The analysis of phenolic compounds in daylily using UHPLC‐HRMSn and evaluation of drying processing method by fingerprinting and metabolomic approaches

The flowers of daylily (Hemerocallis fulva (L.) L.) are called “Jinzhen” which are commonly used as vegetables or seasoning in East Asia. In this study, we evaluated the chemical profile changes with different processing method after harvest. Five different drying methods including solar drying, vacuum freeze drying, steam drying, and hot air drying method were investigated regarding their impact on the chemical constituents in daylily. The major phenolic compounds were tentatively characterized with ultra‐high performance liquid chromatography tandem high‐resolution mass spectrometric with multistage fragmentation techniques (UHPLC‐HRMSⁿ). The UHPLC‐UV fingerprinting and UHPLC‐HRMSⁿ‐based metabolomic approaches were used for identifying the difference between different processing methods. The quercetin 3‐O‐rutinoside, 5‐O‐caffeoylquinic acids are obviously higher in freeze‐dried and steam‐dried samples. Colchicine was believed to be one of the toxic constituents found in daylily fresh flowers; however, no colchicine was found in any the daylily samples investigated.

Practical applications

The drying process is particularly important for handling and distribution of daylily flowers after harvest and it can also prolong the shelf life. However, the drying process may result in degradation of nutrients and quality loss in food. Steamed sunlight dried or hot air drying methods preserve most of the phenolic composition of fresh daylily samples. The purpose of this study was to analyze the phenolic compounds in daylily using ultra‐high performance liquid chromatography tandem high‐resolution mass spectrometric with multistage fragmentation techniques and to evaluate the drying processing method by fingerprinting and metabolomic approaches.