Classification of fermented soybean pastes using inductively-coupled plasma optical emission spectroscopy and multivariate data modeling

Abstract

Fermented soybean paste is widely used in food sauces and stews in East Asia. The main ingredients are soybeans, salt, and water. Therefore, it provides both proteins and inorganic nutrients. Fermented soybean paste consumed in South Korea is produced in South Korea and China. In this study, for 166 fermented soybean pastes collected in Korean markets, nine inorganic elements were analyzed by inductively-coupled plasma optical emission spectroscopy (ICP-OES), and partial least squares-discriminant analysis (PLS-DA) models were developed to classify the samples with respect to their provenances. Among these elements, Mg and Sr were effective variables for discriminating between fermented soybean pastes produced in South Korea and those produced in China. The model trained using Mg and Sr exhibited a classification accuracy of 92.7%. Discrimination power of Mg was rationalized by the difference in Mg concentration between the salts used in South Korea (sea salts) and those used in China (refined salts). Our results indicated that the elemental content of fermented soybean paste was significantly influenced by the salts used as the main ingredients. The combination of ICP-OES and PLS-DA has been suggested as a reliable methodology for discriminating fermented soybean pastes produced in South Korea and those produced in China.