We will eat a dazzling array of food this season but how much of it is safe?


Nothing will spoil a holiday quicker than food poisoning and yet, without taking precautions, your family or your guests may become the next victims of food borne illnesses.   There are at least 6.5 million of cases each year in the U.S. and since food poisoning is underreported, the incidence may be much higher.   Most cases are mild—not much more than an inconvenience—but some 300,000 require hospitalization and 10,000 are fatal.  The number of cases should impress us with the risk and yet by understanding how to keep our food safe and following a few safety precautions, we can protect our food, our families, and our guests this holiday season.

If we are in charge of preparing food, we should know the enemy, the three types of microorganisms that can make us sick.  They are yeasts, molds, and bacteria.  We are surrounded by all three–they are in the air, the soil, the water.  We cannot avoid them but we can control them.  Yeasts are the least threatening.  They can be either friend or foe.  Molds are a more common threat.   Bacteria are the big, bad bullies on the block and are far tougher than molds and yeasts.

Yeast makes our bread rise, turns our cabbage into sauerkraut, but makes us sick in applesauce.  They won’t grow in temperatures below 45 degrees and, at temperatures above 140 degrees, yeasts die.

Molds are microscopic fungi that float through the air, alight on food, (a good reason to keep food covered) and start to grow when conditions are right.  We recognize the invasion of these fungi when their silken threads cause streaks of discoloration in our food or cover it with a mat of fuzz.  There are three ways that mold can make our guests sick even when there is no visible presence.  The mold may be dispersed in the food but still concentrated enough to harm, molds leave behind hurtful microtoxins, and they lower the acidity of some foods allowing bacteria to thrive.  We fight molds in two ways–avoiding contamination as much as possible and controlling temperatures.  Molds don’t grow below 32 degrees and like yeasts, die above 140 degrees.

The three bacteria strains that typically cause food poisoning are salmonella, staphylococcus, and botulism.  All require a moist environment to grow and between 50 degrees and 140 degrees, the bacteria load can grow at a staggering rate.  Under these conditions, foods with minimal contamination can be dangerously loaded with bacteria in just a few hours.  Under perfect conditions, 1000 bacteria can multiply to over 4 million in four hours.  Most moist foods, particularly meats and dairy products, carry bacteria—especially staphylococcus.   Dry foods are safe.  Botulism is the most toxic–the poison thrown off by botulism is so powerful that a single teaspoon of toxin could kill hundreds of thousands of people.   Like yeasts and molds, bacteria can be contained with temperatures.  They are inactive or nearly so at temperatures below 40 degrees.  At temperatures above 145 degrees, they begin to die.

So how do we control the enemy?  First, pick your battlegrounds.  Dry foods are safe.   It’s the moist foods that are labeled by food scientists and health officials as “potentially hazardous foods”.  Diligently keep cold foods cold and hot foods hot.  Cold foods should be kept below 45 degrees Fahrenheit and hot foods above 145 degrees.   The maximum amount of time that potentially hazardous foods can be exposed to temperatures between these limits is four hours.  It is known as the “four hour rule” in the food industry.  The problem is that the four hours are cumulative from the processor to the grocer to your kitchen.  Since you don’t know how long the processor, the deliveryman, or the grocer might have had your food at temperatures within the growth range, you must minimize your holding time.

Let’s see how this might apply in real life.  Say, you would like to serve a nice shrimp cocktail to your party guests during the holidays.  You know about temperature limits.  You’ll chill the shrimp and the dip but you know you won’t keep it under 45 degrees.  But that’s okay—you know the four hour rule.  You won’t allow the shrimp to sit on the serving table for over two hours, well within the four hour limit.  Are your guests safe?   Probably not.  You see the processor may have taken two hours (legally) to chill his catch from 70 degrees to 45 degrees.  Bacteria multiplied during that time.  Two days later, the delivery man allowed these same shrimp to warm above 40 degrees for one-half hour while he unloaded his truck at the grocery store.  And then you bought the shrimp as you began shopping, chatted with a neighbor in the spice aisle, and didn’t get all your groceries bought and in the car for nearly an hour.  Then you stopped for gas on the way home, picked up Johnny, and didn’t get the shrimp into the refrigerator for another hour.  When you serve those shrimp to your party guests, they will have already been at growth temperatures for over four hours.  If they sit on the serving table for two hours, you could have some very sick guests.

Let’s look at another scenario.  For Sunday dinner, you served a large roast.  Your brother-in-law and his family didn’t show and so you have most of it leftover.  Remembering the four hour rule, as soon as dinner is over, you wrap the roast in foil and place it in the refrigerator.  You did everything right.  Well almost.  It may take hours for that roast to cool below 45 degrees.  The foil will hold the heat in and a large block of food will not cool quickly, even in the refrigerator.  Leave it uncovered until it is cooled and divide a large roast or large pot of chili into smaller batches to cool.  Conversely, when you reheat food, get it above 140 degrees as quickly as possible.

In addition to keeping hot foods hot and cold foods cold, are there other precautions that we should take to avoid ugly encounters with food poisoning?  Yes, there are two other precautions that we should be practicing:

• Clean and sanitize work surfaces often.   Recognize that there is a difference between clean and sanitized.  Use a bleach solution or a cleaner with bleach, like Clorox Clean-up, to sanitize surfaces.  (Be careful to keep bleach-based cleaners away from clothes—they do bleach.)

• Avoid contamination—especially from such sources as raw turkey juices and unclean meat thermometers.  Wash and disinfect your hands often.  We recommend using an instant hand sanitizer after washing.

Keep hot foods hot and cold foods cold, clean and sanitize work surfaces often, and avoid contamination.  By doing these three things, we will probably avoid spoiling our holidays with an unpleasant encounter with food borne illnesses.


Free Newsletter.  This article first appeared in the November 21, 2003, newsletter.  If you would like to receive weekly newsletters with helpful articles regarding food and food storage along with new product releases and specials, click here.   There is no obligation and you can unsubscribe at any time. 

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