The desulfite mechanism exploration in a mode: Interaction between casein and sulfite by multi-spectrometry

Abstract

Sulfite is a restricted food additive in various food preservatives. In our previous study, the sulfite was effectively removed by casein in shrimp samples. In this paper, the possible desulfite mechanism were explored by examining the interaction of casein with sulfite by fluorescence quenching spectroscopy, Ultraviolet (UV) adsorption, Fourier transform infrared (FTIR) and circular dichroism (CD) spectroscopy. The binding constant (KS), binding thermodynamics, and the interaction effect on the casein's conformation were investigated. The results showed that casein bound with sulfite via hydrophilic and hydrophobic interactions, with Ks values of 1.07 × 105 at 293 K and 2.78 × 104 at 307 K respectively. The secondary structures and the conformation of casein were changed due to the interaction between casein and sulfite, with a decrease in positive Cotton effect, indicating the casein-sulfite interaction reduced the structural stability of β-sheet folding of casein. As a result, this work provides the theoretical basis for the desulfite mechanism for the sulfite removal by casein in food processing.