Safety 05-What Microorganisms Need to Grow

They say that most of the time you have the 24 hour flu, you have actually been food poisoned.  This is one reason we should talk about what a microorganism needs to grow, so that we can prevent that from happening.  You will remember that microorganisms are what cause food borne illness in the first place, so understanding what makes the tick is an important step in knowing how to control their growth.

By now you already have a good idea of what conditions microorganisms tend to like.  To put it best, they like the same things we do in essence.  There are six conditions that support the growth of microorganisms, with the exceptions of viruses, and we remember them with the acronym FAT TOM.  (Sorry to all the Toms out there!)

F ood
A cidity
T emperature
T ime
O xygen
M oisture

These microorganisms need nutrients to grow on and are especially happy with proteins and carbohydrates.  These are where the potentially hazardous foods come in, such as meats, poultry, dairy and eggs.

pH if you remember from 7th grade science, is a measurement of how acidic or alkaline something is.  The range starts at 0.0 and goes to 14.0 with 0-6.9 being Acidic, and 7.1-14 being alkaline.  7 is the Switzerland of pH, that is to say, neutral.  Microorganisms tend to find themselves most happy in the slightly acidic range of 7.5-4.6, which also happens to be where most foods lie.

You know, from previous articles if you are following along at home, that these little buggers grow best between 40°-141°F.  Going outside the danger zone may not kill them. but merely slow their growth rates.  This is one reason why temperature is only part of the time+temperature equation.

Microorganisms need time to grow and given the right environmental conditions, they are capable of doubling their numbers in just 20 minutes.  If you leave food in the danger zone for four hours or more, the levels of Microorganisms can be high enough to make someone ill.  Makes you think twice about that potato salad at the picnic all day doesn’t it?

Some of the little guys need Oxygen to grown, but not all of them do.  Botulism is one of the tough buggers that is anaerobic, which means it does not require any Oxygen to multiply.

Most foodborne microorganisms need some amount of moisture to grow, but again not all.  The moisture in potentially hazardous foods is just right to provide the organisms what they need to grow.

Well, understanding what microorganisms need to grow will help you be able to keep them from growing, thus helping to keep your food safer.  By eliminating one or more of the conditions you can drastically reduce a Microorganisms chance at getting someone sick.

Deny the organisms moisture and oxygen and you are helping this process.  Wrap and store things well, especially potentially hazardous foods.

Adding acidity and salt to change the pH is another way to help keep them from getting to happy as well.

Overall though, the one you have most individual control over is Time and Temperature.  The four hour rule is a great guide and it also accumulates, so be aware of that.  Keep food out of the dangerzone as much as possible.  Write expiration times on packages, especially if it is picnic, and don’t try to wrap it up for later.  Better to be a little wasteful than to get someone sick!

If you buy dinner at your favorite restaurant, and wrap the leftovers, and have dessert, lets say 1.5 hours til you get home and get it in the fridge (it still has to cool down here too, don’t forget)  Then you decide to take it to work the next day, so there is another half hour if you are lucky, and so we are at 2 hours already, and we haven’t even reheated it.  Let’s say you forgot to put it in the fridge at work, this could add up to 5 hours time total, and that is not including any abuse that may have happened at the restaurant.  This is one reason I tend to cook the daylights out of leftovers, and avoid doggie bags when I am not heading straight home.

Be safe, and think it through with your food, and you will be safe and better in the long run!

Safe Eating!

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One Response to Safety 05-What Microorganisms Need to Grow

  1. Pingback: Safety 06-Food Contamination | The Kitchen Hacker

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