Effect of frost on yield and composition of Aloysia triphylla essential oil

Abstract

Aloysia triphylla, also known as lemon verbena is a medicinal plant with aromatic leaves which produce essential oil rich in citral and has great importance for pharmaceutical and cosmetic industries. The objective of this study was to evaluate the effect of frost on the chemical composition and yield of A. triphylla essential oil. The experiment was conducted at the Campus of UFSM in Frederico Westphalen, Rio Grande do Sul, in July 2014. A complete randomized design with three repetitions was used where three random collections and extractions occurred before and after the occurrence of frost. The oil was obtained via hydrodistillation and analyzed by a process of gas chromatography and mass spectrometry. The total yield obtained from leaves before frost was 0.162% and 0.187% after frost. Essential oil composition was largely not affected by the presence of frost; however, of the macro components, limonene was observed to be most sensitive to frost, accounting for 14.36% of essential oil content before and 10.15% after frost.

Production and composition of Lippia alba (Mill.) essential oil as affected by frost

“…Under conditions of low temperatures and frost formation, the occurrence of leaf necrosis and senescence is common. From the results obtained, it appears that it is possible to collect the plants and extract the essential oil after the occurrence of frost, as described for Aloysia triphylla by Schmidt et al (2016); however, it was observed that complete leaf senescence occurs within two days, requiring rapid collection of plant material to avoid total necrosis and leaf fall.…”

“…Most essential oil storage in plants occurs in glandular and peltate trichomes, located on both sides of the leaves: adaxial and abaxial (Gattuso et al, 2008;Taiz et al, 2021). The essential oil, due to its characteristics, does not freeze, and it is likely that the cells of these trichomes are not damaged, as they have high concentrations of oil and low concentration of water, which helps to keep the structure of their biomembranes intact in the presence of frost (Schmidt et al, 2016).…”

“…The chemical composition of Lippia alba (Mill.) essential oil was identified through chromatographic analysis using an Agilent Technologies 6890N GC-FID gas chromatograph equipped with a DB-5 capillary column (30 x 0.25 mm; film thickness of 00.25 µm) and connected to a FID detector, and the temperature was adjusted as described by Schmidt et al (2016).…”

“…occurs between October and April, where the mean air temperature varies from 12 to 25 °C. As in several species, during winter, there is a general reduction in plant growth rate, probably related to a decrease in mean daily temperatures (Schmidt et al, 2016), along with the total loss of leaves with the occurrence of frost, causing losses and making it impossible to harvest the leaves for essential oil production.…”