Effects of drying methods on qualitative and quantitative properties of essential oil of two basil landraces

• Published in: Food chemistry 2013-12, Vol.141 (3), p.2440-2449
• Main Authors: Ghasemi Pirbalouti, Abdollah, Mahdad, Elahe, Craker, Lyle
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Desiccation - methods; Gas Chromatography-Mass Spectrometry; General pharmacology; Geranial; Medical sciences; Methyl chavicol; Neral; Ocimum basilicum; Ocimum basilicum - chemistry; Oils, Volatile - chemistry; Pharmacognosy. Homeopathy. Health food; Pharmacology. Drug treatments; Plant Oils - chemistry; Temperature
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2013.05.098

•Drying temperatures can decrease essential oil content of basil.•Drying methods can change the chemical profile of essential oil of basil.•Oven drying at 40°C or freeze-drying had the least effect on essential oil. Sweet basil, a plant that is extensively cultivated in some countries, is used to enhance the flavour of salads, sauces, pasta and confectioneries as both a fresh and dried herb. To determine the effect of drying methods on qualitative and quantitative characteristics of the plant and essential oil of basil, two landraces, Purple and Green, were dried in sunlight, shade, mechanical ovens at 40°C and 60°C, a microwave oven at 500W and by freeze-drying. For comparison, the essential oils of all samples were extracted by hydrodistillation and analyzed using GC and GC–MS. The highest essential oil yields (v/w on dry weight basis) were obtained from shade-dried tissue in both landraces followed by the freeze-dried sample of the purple landrace and the fresh sample of green landrace. Increasing the drying temperature significantly decreased the essential oil content of all samples. Significant changes in the chemical profile of the essential oils from each of the landrace were associated with the drying method, including the loss of most monoterpene hydrocarbons, as compared with fresh samples. No significant differences occurred among several constituents in the extracted essential oils, including methyl chavicol (estragole), the major compound in the oil of both landraces, whether the plants were dried in the shade or sun, oven at 40°C or freeze-dried, as compared with a fresh sample. The percentage methyl chavicol in the oil, however, decreased significantly when the plant material was dried in the oven at 60°C or microwaved. In addition, linalool, the second major compound in the purple landrace, and geranial and neral, major compounds in the green landrace, decreased significantly when the plant tissue was dried in the oven at 60°C or microwaved.