Colin Berry thinks, “STURP’s Raymond N. Rogers, top-notch (?) thermochemist, appeared to have abandoned thermodynamics completely when he argued for that implausible Maillard reaction”:
To cite an everday example, you can quickly get bread to go golden-brown in an electric toaster (the classical Maillard browning reaction), but if your toaster was broken, then sitting bread on the lid of the electric kettle, and heating it to 100 degrees will not produce toast, no matter how long you wait – hours, days, weeks etc. Not even slightly toasted. The Maillard reaction is simply not THERMODYNAMICALLY FEASIBLE at 100 degrees Celsius, even if other chemical reactions are occuring at multiples of their normal room-temperature rate. Maillard reactions generally do not get going until the temperature is 150 degrees and above, and there are sound thermodynamic reasons for that which have nothing, I repeat NOTHING, to do with chemical kinetics, the latter being a separate subject from chemical thermodynamics, though interfacing with it as discussed later. Thermodynmaics is about whether reactions are feasible in principle, i.e. go of their own accord. Kinetics is about the rates of reaction that are feasible. Some feasible reactions will not proceed at measurable rate, due to a minuscule rate of reaction, but a non-feasible reaction will not respond to a modest rise in temperature unless that rise (improbably) brings it into the range of thermodynamic feasibility.
So how could Rogers have got it so wrong, despite his impressive, some might say impeccable credentials in the area of thermochemistry?
Didn’t Rogers write (and isn’t this a picture of success):
After these successful experiments, a sample of Edgerton’s bleached linen was placed on four drops of dextrin solution on a plastic plate. A round spot was obtained and the water was allowed to evaporate from the cloth: at this point no colour could be seen on either surface. The middle of the same sample was placed on four drops of Saponaria solution. The wet spot expanded radially through the cloth. The water was allowed to evaporate, and no colour could be observed. The sample was then treated for 10 minutes with ammonia vapour: a very light colour could be observed on the top surface after standing 24 hours at room temperature.
Colin Berry is wrong, again.
‘Effect of time, temperature, and reactant ratio on pyrazine formation in model systems”
Takayuki Shibamoto , Richard A. Bernhard
J. Agric. Food Chem., 1976, 24 (4), pp 847–852
I do not believe in Rogers’ Maillard hypothesis, because of the unicity of the image on the Shroud of Turin. Rogers’ theory implies that, in the case of the Shroud, there was a very unusual set of physico-chemical conditions occurring together by mere chance and allowing the development of this very special image. However, it is extremely improbabe that (a) the only known case of such an extraordinary image is also an unbelievably complete (frontal & dorsal!) one (for every single complete image, we should expect the occurrence of a plethora of partial images – for instance, from a single hand or leg), and (b) it is improbable to the extreme that the only image thus produced also pops up in connection with the very special man who also happens to have the largest impact ever on human history (one expects that this single image, if produced by mere chance, should be connected with some random burial, and not with Golgotha).
This being said, I think that Colin Berry should develop his argument starting from a more complete global representation of the Maillard reaction. For instance, during the different steps gaseous products (water and carbon dioxide) are produced and these should be taken into account. Already during the first condensation step, water is split off, thereby increasing the entropy of the reaction products & pulling the reaction towards the right.
Even if the Sindon Man anatomical Image might well be a “providential image”, this does not necesseraly make it a “miraculous image”. Beside it presents BOTH anatomical excesses and deficits and is not complete (e.g. absence of a neck).
Link posted earlier, but then disappeared – presumably nothing more sinister than a WordPress glitch or security feature.
I don’t allow link only comments.
In Rogers experiment above ,it is true that he wrote that “a very light color could be observed on the top surface after standing 24 hours at room temperature” but the the color seen in the above picture “developed after a few minutes of heating at 66°C” simulating aging.
I guess the same color density could be obtained after some months/years at room temperature alone.
Of course Colin Berry is wrong.
If significant amounts of amines and reducing sugars are allowed to react they will react and produce a color; It is not a hypothesis but a fact.
The question is : how many time to see colored melanoidins ?
All the literature shows that the color can develop within some hours, days, months or years, depending on many parameters and first of all the temperature.
For example, the Amadori rearrangement (one of the first step of the reaction) takes places spontaneously at 25°C.
There is absolutely no doubt that, in Rogers hypothesis, a color must be seen on the Shroud after some months or years (latent image).
Rogers submitted his hypothesis with Arnoldi in a peer-reviewed journal Melanoidins.
Ana Arnoldi is one of the best expert of the Maillard reaction in Europe.
But certainly Colin is a better expert in Thermochemistry than Rogers and in Maillard reaction than both Rogers and Arnoldi !!
1.- Es OBVIO que SIN RESURRECCIÓN no podríamos contemplar la impronta corporal de Jesús. Los productos de la descomposición del cuerpo hubieran producido una mancha informe.
2.- Leyendo los interesantes comentarios de Heimburger y Colin sobre la reacción de Maillard, iba a participar con algún comentario……….. pero me ha surgido una REFLEXIÓN que creo va a suscitar POLÉMICA.
3.- Sea cual fuere el mecanismo de formación de la imagen, químico o físico, el periodo de LATENCIA ha podido ser ( y probablemente ha sido) EXTRAORDINARIAMENTE LARGO, incluso de SIGLOS.
4.- Esto explicaría que en DISTINTAS ÉPOCAS la Sábana habría presentado ASPECTOS DISTINTOS. ( las zonas de MAYOR SATURACIÓN serían las primeras en aparecer)
5.- Épocas en que la Sábana SÓLO mostraría las MANCHAS DE SANGRE.
6.- Épocas en que la Sábana SÓLO mostraría las MANCHAS DE SANGRE, el ROSTRO de manera DIFUSA y algunas manchas corporales no coherentes y por tanto POCO INTERPRETABLES por el observador.
7.- Etc, etc, etc…….
8.- Relatos como el de Gregorio Referendarius (SABIO RELATO) ofrece un nuevo significado bajo ÉSTA perspectiva……..
Colin Berry on his blog now added an interesting comment quoting an old paper by Lea and Hannan. I have this paper (not only the abstract).
This paper is on the “effect of activity of water, of pH and of temperature on the primary reaction between casein and glucose”.
Not exactly the same that expected on the Shroud.
However, it is a good example of the changes in color in a simple “Maillard system”.
What does one read in this paper ?
The changes in color were studied only at 37°C with different values of pH and Relative Humidity (RH).
The color was expressed in Lovibond units. Look at Wikipedia to see what Lovibond (old) scale is. Let’s say that bellow 2 no color is truly seen. At 3 it is yellow, at 5 yellow-brown.
What I read is that after 64 days at 37°C. and 70% RH a color between 2.6 (pH 6.3) and .4.4 (pH 10) can be seen.
More interesting is the subsequent paper here by the same authors :
“A note of the relative rates of reaction of several reducing sugars and sugar derivatives with casein” Biochimica Acta et Bipohysica Acta 4 (1950), p.532-534
that is available for free (I can’t give the link. Just use “advanced search” in Google Scholars).
Now, with the same methods, the authors studied the color development after 4, 8 and 16 days at 37°C (pH 6.3 and 70% RH). They used 8 different carbohydrates.
The Lovibond color for glucose after 16 days of storage was 0.3 (nearly no color, like in the previous experiment). But the color of arabinose was 2.5 and that of xylose was 2.7 after 16 days only. It means, as expected, that the color depends also on the carbohydrate and glucose used in the first paper is one of the worst.
There are many other parameters to study. Particularly the last step of the Maillard reaction (polymerisation and production of true melanoidins).
At least, I hope now that nobody will claim that there is no Maillard reaction and no color at room temperature.
PS: I have just sent the promised document entitled “Rogers’ Maillard reaction hypothesis explained in detail by Rogers himself” to Dan.
Comments are closed.