Characterization of volatile components of microwave dried perilla leaves using GC–MS and E-nose

Different pretreatments followed by the drying process could affect the volatile compounds of dried perilla leaves. This study investigated the discrepancies in the volatile profiles of perilla leaves after ultrasonic pretreatment for 1 min and 3 min and drying at 50 °C, 60 °C, 70 °C respectively using gas chromatography–mass spectrometry (GC–MS) and an electronic nose (E-nose). Perilla leaves are rich in high nutritional value substances and unique aroma components. The results showed significant differences in the aroma characteristics of perilla leaves under different treatment conditions. 70 main volatile compounds were identified and separated into 9 classes. Perilla ketone and beta-caryophyllene were abundant in all samples and could be the key aroma compounds of perilla leaves. Most volatile flavor substances could be better retained under the conditions of lower drying temperature and shorter pretreatment time. Principal component analysis (PCA) of GC–MS and E-nose showed that there were obvious differences between the samples under different treatment conditions. In addition, a correlation analysis was also conducted on the main volatile compounds detected by GC–MS and E-nose, which further explained the differences among samples owing to the various drying conditions.