"Is It Safe To….?" FAQs Answered by our Advisory Board

lemon in drinkFive FAQS from the Shelf Life Advice users are answered below by the scientists serving on our Advisory Board:



Q: Is it safe to have a restaurant put a slice of lemon or lime in your beverage? Is there a risk of contamination from the fruit?


A: Like any raw product, the lemon or lime needs to be handled correctly. [The skin should be washed before cutting; the knife and cutting board should be clean.]  But lemon or lime inserted in a drink by a server or bartender doesn’t seem to be a particular source of unique problems. (food scientist Dr. Joe Regenstein)


[Editors note: It may be too small to see this, but the photograph with this article, which was taken in a restaurant, shows a pitcher of tea with a slice of lemon in it--and the lemon still has a paper label on it!  This certainly doesn't reveal adequate washing of the fruit.] 


 QIs it safe to mix casserole ingredients together (including raw eggs) and then refrigerate the dish overnight before cooking it?


A: I tend to discourage such behavior. It gives contaminants time to grow. However, it’s probably okay for 24 hours if you really cook it thoroughly. But I wouldn’t want to do this with a wet scrambled egg.   (food scientist Dr. Joe Regenstein)


[Editor’s note: This suggests that you shouldn’t mix together soufflé ingredients far in advance of cooking.]


A: Yes, you can do this. Be sure the casserole is refrigerated below 40°F. and cooked to over 160°F. Also, don’t leave it sit out at room temperature for a long time.  (food scientist Dr. Catherine Cutter)


Q: Is it safe to defrost a food and then refreeze it without cooking it first?


A: Yes, I believe it’s safe as long as proper procedures are followed (e.g., thaw in the refrigerator and freeze rapidly).  The procedures are designed to prevent harmful bacteria from multiplying in the food product. The thawing/freezing process may have an adverse effect on the texture and appearance of the food, but it should not make it dangerous to eat.  In fact, some cuts of meat can be tenderized by thawing and refreezing. (food process engineer Dr. Timothy Bowser)


A:  The quality of the product goes down with refreezing. But the real issue is what is done with the food in the period between freezing and refreezing.  If the product is kept at 33°F (1°C) the whole time, it will be safe to consume.  The problem is that the thawing often leads to temperatures that are too warm, and this allows microbial growth on the surface (the first area to thaw and the most contaminated.”  In terms of safety, it really isn’t the freezing/thawing but the temperature while the food is out.  (food scientist Dr. Joe Regenstein)


Q: Is it safe to store an open jar of peanut butter at room temperature (in a cabinet or on the kitchen table)?  What if it’s organic peanut butter and the label says, “Refrigerate after opening”?


A: Peanut butter is shelf-stable.  There is low water activity, and the salt, fat, and thermal heating protect it against the growth of pathogens.  However, if the plant where it was produced had dust, rodents, or other contaminants, salmonella might have made its way into the product. Then the pathogens would still be there even if the product was refrigerated.


Because peanut butter contains a lot of fat, it may eventually oxidize.  Refrigeration and no light will help it last longer.  However, it will be harder to spread if kept in the refrigerator. 


The directions to refrigerate organic peanut butter are there for quality, not safety, reasons.  When organic peanut butter is kept at room temperature, some of the oils may separate from the peanut base.  Stirring will solve the problem.  (food scientist Dr. Catherine Cutter)


A:  You don’t need to refrigerate either the regular or the organic peanut butter. If you’re using the organic product, you can remove the top layer of oil; then you won’t have to stir it. (food scientist Dr. Karin Allen)


Q: Is it safe to eat leftover frozen stuffing that’s been in the freezer for 2 years?


A:  Assuming it was not contaminated when it went into the freezer, it would be safe to eat. But I doubt that it would taste good after 2 years. If you heat it fully and add some new spices, it might taste okay, but the movement of water would probably destroy its texture.  (food scientist Dr. Joe Regenstein)





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


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


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


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


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