Why does the Milk Curdle when I add Vinegar?

Well, I knew that I had to answer this question, but seriously, the chemical bonds and everything look so complicated. Seriously, I went on this site: http://www.itisacqui.it/sitob/formagette/curdling.htm to find out what happens, but it's so hard to understand. ;-;
Anyway, I might ask Ms Zhang for help on it ^^''
Until then, I have a diagram. Of casein.

I'm not gonna lie, I have NO IDEA as to what the labels on the picture are.
All will reveal itself in the due course of time... 

Anyway, I went on yahoo answers and google to try and find out the answer to the question that is on the title of this post.
I'm not even sure if we're allowed to use yahoo answers. LOL.
Ah well, I'll just trust the people with a professional looking profile picture. AHAHAH.


One person said "The hydrogen ions from vinegar (5% water solution of acetic acid) react with -NH2 groups of lysine and asparagine to clot the milk and drive proteins out of solultion."
Um, yeah, so what is lysine, asparagine (related to asparagus?) and MINUS NH2? I understand the NH2 part but why the minus?!! There was also a typo in 'solultion'. Now I know why teachers don't like yahoo answers.

On to the next website. A cooking website. Don't you just love my variation in sources. Not. I should be using books or something shouldn't I? Too bad, it's the 21st century
According to Shirley Corriher on  http://www.finecooking.com/why-vinegar-curdles-milk.aspx "Acid on protein causes the protein to coagulate, because the acid is actually "cooking" the protein strands. When vinegar curdles milk, what you get is a dairy version of scrambled eggs." and that "When in doubt, a little cornstarch is always good insurance to prevent curdling."
Well, at least I can understand this answer... No, I still don't know what "coagulate" is. Why isn't this taught in school? -cries- Anyway, next time I am going to do the following because I'm really tired right now and need a shower:

• Find out why milk curdles when I add vinegar? (what I should have answered here)
• Learn what coagulate is
• Ask Ms Zhang for help
• Try and find more stuff on what happens when I add more vinegar to my milk (there are seriously NO websites with this!!!)

Different Types of Milk

So, for my experiment, obviously I'm going to do more than one experiment, because otherwise it would be too easy and I wouldn't be able to make very many conclusions. I think I said that first I'll do experiments where the independent variable is how much vinegar is added to the milk. My second "lot" of experiments is going to be with a fixed about of vinegar but with different types of milk. So this is research on the the second experiement.

It's said that whole milk is recommended for children, teenagers and body builders, and people trying to lose weight should drink skim milk which is actually funny . This is because, according to differencebetween.net (http://www.differencebetween.net/object/difference-between-skimmed-milk-and-whole-milk/) whole milk has all of the fat from the original cow milk, and usually, there is 3.5% of milk fat** for every cup of milk. However, in skim milk, there is a skimming process where as much fat as possible is taken out. This leaves the skim milk with 0.5% of milk fat, because obviously, not all of the milk fat is taken out.

The fat from skim milk is taken out by centrifuges. (http://www.answerfitness.com/tag/whole-milk-versus-skim-milk/) (hmm. this term seems so familiar. oh yes, year 8 FTW) Based on personal knowledge, centrifuges spin a liquid around and the excess solid is taken away. I'm pretty sure this is also how blood is put into a centrifuge and thats how you can see the plasma, red bloods cells and white blood cells.

 The fact that whole milk has more fat in it than skim milk means it's tastier. Obviously. I hate skim milk. It already smells, so curdling it will make it even worse.

I should really start my experiment.

**is the fatty portion of milk. wikied the definition....^^ (http://en.wikipedia.org/wiki/Butterfat)

SRP update...

I feel so bad, I haven't updated this in so long. I had to read over my posts to see what I had done in relation to my experiment... and realised why I got such a bad mark D: Anyway, I'll try harder from now on.

Ok, so I did a little more research and I found out some really interesting stuff. I might repeat some stuff but it's worth repeating.

Well, from the mixing of the vinegar and milk, you get casin as I've said before, and it occurs when the protein in the milk meets the acid in the vinegar. True plastics, called polymers, are a different in the way that they can be solids or liquids, and the molecules can chain themselves together, which is why you can get stuff like slime.
I got this information from:
http://www.sciencebob.com/experiments/polymer.php

On this website (http://pbskids.org/zoom/activities/sci/plasticmilk.html) it says that the chemical reaction separated the milk into two parts, the curds which is the solid and the liquid which is the whey. Also, on this website, kids as young as 6 did this experiment, which made me feel really bad. But they said that it felt like "wet playdough" and "smelt really bad". Something in my research with variables finally came up and a person said "
The skim milk smelt the worst, the 1% was the best we thought, 2% and whole milk produced the most, but was the bumpiest. " I have no idea what they're going on about with the percentages but I can conclude that whole milk might create more casein. I am seriously wondering why. Another thing to research.

Another thing I found out was that Little Miss Muffet was really eating this, in her nursery rhyme. This is because curds and whey as mentioned above can be made from milk by the help of a coagulant (something that helps cause a transformation of a liquid for example into or as if into a soft, semisolid, or solid mass). I saw the pictures of it and it looks seriously gross...

Um yeah. I'm SO glad I live in the 21st century, because people actually had to eat that stuff back in the day when their milk spoilt. O_O''
Casein was also manufactured into buttons, crochet hooks and knitting needles between the World War 1 & 2.  After World War II advances in technology made casein plastics obsolete.

Templates T.T

I wanted to change the templates... but then I realised that it would look different to the screenshot I gave to Ms Zhang. D:
I'll have to wait until she's marked it then. I am itching to put it on. ;D

I should start conducting my experiment asap. I realised that we missed out 2nd SRP period in a row. ANDOMG, I still haven't buried my plastic bags squares for the experiment
I will do my experiment/s. Soon. I promise. I still need a Coles plastic square though.

Forgot a Variable~ ^^;;

I forgot to include the controlled variables.  They are:

• the temperature of the milk(when the vinegar is added)
• the temperature at which the casein is allowed to settle
• the amount of milk
• the amount of sun the casein recieves (they need to be put into the sun to dry)
• the amount of time the casein is allowed to settle

I can't think of anymore. T.T
Anyway, I hope that's enough. I don't even know when I'm supposed to hand my blog in tomorrow... Ms Zhang, why'd you have to be away? ;D

Variables...

It was so hard to think of the dependent variable... but I figured that it would be the amount of casein produced or the hardness of the casein. Because I haven't done my experiment yet I really wouldn't know how the casein changes when more vinegar is added. So hopefully I can change it when I actually do it? :D
The independent variable is going to be the amount of vinegar (for my first 'batch' of experiments).
Now I must study for my science atomic theory test. May the force be with me. (That would have been funnier if I had Force and Motion as my topic but anyway, I've found a new joke to use on Ivy and Davian. Hohoho.)

Previous Project Ideas

Well, here is my promised post from yesterday~
These are the stuff that I was contemplating on doing for my assignment:

The absorbency of nappies and whether different types of water such as vinegar water, salt water or sugar water would hold the same amount in the nappy. I wanted to do this originally because I have a younger brother and sister who wear nappies. So I could also test the different between boys and girls nappies even though we all know the difference and my brother wears my sister's nappies sometimes anyway . But then I realised that if I were to repeat my experiment a few times, I would have to use a lot of nappies. And trust me nappies cost a lot.

Then I thought of doing how yeast grows under aerobic and anaerobic conditions, and how this affects them. I chose not to do this because... it was too hard and uninteresting (that's actually one of the criteria I think :D). I would have had to do so much more research and planning. Its kind of hard to understand the concepts of it and my poor little brain was experiencing technical difficulties just trying to understand the experiment.


Then I saw the "milk into plastic" experiment. It actually sounded interesting and not too hard. But then Ms Zhang told me all the ways I could do it... and it sounded hard. Haha. Anyway, it would have been a bit boring if it was too easy I suppose. ;]