Ok, I don't want to enter a pissing contest here, but I'll give it a shot.
Having an answer and saying it without qualifying it implies a degree of confidence...
please, are you frickn serious ?
Yes, I was being serious. I just finished a course on evidence-based medicine and a main point being hammered down is that study results are only good as the Level of Evidence associated to it. It is therefore important to be able to critically appraise an article to check its actual value.
Also, wheter we are in medicine, nutrition and other science, we have to follow statistical models and that the results we get are approximations of reality. Clearly in ''purer'' physical sciences this is usually less so, but it is not uncommon to find studies which lack power to differentiate between a null hypothesis and the one being tested or a study which is in error and finds a difference when their is none.
The value of the study is actually more important than the results and that is why I mentionned ''probably'' (statistical significance) and ''no big deal'' (clinical significance).
so, pasteurization would be at a lower temps than coffee and the exposure is much less. seconds or milliseconds, rather than minutes. take note of how fast the damage occurs after 190 f, the temp of coffee, likely brewed just over 200f, when it hits your protein.
Well here, it depends on how soon post-brewing we put the coffee on the proteins. I agree with you that brewing temperature of coffee are between 190F and 200F. However, my interpretation of pouring freshly brewed coffee maybe was different because I let the coffee on the turned off burner for a while before pourring it, maybe 10-15 minutes. Because a coffee at 150F induces medical attention requireing burns in 2 seconds, in 6 seconds at 140F and at 125 it takes 2 minutes (the sip that makes your throat burn like hell when it goes down that you need to drink something cold.)
So when I pour the coffee on my protein powder I wait a little for it to cool down so I don't get 3r degree burns. But I'd have to ask the poster exactly what he does. Because for me, pourring hot coffee would be way closer to 125F and not 190F. Maybe he pours then waits 15 minutes? Or maybe he's got a leathery man-mouth? Chuck Norris would be proud...
well, i guess this is where the bone is buried. "denature" is a blanket term and i would think some types of denaturation would be more or less damaging than others. the way i read it:
While I'll have to disagree that denature is a blanket term. People use it as a blanket but it is just loss of tertiary (3D) structure and potentially secondary structure (loss of non-peptidic links between amino acides). It's a loss of the higher structures.
However, it is true that some types of physical or chemical actions are harsher than others on protein.
But while pasteurization denatures proteins, it leaves its secondary, primary and the individual amino acids intacts. This in itself has largely no bearing on what its going to do after it its the stomach. Because the chemical denaturation process in the stomach is very harsh and then goes beyond denaturation since proteins are cleaved and primary structure is loss through enzymatic proteolysis.
Protein-Bound D-Amino Acids, and to a Lesser Extent Lysinoalanine, Decrease True Ileal Protein Digestibility in Minipigs as Determined with 15N-Labeling
Michael de Vrese3, Regine Frik, Nils Roos and Hans Hagemeister
Journal of Nutrition. 2000;130:2026-2031.
Federal Dairy Research Centre, Department of Physiology and Biochemistry of Nutrition, D-24103 Kiel, Germany and Research Institute for the Biology of Farm Animals, Division of Nutritional Physiology, D-18059 Rostock, Germany
Original article of what is summarized below.
What is a concern to us however, is if the structure of amino acids themselves are damaged or changed, through racemization for example where L-alanine might become D-alanine. D-amino acides are less absorbable then L-amino acids to varying degrees.
For example, a few amino acides are racemization prone like (asparagine, serine, and glutamic acid /glutamine )with heat and alkanization (this will depend on the amount of heat and the high pH). These D-amino amino acids can be less absorbable/digestible than regular L-amino acids. But at temperature of 65C (150) and alkalization, and after 6 hours of incubation, only a few (15% of these damage prone aa)switched to D-isomers reducing the overall digestability of casein from its 93% digestability to 85% digestibility. (Beta-Lactoglobulin goes from 97 to 88 after 24 hours of incubation at 150F and a low pH of 10.5)
The conclusion of this is the following, if the poster leaves his coffee/ protein mix with a scoop of NaOH in it at 150F for six hours, he'll lose about 8% of digestibility.
I am not one who does this and I doubt that anyone does it either, this is why I doubt that this has any significant impact overall.
As for TC's "handled in the most careful way possible, shielded from light and heat and mechanical insult.."...
Well, there is some exaggeration in there, but that's why I like reading his articles.
As for your points on gelation of protein, I must say that what happens when very hot water is poured on the protein, there will be some gelation that occurs, but the gelled protein clumps forming a shell around intact protein making the amount of gelled protien rather limited. However, I have not looked into the actual effects of gelation on protein digestability. Anyway, the clumping that ensues will be broken through the mechanical action within the stomach, because if that weren't the case, you'd probably be seeing protein clumps in your feces just like you see peanuts when you didn't chew them. Since nothing above 0.5 mm diameters leaves the stomach during digestions. If the stomach has not been able to fragment the particles sufficiently or not at all like the peanuts, they will be cleared from the stomach a couple hours latter by Migrating Motor Complexes. Of course, you could argue that when you pour the hot liquid you can make particles that are just under 0.5mm (maybe be grinding around in the cup) that pass through the pyloric and then that the gel substance around it would render the protein clump unassailable by enzymes, which I honestly doubt.
As a compromise, the poster, to ensure that no amino acids are affected should let the coffee cool below the scalding point and then pour it on his protein say a bit below 125F and he should be fine and dandy.
I hope this clarifies my position.
So to each his own. Sugarfree, enjoy your steaming hot proteinated coffee and Swivel, you can always go with a Metabolic Drive frappuccino...
Anyway, you guys should be drinking green tea...