Sugar Promotes Mold Growth?

[Kamahido]

Was reading that from a post in another forum. It didn't sound right to me, so I thought I should inquire. Just remembering when I was a kid finding candy in the car that had rolled under the seat and been sitting there for who knows how long. While I would never eat it, the candy never had any kind of mold of visual decomposition.

EDIT: Perhaps I should have mentioned that we are talking about adding sugar to bar soap. Silly me.

 

[Susie]

A reasonable amount of sugar added to CP soap will not promote mold growth. I know of some soapers on here that use 1 tablespoon PPO. I can't speak to HP, but I use sugar or honey in my liquid soaps at paste phase, and I have never had a problem.

 

[Arimara]

I'm finding that to be ridiculous since sugar, like salt, can actually help preserve foods. As for the candy, I would almost never expect that to grow mold unless a less sweet food item was sprinkled all over it.

If sugar really encouraged soaps to grow moldy, how is it that milk soaps are even popular? Milk, especially less fatty varietys, have plenty enough sugar for bacteria to munch on. I cannot see mold growing on or in a bar soap unless someone added something from which bacteria can thrive AFTER the lye is rendered inactive.

 

[IrishLass]

For what it's worth, I use 2 tablespoons sugar ppo in my batches and have never, ever gotten mold.


IrishLass

 

[earlene]

From what I remember from biology is that sugar is a nutrient, which supports life. Sugar facilitates bacterial & fungal growth, which can in fact occur both on bar soap and in liquid soap. As a matter of fact, before hospitals started using liquid soap, bar soap was the norm. I recall when we switched over and it was because of the high incidence of bacterial contamination. Then along came studies that showed evidence of bacterial contamination in liquid soap.... Then along came hand sanitizers and now they are suspect as well... More shall be revealed, I suppose.

Sugar can also feed certain fungi, but inhibit others. Seems contradictory, I know, but them are the facts as I understand them. (Molds/moulds and yeasts are both fungi.)

Yes, in high concentrations some sugars can be used as a preservative of sorts. Just as salt is used as a preservative in high concentrations. (Salt pork; fruit preserves.) I think pH plays a role in some cases as well, but I am not sure if it does in all cases where salt & sugar are used as preservatives. I believe the amount of water displacement also plays a part in these cases.

But as it relates to bar soap, it would be interesting if anyone has actually done any research on the concentration of sugar in bar soap and its effect on bacterial or fungi growth. How much of the sugar molecule is actually left in the soap after it meets lye is another thing I wonder about. Not sure about yeasts and soaps, but that would be interesting, too.


~~~~~
Edited because my computer was acting extremely weird and I had ended up with double posts and duplicates within the same post. Reboot necessary. I hate when that happens.

 

[milky]

Earlene, my thoughts exactly. I think a good example of how small amounts of sugar feed rather than inhibit would be how people add sugar to the water used for hydrating yeast for making bread. A little bit of sugar helps get the yeast nice and active while a lot of sugar in the water is bad for it (according to one of the many bread books I have somewhere). But that is bread, not soap..
A "sugar in soap" experiment would be really cool!

 

[BrewerGeorge]

Decomposition, mold/bacteria/fungi/yeast growth requires water. Sugar is food, but food doesn't help if there's no water - which is why table sugar has an unlimited shelf life. Same applies to soap that's not wet. When soap IS wet, then it's a solution with a pH too high to support any kind of mold growth. So it's next to impossible to have problems on the bars themselves.

The potential issue comes when enough water is added to dilute the soap enough for the critters to survive. Think the perpetual puddle in the bottom of the soap dish that your properly-designed holder suspends the soap above. Every time you reach for that soap with wet hands, you drip a bit into the puddle, but not too much soap gets in there. THAT is where you can sometimes see mold or bacteria growth.


Sugar and salt as a means of preserving foods primarily act as drying agents. High concentrations of either around a food first draw moisture out of it via osmotic pressure - essentially drying the food itself. Secondarily, as long as the salt/sugar concentration stays high enough around the food, any subsequent bacteria or yeasts will themselves be dehydrated to death by that same osmotic pressure which protects the food long-term.

 

[kchaystack]

What George said!

FWIW,

That is why honey never goes bad - unless extra water is introduced. THEN mold and bacteria can start to grow.

 

[mx5inpenn]

Bacteria need more than one thing to grow. Fat Tom is a widely used acronym in the food industry. Food, acidity, time, temperature, oxygen, moisture. Obviously there are exceptions such as anaerobic bacteria like botulinum. But for the most part, all those apply. I don't ever worry about bacteria with soap and anti bacterial is kind of an oxymoron in my opinion. Because soap is alkaline, it already is all by it's lonesome.

 

[topofmurrayhill]

Bacteria are pretty easily inhibited by the pH of soap. Mold is more adaptable and can grow on most anything. It's lucky we don't get it on soap more often (it happens), but I imagine there is plenty to feed mold in a soap bar without worrying about a little sugar additive.

 

[FNG]

Decomposition, mold/bacteria/fungi/yeast growth requires water. Sugar is food, but food doesn't help if there's no water - which is why table sugar has an unlimited shelf life. Same applies to soap that's not wet. When soap IS wet, then it's a solution with a pH too high to support any kind of mold growth. So it's next to impossible to have problems on the bars themselves.

The potential issue comes when enough water is added to dilute the soap enough for the critters to survive. Think the perpetual puddle in the bottom of the soap dish that your properly-designed holder suspends the soap above. Every time you reach for that soap with wet hands, you drip a bit into the puddle, but not too much soap gets in there. THAT is where you can sometimes see mold or bacteria growth.


Sugar and salt as a means of preserving foods primarily act as drying agents. High concentrations of either around a food first draw moisture out of it via osmotic pressure - essentially drying the food itself. Secondarily, as long as the salt/sugar concentration stays high enough around the food, any subsequent bacteria or yeasts will themselves be dehydrated to death by that same osmotic pressure which protects the food long-term.

George nailed it. Well put!