Changes in fingerprint and chromaticity values of Mori Cortex during stir-frying process

Abstract

This study aims to reveal the dynamics of the HPLC fingerprint, chromaticity values, and main chemical components of Mori Cortex during the stir-frying process. The fingerprints of raw and processed products of Mori Cortex were established. The content of mulberroside A, oxyresveratrol, kuwanon G, and kuwanon H in the samples and the chromaticity values of the samples were determined. Furthermore, the similarity evaluation of fingerprints and the correlation analysis between fingerprints and chromaticity values were carried out. The results showed that the fingerprints of raw and processed products of Mori Cortex had high similarity, and the overall changes in the content of the main chemical components in the stir-frying process were similar. According to the experience, when the stir-frying is moderate, the total chromaticity value difference |ΔE~*_(ab)| is above 1.5. With the extension of stir-frying time, the L~* and E~*_(ab) values keep decreasing, and the a~* value keeps increasing. The results of the correlation analysis between fingerprints and chromaticity values showed that peaks 1(5-hydroxy maltol), 2(mulberroside A), 3, 4, 6, 7, 11(oxyresveratrol), 14, 17(kuwanon G), and 18(kuwanon H) had significant correlations with the chromaticity values. Quantitative analysis of the four components with higher content showed that the content of the four components decreased to varying degrees when the stir-frying was excessive. In addition, 5-hydroxy maltol was produced after stir-frying of Mori Cortex, and the fingerprint and chromaticity values showed regular changes during the stir-frying process. The chromaticity can be included in the evaluation of the stir-frying process of Mori Cortex, which provides a reference for standardizing the quality of stir-fried Mori Cortex.