Protein-sugar interaction between Asini Corii Colla (donkey-hide gelatin) and Lycii Fructus (goji berry) evaluated by temperature-resolved ATR-FTIR and moving-window two-dimensional correlation spectroscopy

Abstract

Using Lycii Fructus extract (LFE) as a complementary ingredient to ameliorate the poor taste of Asini Corii Colla (ACC) is a promising way to produce ACC-based formula dietary supplements with pleasant taste and combinational functionalities. However, the possible interactions between ACC proteins and LFE sugars should be concerned. Temperature-resolved ATR-FTIR and moving-window two-dimensional correlation spectroscopy (MW2D-COS) were employed in this research to examine the heat-induced changes of ACC-LFE mixtures with different mass ratios. When the mixture containing LFE half of or equal to ACC, the lyophilized LFE sugars acted as amorphous matrix to stabilize the secondary structures of ACC proteins and raised the protein transition temperature from 125 °C (pure ACC) to 133 °C and 138 °C. But the interactions between LFE sugars and ACC proteins in the mixture containing LFE twice as much as ACC are complex, which decrease the protein transition temperature to about 115 °C. Therefore, the ACC-to-LFE mass ratio is crucial to the stabilization and functionality of ACC-LFE formula dietary supplements. This research also shows the potential of temperature-resolved ATR-FTIR and MW2D-COS in assessing the formula compatibilities of food or pharmaceutical preparations.