FAQs about Products We Use with Food

fridgeSafety is the overarching theme connecting these FAQs about the following subjects:

1) plastic bags on rolls in the supermarket, the ones consumers put loose produce and rolls in;

2) kitchen items (the dishwasher, fridge and freezer, and nonstick pots and pans);

3) the gas grill.


 The answers come from four Shelf Life Advice Advisory Board scientists.


At the Grocery Store


In the grocery store, those rolled-up plastic bags for consumers to deposit their produce or rolls in are sometimes difficult to open.  After selecting loose produce, sometimes I have to lick my fingers in order to get the bag open. By doing this, could I ingest enough pathogens to make me sick?


Food scientist Dr. Joe Regenstein: "In theory, any time you lick your fingers you risk swallowing pathogens.  Obviously, handling fruits and vegetables increases the chance of coming in contact with contaminants.  It's usually possible to open those plastic bags by vigorously rubbing the top pieces (the open side) together." 


Food process engineer Dr. Tim Bowser:  "I refrain from licking my fingers after handling produce or other surfaces that are exposed to public handling or traffic!  A better idea would be to wet your fingers using some source other than your mouth. You can usually find some water in the produce department, where produce is sprayed, ice chips are used, and condensation sometimes forms on produce.  But, in case none of these sources of moisture is available, bring an antiseptic wipe along and use that to wet your fingers. That will sanitize them at the same time!"


Food scientist Dr. Karin Allen:  "When you're shopping for groceries, don't lick your fingers or rub your eyes or nose!  Keep your hands away from your face. A shopping cart handle is a dirty, disgusting thing. A child who sat in the seat and held on to that handle may have sneezed on it or even picked his/her nose. [Some stores have sanitizing wipes available where you pick up your cart; it's a good idea to use one of these.] To open the bag, rub the top together."


Food Scientist Dr. Catherine Cutter:  "Don't lick your fingers! Wet your fingers with condensation in the produce department or a hand sanitizer. Then, rub the top of the bag back and forth; it will open easily. You can then turn the bag inside out and pick up the produce with your hand inside the bag without actually touching the fruit or vegetable.  Then reverse the bag."


In the Kitchen


Should I throw out nonstick pots and pans once the inside gets scratched and the nonstick surface starts to flake off?  At that point, is the surface a health risk?


Dr. Bowser: "I use nonstick cookware and feel the hazards are insignificant. I believe that any of the finish that scratches off the cooking surface and becomes trapped in the food will pass through my system without incident.  The nonstick finish is inert, and my digestive tract is not capable of breaking it down into any compounds that could harm me."


Dr. Regenstein: "I've heard some claims of danger, but none have reached long-term credibility with me.  I use such a pan regularly and do not worry about it.  However, I don't cook bacon, so I do not tend to fry at very high temperatures."


Dr. Allen: "I throw away damaged nonstick pans.  If the surface is compromised, it is more likely to release gas, which is of a health concern.  Some tips for using nonstick cookware: 


  • Don't use metal utensils to stir food in a nonstick pan.  Instead, I recommend silicone-based spatulas, which are heat-resistant up to 450°F. 
  • Let the pot or pan cool down completely before washing. 
  • Don't use coated cookware to heat foods to a high temperature."


How hot does the water have to be for my dishwasher to do a good job of cleaning and sanitizing my dishes and utensils?


Dr. Bowser: "Hot water helps, but, when it comes to cleaning, most of the work is done by the detergent, so you should check the recommendations of your detergent manufacturer. The manufacturer of Cascade® does not recommend a particular temperature for their product, claiming that it is designed to work well over a range of temperatures. The maker of Finish® recommends 120°F.


"When it comes to sanitizing dishes, commercial dishwashers use two basic methods:  heat or chemicals. In the hot water method, water is heated to 180°F to quickly kill bacteria. For the chemical method, sodium hypochlorite (bleach) or another sanitizing agent is added, and water is heated to about 120°F. Both of these methods are effective at killing bacteria. Temperatures lower than 180°F can be effective, but longer dwell times at the given temperature are needed to ensure microbiological kill."


I believe that, if a refrigerator is over-packed with food, it won't cool properly because the cool air can't circulate.  But I'm wondering about what happens if a fridge has very little food in it.  Will it also not keep things cool enough?


Dr. Regenstein: "Air movement is important, but the quantity of food in the refrigerator determines the 'reserve' of cool – it serves the same role as ice. Therefore, too little does mean the heat from opening the door will have a larger impact, but not a great deal, I suspect."


Dr. Bowser: "An over-packed refrigerator can prevent cold air from circulating, resulting in uneven cooling. Some space is needed for the cool air to flow. 'Thermal mass' also helps the refrigerator to maintain its temperature when the door is opened and closed frequently. All of those important items you keep in the refrigerator (such as milk, butter, fruit, vegetables, and meat) are cold and contribute thermal mass to the refrigerator. When you open the door, the cold air drains out and is replaced by warm air. After you shut the door, the cold items in your refrigerator help to quickly cool the warm air that entered when the door was opened. This action minimizes the time period of air temperature swings in your refrigerator and helps to prevent the refrigeration system from turning on and off too frequently."


I've read that a freezer works best when it's full of food.  Right?

Dr. Bowser: "Yes, this is correct for the same reason as the well-stocked refrigerator keeps the air cooler. It is good to leave some space for air flow in an upright freezer. Most horizontal freezers refrigerate via conduction (not air convection); in this case, air flow is not as important."


Dr. Cutter:  "If you're putting a large amount of food that's not frozen into your freezer,  be sure to divide it into smaller packages (freezer-wrapped in plastic) so that all of it--including the middle--will get frozen.  Once all the product is solidly frozen, it can be repacked more tightly so that it will take up less space in the freezer."  


At the Grill


Is it necessary to clean the grill before or after every use?


Dr. Bowser: "The heat will kill the bacteria as long as the grill is properly warmed and the food chunks are small enough to be completely heated to their core. My question is this:  'Who wouldn’t want to clean their grill before using it?'''


Dr.  Cutter: "If you don't like the idea of putting a beautiful steak onto dirty grill grates but you also don't enjoy scrubbing those grates, I recommend disposable aluminum grill liners.  If you don't find them in a local store, you'll find several brands of these sold online.


"If you are in the habit of scrubbing those grates with a wire brush, be forewarned: many people have wound up in a hospital emergency room with serious injuries because pieces of the metal bristles come off the brushes and wind up in grilled food." 


How safe are those fake coals used in gas grills (to line the bottom and make the grill heat evenly)? Are they putting something on our food that could be harmful?


Dr. Bowser: "Most of the fake coals that I am aware of are lava rock or ceramic. These are natural substances that are relatively inert and safe."





Karin E. Allen, Ph.D., Utah State University, Dept. of Nutrition, Dietetics, and Food Sciences


Timothy J. Bowser, Ph.D., Oklahoma State University, Dept. of Biosystems and Agricultural Engineering


Catherine N. Cutter, Ph.D., Pennsylvania State University, Dept. of Food Science


Joe Regenstein, Ph.D., Cornell University, Dept. of Food Science 



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