• Question: I know it's kind of a weird question, but if you putted a drop of saliva onto some sugar and leave it there for a long time, what would the amylase on the saliva do to the sucrose on the sugar? Would it dissolve it because sucrose is a simple Carbohydrate? THANK youuuuu?

    Asked by Alba? to Andrew, Dan, Emilia, Helen, Katy, LauraAnne, Stephanie on 9 Nov 2016.
    • Photo: LauraAnne Furlong

      LauraAnne Furlong answered on 9 Nov 2016:

      This is a great question, but I’ll admit it’s been a very long time since I did anything about this and I can’t remember a huge amount about the biochemistry behind it. Sorry can’t be of more help but this is one for one of the physiologists to answer I think!

    • Photo: Helen Hanstock

      Helen Hanstock answered on 11 Nov 2016:

      So, I don’t know what it would look like because I’ve never tried doing that. I think the sugar would dissolve in the saliva but that’s because sugar is water soluble, not because of the enzymes. But I can have a stab at the biochemical process that would (or would not) happen!

      As you correctly say, saliva contains alpha amylase which is an enzyme that breaks down complex carbohydrates into simple carbohydrates. Typically it breaks down starch (e.g. in grains/bread) into maltose. Maltose is a disaccharide (two-sugar molecule) consisting of two glucose monomers bound together. That’s why if you keep a piece of bread in your mouth for 30 seconds or so it will start to taste sweet.

      The next step in the digestion of starch comes from a different enzyme, maltase, which breaks maltose into 2 x glucose monosaccharides. Maltase is actually found a lot further along the digestive system, in the small intestine.

      So, alpha amylase digests starch into sugar but doesn’t digest the sugar any further – that happens later.

      Hope this (kind of) answers your question!

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