Curds, no Whey!

By: Bryant W.

1.

We did this experiment because it was fun and simple kitchen chemistry.

It also let us know what type of milk is best for cooking.

I thought about other experiments but this seemed like the best one.

2.

A protein in the milk called collagen is negatively charged and the loose hydrogen ions in the acid are positively charged.

Since opposites attract, the milk clumps together and forms curds.

The watery liquid left behind is called whey.

3. Before I began the experiment, I thought

the protein deprived, but fat rich heavy cream would create the most curds.

And the protein rich but fat deprived skim milk would create the least curds.

RESULT: The heavy cream created a mere 14 grams of curds.

And the skim milk created 36 grams of curds. But fat does have an influence on curdling. The half and half created 89 grams of curds.

4. The whole milk created 70 grams of curds. 2% milk made 54 grams of curd The 1% milk created 37 grams of curds. Curdling milk is necessary for cheese and

yogurt making but it is done even more carefully at the factory.

Curdling is bad if you’re making gravy.

5. After the experiment, I learned you

need protein but not fat for curdling to happen.

Fat in milk increased the curds but is not necessary for curdling.

If you do not want milk to curdle while cooking, low protein milk is your best bet.

These are some pictures of the results

Results Chart

Curdling Properties of Milk

  Protein per 8 oz Fat per 8 oz Amount of Curdle

Skim Milk 8 grams 0 grams 36 grams

1% Milk 8 grams 2.5 grams 37 grams

2% Milk 8 grams 5 grams 54 grams

Whole Milk 8 grams 8 grams 70 grams

Half and Half 8 grams 24 grams 89 grams

Heavy Cream 8 grams 80 grams 14 grams

       

Each 8 oz sample of milk was slowly heated to 200 degrees F.

When the sample acheived the desired temperature, 1 tablespoon of

white vinegar was added, and the mixture was allowed to cool.

       

When the samples cooled, the contents were strained so that

the curd (curdled part) was seperated from the whey (liquid part) and then

measured by weight.    

       

The End