Questionable cheese experiment

We have been very fortunate to finally find a source of raw cows milk from a nearby village, where the cows are allowed to be on pasture and for the winter are fed a clean source of hay.  Since the milk supply has been abundant at a very affordable cost I decided to play around with the different products we could make from the milk, and also ordered Kates book for even more inspiration.  Still waiting to receive the book..

One thing we started doing was making our own clabber by simply letting the milk sit in a jar covered by a paper towel on the counter for a couple of days.  The texture turned into an almost yogurt like consistency and was very pleasing to eat on its own, or sometimes mixed with some honey or sugar and fruits jams.  

One of the jars ended up sitting for too long, so I decided to let it be to see what it turned into.  Its been maybe 3 months now. After the first month there was a very strong cheesy fragrance that came out of it, and a few layers that developed.  When taking the paper towel off and looking inside it never turned any colors.  It pretty much stayed white the whole time, except for now.  Now there is a darker patch of mold forming closer to the lid opening.

Im wondering if any of you have better insights for what might be taking place here?  

What is the difference between clabber and yogurt?  

How long can raw milk stored in a clean glass jar still produce an edible product?

What would those products be called at the progressive stages of fermentation, and what are the layers?  

Aside from bad smells and rainbow colors, what other signs should we look for to know whether or not the fermented milk products should be avoided?  

Im really hoping Kates book will help offer insights when we finally get it. (International order)  

Here are a couple of pictures of the questionable milk cheese mystery stuff still sitting in the jar:

*I* would call any sufficiently thickened, soured dairy goo yogurt. Lots of people, I think, would insist that it be cultured with bulgaricus before calling it yogurt. I'm interested to see what other responses you get.

I'm concerned about your mold and would recommend not tolerating its presence. My experience is that most people would tell you to get rid of that jar because mold is everywhere, but if it's only on the edge of the bottle, I might try to wipe it upward and out with a rag dipped in vinegar, so that I could continue the experiment.

I second all parts of Christopher's assessment. I'd very carefully and thoroughly get all the mold out, and transfer it to a very clean jar. It may also be time to move it to the fridge.

I have about a quart of raw milk in the fridge, that I'm doing almost the same with. No paper towel, because I didn't want it to pick up fridge smells, so it's actually sealed. It's been in there since... December. I really ought to go pull it out and see what's happening with it. Maybe after I feed the sourdough, for Sunday's bread...

It would be interesting to do that with two jars filled from the same milk at the same time, one put in the fridge and one left out. Different microbes have different temperature-sensitivities and I bet the two cultures would come to be dominated by different bacteria.

What is the difference between clabber and yogurt?

It depends on how precise you want to get for a definition.

If you are eating clabber like you would eat yoghurt, then it is your version of yoghurt and it doesn’t really matter what the official definition is - you are getting fermented food from milk and that is what is important at the end of the day.

By official definitions, yoghurt uses specific added cultures that thrive between 40ºC and 45ºC (104ºF to 113ºF). Before culturing, most yoghurt is also heated to above 82ºC (180ºF), to change the proteins in the milk so that it turns out thicker.

There are also Northern European cultures such as viili that will thicken milk at room temperature, these are not by strict definition yoghurt, but are often referred to as “room temperature yoghurt” because they are used in a similar way to yoghurt.

How long can raw milk stored in a clean glass jar still produce an edible product?

It depends… Firstly if there is any contamination, and whether it is a small amount or if there is a lot of it, and secondly on the temperature it is stored at - the cooler the temperature, the longer it will store. One of my cheese book readers said she had made cheese from milk stored for a month - that must have been very clean milk, stored very well. I personally just prefer to use milk as fresh as possible - the cheese yields are higher and the chance of unwanted bacteria taking over lower.

What would those products be called at the progressive stages of fermentation, and what are the layers?

Looks like you have curds at the bottom of the jar, followed by whey, above that could be fermented cream, or curds that have for some reason separated from the other curds, and it looks like it might have some coliform bubbles in it. The very top layer is the one exposed to airborne yeasts and moulds - some of these will be good, some of them not so good. The darker colouring to the top of the jar in the photos with the lid off makes me think it is not something I would eat. I sometimes get similar looking jars if I leave my kefir culturing too long - I don’t drink it when it gets to this stage, I just rinse the grains thoroughly and culture them in fresh milk.

The white moulds you are getting look like normal camembert-type white cheese moulds. The blue-green stuff also looks like a common type of edible cheese mould. I would not personally eat these unless they were on a cheese that had been drained and was aging - the liquid content of your jar makes it more likely that there could be unwanted stuff in it, as the drying-out process of making cheese, where the curds lose liquid over time encourages the helpful bacteria while discouraging bad stuff.

Aside from bad smells and rainbow colors, what other signs should we look for to know whether or not the fermented milk products should be avoided?

Good question. I think this will change from person to person, and that we’ll all have different standards of what is fine for us and our families and what isn’t. Listeria may be a concern for pregnant women and elderly people. If you’re serving it to guests who aren’t used to raw and fermented foods then you’d probably want to be a bit more careful too. Smell is an excellent way to tell, tasting a small amount also - if it tastes pleasantly sour, then it’s probably fine for most people, if it tastes at all bad, then probably best to feed to the chickens.

Dave Burton did some projects with fermented milk several years ago so I thought you might find this interesting:

https://permies.com/t/97704/Dave-Burton-Fermentation-Journey#825574