Decrease of available lysine in thermally treated gelatin followed by LC–UV: Influence on molar mass and ability to helixes’ formation

Available lysine (AL) content, weight-average molar mass (Mw) and kinetic of α helixes’ formation have been determined in thermally treated gelatin (75 °C) during 2, 6 and 8 days. Quantification of available lysine in gelatin sample by LC–UV has been developed. Thermal treatment during 8 days led to a decrease of AL content from 3.1 g/100 g of gelatin to 2.3 g/100 g of gelatin. In the same time, Mw increased from 6.7 × 105 g mol−1 to more than 2.0 × 106 g mol−1 and α helixes’ formation ability was strongly affected. Thermal treatment led to the reaction of available lysine group with other functions present in its environment. Intermolecular cross-links led to a high molar mass compounds’ formation and limited protein chain unfolding which is an essential step for helixes’ formation.