2.3. Extraction of Cuticular Wax

Cuticular wax was extracted using the method of Dong et al. [26], with modifications. Specifically, each group randomly selected ten plums (containing three replicates) and entirely immersed them in 500 mL beakers containing 300 mL chloroform/methanol (4:1, v/v). The beakers were placed in a water bath at 40 °C, and the fruit was stirred for 30 s. Each fruit was extracted three times. The extracting solution was transferred to a round-bottom flask, concentrated at 40 °C using a rotary evaporator, and transferred to a brown bottle (40 mL). The wax extract was then dried with a stream of nitrogen gas and stored at −80 °C for subsequent gas chromatography-mass spectrometry (GC-MS) analysis.