Simple Sugars: Fructose, glucose and sucrose

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Glucose, fructose, sucrose

Glucose, fructose, sucrose

Simple sugars are carbohydrates. Glucose and fructose are monosaccharides and sucrose is a disaccharide of the two combined with a bond.  Glucose and fructose have the same molecular formula (C6H12O6) but glucose has a six member ring and fructose has a five member ring structure.

Fructose is known as the fruit sugar as its make source in the diet is fruits and vegetables. Honey is also a good source.

Glucose is known as grape sugar, blood sugar or corn sugar as these are its riches sources. Listed in food ingredients as dextrose.

Sucrose is the sugar we know as sugar or table sugar. Typically extracted as cane or beet sugar. If sucrose is treated with acid or heat, it hydrolyzes to form glucose and fructose.  This mixture of sucrose, glucose and fructose is also called invert sugar.

Nutritionally, these sugars are the same as they all provide 4 Cal/g. This is true for starch and other digestible carbohydrates too. Of the three sugars, fructose is the sweetest and glucose the least sweet, so typically less fructose can be used than table sugar (sucrose) – if sucrose has a sweetness of one, fructose is 1.7 and glucose 0.74

Fructose is more soluble than other sugars and hard to crystallize because it is more hygroscopic and holds onto water stronger than the others. This means that fructose can be used to extend the shelf life of baked products more than other sugars.

Wikipedia has lots information on sugars, including information on the three I am interested in fructose, glucose and sucrose.

46 thoughts on “Simple Sugars: Fructose, glucose and sucrose”

    • James

      I don’t know how sucralose is made. Three of the hydroxyl groups (OH) are replaced by chlorine atoms. It is probably patented – a list of patents with sucralose in the title can be found at Patentdocs

  2. Just an interesting aside. Fructose upsets some people’s stomachs. I used to get this wretched fruitopia drink back in the 90’s and it consistently upset my stomach, but I never really new why until I started sweetening my coffe with fructose which had exactly the same effect…

    • You would end up with just over half a gram of glucose (0.53 g to be precise) when 1 g sucrose hydrolyzes. You would have the same amount of fructose. It is slightly over 0.5 g because water is added across the bond.

  4. I guess twice in a row you said glucose when you meant sucrose. You said above “Glucose and fructose are monosaccharides and glucose is a disaccharide of the two combined with a bond. Glucose and fructose have the same molecular formula (C6H12O6) but glucose has a six member ring and fructose has a five member ring structure.”

    So you are wrongly saying that glucose and fructose combined equals glucose.

    • Chuck,

      I changed the one time I got it wrong. Thanks for pointing out my error.

      In the second sentence, I am correct to say glucose when I say glucose.

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  6. I think your structure of sucrose is wrong. Correct me if I’m wrong, but sucrose has only eleven oxygen atoms not twelve like shown here.

      • Is this an image you created? I’d like to use it in a Biology 101 library guide (for a community college library). Is that ok with you? If so, what sort of attribution would you like?

  9. what is the best sugar and in what general quantity for flowering and or budding type plants?

  11. what sugar has the most activity during fermenation glucose,sucrose or fructose?
    What is ease of fermenation?

  14. How do corn syrup, table sugar, and water react to form a hard candy?

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    • Unfortunately, this is a website that is not peer reviewed and selective with the science that it uses. I definitely agree on exercising daily though.

    • My question would be, what is the difference between “fructose” and “high fructose corn syrup” and is it acceptable to compare them as the same substance?

      • Fructose is a pure compound. High fructose corn syrup is 55% fructose and 45% glucose. They are not the same substance.

  17. There is also a lot of academic writing about serious health concerns related to fructose excessive consumption.

    Here a (“peer reviewed”) example :

    (Liu et al. ‘Effect of pioglitazone on insulin resistance in fructose-drinking rats correlates with AGEs/RAGE inhibition and block of NAPDH oxidase and NF kappa B activation’. European Journal Of Pharmacology. online:http://www.sciencedirect.com.libezproxy.open.ac.uk/science/article/pii/S001429990901111X)

    Too much fructose is dangerous for your health. Sweetener are not any better. The only healthy choice is getting rid of the sweet-taste addiction.

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    • aLl those which contain aldehyde groups,ketonic group,in hemiactal nnhemiketal form n reduce tolln reagnt thy R called reducing while othrs in which such proprty absnt they arr called non reducng

  23. I feel that dextrose(glucose) would be a better sweetener for health reasons, but don’t know a good place to purchase it for home use. Any ideas on where I can buy it?

    • I have also concluded that dextrose would be better, but not best.
      Have you searched online for it, or for “corn syrup + (dextrose OR glucose)”? Old-fashioned corn syrup was glucose, aka dextrose.

      I agree with the person who pointed out that curing oneselves of addictions to sweet foods is the best approach to trying to preserve our health.

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  27. why is fructose regarded as d most sweetest amongst glucose and galactose. ans pls

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  30. hank you for sharing this article that helped me in my essay. And it will be useful information to anyone who is studying medicine just like me. : D

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    • There really isn’t a sugar in quantity you can use if you have diabetes. The noncaloric sweeteners can be used to replace sugar.

    • Sprouts sells some sugars made of xylitol and other sugar alcohols, which have a low glycemic index and low caloric content.

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