Influences of Drying Conditions on Quality Attributes, Taste and Volatile Compounds of Celery Leaves

Celery leaves account for 5–10% of the celery weight and are rich in nutrients, but they are usually discarded as waste. To explore this resource, hot-air drying (HA), intermittent hot-air drying (IHA-A and B), vacuum hot-drying and freeze-drying (VH and VF) were used to systematically investigate the effects of drying conditions on quality attributes, taste and volatile compounds of celery leaves. VF could better maintain the quality attributes, while IHA-B leaves were rich in taste and volatile components. The results indicated that both drying temperature and vacuum environment had significant effects on quality attributes. In terms of taste, reducing the drying temperature enriched the taste of celery leaves; however, in vacuum drying, the high temperature could contribute to increase the contents of total free amino acids and bitter amino acids. For volatile compounds, different drying conditions gave celery leaves different aromas, and IHA treatments resulted in a significantly higher content of volatile compounds than other treatments.