Basic Chemistry..Why amino acids are stable in water!!!

Guvnor wrote:

Excellent post hardtrainer! Good to see I am not the only who noticed all the 'internet gurus' misinformation on this forum, and not just on denaturation of protein I might add!

One other point - isolate is not better protein/whey merely one which spent more time being processed. Only the % of protein changes.

Expect to get some flax for your post mate. People don't like to be called up on their shortcomings!

hardtrainer wrote:

There has been a lot of misinformation about protein denaturation, amino acid degradation and so, with particular reference to some magic 20 min rule in consumption of whey protein shakes. Most of it is akin to the kinds of rumours and myths that we have no doubt all seen from that spectacularly stupid article on the creo-munchers in the health supp. of the IT this week.

Some folks here should know all of this already, coming from a science background like myself. Amino acids are stable biological chemicals. Simple. They are complex molecules held together by strong bonds. They can be broken down, thats true, but with the aid of a) enzymes or b) chemicals. Water/milk/juice will not damage any amino acid.

Amino acids are either hydrphobic or hydrophillic, but this doesn't make them any less stable in water, this just affects the likely position of these amino acids within a polypeptide (protein).

Whey proteins are no different to other proteins. They are marginally less tolerant of high temperatures (above 75ºC) than casein, but they are remarkably more heat tolerant than many other proteins, including collagen. So, what about the protein in our whey shakes. Simply put, regardless of what the manufacturer says on their website, the majority of whey isolates, concentrates and so on, comes as a by product of cheese manufacture. Now, the exact point during this process that the whey is sourced from varies and this variation affects both the quality of the protein (in terms of the proteins natural activity) and the cost.
There are a number of dairy research institutes (notably in the US and India) which have been pioneering dairy protein fractioning, lactoferrin, lactoperoxidase, whey isolates and so on, but the protein that we are mostly getting as our whey powder really does come from cheese production.

There are many buzz words; cold-filtered, reverse osmosis, ion exchange, hydrolysed, bio-available and so on. Simply put, the whey is separated, often very crudely, and is then purified to remove waste and any remaining carbohydrates. At this point, most of the whey protein has been denatured. That is to say that the secondary and tertiary structure of the proteins is destroyed. You are left with the perfectly intact, polypeptides, with the same sequence of amino acids as before. Now there is a problem. Hydrophillic vs hydrophobic amino acids. Since hydrophobic aa's are repelled by water, the polypeptides will form a random configuration, based mostly on the aversion to water that is exhibited by the hyrdophobic aa's. These conformations are not biologically active, they don't perform any function and they are not stable. This is seen as coagulation. The same process that causes the white of an egg, for example, to go solid when cooked.

When manufacturers talk of hydrolysed protein, they simple mean that the protein has been denatured by breaking the hydrogen bonds that stabilise the secondary structure. Why does this make protein more bioavailable? Well, simply put, native state proteins (with sec. and tert. structure intact) are greatly more resistand to enzymatic digestion, i.e. breakdown into amino acids, which are utilised by the body. This is not to say that it cannot be done, it is done, every time we eat raw protein sources, including all the cheek cells and cells lining the alimentary canal (the ones that get to our stomach anyway) that we digest every day. Peptases in the stomach break the peptide bonds, releasing the individual amino acids which the body can then use to build and repair muscle and also for use as energy and as components for hormones, or even as neurotransmitters (glutamate).

There you have it. Thats the basic biochemistry of amino acids and proteins, all that is relevant to the discussions about denaturation of proteins in whey shakes anyway. The idea that any amino acid breaks down spontaneously in water is untrue. They don't. Proteins can denature in water, many of them do, as the pH of water may not be optimal for them. This has no negative effects on their nutritional value, if anything it increases it by making it easier for your body to breakdown. Cooking protein (collagen in meat etc) helps to break down and denature the protein making it easier to digest. But then the acid in our stomach does a good job of that too, unless the protein has some particular resistance to it (like the coat proteins of many parasites, membrane proteins of bacteria etc).

So go ahead, knock yourselves out. Mix your protein with water, with milk, with juice, whatever you prefer. Wait an hour, wait two, it won't make a blind bit of difference to the nutritional value of the protein. The whey proteins you're drinking are no longer in any way biologically active anyway, they been heated, acid treated, purified, partially digested and spray dried already. Rehydrating them just makes them easier for you to ingest. Seriously, have you ever tried to eat a spoonful of protein powder? Go on, try it.

I hope this has cleared up, once and for all, the myths and magic 20 mins to consume rule, that get offered up as science on these forums.