Analysis of Nε-(carboxymethyl) lysine content in oriental foods

In this study, high performance liquid chromatography-mass spectrometry (HPLC-MS) was used to establish a simple and stable method in detecting Nε-(carboxymethyl) lysine (CML) in foods; a quantitative determination of the CML content in four common-types of food in China (liquid foods, instant powders, seasonings, solid or semi-solid foods) was carried out. The optimal mobile phase composition for HPLC-MS was 30% methanol, and the analysis time and retention time for CML were 6 min and 3.7±0.1 min, respectively. The CML levels in the foods were as follows: -bound form and free form in liquid foods were 2.72~5.18 μg/mL food and 0.05~1.78 μg/mL food; bound form and free form in instant powders were 0.84~63.00 μg/g food and 0.73~14.37 μg/g food; bound form and free form in seasonings-were 0.86~42.80 μg/mL(g) food and 7.69~821.02 μg/mL(g) food; bound form and free form in solid or semi-solid foods-were 0.63 ~ 61.22 μg/g food and 0.24~9.29 μg/g food. The highest CML content was found in dark soy sauce (bound form: 0.97±0.11 μg/mL food; free form: 796.35±24.67 μg/mL food), and the lowest CML content was observed in quick-frozen steamed buns (bound form: 0.66±0.03 μg/g food, free form: 0.42±0.02 μg/g food). ©, 2014, South China University of Technology. All right reserved.