Properties of beer (part 3)

Following up on the previous two blog posts, this will be the final post on the properties of beer and how to determine them.

A typical biochemistry test is to determine the bitterness of the beer. The bitterness is dependant on the used hops. Hops contain Iso-α-acids which is the organic component that determines the bitterness. To determine this we use a ultra-violet spectrophotometer. Each specific compound has a specific absorbance of light. Light consists out of an entire spectrum of colours, each having their own specific wavelength. The absorbance of the Iso-α-acids is 275nanometers. This is light we can’t see with our bare eyes as our visual spectrum ranges from 400-750nanometers.
These bitter-acids are extracted out of the beer by adding iso-octane. This component absorbs all the bitterness out of the beer. Because of the different densities, the bitter phase floats on top of the beer. This top layer which contains the bitter components can be extracted. After measurements in the spectrophotometer we get a measurement for the turbidity which is directly proportional with the amounts of bitter-acids in the beer displayed in ppm (parts per million).

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Another very important parameter is the turbidity. Whether a beer is see-through or turbid depends on the yeast in the bottle. Often, breweries will use secondary fermentation or fermentation in the bottle which means that a small amount of living yeast cells is placed in the bottle together with the beer. This has a couple of advantages, firstly, as the yeast cells are alive, they use up the small amount of oxygen in the bottle for their own respiration while producing extra carbon dioxide. As oxygen produces off flavours in the beer the yeast cells allow the beer to have a much longer shelf life (3-4 years) in comparison to non secondary-fermented beers (6month shelf life). Secondly, the yeast in the bottle matures the beer over time giving it specific flavours necessary to perfect the beer.

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Left: clear beer, not secondary fermented ; Right: turbid beer, secondary fermented

The turbidity is measured with a turbidity meter. It sends a ray of light through the bottle at a 100% intensity. Depending on the turbidity in the bottle, the light ray gets reflected, lowering the intensity of the light ray, and is measured on a sensor at the other side of the bottle. Depending on the decrease of the light intensity the turbidity can be calculated. A brewers wish is that the yeast sticks to the insides of the bottle, this indicates good yeast. A certain amount of turbidity can be wanted but too much is never good. It won’t do you any harm but will cause a bit of stir in your intestines after a few beers. So often the turbidity is measured once when the beer is at rest and once after making a few gentle pouring movements with the bottle. If there’s much more turbidity afterwards then you know that the yeast doesn’t stick to the bottle.

As 2016 comes to an end so does this blog. After reading through this I know for sure that many of you will be able to craft a perfect and delicious beer. Happy holidays and I’ll raise my beer on a good and prosperous 2017. Cheers! “dif-tor heh smusma” as Spock would say or “live long and prosper”.

~Blanckey the Brewer, signing off.

Properties of beer (part 2)

As stated in a previous blog post this post will be a follow up on the properties of beer and how to determine them. So without further ado, let’s jump right into it.

04refalc11-5To determine the alcohol percentage of beer, the beer needs to be degassed (eliminating the carbon dioxide). This is done by pouring about 20ml of beer (as I only needed a small amount) in a open flask and placing it on a slow shaker for over 4 hours. Hereafter the beer was poured over a filter into another flask to get rid of any contaminants from the air or yeast.
To determine the amount of alcohol a distillation is performed. This is basically the technique to make whiskey and gins. It’s a rather ‘old fashioned’ way of determining the amount of alcohol and is only done on a small scale. A distillation works as follows. The decarbonated beer is heated allowing it to evaporate. The formed gas consists of alcohol fumes and water vapor. The gas moves through a tube that is water cooled allowing the gas to go back to its liquid state (condensation) and is collected in another flask. This collection flask contains a small amount of cold water. This is necessary to make sure that the alcohol doesn’t evaporate again as it has a much lower boiling point than water. The density of the solution is determined by a ‘density measuring module’. All data is eventually used in the formula of Balling and the alcohol percentage is displayed in ml/100ml or %V as displayed on all in-store bottles.

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Destillation setup

The head on a beer is a piece of art, it has to be perfect and, most importantly, stay. Unless you’re chugging a beer at 2am at your local nightclub, no one wants their beer collar to disappear in seconds. Measuring how long the collar of the beer lasts is described as ‘foam stability’. The equipment used for this test is called the ‘Nibem Foam Stability Tester’. To conduct this test you’ll need foam, a lot of foam. This can be done by injecting CO2 gas in the beer itself causing it to foam excessively. This foam is then captured in a standardized glass of 25cl. Once the glass is completely filled with foam it’s inserted into the machine which contains electrodes. These automatically detect the foam and follow the degradation of the foam in real time over a length of 30 millimetres.

Be sure to check the next, and last, post of the blog on how to determine the last properties of beer. Cheers!

Blanckey the Brewer

Properties of beer (part 1)

As a masters student in industrial engineering at the university of Ghent I follow the course ‘Brewery technology’. After being lectured every week about the brewing process and the necessary calculations I finally got to put my acquired knowledge to the test.
I got assigned a ‘brewing day’ in which I had to performed tests on one of my favourite beers ‘Grimbergen Gold’ while maintaining the brewing process of the local beer ‘Bijloke’, brewed exclusively at the University of Ghent.

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Production of Bijloke at UGent (background)

In the next blog posts I’ll explain the fundamental tests to determine the properties of beer. These tests determine the amount of Carbon Dioxide, Oxygen, alcohol percentage, living yeast cells, foam stability, bitterness and turbidity. The properties of all factory bottled beers are already precisely determined, therefore these can serve as a reference to compare with my personally found values. In reality these tests are obviously not performed on every bottle. As the entire industrial process is so precisely controlled there’s barely a chance that the pre-determined values would differ. If on the other hand the brewer decides to change the recipe or brew a new type of beer, these tests become very fundamental to know whether they’re on the right track.

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Henry’s law: the higher the pressure above the liquid the more dissolved gas in solution

An important test is to determine the amount of CO2. Carbon dioxide gives beer its fizzy properties as it does in all carbonated drinks. The principle of this test is to determine the pressure in the bottle of beer according to Henry’s Law. Henry’s Law states that the concentration of dissolved gas in a liquid is proportional to the pressure in the gas in equilibrium with that liquid. This basically means that the concentration of a gas (here CO2) in the beer is proportional with the pressure of the head volume in the bottle. How higher the pressure in the gas above a liquid, the more gas is dissolved in the liquid. To perform this test, the bottle is shaken thoroughly and the maximum pressure of the gas is measured with a manometer. All this pressurized gas is then drained through a tube and into a column with a specific liquid in it. The amount of CO2 gas can then be calculated through a complex formula depending on the amount of liquid that is pushed away by the gas volume.

 

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Henry’s Law: In a bottle or can, depending on the pressure, CO2 is dissolved in the liquid. When opening a can the pressure in the can disappears allowing the gas to escape from the liquid, making the well know “psshh” sound.

The life of a scientist isn’t always that bad as technology keeps evolving every day and allows automation for almost everything these days. It makes difficult tasks as easy as pressing a button. That is to be taken quite literally as determining the amount of oxygen in the beer only required punching a hole through the bottle cap and let the machine do its work by pressing ‘start’.

Be sure to follow up on the next blog posts for more laboratory beer tests, cheers!
~Blanckey the Brewer

Fermentatio

On Friday the 2nd of December I had the honour of being invited to a beer brewing seminar. It was hosted by Fermentatio, a society established in 1887 uniting industrial and amateur brewers.

The day started with following the directions towards the auditorium. While everyone was chatting away with old friends and business partners I sneaked through the crowd towards the coffee table. Grabbing myself a cup of coffee that tasted absolutely horrible, though the accompanying biscuit made up for it. I entered the auditorium and took place, while almost spilling my coffee, at the last row which was assigned specifically to students. After waiting for almost 45 minutes everyone finally took a seat and the presentations started.

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The first speaker was someone from the Belgian company Meura talking about their special type of mash filters. As I mentioned before in this blog-post, mash is the malt soaked in warm water. Meura developed a special filter with an inflatable membrane, being up to 10% more efficient than others. Hereafter we received a presentation on research of DMSO, which is a chemical compound that produces off-flavours in beer, and about a microchip that allows the fermentation of yeast in micro-droplets.

After the break we got lectured about cultivation processes of brewers yeast, the oxidisation process to remove iron and manganese out of the brewing water and about fungi of barley and their mycotoxins  .

Fungi and mycotoxins are basically the nemesis of beer brewers. The fungi we’re talking about is Fusarium which is a large genus of filamentous fungi of which ‘Blight’ is a member, which is a very well known plant disease that led to the Great Irish Famine. Mycotoxin is a secondary metabolite from fungi. Primary metabolites are components that an organism produces in order to survive, secondary metabolites are compounds produced when the organism is satisfied with its primary nutrients. Secondary metabolites can vary from toxins to antibiotics to (citric)acid. There’s a whole world out there specialised in the production of these components but let’s not swerve too far in that direction.

When a brewer buys his grain he doesn’t use them right away; they’re stored in silo’s or containers at low temperatures. This storage environment needs to be perfect because if it’s too moist or the temperature isn’t right the Fusarium can start cultivating in the grains and spread rapidly (if present in the grain or air).

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Fusarium head or Blight

The TDI (Tolerable Daily Intake) of a mycotoxin is 0,06 microgram per kilogram. In case a mycotoxin has cultivated in a batch of beer an intake of only 3 beers is enough to reach that daily dose. Hear me out before you start throwing all your beers out in fear of becoming ill due to these toxins. The human population is immune to 90% of all mycotoxins from the Fusarium family. Dr. Anneleen Decloedt performed research at the University of Ghent on examining beer types which might contain mycotoxins where less than 90% of the population is immune. As conclusion she found that those types of beer are: fruit beers, Trappists and sour beers.

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Research performed by Dr. Anneleen Decloedt

You might ask yourself, “why all this research, aren’t the laws for health and hygiene extremely strict”? Yes, you’re right though what’s happening in the modern days is that many toxins and viruses are mutating to resist the current cures and vaccines. The same happens with mycotoxins. Once they’re mutated we’re not resistant any more to that ‘new’ type of toxin and the health and safety laws do not incorporate these modified toxins.