Re-pitching is an obvious step towards a more efficient brewery and when using quality products, a better beer. In this article Andrew Paterson, the technical sales manager for UK, Ireland and Scandinavia at Lallemand Brewing explains all.

It is often stated that beer is produced from only four ingredients, malted barley, yeast, hops and water. In the days of very highly processed foods more could, and probably should be made of this fact. This outward simplicity hides the incredible variety within each of these ingredients. Every few years new barley varieties appear with greater farm yields, or better malting performance; some impart other advantages such as better beer stability, extract or aroma.

These new developments combined with new and old malting techniques mean that brewers have hundreds of potential malts to choose from when designing beers. Hops similarly benefit from a continuous R&D pipeline to improve agricultural performance; but also to produce greater bitterness along with plethora of different flavours and aromas. Hop companies continuously compete to have the next most exciting proprietary aroma variety. Yeast has a similarly exciting innovation programme.

In recent years Lallemand has released yeasts derived from selective breeding programs which cannot ferment maltose and can naturally produce low alcohol beer, and in parts of the world where it is permitted, we have marketed a yeast capable of producing lactic acid which was created using genetic modification. Increasing the availability of a diverse range of dried yeast strains is one of our core business goals.  

R&D programmes represent a significant cost to those who run them, and so new varieties of barley, hops and yeast tend to be sold at a higher price than their predecessors. On a cost per kilo basis yeast can represent one of the more expensive commodities procured in a brewery. Fortunately, in the case of yeast, there is a very simple way to minimise this cost.

During fermentation yeast divides three to five times meaning that you will end up with an order of magnitude more cells at the end of the fermentation compared to when you started. Many economically minded brewers, particularly those on the larger end of the scale will re-pitch their newly grown yeast into the next fermentation, thereby halving the yeast spend on the subsequent batch.  

Each year, my colleague Alix and I run a course on Yeast Handling and Microbiology under our BrewEd initiative. This puts brewing education at the heart of what we do. The course aims to provide an overview to brewers of the economics of re-pitching as well as teaching practical microscope skills and making yeast handling suggestions which can be easily implemented in any brewery.

Frequently, prior to attending we find brewers are convinced of the economic sense of re-pitching, but lack the confidence to manage the logistics leading to them choosing lower cost inferior products for pitching and ditching, over higher quality ones that can be reliably reused. To provide reassurance, YES YOU CAN DO IT!, we focus on the following key areas during the course.

Yeast Viability – Put simply, this is the number of cells within the slurry which are alive. Measured by staining and microscopy, the metric is usually presented as a percentage viability. Ideally the culture would be >90% viable. When it is not, there are ways to mitigate the deficiency which in turn will lead to improved the health in the subsequent yeast crop

Yeast Pitching Rate – While strain and brand specific, there are rules of thumb which can be used to guide pitching rates in the first instance. The often quoted 1 million cells/ml/⁰Plato for an ale and 1.5 million cells/ml/⁰Plato for a lager is a good place to start. The number of live cells in the yeast slurry, and by extension, the amount of slurry you require for a healthy fermentation are estimated using an Improved Neubauer Haemocytometer and microscope

Yeast Storage and pitching – Yeast should be stored cold at <4⁰C and for the minimum amount of time possible. This can be as simple as a clean sealed bucket stored in a fridge, or as complex as dedicated yeast brink with temperature control, agitation and load cells to measure the amount of yeast present. Yeast is usually pitched by weight using platform scales in craft breweries, or by measuring the quantity of yeast that has left the storage vessel in the case of a brewery using dedicated storage tanks. Some breweries can even measure viable cells inline using capacitance, achieving very high levels of accuracy.  

Nutrition and Oxygenation – While dried yeasts can be initially pitched directly, any yeast repitched after generation zero requires the addition of supplemental oxygen to the wort. The reason for this is that yeast requires oxygen to create sterols which play a vital role in stabilising the cell membrane of the yeast. Without it fermentation will be sluggish and will fail to fully attenuate. All fermentations require a source of Free Amino Nitrogen (FAN), which should be present at 150-200ppm for a standard gravity fermentation, but up to 350ppm for a very high gravity wort. For a scenario where nutrient is required I recommend a complex yeast nutrient such as YeastLife Extra. As well as FAN, YeastLife Extra also contains zinc, vitamins and minerals which are important for healthy yeast metabolism.

If a brewer adheres to the above points, and most importantly, pays good attention to working in a consistent hygienic fashion and with good record keeping, there is absolutely no reason why they can’t re-pitch a dry yeast several times. The equipment required is low cost and accessible to all, with solutions available for every size of brewery.

The learning curve is easier than many expect, and once routines are established you can quickly achieve meaningful cost savings and improved process consistency. Re-pitching is an obvious step towards a more efficient brewery and when using quality products, a better beer.   

Lallemand will run this course again in 2026. Keep an eye on our social media for updates. Follow us at @lallemandbrewing and feel free to reach out in the meantime if you would like to discuss re-pitching in more detail.