My yogurts are slimy. When taking a spoonful, long threads form on the sides, never breaking.
I use pasteurised milk, sometimes milk powder, and store yogurt as starter. The problem disappears if I use low-lactose milk but it is very expensive so I would like to find another solution.
Has anyone had (and solved) this problem?
edit: I should add that the low-lactose milk is also ultrapasteurised. Is it about sugar types or about competing bacteria from the simply pasteurised milk?
Hey, Welcome to the Cheese Forum!
Do you re-pasteurize your "regular" milk before cooling it to add the culture/store yogurt?
I've never made yogurt from store bought milk, having my own cow and lots of raw milk available. Before I used the method I learned here, I had several batches that were slimey or really thin. I wasn't consistent with my temperatures, as I was experimenting and trying to find something that worked well.
Then there was a great discussion on this forum about heating milk to 180-185 degrees Fahrenheit and holding it there for about 20 minutes before cooling it down to 100-110 degrees and then culturing it. I've used that method ever since and have gotten good, thick yogurt every time.
Can you post the method that you use, as that might help us answer your questions better, too?
I heat up the pasteurised milk together with a little powdered milk to 40-45C (104-113F) and then add the culture. The I keep the temperature there for 8-10 hours (home-size yogurt maker).
I see that your experience concords with mine. But I would like to understand whether it is related to lower lactose content in ultrapasteurised milk (or long-heated) or if it is about competing bacteria in the pasteurised milk.
Rips,
I usually use one percent store milk and I will occasionally addsome dry powder (when I remember). I have always heated to 180 the cooled to 116 and add a couple of tablespoons from the previous batch and hold overnight. It's just the way I was taught and have since seen similar directions in several texts. I started over six months ago with a packet of culture and have been going strong ever since making a half gal. every 5-6 days.
You need to heat to 165F minimum, 185F is better. The success you had with low lactose milk is because it is ultrapasteurized, not because of the sugar content. Scalding of the milk is required for yogurt (and ice cream) to denature (or "crack") the protein.
Rips, welcome, I use store bought whole milk and same as MrsKK & Steve I've also found that I get much better results when heating milk to 180F and then cooling or just setting aside to cool than if I don't. When I didn't, I don't remember getting a stringy texture . . .
Francoise, now that's interesting, I thought by re-heating I was re-pasteurizing the milk to reduce competing bacteria and I couldn't figure out why given it was fresh store bought pasteurized milk. If you or anyone has time, any more details on denature/cracking the proteins would be appreciated.
Sure, John. The basic principle here is protein denaturation. This is when a complex protein "unwinds" and forms smaller strands. The heat cracks open the protein.
The two major proteins responsible here are lactoglobulin, and lactalbumen. What happens is that they crack at slightly different temps and different rates at those temps. The lactoglobulin goes first, and then the lactalbumen follows. When the lactoglobulin denatures, the strands of it bond to the casein micelle complex, specifically, to the outer k-casein "shell". This is not so cool, because micelles cannot bond well when that happens. This is why UP milk doesn't work for cheesemaking. Now after that, the lactalbumen steps in, due to the longer heat/time for yogurt-destined milk that UP milk typically doesn't undergo. The lactalbumen acts as a putty... it fills in the gaps on the micelle complex. With the micelles "smooth" again, the nature of the bonding changes. When I meant putty, what I'm really talking about are chemical bonds. Anyway, with the lactalbumen in place, the stage is set for the pH change, which drops the micelles out of solution and causes them to bond into a matrix that retains water very well.
Also, wanted to comment on the stringy texture. UP procedures are different, so two UP products may be very different in their chemical and salt makeups. Also, bacteria can form long chains or have long polysaccharide complexes in the outer casing, which could contribute to a "slimy" mouthfeel. This actually does have to do with the types of sugars and other food that the bacteria consume. Also some strains are more prone to chain forming than others, leading to ropiness. But with the heat treated milk, it is not an issue because you get such a firm curd set that retains water well.
In the end, if you want to replicate commercial products, follow commercial processes. For yogurt, that's 185°F (85°C) for 30 minutes or 203°F (95°C) for 10 minutes. 165 is not terrible, like Francois said, but you have to cook it longer.
Thank you all for great answers.
As both milk types (pasteurised and ultraP) will have to be heated up, I will opt for pasteurised milk, which is the cheapest and most readily available in Norway. Of course I will try something next time I visit my parents-in-law at their huge dairy farm...
Further question: we have several types of buttermilk made with mesophile bacteria. Will I need to follow the same heating procedure as for yogurt for the buttermilk to thicken?
linuxboy, I worked on blood coagulation a long time ago and I think I get precisely the matrix-thing. Is it actually a covalent gel?
rips, are you asking if fibrin covalent cross-linking is comparable to casein micelle bonding? Yes, but of course the blood coagulation cascade is much more complex.
I have to report a great success! I followed the forums advices and my yogurts were beyond all expectations! By far the firmest texture ever and without powdered milk! I'll just have to fine tune the heating so I loose no time in overheating/cooling.Thank you very much.
I'm so happy we could help you find success in yogurt making.
What are your plans for your next dairy adventure?
I have just put a jug to ferment while I'm at work, to use as buttermilk, and another liter of the same culture (Lactobacillus acidophilus La-5, Bifidobacterium Bb-12) to make a kind of cheese this evening. Can you suggest cheeses these bacteria are adequate for?
linuxboy
- Thanks for the detailed response! I've read it three times and I think I understand what scalding or pasteurization does to the milk's structure ("unwinds" or "cracks" complex proteins to form smaller strands) in addition to killing off microorganisms.
- But why do I need to do this when using already pasteurized milk from store to make yogurt or ice cream?
rips
- Buttermilk is a common mesophilic starter culture, I've used store bought buttermilk many times for making several cheeses. To use it it needs to be concentrated and thus thickened just follow these simple steps (http://www.cheeseforum.org/Recipes/Recipe_Mesophilic_Culture.htm), no high heating. If you haven't made cheese before I'd recommend using it to make simpler cheeses such as Cream Cheese or American style Neufchatel (light cream cheese) or Feta.
- I've never left a jug of milk to ferment naturally, I think that's how you make clabber, not buttermilk, there are couple good threads here (https://cheeseforum.org/forum/index.php/board,188.0/sort,subject.html) on making clabber to be used as a mesophilic starter culture.
- Those two microorganisms are Thermophilic lactic acid producing starter cultures (http://www.cheeseforum.org/Making/Starter%20Cultures%20-%20Manufacturered%20Products.htm#Choozit_ABY-2C), often used in yogurt (see ingredients picture) (https://cheeseforum.org/forum/index.php/topic,543.msg9665.html#msg9665) and can be used in high heat cheese making recipes, recommend look in the Hard Cooked (https://cheeseforum.org/forum/index.php/board,72.0.html) & Hard Grating Type Cheese Boards (https://cheeseforum.org/forum/index.php/board,73.0.html) for ideas of what cheeses it could be used for.
Some info here on meso vs thermo starter cultures (http://www.cheeseforum.org/Making/Starter%20Cultures%20-%20Function.htm).
John (CH): when I said "put a jug to ferment", I meant with store-bought buttermilk. I wouldn't dare leave milk on its own (though I've done it with bread dough counting on wild yeast...) And I did the concentration routine ;) But now I'm wondering if the other jug meant for cheese making will be too fermented (10 hours at room temperature).
linuxboy:
Quote from: linuxboy on January 19, 2010, 05:01:48 PM
rips, are you asking if fibrin covalent cross-linking is comparable to casein micelle bonding? Yes, but of course the blood coagulation cascade is much more complex.
Yes, that was my question: whether "yogurt bonding" is covalent as opposed to "weak". And for the coagulation cascade, though very complex, I can't remember if it plays a specific role other that producing the actually reactin molecules.
Quote from: John (CH) on January 21, 2010, 11:13:47 AM
But why do I need to do this when using already pasteurized milk from store to make yogurt or ice cream?[/li][/list]
Pasteurization and high heat treatment are not necessarily the same thing. Whereas a high heat treatment fulfills the PMO regs for pasteurization (30 min @ 145F, 15 secs @ 161F, etc), it is held for a lot longer and at higher temps. So ordinary pasteurized milk is much more intact than milk that has been scalded for yogurt. Even UP milk may not work as well because with UP milk, the lactoglobulin may be mostly denatured, but it takes longer for lactalbumen. One key aspect here is time. So UP milk treated for a few second at ultra high temps doesn't work as well as heat treated milk.
So just a follow up. My buttermilk was still thin and without taste after 12-14 hours but suddenly after 24 hours, it had stiffened like a yogurt. I just had to stir with a spoon to get the perfect texture and the taste was great :)
As for the cheese made from the other half of the buttermilk (after 12 hours). It'll just be a fresh cheese. I'll be away for two weeks and I don't want to start maturing a cheese now. It looked, tasted and behaved a lot like mozzarella, but I read afterwards that mozzarella has to be heated up and kneaded.
I have discovered the reason for sliminess.... let me explain. I live in Turkey in a very small village and buy my milk each day from the neighbour who spends each day, every day with her two cows, moving them along the green pastures like the shepherds would have done hundreds of years ago back in England. I have learnt to speak Turkish and chat regularly with the village ladies. The last 3 times I have made yoghurt, it has been very slimy and I thought it was my mistake somehow with the weather having warmed up a lot lately and possibly leaving my pot too long in its blankets to set. However, today I spoke to the villagers and they explained to me that the cow is pregnant and this is the reason the milk has become slimy and this is how they first learn that a cow is pregnant. I just thought this was quite fascinating and thought it was worth passing on to others who have also been affected by this. Some of the villagers actually prefer this slimy texture and consider it delicious, but actually I have chosen to purchase my milk from the other neighbour for the next 5 months until the calf is born.
That is really fascinating Pipis - and welcome to the forum...you can learn something every day, when you have an enquiring mind!
Thanks Pipis, this clarifies for me, have been battling this for the last month, probably even more and it corresponds with calving season which will probably be sometime in September. Have tried pretty much everything else, I was usually heating up to 75^C for a minute or so and it always made delicious yoghurt (I use raw milk), not real greek style thick but with a bit of acidity and not slimy at all. Until about a couple of months ago. Unfortunately I opened new batch of culture at the same time so this was first to blame. I got a different culture from another source and it doesn't seem to be doing any better. Heating up to 95^C for 10 minutes makes very thick yoghurt but appears slime is still there, particularly in whatever little whey is left. I used to love it but am feeding it to the dogs now once it accumulates on the top (once I take some yoghurt out, I have 1 litre pot). Was thinking my 99% alcohol was not doing the sterilizing equipment properly or something but was also starting to suspect the milk. :o Since our source of raw milk is drying the herd off for calving in a couple of weeks will see how we go with another source when I am able to find it since prohibition on raw milk here is becoming ludicrous. Booze and cigarettes in dairy on every corner but oh no, raw milk, you will die from it... :-X
Glad I found the forum, I was starting to doubt my yoghurt making capabilities.
Welcome Whitewolf! yes, this forum is the place to be for the most obscure, as well as the commonest questions and problems.
Hi everyone!
I have been searching the web for some days now to find what causes slimy yogurt and found this forum very interesting and informative. I therefore would like to ask for your opinion on whether Yeast has anything to do with making such gluey texture. On the web,some have mentioned that the problem is due to yeast ( which might have accidentally got in the milk), which have made me both anxious ( since I've been told to consume yogurt to cure my yeast infection!) and wondering if at all such thing can scientifically be possible! ( I have always thought that the bacteria in the yogurt defeats the yeast...so how would it be possible to grow yeast where these bacteria culture?)
I would be grateful if anyone can share their ideas with me
Thanks
Azi
I admit to not having read each and every post, I'll go back and read. We have had the same results with using starters, but I think wifey has had good results with "Karoun" brand as a starter. Do they sell Karoun in where you are?
Richard