Intermittent drying of Lippia origanoides: influence of the process on the quality of the extract and energy consumption

This study investigated the effect of intermittent drying on the specific energy consumption, plant extract yield, content of phenolic compounds, flavonoids, and antioxidant activity of L. origanoides leaves. Drying tests were carried out at the Postharvest Laboratory of Medicinal, Aromatic and Spice Plants of the Agricultural Engineering Department of the Federal University of Viçosa, Viçosa, MG, Brazil (20 ° 46 '13, 5 ”S; 42 ° 52 ' 23.3 ”W, and 645 m altitude) in June 2019. The experiment was conducted using a 3 × 4 factorial scheme matching three drying temperatures (50, 60 and 70 °C), with two drying methods: drying continuous and intermittent drying (with three intermittent ratios between drying and resting in minutes: 10/20, 15/15 and 20/10). The design used was completely randomized and with three replications. Drying with a 10/20 intermittency ratio reduced the specific energy consumption during the drying of L. origanoides leaves at 50 and 70 °C. The application of the 10/20 intermittency ratio maximized the yield of plant extract during the drying of the leaves of L. origanoides at 60 and 70 °C. Drying with a 10/20 intermittency ratio maximized the content of total phenolic compounds and total flavonoids at all evaluated drying air temperatures. Intermittent drying did not significantly affect the antioxidant activity of the plant extract of L. origanoides leaves.