Quickie response to Thibault Heimburger re that 1949 Lea and Hannan paper on the casein-glucose Maillard reaction.

Hello again Thibault. To avoid any misunderstanding re your latest comment on The Other Site, let me tell you how I came to link the 1949 Lea and Hannan Biochim.Biophys.Acta paper with the claim that the rate of the casein-glucose reaction increases a massive 40,000-fold between 0 degrees C and 80 degrees C.

Like you,I make a lot of use of Google Scholar, and in the course of searching for temperature effects on Maillard reactions I came across the following  2006 thesis from V.M.Totlani of the  Pennsylvania State University.

It was there I found my first reference to Lea and Hannan (1949):

and here is the Ref 23 that the author cites:

I also found an independent source for linking the 40,000 factor with that same paper in a volume called “Advanced Dairy Chemistry” Vol 3. although that may be where Dr.Totlani got his reference.

Now I only have the abstract, which does not specifically mention the 40,000 factor, although  it does refer to an exceptionally high Q10 value of  5.? something  when operating at very low temperatures (up to 9 degrees or so) – this from memory.

You say you have the entire paper, but you also appear to be suggesting ( I may be mistaken) that there is no mention in that paper of the 40,000 factor.  Is that so? Have both my sources quoted the wrong paper?

 

……………………………………………………………………………………………………………..

As a courtesy, I would have alerted you  Thibault to this posting by inserting a link on The Other Site, as I tried to earlier for anoxie and Jos, but Dan Porter is up on his high horse again, passing judgement on my “netiquette”, deleting my links, and engaging yet again in some highly personal remarks at my expense. I shall be avoiding that site and its despot of a blogmeister even more than I do already – at least for the forseeable future. I simply don’t have the time or patience to respond to the steady stream of low-level ad hom flak that emanates from that site.

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About Colin Berry

Retired science bod, previous research interests: phototherapy of neonatal jaundice, membrane influences on microsomal UDP-glucuronyltransferase, defective bilirubin and xenobiotic conjugation and hepatic excretion, dietary fibre and resistant starch.
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3 Responses to Quickie response to Thibault Heimburger re that 1949 Lea and Hannan paper on the casein-glucose Maillard reaction.

  1. Thibault HEIMBURGER says:

    Colin,

    The “40,000 fold” is not found so in the document. However, I have found what follows :
    ———————————————–
    ” Effects of temperature : (….)
    Casein-glucose … were held in equilibrium with an atmosphere of 70% RH, at temperatures of 0, 10, 20, 28.5, 37 and 55°C, as described above, and examined at intervals for free amino-N content and for color. …A further experiment was, however, performed at 70°C to obtain a figure of less accuracy.
    When the results were plotted it was found that all the curves of amino loss against time were of the same general shape and tended to the same final value. The rates could therefore be compared quite adequately by considering only the initial reaction rate determined by drawing the tangent at zero time to the smoothed curve. A number of readings were taken at short reaction times to ensure the accuracy of the initial portion of the curve; The values for the initial rate, expressed as % loss of amino N per hour, were :
    0°C: 0.0015
    10°C: 0.0067
    20°C: 0.034
    37°C: 0.71
    55°C: 9.3
    70°C: 58.”
    ——————————————

    I assume that these numbers are the basis of the “40,000 fold” statement (0.0015 x 40.000 = 60)
    But it is the VERY INITIAL rate of the reactions (and not of the color) that finally “tended to the same final value”.
    This has nothing to do with the development of the color in the first weeks as explained in my comment on Dan’s blog.
    Of course the temperature has a critical influence on the rate of the Maillard reactions but there is no doubt that many of them can give a yellow-brown discoloration within some days, months or years at room temperature (Rogers explained that in the paper I wrote that is now on Dan’s blog).

  2. colinsberry says:

    But those figures bear out exactly what I’ve been saying all along: there is negligible reaction between the amine source and the reducing carbohydrate at lower temperatures up to and including room temperature, even up to 37 degrees.

    0°C: 0.0015
    10°C: 0.0067
    20°C: 0.034
    37°C: 0.71
    55°C: 9.3
    70°C: 58.”

    Each additional 10 degree rise in temperature (albeit not measured here in that precise interval except at the beginning ) produces a vast increase in reaction. It’s way in excess of the Q10 of 2 or even 3 that Rogers cited, making it sound as though the Maillard reaction were a typical reaction in kinetic/thermodynamic terms when it clearly is not, being far more temperature-sensitive as these (admittedly incomplete) data show. OK, so one is not measuring polymerised end product, only the essential first fixation of nitrogen, but if the first step follows these kinetics, and the putative exposure to amine was brief – at most a day or two (if that) – then the final yellow colour that would develop on standing would presumably be in rough proportion to the values in this table.

    Sorry, but the kinetics and/or thermodynamics of the Maillard reaction (initial step included), in particular the temperature response curve, are all wrong for image formation in the range of normal environmental temperatures – say up to 40 degrees C. The Maillard reaction simply does not fit the bill. It is a process that needs much higher temperatures, say 50 degrees or above, to stand any chance of producing an appreciable yellow or brown colour by the proposed mechanism of brief exposure to amines, even if the subsequent incubation period were to be centuries….

    Thank you for your interest, Thibault… but I’m sticking to my guns on this one. I recognize a dud hypothesis when I see one….

  3. colinsberry says:

    PS: thanks btw for suggesting how that figure of 40,000 might have arisen from the data you extracted. But it still does not explain where that 80 degrees C figure came from. I’ll take your word for it not being in the paper, which makes one wonder if someone has seen additional Lea and Hannan data elsewhere and wrongly attributed it to their 1949 BBA paper. I see that paper was just one of a series, so it’s not impossible.

    How ludicrous – sickening in fact – that 60 year old science is still behind a pay wall.

    On a totally different subject – what’s your view Thibault on post mortem ‘fibrinolysis’ of external blood clots? .Do you think that sequestered plasminogen would/could be activated under such circumstances sufficient to allow previously dried clots to re-liquefy to imprint on linen as good, if not better, than freshly-shed blood? Can moisture-retention, for whatever reason, really do that?

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