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  • dextrin malts

    I have a question about dextrin malts that's been nagging at me for a while. I hope you can help. Dextrin malts are generally advertised as having the capacity to improve body, mouth-feel, palate fullness, and foam stability due to dextrins created during the malting process. I have read that the dextrins are created by roasting moist barley at a high saccharification temperature, tipping the balance of the converted endosperm to intermediate length carbohydrates, i.e. dextrins, rather than simpler sugars created in crystal malts. It is also my understanding that dextrin malts are subsequently kilned at fairly low temperatures in order to keep the malt reasonably neutral in flavor and color. So, it would seem to me that these dextrins would be subject to enzymatic degradation in the mash. After all, unless they are limit dextrins, which would not be subject to further a-amylase or b-amylase activity, the dextrins contributed by the dextrin malt would just be one step closer to complete conversion than starch from the base malt. Yet, I know that dextrin malts do indeed contribute a significant amount of nonfermentable extract. So, what's going on here?

  • #2
    Dextrin Malt Characteristics

    This is an excellent question! I hope my attempt at an answer does it justice.

    Dextrin malt is essentially undermodified malt that has gone through saccharification and then dried. It does not contain any products which result from thermal degradation. Thus, there are more sugars present due to the breakdown of starch in the kiln or roaster.

    As we know, saccharification is brought about by the joint action of alpha and beta amylase. Saccharification takes place in steps, or in other words, the amylose and amylopectin moieties of the starch molecule are generally degraded to smaller units.

    Alpha-Amaylase is more resistent to high temperatures than beta-amalyse and its optimum temperature at mashing is 70 degrees C, but it is destroyed at 80 degrees C, whereas the optimum temperature of beta-amylase at mashing is 60-65 degrees C and it destroyed at 75 C. Thus, the higher the heat used at mashing, the greater proportion of dextrins in the wort.

    A prolonged temperature rest at 60-65 degrees will yield a wort rich in maltose. If, however, the temperature of the mash is raised at the outset to 70 degrees C, the dextrin content will be proportionately increased and thus the fermentability of the wort can controlled.

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    • #3
      I still don't get it. Why don't the dextrins of the "cara" malts convert to smaller maltose units when added to mashes at standard saccarification temperatures?
      Phillip Kelm--Palau Brewing Company Manager--

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      • #4
        second that

        I have had the same question about dextrin malts and found the Cargill answer a bit lacking.


        Perhaps when Dextrin malt when used causes overabundance of long chain carbohydrates to be present in the mash and they can not be broken down in the time that most mashes take place. In essence the Vmax of the a and b amalyse is reached and through careful management of time a carbohydrate profile that has more rich in lpolysarrachides is achieved and hence more 'mouth feel and body'. But I have yet to hear someone in the biz say this.......

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        • #5
          Dextrin Malts

          Another factor is the caramelization. It is true that fermentable sugars are formed in the production of caramel malts but they are then caramelized at high temperatures. Caramelized sugar is much less fermentable.

          Rate of conversion limitation is less likely given the relatively small amount of caramel malt used and the overabundance of enzyme available from the pale malt.

          Cargill

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