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Using ethelyne gas to convert starch to sugar

  1. Mar 3, 2013 #1
    It is commonly known in the fruit industry that ethylene gas is widely used to boost a fruit's ripeness. i.e. fruits are harvested when they are still unripened, but prior to selling them on the market, they are exposed to a dose of ethylene gas, which are fruit's hormones to convert its internal starch to sugar. Hence, the sweet taste of ripened fruits.

    I would like to know if the same effect can be applied to flour such as wheat flour, corn flour, etc. Would a flour paste i.e. flour mixed with water, and exposed to ethylene gas convert the starch to sugar? And therefore a sweet sugary solution (mainly glucose) can be extracted after this process.

    And since flour is in small particles, would stirring the flour paste in presence of ethylene gas to convert it to sugar be an almost instantaneous conversion? As compared to ethylene gas on fruits, which could take 24 hours or more due to its size as a whole fruit as well as exposure to ethylene gas only on the outside skin surface of the fruit?

    Thx in advance for your answer.
    Last edited: Mar 3, 2013
  2. jcsd
  3. Mar 3, 2013 #2


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    No. As you mention, ethylene acts as a hormone that tells the plant cells to begin producing the enzymes required to break starch into sugar. In preparations where the cells are dead or removed, such as flours, ethylene will have no effect.

    There are enzymes that you can add to starch solutions that will convert the starch into sugar, such as amylase. In fact, our saliva contains amylase, which is why starches will begin to taste slightly sweet if you chew them enough. There are also chemical means of breaking down starches (although these generally are not as efficient and produce dextrins instead of simple sugars).
  4. Mar 3, 2013 #3
    Ok, so the key would be to add amylase instead of ethylene gas. I had thought about it but aware that amylase worked best at an optimal temperature of 60C thereabouts. Now if I didn't have the luxury of a 60C temp, but only room temperature amylase solution of 25C, would the starches be eventually converted fully to sugar given enough time? Would a few hours or overnight be a good estimate? If I can't control the available temperature, I could control other areas such as providing it constant agitation. Would agitation increase the rate of which starch will be converted to sugar at a shorter duration?
  5. Mar 3, 2013 #4


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    I don't know which amylase enzymes are commercially available, but I'd think you could find an enzyme that acts optimally around room temp or slightly above room temp (e.g. 37oC). As to the conditions required for full conversion, you'd probably have to search the literature/perform some pilot experiments to figure that out. Gentle agitation of the solution would probably help the reaction by keeping the solution well mixed but agitation that is too vigorous can inactivate the enzymes.
  6. Mar 3, 2013 #5
    That's interesting to know there are such amylase enzymes that work optimally close to room temperature. I'll definitely try to find out more about it. Usually both types of alpha and beta amylases are needed to break down starch to sugar. I'll see if there are both types that work around room temperature.

    To fill you in more, I'm actually research the process to extract sweep sap from old palm trees. The palm trunks are shredded finely before it sent to a roller mill to extract the juice. The shredded trunks actually consists a generous portion of starch and the rest is fibrous woody material, hence the sweet sap. But I'm trying to see whether we can use amylase to convert remaining starches in the shredded material into sugar before it gets to the roller mill. All this must be done at normal outside temperature to reduce processing costs. Hence, I'm trying to figure out the wait time for most of the starches to convert to sugar. And as for agitation, we are trying to use a long and slow screw conveyor to feed the material into the roller mill, so hopefully by the time it reaches the mill, the shredded material is nicely agitated and most of the starch convert to sugar by then.

    Any feedback or opinions on our proposed process would be greatly appreciated. Thx
    Last edited: Mar 3, 2013
  7. Mar 12, 2013 #6


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    Try using cellulase on that wood fiber.
    http://www.enzyme-india.com/cellulase-enzymes-dietetic.html [Broken]
    Last edited by a moderator: May 6, 2017
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