pollination

#Advent Botany Day 23: Vanilla – nothing plain about this flavour!

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I’m not one for cream on my Christmas pudding, it just has to be custard or ice cream and so what I’m really admitting to is a love for vanilla. Vanilla is the quietest spice at Christmas but there is so much more to vanilla than merely two scoops of icecream.

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Natural vanilla is the fruit and seeds from a tropical, climbing orchid. There are other edible orchids (e.g. Dendrobium flowers and salep tubers), but it is certainly the most commonly used in food preparation.  Some orchids are harvested from the wild to eat (such as Orchis mascula and O. militaris for salep), but given the demand, luckily this isn’t true for vanilla. There are over 100 orchid species in the Vanilla genus, but the most commonly cultivated species is Vanilla planifolia (more commonly known as Madagascan or Bourbon vanilla).

V. planifolia is native to Central and South America, and was first domesticated by the Totonac people of east Mexico, who used it exclusively until Aztec conquerors demanded vanilla as a tribute. The Spanish conquistador Cortez brought vanilla to Europe, where initially it was only mixed with cocoa and drunk, but later was used in other deserts. Vanilla was very expensive during the 16th to 19th century, as Mexico had a monopoly on this luxurious spice. The reason for this was discovered by the French botanist Charles Morren who in 1836 observed Melipona bees pollinating the flowers, which have a range limited to Mexico. Therefore, the only way to cultivate vanilla elsewhere is by hand pollination. Morren experimented with hand pollination methods but the method still used today was devised by Edmond Albius, aged 12, in 1841. A twig or blade of grass is used to lift the rostellum, separating the stigma and anthers, and the thumb is used to transfer pollen to the stigma. The process is further complicated by each infloresence only lasting for 24 hours.

Vanilla is labour intensive to produce, so natural vanilla is still the second most expensive spice (after saffron). Albius’ method allowed vanilla to be grown in what is now Madagascar, Reunion and the Comoros Islands, which today account for 80% of the world’s vanilla pod production. You can find more about vanilla from the National Geographic website and an interesting site dedicated to vanilla.

For centuries vanilla has been used to flavour our foods, drinks and even pharmaceuticals but the main extract from the vanilla pod, vanillin, wasn’t isolated until 1858. Nicolas- Theordore Gobley obtained it by completely evaporating the vanilla extract and then recrystallizing it from hot water in order to separate it out from all of the several hundred other components found in the extract. Since the 1870’s companies have competed to produce synthetic vanillin from clove oil, lignin, guaiacol and glyoxylic acid. More recently, Rhodia has marketed a “natural” vanillin which is prepared using microorganisms. You can find out more about the structure of vanillin here.

Around 2% of the dry weight of the cured pods of Vanilla planifolia is vanillin. When the seed pods are first harvested, they are green and lack the vanilla flavour and aroma. Curing of the vanilla pods consists of just four steps. “Killing” often entails the pods being frozen or blanched in hot water to initiate reactions which develop the aroma. Sweating involves stacking pods within layers of wool for 7-10 days in a very hot (45–65 °C) and humid environment. Drying occurs to reduce the remaining moisture content to around 25%  in order to prevent rotting. Conditioning is the final step where the pods are left in the box for several months before being graded. It is after this curing process that vanillin develops the aroma and flavour that we have come to know and love.

To get into the Christmas spirit I’ve found some very Christmassy treats for you to make at home yourself:

A tropical Christmas pudding with a vanilla glaze and  beautiful danish cookies (vaniliekager) recipe.

 

Advent Botany 2016 – Day 20: Virgin birth and hidden treasures: unwrapping some Christmas figs — Culham Research Group

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By Katherine Preston & Jeanne Osnas Figs reach their peak in summertime, growing fat enough to split their skins under the hot sun. It’s nearly impossible to keep up with a bountiful tree, and many a neglected fig is extravagantly abandoned to the beetles. Beetles gorge on a fig@BitKblog But here we are, halfway around…

via Advent Botany 2016 – Day 19: Virgin birth and hidden treasures: unwrapping some Christmas figs — Culham Research Group

#AdventBotany – Getting stuffed at Christmas: Sage

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Common sage specimen, seeds and illustration on a 19th century herbarium sheet from Leo Grindon's cultivated plant collection
Common sage specimen, seeds and illustration on a 19th century herbarium sheet from Leo Grindon’s cultivated plant collection

There are many more gastronomically interesting options available at Christmas time, but I’m still always drawn to the reassuringly traditional sage and onion stuffing. Nowadays, in addition to stuffing poultry, sage is most commonly used to flavour other meat dishes (particularly sausages in British cuisine). However, its scientific name, Salvia officinalis, shows its heritage as a medicinal herb. The species name ‘officinalis’ comes from the Latin word officina referring to a monastic storeroom for herbs and medicines. Sage was recommended for all kinds of ills, from wounds and sore throats to hair care and fertility problems. There’s something about this suggestion for ‘Great Sage’ from Gerard’s Herball, however, which seems especially appropriate for overindulgent holidays:

‘Sage is singular good for the head and braine, it quickeneth the sense and memory, strengtheneth the sinews….’ John Gerard, 1597

This year, perhaps an extra bit of sage with my turkey could give me the edge over my competitors in any after-dinner Christmas boardgames!

John Gerard's herball, 1597
John Gerard’s herball, 1597

 

Sage is in the mint family (also known as the Lamiacaea). Many of the plants in this family are aromatic, but sage also shows some other very recognisable characteristics such as a square stem, leaves in opposite pairs and flowers with bilateral symmetry with the five petals fused to give the appearance of an upper and a lower lip. Originating from the Mediterranean, sage enjoys plenty of sunshine and doesn’t like to get too wet over winter, but is quite tolerant of low temperatures. The furry leaves help to keep insect pests at bay, but cultivars which flower freely are very attractive to pollinating insects such as honeybees and many different bumblebees.

sage

The sage flower has an interesting mechanism for getting pollinated. As pollinator enters the flower looking for nectar it has to push past the base of the stamens which are blocking the way. This acts as a lever, so that the stamens tip forwards and leave pollen on the back of the insect. When it visits another flower, the insect can brush against the female stigma depositing the pollen. Some bees have learnt to cheat, however, and you can find small holes at the base of flowers where a bee has bitten through and drunk the nectar from the outside.

19th century botanical teaching model of a sage flower produced by Brendel, Germany.
19th century botanical teaching model of a sage flower produced by Brendel, Germany.