FAQs about Ground Beef, Seasonings, Olive Oil, Lemon Wedges, and Fish

ground beefJudging by the questions sent to health websites and publications, it seems that the more consumers learn about food safety, the more anxiety they have related to this ingrained habit we have of eating. Here are some foods consumers have worried about recently: rare ground beef, imported spices, olive oil for cooking, lemon wedges in water, and farmed salmon. These Q/As provide some understanding of the issues and some techniques for getting around the risks of contamination. Many of the answers quote scientists on the Shelf Life Advice Advisory Board.


Cook my burger to 160°F?  But I love it rare!


Sorry, but, for safety's sake, the government's recommendation is 160°F, which, will give you a well-done burger.  To enable you to consume your burger somewhat rarer, here's a tip you may not like.  According to food scientist Dr. Karin Allen, if your ground beef comes from a more expensive cut of meat that's from a single muscle, it's less risky to cook it less. "Bacteria can't be inside a single muscle, but chuck steak is comprised of different muscles." Food scientist Dr. Catherine Cutter adds this point: For the internal muscle to be sterile, the steak must be intact--not tenderized or needle-injected. "If the surface is compromised, that creates issues, such as internalizing any bacteria that are on the surface." To reiterate: those that want to make rare burgers at home should buy an expensive steak, chill it well, grind it up at home, and start to cook it immediately.  Now who would do all that? 


Food scientist Dr. Clair Hicks elaborates:  "If hamburger has gone through the normal retail chain, it is several days old by the time the consumer purchases the product.  This is sufficient time for a pathogen to grow to substantial numbers; thus, the hamburger needs to be cooked to a well-done temperature to make it safe.  However, if a restaurant is grinding its own beef from a sub-primal cut of meat (not trimmings), the amount of bacteria on the meat is not of much concern. The meat must be ground just before being cooked and kept fresh by being held between 32°-36°F.  If these conditions are met, fresh ground burger is safe to serve in the130°-135°F range without concern. Time and temperature are everything."


Food process engineer Dr. Timothy Bowser mentions some solutions for the lover of rare burgers: "There are several ways to make hamburger cooked at lower temperature safe to consume:  (1) long, slow cooking in sealed plastic bags submerged in a water bath (sous vide) followed by quick searing of the surface; (2) irradiation prior to cooking; (3) bactericides, such as ammonia; and, (4) high pressure processing prior to cooking."  But here's the catch: "most of these methods are not popular with consumers and/or restaurant chefs."


A final word on this matter:  Dr. Cutter points out that you cannot tell whether ground beef is cooked to a safe temperature by checking the color and/or texture.  These are not reliable methods.  A burger that's brown in the middle may still be undercooked; one that's pink inside may be cooked well above 160°F.  (For confirmation, see the FSIS article "Color of Cooked Ground Beef as It Relates to Doneness.")


Restaurants often have a disclaimer on the menu saying that, if you order your meat rare, the risk is yours.  However, says Dr. Cutter, despite the disclaimer, if you get a food-borne illness from the restaurant's food, the restaurant and/or supplier of the ground beef may have to pay for your medical care.


Will cutting food with a rusty knife make me sick?


Here is Dr. Bowser's response: "I don’t think a rusty knife is necessarily harmful, but it might cause harm because it is probably not sharp either and could be difficult to cut with. A nasty cut from a rusty knife could be very hurtful. The rust may also harbor dirt and bacteria. A little bit of 'clean' rust is a good source of iron, but a knife blade is not the best place to get it!


"Personally, I prefer to use carbon-steel knives for certain chores because they are very easy to sharpen and seem to flex better than the stainless-steel knives I own. Sometimes they get a tiny trace of rust on them, probably from moisture in the air reacting with the steel, and I just go ahead and use them as is. If the amount of rust is more than I like, I polish it off with a green scrub pad."


Are imported seasonings safe?


The monthly newsletter Consumer Reports on Health ran a recent article dealing with this question.  According to this article, the U.S. imports more than 80% of the spices sold here, and the average per-person consumption of all spices is 3.6 lbs. The article was probably inspired by last fall's FDA report, which said that that 12% of imported dried spices contained "filth"  (insect pieces, rodent hairs, etc.) and 7% of  these seasonings (including leaf-based ones such as basil and oregano) contained bacteria that could cause illness.  The most highly contaminated were those from Mexico and India.


Despite the statistics, the article points out that there's little to fear from seasonings.  Here's why:



  • Most are treated by their domestic importers with methods that kill the harmful bacteria.  (Such methods include X-rays, gamma rays, or sterilization with steam or gas.) 
  • If the spices are used in processed food that's been cooked, the risk of illness is reduced. 
  • A little "filth" is unavoidable and, says the FDA, it won't actually harm you.  Almost all foods coming from the natural environment contain small amounts of "filth."



The article has these two suggestions for people preparing food at home:



  • If possible, add spices before cooking instead of after.  High heat kills bacteria.  But, food scientist Dr. Joe Regenstein points out, "you may need to use more spice because heat can reduce the strength of the spice."
  • If you need to add seasonings to a cold dish, buy fresh herbs and wash them well.



Is it safe to fry foods with olive oil?


The only risk of cooking with olive oil relates to its smoke point, says the Tufts University Health & Nutrition Letter. The smoke point is "the temperature at which gaseous vapor becomes visible, indicating that the hot oil is beginning to decompose."  Heating oil past this point a) can create harmful by-products; b) may cause off-flavors; and c) may destroy important nutrients.  Refining oils raises the temperature of the smoke point. Unrefined extra-virgin olive oil has the lowest smoke point of all types of olive oil, so it's best used for salads, not cooking.  For cooking, the newsletter recommends olive oil labeled "pure" or "light."  These have smoke points ranging from 425-470°F, high enough for most cooking purposes.


About.com says, in general, vegetable-based oils are better than animal-based oils (for example, butter or lard) for high-heat cooking such as sautéing and deep-frying.  But there are exceptions.


Note:  Don't confuse the smoke point with the flash point, which Wikipedia defines as "the point at which the vapors from oil can first ignite when mixed with air."  This is a much higher temperature and is obviously of immediate concern, Dr. Regenstein points out.


Is farm-raised salmon less healthy than wild salmon?


According to the newsletter Consumer Reports on Health, "Both contain high levels of omega-3s, the fatty acids that may support heart health." However, the newsletter says, farmed salmon may contain higher residues of mercury and pesticides as well as higher levels of possible carcinogens called PCBs.  The risk with farm-raised salmon depends upon two factors: 1) how the salmon were raised and 2) what they were fed.   The publication recommends paying a bit more and buying wild salmon.


Do I need to wipe out my microwave every time a little liquid or solid food gets on the walls or the rotating plate, or is the microwave self-cleaning? 


Both Dr. Cutter and Dr. Regenstein point out that a microwave heats food unevenly.  (That's why microwaves come with a rotating plate.) Therefore, when spills occur, to be safe, err on the side of caution; clean and sanitize the area of the spill.  For cleaning, Dr. Cutter says warm soapy water is fine.  For sanitizing, she likes the lemon scent of some antibacterial sprays, but any antibacterial spray, wipe, or pad will do the job.


Is it safe to have a restaurant put lemon in my glass of water or cup of tea?


If you must have lemon in your water or tea, ask the server to bring the lemon wedges on a separate plate. Then you can squeeze the lemon in yourself.  Pathogens on the lemon peel can get into your drink from the peel, the knife, or the dirty hands of the person doing the cutting.  Dr. Cutter is wary of pathogens that may be thriving under a server's long fingernails.


Here's Dr. Bowser's comment on lemon wedges in tea: "Hot tea should provide enough heat to kill the pathogens on a lemon wedge. If the tea is not hot, or if it cools rapidly, the amount of heat applied to the lemon's surface may not be sufficient to kill all pathogens that may be present."


What about fresh lemonade made at a stand at a fair or outdoor market?  Dr. Cutter doesn't worry about drinking these types of beverages, especially if the lemonade chef is wearing gloves and follows food safety regulations.  She feels that regulations require these servers to follow safe procedures.  Also, the high sugar content, combined with the acidity or the lemonade and cold ice, can provide some protection against bacterial growth.


What about lemon wedges at home? Dr. Regenstein offers this reminder: Before dunking a lemon wedge in your drink, wash the peel well and be sure to use a clean knife and clean cutting board. Before washing, remove that paper sticker on the peel!


A recent Huffington Post article contains a lot of unappetizing details about germs on lemon wedges.  But it ends with this practical advice: "...sometimes you really do have to trust your immune system to do its job. Microbes are ubiquitous...You're not going to escape unscathed forever."  Dr. Cutter quipped that for some people, "The key to a healthy immune system is constant challenge."





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


Clair L. Hicks, Ph.D., University of Kentucky, Dept. of Animal and Food Sciences


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


fsis.usda.gov "Color of Ground Beef as It Relates to Doneness"



Consumer Reports on Health, "Are Your Seasonings Safe?" March 2014.


Tufts University Health & Nutrition Letter, "Ask Tufts Experts,"  February, 2014.


About.com "Cooking Oil Smoke Points"



Wikipedia "Smoke Point"



Consumer Reports on Health, "On Your Mind," March 2014.


huffingtonpost.com "This Will Make You Never, Ever Want To Put A Lemon Wedge in Your Water Again"




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