Secretory structures of aromatic plants

To know more about how and where plants produce essential oil I bought the booklet:
'Secretory structures of aromatic and medical plants' 

This book, written by Katerina P. Svoboda and Tomas G. Svoboda, gives sharp microscopic images  of the different structures in the plant responsible for producing oil. There are several oil-secreting structures:

 

 The simplest structure consists of  one single cell. This leaves of the magnolia has individually cells producing essential oils.

 

The system is simple: oil is sampled in the vacuole (in cell) equipped with a membrane. The cells are isolated and have an other internal cellular structure than the cells around it. Biosynsthese of all the constituents of the essential oil takes place in plastids (same type as the organelle chloroplasts) and in the cytoplasm of the oil-producing cell.



There are also plants such as Eucalyptus, who possess a cavity surrounded by a large number of oil producing cells within the plantstructure. These so-called excretory cavities are the place where the plant produced essential oil are being stored.

 secretory cavity in citruspeel

 



Even citrus fruits like orange have such cavities lying in the epidermis of the peel. This also explains that when peeling an orange you smell citruslike odors. 



Lavender oil gland 

In the Labiatae family, and thus all kinds of lavender, you come from a very different structure. On the epidermis of the plants are spherical glands with two cells connected to the epidermis cells.



 Figure 3: Glandular trichomes in Lamiaceae. o=oil drop, sc=subcuticular storage cavitiy, h=head cells (site of terpene biosynthesis), s= stem and b= basal cells. (Modified after Fahn, 1979a)

Stems and flowers of flowering plants are also littered with these glands.

Marjoram SEM photo



Like marjoram (Origanum Majorana) are photographed with a scanning electron microscope (SEM), and below a photo of rosemary.

Such structure also explains that if you touch a plant essential oil is released.
Even if plants like lavender is dryed when sqeeuzed the lavender oil kept in the glands will be released.

 cross section of a needle of a conifer



An even more complex structure are secretory ducts. Such channel-like structure found  for example in the conifers. Such ducts make a connection from the roots of the tree to the leaf, flower and fruit.

 Magnification of ducts in wormwood. There are two ducts here, the one on the left is old enough to have developed a small lumen and epithelium; the one on the right has not yet reached the stage of having a lumen. The arrow points to an area where the cells might be starting to pull apart – the black material between the cells might be the first stages of the breakdown of the middle lamella (there are places in the upper part of this micrograph where there are similar amounts of dark material between cells





 Transverse section of needle leaf of pine (Pinus). The needles of pines and many other conifers have resin canals with complex epithelia.

These channels  are composed of an epithelium which surrounds a central cavity. Some of these cells forming the wall of the cavity will change into secretory epithelial cells.The oils  are biosynthesised within their leucoplasts and move via the endoplasmic reticulum into the cavity. The ducts are relatively close to the surface of the leaf. Not without reason. The smallest animals will take off  immediately after a bite out of a pine needle because of the bitter taste which is given by the resins. This is a protection for conifers.
Who wants something more to read about about plant anatomy: http://www.sbs.utexas.edu/mauseth/weblab

Distilling liquor

 

If your talking about distilling it's a separation method based on different boiling points. In the dutch language 'distilleren' means distilling alcohol. To also get acquainted with distilling I have followed a course during the past few weeks given by Pieter Rijneveel in Dordrecht.

Pieter has a distillery http://www.slijterij-vwk.nl/  and according to traditional methods  he distills with a single-walled copper kettle. During one evening we visited a distillery of van Toorn in Vlaardingen

The photo above is a still from the distillery. Distiller Leo Fontijne gives some explanation about the production process of liqueur, genever, brandewijn and advocaat. He is the only producer of  'schelvispekel'. See the website http://www.schelvispekel.nl/





In addition to theory there was also room for making liquor. I got a jerry can, yeast, a bag of sugar and a water lock . The intention was to ferment  a sugar solution for 3 to 4 weeks and and distill the alcohol off.

fermentation of sugar solution


Here is the recipe for fermentation, including:

1 kg sugar in 1 liter water and simmer for 5 minutes

dissolve the sugar water to a total volume of 5 liters in a fermentation tank, then let cool

Take about a half liter of solution and solve 1 gramof yeast and a crushed vitamin C tablet in it.
Bring this mixture back into the fermentation tank and end it with an airlock.
Shake the tank daily.

 

equation for the fermentation






ethanol model


 

A few weeks later the sugar solution, now about 10% fermented into alcohol, could be brought into the still. This is the smallest still Pieter has and is made from parts of a central heating boiler.

In the proces of distilling  alcohol a good cooling and separation of water and alcohol is important. The separation of the alcohol and water is made possible by a vertical column filled with marbles.



top of the still




After this separation column and the thermometer are some water coolers that make that alcohol vapor is condensed well.

 After some 20 liters of fermented sugar is transported in the still Pieter closes the boiler off and closes the cracks with a paste of flour and water.

Then the gas burner under the boiler is lit. After about half hour, the first distillate from the condenser drips into a beaker. Of course we throw the first 200 mL of distillate away because of traces of methanol in it.

Meanwhile we are working on skinning and filleting of an orange.

The essential oil in the peel with cinnamon and cloves maak sure we get a good taste of the liqueur. The sugar content of the liquor is achieved by 1 kg of sugar to 1 liter to resolve.

To make a good liquor we have 1 liter sugar 1 liter water, 1 liter of alcohol plus the orange rind and cinnamon cloves needed. This mixture must be left at least for 4 days to extract and then filter and divide into bottles. The result: an orange liqueur with an alcohol content of about 33% and 25% sugar content.

 In total, there are 2.5 liters orange liqueur made. Enough to get some bottles to give away for Christmas. I have not yet had any comments from people who have tasted the liqueur.

 When I poured the  liquor in smaller bottles it smelled very good! Do you want to know more about where liquor and beverages in general are produced click on this link:

http://www.pdcg.nl/left/drankenbank/introductie.php?grp=17&pg=846