How is milk digested?

[HYMN]

I have been assigned a task to look into how changing the concentration of bile salts affects the rate of digestion of lipids by lipase. I have been told that this should be modelled using the following procedure:

Adding whole milk to a test tube
Adding sodium carbonate
Adding bile salts of variable concentration
Adding a few drops of phenolphthalein as an indicator (turns pink)Bringing the solution up to body temperature
Then adding lipase and recording how long it takes for the pink solution to turn clear.

I understand the procedure and have carried out the experiment, started over & taken averages etc., but I am a little stuck as to the explanation behind what is going on. I found that, as predicted, the greater the concentration of bile salts used, the quicker the solution turned from pink to clear.

Would I be right in presuming that sodium carbonate is added to get the pH alkaline enough to cause the indicator to turn pink? And the solution turns clear because of the release of carboxylic acids due to the breaking down of the lipids, which are acidic?

Any help here would be wonderful

HYMN.

[chymera]

Yes, your presumptions are correct. It would be useful to use an indicator with a wider range since it may give information about how the reaction evolves over time and to what percent the lipids are broken down. But it has little relevance if you had a basic assignment

[geb]

I don't know where you shop, but personally I'd never buy undigested milk. It's terrible for you. And it's too damn much work! I purchase "Redigest" at my local D&W food mart.

Within seconds of consumption this stuff is lookin for daylight, if you get my meanin. In one end and...
Personally, I just keep the plastic gallon right on the tub rim next to the john.

Tastes great. No calories. What could be more American?!!!!!!!!!

[nicolee]

Will this be helpful?

http://quick-help.net/How-Milk-Digested

[wheel]

Actually, milk has lactose and some dissolved protein. So, there will be 2 different part of digestion of milk. Lactose is digested to glucose and galactose by lactase enzymes. Whereas the dissolved milk is first coagulated by rennin. The coagulated protein is known as caesinogen. Then, caesinogen is further digested to polypeptides by pepsin enzymes found in the gastric juice secreted inside our stomach. After that, the digestion of polypeptides goes on the normal way.

I hope my explanations help.