SciChef – How to react alcohol with oil to make a cooking ester

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SciChef – How to react alcohol with oil to make a cooking ester

By Dr Garth Cambray

SciChef is a new section in ScienceinAfrica which will show you how to be a SciChef, producing gourmet foods and ingredients that are interesting, unique, and will allow you to impress your friends. Here create some unique oils which give all the benefits of flavour but without the greasiness.

Honey and Brandy oil

If one looks at the structure of a vegetable oil it consists of a glycerol molecule with three fatty acids attached to it. In normal cooking processes, heat damages the oil. The glycerols gradually get separated from their fatty acids producing a range of foul tasting and/or carcinogenic compounds. That’s why we change cooking oil when it goes brown or black (depending on how long we wish to live).

It is possible to react an alcohol molecule with each fatty acid, creating an alcohol fatty acid ester. The glycerol then separates from the alcohol fatty acid ester. You can then use the alcohol fatty acid ester (AFE’s) as a novelty cooking oil.

But, if we want to be really crafty, we can use matching oils and alcohols. In this recipe we will produce two matching AFE’s. First we will take brandy, produced by distilling wine made from grapes, and we will react it with oil pressed from grape seeds to make Brandy alcohol esters of grape fatty acids or Baegfas oil.

Secondly we will take mead, made by fermenting sunflower honey, and distil it to produce mead spirits which we will react with cold pressed sunflower oil to produce Mead alcohol esters of sunflower fatty acids or Maesfa oil.

In this way we will combine the alcoholic ‘spirits’ produced by fermenting the sugars of two types of plants, with the fatty acid ‘souls’ of their seeds to produce novel, delicious, and exciting ingredients.

Making Alcohol Oils

What will you need?

Mead on the left is distilled to produce mead spirits which are then dried to give close to pure alcohol (middle) by mixing with gypsum. Oak cubes were added for flavour. Sunflower oil (right) is extracted from the seeds of sunflowers, which were because the flowers were pollinated by bees while making sunflower honey.

Safety equipment
Although you are making food, this is flammable food, and some of the ingredients are a little dangerous. Hence, you will need a fire extinguisher, eye protection (although normal lab goggles are fine, welding goggles are far stronger and look even sillier). For some steps alcohol fumes will be released and if you do not wish to inhale these an activated carbon gas mask helps. A pair of kitchen gloves will stop you spoiling your food by getting wet fingerprints in the ingredients.

Ingredients
Brandy, Mead, Lime, grape seed oil, cold pressed sunflower oil, food grade sodium hydroxide (note, chemicals are available in various grades, normal reagent grade sodium hydroxide has a purity of about 99% - you don’t know what the other 1% is, whereas for food grade products you can be sure that whatever the

Grape seed oil is made by extracting the oil from grapes. The seeds are a by-product of the wine industry where grape juice is fermented to wine. The wine is distilled to give brandy (right). Brandy is 43% alcohol, hence to produce 43ml absolute alcohol you will require 100ml brandy – in a perfect world, so rather count on using 150ml brandy.

1% is, it shouldn't hurt you, but check the package label anyway).

The reaction

We need to make ethyl hydroxide – a chemical powerful enough to steal the fatty acids from the glycerol.

To do this, we have to remove all the water from our alcohol mixtures. The brandy contains about 43% alcohol, so one small distillation and reflux step (see an earlier article on refluxing) concentrates your alcohol to 80 or so %. For the mead, distil your mead and reflux it to get it to about 80%. Add lime (equal volumes) to the alcohols and shake up vigorously. Shake every few hours for a day. Allow to settle. You have now removed most of the water from your alcohol.

Take your sodium hydroxide and weigh out 0.3g and mix it into 20ml of pure alcohol. Immediately close the container with the alcohol. Pure alcohol is very hygroscopic and will absorb moisture, which will damage reactions further down the line.

Dried alcohol measured out to 20ml is poured into a small airtight mixing vessel with 0.3g sodium hydroxide.

Let the alcohol and hydroxide dissolve over a period of a day – shaking helps.

100ml of oil is placed in a flask and heated until all popping sounds, produced by small amounts of water evaporating, are absent. Note that it is wise to wear protective goggles from this point onwards.

Heat 100ml of oil until you stop hearing popping sounds – popping sounds are small amounts of water evaporating – water will stop your trans-esterification reaction so it is important to get rid of it.

Once the hydroxide is dissolved, pour the 20ml alcohol into 100ml oil and mix. Place in a closed bottle and put in a container of warm water at 55° C.

Shake the alcohol oil mixture together. If you have everything right, you will begin to see glycerine precipitating to the bottom of the container and after two hours you will have nice clean oil at the top. If you get it wrong you will have margarine in a few minutes.

Allow the oil to cool to 55°C and add your alcohol hydroxide (ethyl hydroxide) solution. Shake gently.

You now need to wash your oil to get the remaining hydroxide and alcohol out. Do this by pouring the oil out into a separate bottle and adding some hot water to it. Gently shake and then pour the oil off once it separates. Do this five or so times.

Take the oil and heat gently to 80 °C and it will go clear. Scoop off the clear oil and place in a bottle.

Congratulations – you have now made a really expensive, really fancy oil!

Recipe Suggestions

When cooking with Alcohol fatty acid esters it is important to remember that they have lower boiling points than their parent oils, and higher boiling points than their parent alcohols.

In other words, if you fry your food at high temperature, your lab or kitchen will rapidly fill with oily vapours.

After a few minutes you will begin to see glycerol settling to the bottom of the vessel as the reaction completes. After washing and settling the water out, then heating and filtering, the clear fatty acid ethyl esters are ready.

Ingredients (one serving):

Brandy alcohol fatty acid esters.
Mead alcohol fatty acid esters.
Wine or mead vinegar.
One decent rump steak.
1 potato
1 baby marrow.
1 patty pan
1 medium large mushroom
lettuce, parsley, tomato, oreganum, garlic.

Fry steak on medium heat in a Teflon coated pan with 2 tablespoons of Brandy alcohol fatty acid ester. As the steak cooks, the oil will evaporate, so top up periodically.

Fry the vegetables separately in Mead alcohol fatty acid ester.

Bake potato.

In a small container add 1 tablespoon of Mead alcohol fatty acid ester and mix with a tablespoon of vinegar (mead or wine vinegar). Shake vigorously and add a slice of garlic.

After a long day in the lab, any SciChef definitely needs a good tasty novel meal. Here, our SciChef, Dr Garth Cambray enjoys a quiet meal prepared with Mead alcohol/sunflower oil and Brandy alcohol/grape seed oil fatty acid esters. Science tastes good!

Arrange all cooked food on a warm plate, halve the potato, drizzle the potato and salad ingredients with the mead alcohol fatty acid ester vinegar mixture.

Eat and enjoy! You will note that the advantage of cooking with the alcohol fatty acid esters is that the oil is much lighter and less greasy than the parent oils. This allows one to still get the extraction of flavour that is so important with oil and food, without getting the greasy effect. Because the fatty acid esters evaporate easily, one can control the level left on the food, meaning that at the end of the process, you can let most of the oil evaporate, leaving the flavour that it had extracted on the surface of the food.

More information:

For information on Mead see www.iqhilika.co.za