Does sugar inhibit mold growth?
I was reading a post earlier regarding maple syrup being left out overnight. They were asking if their beloved Maple syrup was still safe to consume. In the comments I believe someone brought up this question I am asking, I'm sure I could do the research and find out but hey whats the fun in that. So here's my question does the sugar in Maple syrup or any product for that matter inhibit the growth of mold.
Also if its true, how much sugar is needed percentage wise?
Does it matter what type of sugar?
Best Answer
Water activity is the big issue in preventing microorganism growth in sugary solutions.
Water Activity of Foods Table Includes limit points for various types of bugs. A few molds will grow down to 0.60Aw.
Water Activity of Sucrose and NaCl Solutions From which: 180 g sucrose + 100 g water will give you a 64% sucrose solution. That'll have a water activity of 0.87, which is low enough to prevent proliferation of most bacteria, but not molds or quite, yeasts.
Oh yes, the question: A water activity below 0.8 will prevent growth of most molds, so at room temp. your syrup (Aw ~.85) will likely eventually pick up some mold, but not much in the way of bacteria.
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Quick Answer about "Does sugar inhibit mold growth?"
Yes. Sugar does inhibit growth of mold.Does sugar kill mold?
Molds grow best in warm, humid conditions, but can also grow at refrigerator temperatures. Molds tolerate salt and sugar and can survive on high-acid foods like jams, pickles, fruit, tomatoes and cured salty meats such as bacon, ham and bologna.Does sugar help mold growth?
High concentrations of sugar will suck the microbe's vital water right through its cell wall, causing it to dehydrate. This process is called "osmosis," and it can be deadly for bacteria and mold.Why does sugar not grow mold?
Highly concentrated solutions of sugar prevent microbial growth because they essentially dehydrate the microorganisms that try to grow in them. I regularly make 50% (w/v) solutions of glucose in lab, store them at room temp, and never see any microbial growth in them.What inhibits the growth of mold?
Clean and dry any damp or wet building materials and furnishings within 24-48 hours to prevent mold growth. Clean mold off hard surfaces with water and detergent, and dry completely. Absorbent materials such as ceiling tiles, that are moldy, may need to be replaced.How Does Sugar Water Affect a Plant's Growth?
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Answer 2
TLDR;
Yes. Sugar does inhibit growth of mold.
How does this work?
Several reasons:
- Sugar prohibits growth through osmosis / dehydration.
"The most notable is simple osmosis, or dehydration. Salt or sugar, whether in solid or aqueous form, attempts to reach equilibrium with the salt or sugar content of the food product with which it is in contact."
Source: http://www.scientificamerican.com/article/how-do-salt-and-sugar-pre/
- Sugar weakens the molecular structure of pathogens' DNA
Salt and sugar's other antimicrobial mechanisms include interference with a microbe's enzyme activity and weakening the molecular structure of its DNA. Sugar may also provide an indirect form of preservation by serving to accelerate accumulation of antimicrobial compounds from the growth of certain other organisms.
Source: http://www.scientificamerican.com/article/how-do-salt-and-sugar-pre/
Answer 3
I can try to answer that question in terms of jam (I have a glass of strawberry jam in front of me right now).
The sugar content is about 50% by weight, so 50g of sugar in 100g of strawberry jam. The label claims there are no other preserving agents in the product and that you may store it for a long time (about a year or more) in the refrigerator.
The sugar is supposed to bind the available water, which helps to inhibit the growth of mold. I guess the osmotic effect will also drain water from the cells of the mold. It is important to keep other impurities out of the jar (like breadcrumbs), since mold might start to grow THERE and spread to the remainder of the jar eventually.
I know people who successfully store jam non-refrigerated for many months without any problems with mold.
For the type of sugar, I believe there are differences (fructose is said to react a lot faster with protein, for example) but I don't know how they affect the growth of mold. My glass of jam contains regular white, refined glucose.
Answer 4
Heavy Sugar syrups (including maple) are dessicants. They inhibit bacterial growth and many molds, there are however molds that grow on sugar syrups.
Those sugar syrup molds however take weeks or months to develop and they'll float right on top.
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