Making Starter Culture

This week we were down to our last pots of frozen starter and needed to culture some more ourselves. We had done a trial run about 4 weeks ago which seemed to have worked so on Monday & Tuesday we made up another couple of batches.  Monday’s was made using St James whey and Tuesdays’s was made using milk.  As yet I’m not really sure what the difference will be between the 2 of them or indeed if there will be any.  One theory says that the starter will work more powerfully in a less fat rich medium than milk as the fats can inhibit starters whereas in whey, there is available lactose for them to consume but hardly any fat.Some cheesemakers culture up starter every 2 or 3 days and don’t freeze it, but for the quantities that Martin needs to use it in, this is simpler and if it’s frozen at the right time you don’t harm the bacteria.  They need to be put in to freeze in the lag phase before they start reproducing because once they start to reproduce they’re vulnerable.

So on Monday we made the starter up in whey (largely to be honest because I’d already set both vats of milk by the time Martin came down to the dairy).  And on Tuesday I took out a  litre of milk from one of the vats before I added the starter or rennet and we made up starter in milk.  The process was basically the same though – we poured 1 litre of whey into a sterilised stainless steel container which was then put into a pan of water and put on the hob.  The water in the pan boils but the whey doesn’t reach the same temperature and is basically pasteurised.  It then needs to cool down of course because the bacteria in the starter work best at around 30C and will be killed off at the sort of temperatures involved in pasteurisation.  Interestingly when heating whey, of course, you make ricotta, so the curds need to be strained out after it has cooled and before the starter can be added.  This doesn’t happen when making milk starter but you do have to dispose of the skin that forms on the top of it as it cools.

Each day we take a pot containing about 100ml of starter and in general we tend to use only about 65ml at the most so there is some spare. Once the whey had cooled down, therefore, we added 10ml of this starter to the whey and stirred it around to distribute.  If making in larger quantities, the rule would be 1% starter.  Then the whey and starter was poured into pots which were chilled in the cold store for about 20 minutes before going into the freezer.

To use, we take them out of the freezer the day before at ideally about 12 or 12.30 and it takes about half an hour to thaw out and then the bacteria get to work.  By the following morning when we’re ready to use them, they will have acidified.  If using the milk starter, as it acidifies it will also thicken to look less like a pot of milk and more like yoghurt.  The whey starter however doesn’t so we have to do a titratable acidity test on it to check it.

So far I’ve only used the new starters twice though so it’s hard to draw any meaningful conclusions on which is more active and effective from 2 TA readings but it will be interesting to see if the theory that the fats in milk inhibit the starter does actually work out in reality.

Monday’s starter made in whey
 Tuesday’s starter made in milk


Introducing St James

St James is a square shaped washed rind cheese weighing from about 1.5 to 1.8 kilos.  Milk is pumped through the wall into the dairy from the milking parlour and into a 70 litre hemisphere vat and a 65 litre curdling tub (which fills up to about 45-50 litres full).
Martin & Nicola only milk in the mornings – most people I’ve been aware of milk twice a day in the morning and the evening but they only do it the one time.  The milk never hangs around, even for a few hours, and is completely fresh. If milk is kept overnight, it usually has to be cooled down to limit the possibility of any unwelcome bacteria growing, either simply spoilage organisms which could create some bitter or stale flavours or in the worst case the sort of bacteria that cause food poisoning (although in a healthy flock which are well managed this is pretty unlikely).  I think another important consideration as well is that it never needs to be cooled either, so it only needs a little gentle heating at the start of the day to get it to the right temperature for the cheese recipe.  Cooling the milk down and then heating it up obviously has an effect on the fats and proteins in the milk and does disturb them a little.  The risks are that the fats or proteins might become damaged with a rapid temperature change or too prolonged a temperature change such as one from about 4C (the temperature of many bulk tanks) to the one at which the recipe needs which could be in the 20s or 30s.  Again this can affect the flavours that the cheese develops later.  Gentle handling is key and as Martin and Nicola don’t store any evening milk, it’s one less stage that they need to worry about.  So the milk is about sheep temperature to start with and is gently heated up a few degrees and starter is added.
All starters are not equal.  This year they are using a bulk starter culture which has a texture a little like drinking yoghurt.  It’s called MT36 and is generally considered by those in the cheesemaking business to be a pretty sexy little bunch of bacteria.  It has an impressive pedigree; some of the cheeses made with it include Kirkham’s Lancashire, Stichelton, Gorwydd Caerphilly and Duckett’s Caerphilly.   Charlie Westhead at Neal’s Yard Creamery has used it in some of his Ragstone to pretty great effect and he also uses it for his Creme Fraiche (officially the best creme fraiche I have ever eaten…ever).  On the more technical side, it is apparently a very complex bunch of bacteria.  Those who know about these things (I’m afraid it’s a level of detail beyond me at this stage) speak in reverent tones about the different organisms in it and of course the potential for unlocking flavour from the milk as a result.  The bacteria in the starters release enzymes to break down the proteins and fats of the milk and the flavours are unlocked primarily from the protein breakdown. Each enzyme releases a different potential for flavour and the more different types of bacteria you have and by extension the more different types of enzyme, the more you have possibility for creating complexity & depth of flavour which is what makes the variety of bacteria in MT36 so exciting for the cheese geeks out there.  Another way of looking at it is that it tastes delicious.  At Gorwydd Farm they make up a batch of starter to have in the house for breakfast instead of yoghurt and I am toying with the idea myself of taking home the leftover starter that we don’t use in the day’s cheesemaking to culture on and have it for breakfast myself.
Returning to the recipe however, the starter is added and left for about half an hour before the rennet’s added.  By this point the bacteria haven’t really got active so their growth and the build of of acidity that accompanies this happens not only in the set curd but largely happens once the cheeses are moulded and are draining overnight.  The rennet starts to change the milk structure after anything from about 12 to 15 minutes where you can see particles of curd developing.  This point is called flocculation and however long it takes to get to flocculation is a quarter of the full set time.  In other words if it takes 12 minutes (like it did yesterday), then you’ve got a further 36 minutes until the curd should be cut.
If you leave it too long then the rennet has set the curd too hard and it can be difficult to release the whey when the cheeses are draining overnight and if this happens then the rate at which the acidity develops, changes.  Whey trapped in the drained cheese will lead to acidification after the cheeses are turned out of their moulds.  This means that when they are turned out, they are quite soft and bendy but whereas you might think this would lead to softer cheeses, actually the reverse happens.  The trapped moisture means the bacteria can continue to work even though you actually no longer really want them to and as they work they create more acidity.  The acidity then attacks the minerals in the curd and in particular the calcium and you end up with harder, brittle textured cheeses.  Demineralised is a term that gets quoted to describe this texture and it can be desirable if you are making something crumbly like Cheshire but St James is meant to be supple and to break down to a completely full oozing texture and for this, keeping the correct amount of calcium in the curd is the aim.
So as we’ve been spending the week making St James, drainage has been a key consideration.  Given that I’ve been making most of the cheese this week and it would be fair to say I’m quite a novice, that we’ve not exactly got it right yet.  I’ve managed to heat the milk a bit too high so the rennet went too quickly.  I’ve missed the flocculation point because I was washing up the moulds the curd would later be ladled into so the whole measuring of when to cut became an element of guesswork rather than something I was on top of.  Yesterday I was happiest with it on 1 vat, but because we’ve been setting 2 lots of milk, I then missed it for the 2nd one.  Martin said the other day that the technical understanding is only part of successful cheesemaking.  He reckons good time management is actually a more important consideration.  I think he’s probably right.
So assuming you do hit the flocculation point and make the right calculation, you then cut the curd into long strips which are a little more narrow than a finger’s width in first one direction and then across that so that they are cube shaped.  Cut them too big and again it will drain slower and you risk those brittle cheeses.
We have then been experimenting with leaving the curd so that the whey can begin to drain off before we ladle this cut curd into the cloth-lined square moulds.  The experiments this week have shown that if you leave the curd too long, that too can set the cut pieces too hard and they don’t drain so well later.  The ideal time so far appears to be about 20 minutes which allows about 7 litres of whey to rise to the top but leaves the curd cubes still soft enough that they will knit together well when they are ladled into the moulds and again the whey can drain out.
Cut to the right size and left for the right amount of time, the whey is poured off in jugs and the curd is then ladled into moulds.  Here again, the ladling technique also affects how big your curd pieces are and again how well the cheese will drain.  We’re aiming for relatively shallow ladle scoops and smallish curd pieces.  Also you want to ladle relatively quickly as the longer you take, the longer you leave the final curd bits and they are firming up all the time.  Martin has said to aim for 15 minutes to ladle the 70 litre vat.  It would be fair to say I haven’t managed that yet although I think I’ve got it to roughly 20 minutes so that elusive  15 minutes is in my sights.  Maybe next week.
After ladling, the draining cloths that line the moulds are pulled up and folded gently over the top.  20 minutes after that we pull the cloths up again, quite decisively and then fold them more tightly over the top.  The cloths are then pulled up again an hour later and a further hour after that.  This too helps aid drainage – you can hear the increase of whey dripping off the end of the draining table as you start pulling the cloths about. Then that’s my part of the job done as the final stage for the day is done later by Nicola or Martin if he’s not working in the shop that afternoon.  At about 5ish, the cheeses are unwrapped, turned, re-wrapped in the cloths and put back into the moulds with a wooden  block on the top which will press it just slightly and encourage more whey to drain out overnight.  Put the blocks on too soon and although you’d think you were allowing more time for the pressure to drive the whey out, again (it’s a bit counter intuitive), this actually keeps moisture in!  It presses the moulded curd mass at the edges but before it’s had enough time to all settle down and knit together enough so actually by forming harder curd at the edges the whey is trapped in and yet another way of getting those brittle cheeses that we don’t want.
So then the cheeses drain overnight and first thing in the morning, they are turned out of the moulds, turned over and assessed.  If they are still soft and whey filled, they are kept in their moulds on a trolley in the dairy for a day to drain further.  At this stage however we know that they’re holding too much moisture and they aren’t going to be the supple cheeses we’re after.  If they have drained well overnight, then they don’t need the support of the moulds but they do sit in the dairy for a day on boards before they are salted.  Salting happens one side at a time and over 2 days.  By now we’re on day 3 & 4 of the make so it isn’t until day 5 that they go into the cold store and get their very first rind wash.
Rind washing is another parameter that we’re playing with.  Until yesterday, Martin was waiting for the joiner to put a door in between his 2 cold rooms.  Until that happened we had the St James store running quite cold in order that it would help the Swallet development (as they were drying in the room next door).  Now we’ve put the temperature up a bit and the fans don’t kick in as often which means it’s a stiller, more humid atmosphere in there and this should help the rind development.  While the store was colder and dryer, we were needing to wash the cheeses daily but with more humidity, we should be able to do less washing once the rind has started to establish itself.  The washing develops a pink / orange rind of Brevibacterium linens (among other things) which likes the extra moisture.  This releases further flavour as the bacteria that for the rind also release enzymes which break down the curd further, softening the texture from the outside in but also unlocking flavour as they go – characteristically quite savoury, meaty and sometimes smoky flavours.
So next week our plan is again to make St James only and no Swallet so the focus again will be getting that rennet temperature right and the curd cut and ladled to the right size and left for the right amount of time in the whey and the draining cloths faffed around with sufficiently and the blocks put on at the right time and not too soon.  Of course, it has rained this weekend and just in time too as Nicola was running out of fields to put the sheep on as the grass wasn’t growing back quickly with the sunny weather.  Rain will mean more milk for one thing – the sheep move around more and eat more so produce more.  It will also mean that as they’re eating the new grown grass the fat and protein levels of the milk will vary.  This is the final variable piece of the jigsaw.  Whereas with feed, you can’t really increase the protein content of cows milk, you can in sheeps milk.  With cows, what you can influence is the balance between fats and proteins in the milk by feeding so that they produce greater or less fat content and therefore because of that the ratio between the 2 can be tailored to the protein’s advantage.  This is important for harder cheeses like Cheddar for instance. However sheep can be fed to produce more protein which means there’s even greater capacity for variability of the milk and therefore a whole new set of parameters to consider when it comes to the milk we’ll get next week and how we will have to adapt those parameters of the recipe that we’re already juggling to get the cheeses to drain at the rate we want them to.
It’s going to be interesting.  Life as a cheesemaker, would appear never to stand still.PS – A sort of disclaimer.  This is St James cheesemaking as best I understand it so far.  That’s not to say I’ve got it right yet so if you know something I don’t or can see where I’ve not understood something correctly, please tell me!  Thanks.