Northern Dairy Starter Seminar 2025 - A Roundup

Northern Dairy Starter Seminar 2025 – A Roundup

18th September 2025

The slides of the seminar are available for all at: Seminar Slides
The slides on the background/history of starter culture: Starter Cultures
The more detailed minutes of the seminar and findings/discussion if you want to know more have been recorded at: Minutes

This year’s Northern Dairy Cheese Seminar’s held at The Courtyard Dairy was commissioned investigate ‘Starter Culture’.
14 cheesemakers got together from around the UK at The Courtyard Dairy for a seminar to investigate how starter choice and usage can affect the cheese.

Background

Starter cultures are a unique mix of bacteria designed to ferment milk [turning the lactose in milk into lactic acid]; a key part of the cheesemaking process – helping preserve the cheese, drain out the moisture and influencing end flavour. Since the 1900s bacteria for cheesemaking have largely been cultivated in aseptic techniques by laboratories. They are then purchased by cheesemakers and added in to kick start the process of making cheese (hence the name ‘starter’) – but there are many strains, types, brands and varieties.
This seminar was developed to explore how these cultures impact cheesemaking: what affect they have on flavour and texture; and how we can control and use them to our advantage and to make consistent cheese.
We explored how to deal with the challenges of making cheese and coping with managing bacteria – how small changes with starter culture, and therefore drainage and acidification, affect the outcome of the cheese.
Could we match which Wensleydale and Gloucester that were made with the same starter culture?
Do we think that was because of the acidification profile/speed or the starter make up?
How much did that bacteria chosen impact the final flavour of the cheese?
We didn’t promise any answers – just a round table discussion with cheesemakers, looking at the data, tasting cheese and discussing how starter can affect acidification, drainage, and final flavour and texture in the cheese.

The methodology

In a completely unique experiment in the cheese world, two traditional British Cheese recipes were made the same week at The Courtyard Dairy using the exact same equipment, milk source and maturation method. This eliminated any differences caused by the nuances of their farming methods and equipment.
The recipes chosen were Wensleydale (as it uses a low amount of starter culture (0.3% by volume) and low temperatures and acidities in the making; and Gloucester (uses 2% culture by volume) and higher temperatures/acidities in its recipe – hence the different texture and flavour. Both were matured for 3 months.
The recipes were then replicated over several days, only changing the blend of bacteria used to make the cheese.

Comparing the starters

When you make cheese, you manage how the whey is drained off, alongside how much the curd ferments (acidifies) – thanks to that bacteria put in. How the curd ferments, drains and what bacteria are used all affect the nuances within the end cheese.
We could see from the graphs just how fast, and different, various brands of starter culture grow when incubated in lab conditions and UHT milk. We were interested to see what impact these different strains had on our cheese in a real live cheesemaking environment – and then at the later seminar, using this data, could we then control a particular ‘starter culture’ by what we did in cheesemaking.
For the seminar we used a whole range of cultures from freeze-dried, to homemade, to ‘traditional’ (see historic notes below), but in this pack we’ve given you just two to try, both ‘old-fashioned’ traditional starter cultures originally developed by the Milk Marketing Board and British Agriculture Colleges in the 1930s-1970s; nowadays maintained by Maryland Labs/Barbers Cheddar in Somerset.

Seminar Roundup

The seminar started by recapping starter history, their development, current types (DVI/Bulk/Natural), and recommended usage/bulking methods.

Then, to investigate the differences between starter cultures, the 8 cheeses that had been made several months earlier were tasted and acidifications compared.
The cheeses had been made using a range of four different mesophilic starter cultures (DVI and bulk) and two recipes (Traditional Wensleydale, (at low temp, low acidity at milling and minimal starter) and Gloucester (higher temp, scald, high amount of starter and a higher acidity at milling).
[The control for the cheesemaking was the pH at milling in both cases; aside from that we let the starter run its course.]

The experiments gave different acidification profiles, rennet to mill times and moisture contents. As expected, all the batches did turn out different, but the Wensleydales exhibited much more variance in the final cheese.
Yet it was impossible to identify particular starters on tasting and even to try to match the same starter from the Wensledyale across to the Gloucester; the group favourite of Wensleydale and Gloucester also having different preferred starters.
Discussion was had on whether this was due to the rate of acidity from these starters (ranging from 3hr10 ‘rennet to mill’ to 5h40) and the key points of control to steward that curve and the ‘tempo of the make’ to get the desired textures and flavours we want.

The discussion then led onto thoughts about how we might take action in future makes, and how the attending cheesemakers currently dealt with controlling acidity in their make and the affects it has.

Bacteria Culture Cheese On the second day of the seminar, we experimented with how temperature affects the make at the blocking & turning stage; following the Gloucester make but splitting the curd at the blocking stage – one being cooled (relatively fast) to 26C; the other holding its temperature at 34/35C; and also experimented with how salt limited acidification on the press.

As expected, the cooler side acidification stalled, however it soon picked up tempo and did reach its target pH only 2 hours late; the interesting thing was moisture loss on the cooler make (much less pre milling; and awful lot on the press; ending up with less moisture than the hot make – it will be interesting to see the fat content of both cheeses).

More importantly, how will it taste – we will find out in a few months.

There were many other side positive side discussions had too – from how people manage the tempo of their own make, to what is key for their acidification profiles, the advantages of measuring moisture content to how important is measuring flocculation, and it was also a “a great reminder that cheesemaking can be fun” [Joe Davenport].

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