Effect of pH on the stability and molecular structure of nitrosyl hemochromogen

卷:196

Yu, Chensha ; Jiao, Jingzhi ; Ma, Lizhen ; Sun, Weiqing

Yangtze Univ

关键词: Nitrosyl hemochromogen;    Stability;    pH;    EPR spectrum;    FT-IR spectrum;   

DOI  :  10.1016/j.foodchem.2015.09.067

学科分类：食品科学和技术

【 摘 要 】

This study explored the effect of pH on the stability and molecular structure of nitrosyl hemochromogen (NO-Heme) using ultraviolet (UV), electron paramagnetic resonance (EPR) and Fourier transform infrared (FT-IR) spectroscopy. The NO-Heme was extracted from pre-cooked cured beef and was dissolved in an 80% acetone solution pre-adjusted to different pH values with 2 mol/L HCl and 2 mol/L NaOH. The results show that pH significantly influences the optical properties and stability of NO-Heme. Strong acidic and weak basic conditions favor the red stability of NO-Heme. The conjugate structure of NO-Heme changed under strong basic conditions, as the NO- group was shown to be still associated with the iron porphyrin, but the color of NO-Heme changed from pink to yellow. NO-Heme is extremely unstable at weakly acidic pH, and this may be the why pH affects the apparent color of cured meat products during storage. (C) 2015 Elsevier Ltd. All rights reserved.