técnicas, CP-3000, Santa Fe, Argentina.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Rintoul
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D003094:Collagen / Q000737:chemistry; D005780:Gelatin / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D044367:Phase Transition; D012996:Solutions; D055672:Static Electricity; D013696:Temperature; D013816:Thermodynamics
chemical_list: D001704:Biopolymers; D005782:Gels; D012996:Solutions; D005780:Gelatin; D003094:Collagen
keywords: biopolymers; gel; gelation; kinetics; phase transitions