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rake922
01-19-2007, 09:49 PM
"One of the big problems with mixing a drink to sip
on is that protein (any protein) will begin to denature after a few
hours after being mixed. This means it's going to be breaking down
before you even ingest it and your body will not be able to utilize it
fully. "

boyscouT
01-19-2007, 10:12 PM
All proteins are broken down to amino acids, then re-formed within the body.

Bio 101.

in10city
01-20-2007, 02:26 AM
"One of the big problems with mixing a drink to sip
on is that protein (any protein) will begin to denature after a few
hours after being mixed. This means it's going to be breaking down
before you even ingest it and your body will not be able to utilize it
fully. "
I'd be more concerned about the taste and about this...

http://www.designerwhey.com/html/DW_faq.html

Q. Why should I mix protein into a drink and consume it immediately?
Immediately does not mean instantly. However, drinking within 30 minutes of mixing is smart since pure protein in the liquid form is an extremely fertile environment for airborne bacteria growth. Leaving a protein drink (reconstituted from powder) in a refrigerator for two hours is probably okay, but not overnight.

garlichead
01-20-2007, 06:44 AM
Denaturing has no effect on the values of amino's in protein.

rake922
01-20-2007, 08:18 AM
All proteins are broken down to amino acids, then re-formed within the body.

Bio 101.

how did you vote

Aquilius
01-20-2007, 08:52 AM
Denaturing has no effect on the values of amino's in protein.

Well, it actually can have an effect concerning the digestibility of protein (thus protein absorbion), e.g. egg in raw form is digested for maybe 50%, but after it's been cooked and thus denatured, it's roughly 90%, see: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=9772141&query_hl=6&itool=pubmed_docsum

However it (denaturization) won't happen under the described circumstances to the typical protein shakes used. A standard protein isolate, mixed in water, will not denaturate. Nor will it get mouldy or infected by yeast after 30 minutes (especially if it is low-carb. E.g. yeast, the most common airborne contaminant, does use carbs, not protein, IIRC). I can imagine, though, that a shake mixed with (unchilled, non-pasteurized, raw milk) is just as "stable" or prone to degradation as the milk. I can also imagine that weight gainers, or powders with carbs are more prone to go bad, quickly - I'd guess if you leave a protein/carb shake (such as a PWO shake) container closed but uncleaned, it would show visible signs of mould after less than 48hours, meaning it would have been "bad" much earlier.

The rule of thumb here is, IIRC, that each increase of 10 Celsius in temperature will double the speed of growth. For a chilled environment, I cannot imagine anything critical to happen to a water based protein shake within 24 hours.

Regards,
Aquilius

rake922
01-20-2007, 12:26 PM
........

in10city
01-20-2007, 02:33 PM
You might find some interesting things in these notes... Food Science and Nutrition 822 : Food Proteins (http://class.fst.ohio-state.edu/FST822/lectures/lect.htm)

boyscouT
01-20-2007, 03:25 PM
how did you vote
I voted no.

Read Aquilius' and 10's posts.

in10city
01-20-2007, 04:59 PM
This too... Nutritional and Functional Characteristics of Whey Proteins in Food Products (http://jds.fass.org/cgi/content/abstract/81/3/597)

danimal81
01-20-2007, 05:35 PM
"One of the big problems with mixing a drink to sip
on is that protein (any protein) will begin to denature after a few
hours after being mixed. This means it's going to be breaking down
before you even ingest it and your body will not be able to utilize it
fully. "

if you're talking about protein powders and whey, i'm pretty sure its between 4-8 hours if mixed in either milk or water