Brewing

 

There is nothing more artisanal than brewing

Humanity has been brewing beer since at least 5,000 BC. And during the intervening 7,000 years we have come up with many ways to do it!

Nowadays most beer is made by taking cereal grains and fermenting them with yeast. But, you can use other feedstocks and other microbes, and indeed make other things than beer (or even alcohol), if you wish to.

Evolva keeps two out of three things unchanged. We keep the yeast, and we keep the cereals (we typically use corn or wheat originated sugars as the feedstock). But, we don’t make alcohol and instead focus on making other, rather more valuable ingredients.

We are brewers for the 21st century.

Fed-batch fermentation and its use in development

Once a promising yeast has been developed, we test it in small-scale (1-10 litre), fed-batch fermentation. “Fed-batch” is a single run (“batch”) fermentation where the yeast is fed continuously during the fermentation. This ensures that a yeast culture of good density is formed and that the sugars we feed it turn into the desired ingredient rather than alcohol. Results from each fermentation run are fed back to the yeast development teams, allowing them to further improve the yeast in a highly iterative process. The underlying aim is always to ensure that the yeast turns as much sugar as possible, in as short a time as possible, into the desired ingredient.

Scaling up to final production

When yeast strains have been developed that behave well in small-scale fermenters it is time to “scale up” – to make sure the process works well not just at small scale but also in a 20,000-500,000-litre fermenter (typical “commercial” scale).

Baker’s yeast is a quiet and easy organism to work with. Like every other living organism, it responds to changes in its environment. Big fermenters differ from little fermenters. Whilst growing yeast at large scale is something done every day, all over the world, we still need to see how each particular yeast strain will respond to “growing up”.

To do this, we take a step-wise approach. Typically the first step might be to test the yeast at 100-500 litres, trying the same fermentation conditions that worked at the 10-litre scale. If that does not give the same results as before then (and it normally is “off” by a least a little) then we change some of the fermentation conditions (f.x. temperature, pH, oxygen flow, feeding rate, nutrient supply, etc.) until we get to conditions where the yeast is as “happy” and productive as it was at the smaller scale. Once it works at 500 litres, we move up to 5,000 litres—and onward and upward from there. If we are feeling brave, we might take even bigger steps than these.

Product Purification (also known as downstream processing or DSP).

Once we have completed a fermentation, we filter out our yeast, and then purify the desired ingredient from the broth. Such processes usually rely on a combination of filtrations, extractions and crystallisations, eventually giving you the desired ingredient in a pure form.

The DSP process is custom designed for each ingredient (although many of the steps will be similar between different ingredients).  Design of the DSP process starts in the lab, and continues throughout the ingredient’s development, and indeed even once the ingredient is on market.  Key aspects of a good DSP process is that the process is simple, robust and environmentally sound.  Of course it must also recover as much as possible of the ingredient that has been made by the yeast – a good recovery rate in the lab normally translates to a good recovery rate in full production.

Continuous Improvement

Once an ingredient has been launched, we do not stop there.  We keep working to make the production process more efficient and sustainable.  Typically there are five aspects that can be improved to reduce the cost of production over time

  • The yeast itself.   The more efficiently our yeast can turn what we feed it into the desired end-product, the better the process.  So identifying and improving bottlenecks within the yeast itself is something we keep working on.   Efficiency can be measured in several different ways, but one of the most useful is productivity (how many grams of final product does the yeast make per litre per hour).  As fermentation costs are proportional to the performance of our yeast strains, a doubling of productivity will roughly halve the fermentation costs
  • Feedstock use and the fermentation process.  It is not just the yeast. We can also improve the fermentation  process itself to reduce the use feed stocks such as glucose and vitamins, benefiting everyone.
  • The purification process.  Purification can typically account for as much of the cost as the fermentation itself.  The more of the final ingredient that we can recover from the broth, and the fewer and simpler the number of steps we have to carry out to do so, then the better.
  • Increasing the scale.  It takes more or less the same amount of manpower to run a 20,000 litre fermenter as it does to run a 500,000 litre fermenter.  Fixed costs can be spread across more tonnes of product.  So by making more of a product, we can make it cheaper
  • Production location.  Different production facilities will have different cost structures – the price of the biomass we feed to the yeast, the cost of energy, the level of automation etc.  Over time it becomes feasible to move to lower cost locations, whilst always maintaining a high level of product quality.

Importantly, these five factors all act to reinforce each other, multiplying each others effects.  By improving across all aspects simultaneously it becomes possible to significantly improve production efficiency year on year.

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