flatzko at fbch.tuwien.ac.at
Thu May 11 12:26:09 EST 1995
nstn1014 at fox.nstn.ns.ca (Tim Ansems) wrote:
> We are a couple of grade twelve honours biology/chemistry students working on
>a term project. Our project simply involves making malt from barley seeds and
>unfortunately this practice isn't very common today. We have the procedure to
>make the malt but we need more info on why the steps are necessary....Why does
>the barley have to germinate? Why does it later have to be kilned? Why can't
>yeast function in the presence of starch? What is the function of the
>barley's endosperm? As well we are having some trouble finding out the exact
>chemical reasons of why iodine acts as an indicator for starch. If anyone can
>help us out it would be greatly appreciated!
>Tim & Luke
During germination alfa-amylase is formed, which is needed to break down starch
to soluble saccharides, mainly maltose.
The drying process helps to remove the small roots of the germinated barley. They interfere with
the subsequent mashing process.
Yeast itself is not able to produce amylase, therefore it depends on the enzymes provided by the malt.
Only maltose formed by enzymatic action can be transformed into carbondioxide, ethanol and biomass.
The insoluble parts of the malt are later used as filter material for clearing the wort.
Iodine molecules "change their colour" when trapped into a starch helix.
Hope this helps
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