Intermittent drying of clove basil leaves: Process optimization and essential oil yield

Abstract

This study investigated the effect of a drying method with intermittent ratios on the effective drying time, specific energy consumption and essential oil yield of clove basil (Ocimum gratissimum L.) leaves. The drying tests were conducted at the Postharvest Laboratory of Medicinal, Aromatic and Condiment Plants, from the Departamento de Engenharia Agrícola of the Universidade Federal de Viçosa, Viçosa, MG, Brazil (20° 46’ 13.5” S; 42° 52’ 23.3” W, and altitude of 645 m) in October and November 2017. The experiment was conducted by using a 3 × 4 factorial scheme including three drying temperatures at 50, 60 and 70 °C, with four drying processes: continuous drying and the following three intermittent drying/tempering ratios in minutes: 10/20, 15/15 and 20/10. The design was completely randomized and with three repetitions. The application of the 10/20 intermittent ratio reduced the effective drying time and the specific energy consumption. Regarding the essential oil yield, the use of the intermittence presented different results for each temperature of drying; the highest yields were observed with continuous drying at 50 °C and drying with the 20/10 intermittent ratio at 60 °C. The results indicate that intermittent drying at 50 °C is not recommended to preserve essential oil yields.

Drying Characteristics of Dracocephalum moldavica Leaves: Drying Kinetics and Physicochemical Properties

“…De Suza et al [24] showed that an air-drying temperature higher than 50 • C causes significant decreases in the content of the essential oil of clove basil leaves. However, other authors found that the highest essential oil content in dry Piper umbellatum L. leaves is obtained when the air-drying temperature does not exceed 40 • C [25]. On the basis of the presented data it can be concluded that the quantity and quality of oils and other bioactive compounds are most affected by the drying method and drying temperature.…”

“…Sublimation and vacuum drying were carried out to obtain a constant dried material humidity of 10%.We did not carry out convection drying at 20 • C, because this kind of drying at such low temperature is ineffective, takes a long time, can lead to the development of microorganisms and often does not allow to achieve an adequate level of moisture content after drying. The drying temperature was selected on the basis of the literature data mentioned in the introduction [21][22][23][24][25].…”

Automated Air Conditioning System for Agricultural Product Drying and Storage

“…Extensive research has explored alternative approaches to high temperature drying (Bala, 2016;Onwude et al, 2016;Tiwari, 2016;Regal et al, 2020;Souza et al, 2020). However, grains are extremely sensitive to heat (Oliveira, 2013), and inadequate drying can negatively impact qualitative factors such as acidity, protein levels, germination, and appearance.…”