Sucrose vs. Glucose in YEast Fermentation

[Cris1111]

Hi there
I recently conducted an experiment in which I tested different substrates in yeast and which ones would be metabolized most efficiently. I mixed malt syrup (maltose), corn syrup (glucose), and refined sugar (sucrose) into different bottles that each contained one cup of warm water. I sealed each of the bottles that contained the solutions, with balloons (as a means of collecting the C02 produced) and waited for a total of 2hrs. After this time, however, I noticed that the yeast in the solution with the sucrose was metabolizing the quickest, and produced the most C02 (the most inflated balloon). In one of your earlier posts, I read a question pertaining to this same topic, in which one of the answers talked about how glucose would be the most effective substrate. I was just wondering, if this is the case, why is it that I observed differently; the results I collected show that sucrose solution allowed for the balloon to become the most inflated.
The circumfrence of the balloon with the glucose solution was 11.8cm, while the balloon for the solution with sucrose was 52cm.... Did I do something wrong?

[mith]

Are they all the same concentration?

[Cris1111]

Are they all the same concentration?

yes they are. all of the bottles contain 1 cup of water at 115 degrees Farenheit , along with 3 tbsp of the approriate syrup, and 3 tsp of dry active baker's yeast.

[JackBean]

if you use crude syrup, you definitely won't have the same concentration, first the composition may differ between plants of the same species, second they will have different sugar levels between different plants

[Cris1111]

if you use crude syrup, you definitely won't have the same concentration, first the composition may differ between plants of the same species, second they will have different sugar levels between different plants

well actually im not so much caught up in whether or not the concentrations are all exact in terms of the syrup i used. All of them have one or two ingredients in them;
I'm more just wondering if its ever normal when yeast metabolizes sucrose more effieciently than glucose?

[JackBean]

but it is important. If you had 10 kg of apples, you would do better, than if you had 0.1 kg of meat

[mith]

Here's the problem, if you want to compare them you'd need the same concentration of sugars in each. And by concentration I mean # of molecules of sucrose/glucose/maltose etc. The problem is you have no idea what the original concentration inside the bottles are and therefore you don't know how much food you've fed to the yeast. Assuming one solution is twice as concentrated as the other, you'd invariably get the higher results for that sample.

Assuming the same energy content for each, you can probably look at how much carbs/sugars are in each "serving" in the nutritional info. That should give you a way to quantify the sugar per unit of syrup.