Abstract
Essential oil extraction of wild caraway and thyme was performed using a classical (HD) and microwave hydro-distillation (MWHD) and a laboratory supercritical fluid extraction (SFE) with a carbon dioxide as solvent. Our experiments demonstrated that the extraction yield of the essential oil performed in same conditions was influenced by the location of growth area; the maximum extraction yield of 10 ml 100 g-1 caraway was obtained from dried seeds collected from Csíkmadaras. This quantity far exceeded the yield of the Újtusnád samples. In the case of wild caraway (Carum carvi L.), the extraction method influenced thecomposition of the essential oil (carvone/limonene ratio), the highest limonene content being achieved by classical hydro-distillation. In the case of thyme, this effect was not detected, the thymol/carvacrol ratio was independent from the given extraction method. The obtained thyme essential oil possesses high antimicrobial activity demonstrated by agar diffusion test. The thyme extract provides a good protection against microorganisms collected on the surface of fresh vegetables following bacterial stains: Citrobacter portucalensis, Pseudomonas hunanensis, Pseudomonas baetica, Pseudomonas parafulva, Bacillus mojavensis and Enterobacter cloacae. Protective effect was also detected on the vegetable surface of by chitosan-based edible film coating during a 6-day-long storage period at a temperature of 4 °C. The caraway essential oil used as soft cheese seasoning with a direct, dilution-free method, proved to be unsuitable because the uneven distribution and confer a strong, unpleasant taste to the product in comparison with the ground wild caraway seed-dressed cheese.
Highlights
The use of plant-based compound in human nutrition as nutraceuticals is becoming increasingly widespread (Gupta, 2016)
We investigated the antimicrobial effect of the thyme extract and some of the commercially available essential oils; while in the second experiment we measured the flavoring effect of the wild-caraway essential oil in cheese
Our experiments demonstrate that the growing field has great influence on the essential oils yield but less on the of the two main components ratio
Summary
The use of plant-based compound in human nutrition as nutraceuticals is becoming increasingly widespread (Gupta, 2016). Of the approximately 3000 known essential oils in 2004, 300 were used in industrial quantities (Burt, 2004). Their use in the food industry, in addition to the characteristic aroma, is mainly due to the antimicrobial effect of some of their components (Preedy, 2015; Shojaee-Aliabadi et al, 2018). Many laboratory and industrial processes are known for extracting essential oils, starting from classical to modern energy input (microwave, pulse, oral, ohmic) methods (Mandal et al, 2015). For the extraction of essential oil, classical water vapor distillation is used (both at the laboratory and in the small scale); in industrial-scale production, percolation, solid-fluid extraction and, last but not least, the supercritical fluid extraction method is extended (Roohinejad et al, 2018)
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