I recently started reading Yeast: The Practical Guide to Beer Fermentation by Chris White & Jamil Zainasheff to get a better understanding of Yeast. I had read some basic information in the past, but it wasn’t until I started reading this book that I have began to understand the imperative importance of yeast in the brewing process.
It goes much deeper than just “yeast eats sugar and makes alcohol” which, although a bit dumbed down, was my basic understanding before.
Looking back now at times when I brewed beer from kits, as well as my recent extract brew experience, I didn’t choose in the right way. It was based – I’m afraid to say – on what was cheapest. Don’t worry (I could see the worry on your face) I will no longer use price as a way of choosing a strain in the future.
Anyway, as I have been working my way through the book I have been taking notes, which I’ve decided to put up on this blog as a way to document my growing understanding of these tiny, but hugely vital microorganisms.
Only 55 pages in, but here is what I’ve learned so far.
Very Quick History
Although yeast had been observed in the past – under the microscope around 1680 – it wasn’t until the mid-1800s that Louis Pasteur established that yeast was a living micro-organism Previous to this, it was believed that yeast was simply a by-product of fermentation. Pasteur experimented for many years with various yeast cultures and sugars to better understand what made it tick.
One of the 1st breweries to adopt his ideas was Carlsberg. Under Emil Christian Hansen the brewery’s lab managed to isolate the 1st Lager strain of yeast – Saccharomyces uvarum (today known as S. pastorianus).
Due to the fact that Lager yeast has specifically used and therefore well cared for, with the brewers understanding what to expect from it, lager became clearer, more consistent and gained a longer shelf life. Ale production was not as sophisticated with wild yeast and bacteria problems common place. This led to a rise in lager drinking, over Ale.
Very Brief Overview
- Yeast is a part of the fungus family and is a single cell organism.
- There are over 500 species of yeast – each with thousands of strains.
- Yeast coverts sugar into alcohol, CO2 and other compounds that influence the taste and texture of fermented food and drinks.
- Different strains of yeast produce different flavours and characteristics. Knowing what different strains of yeast produce – in terms of aroma, flavour, etc – goes a long way to producing beer that matches your intended vision.
- Yeast requires nutrients to improve and/or maintain good health and performance.
- Temperature control is essential for consistent beer. If there is a problem – and contamination can be ruled out – the majority of the time the issue will be temperature related.
- There are two main species of yeast favoured for the brewing of beer:
- S.Cerevisiae (ale yeast)
- S.Pastorianus (lager yeast)
Next up in the book is the section on how to choose the right yeast for your beer. This is something I’m quite interested in, so once read and digested the information I’ll no doubt write-up a post about what I learn.