Thursday, September 11, 2014

Chicken noodle soup often brings back warm memories for most people. Whether you remember Mom bringing you fresh warm soup when you were sick, or if your memories revolve around snowy wintry evenings, sitting down for a cup of steamy soup to warm up after shoveling the driveway, most Americans have some emotional attachment to this simple creation.

Chicken soup triggers a different memory for me; it goes something like this: it's a crisp fall day and you've been invited to a picnic tomorrow. You've been asked to bring a dish and you're excited to try out your mother's world famous chicken noodle soup recipe. After stopping by the grocery store to pick up fresh veggies and chicken breast, you head home to begin your afternoon of work. You've prepared chicken stock from scratch (boiling together veggies, seasoning and non-edible chicken pieces and bones) and have added your cooked chicken bits, fresh chopped veggies and al dente cooked wide egg noodles a local Amish shop produces. You bring the pot up to a boil, place the lid on and turn the gas down to a simmer for 25 minutes. You're using your family's hand me down soup pot that youre certain has five generations of love cooked into that copper bottom. This pot is different than your newer conventional pot because the pot edge and lid form a swan like s curve around the entire edge. With your borderline OCD behavior, your cooking area is immaculate, all pots, utensils and associated goods are sterile before and during use, and the pot edges are never dirtied. After 25 minutes of boiling and simmering, you turn off the burner, careful not to disturb the pot, and proceed to head off to bed after your evening of toiling away at the stove. An hour later, your mother wakes you up exclaiming that you've left the soup out on the stove and you need to put it in the fridge or it'll surely spoil! You obviously don't want to give your friends food poisoning at the picnic, so do you get out of bed and refrigerate the soup, or is it okay where it's at? Explain your answer.

I'd like to take a moment to thank Dr Rachel Robson for the general basis of this question and apologize for any inaccuracies. Dr Robson had the unfortunate opportunity to teach my microbiology course during my undergraduate education. She did an impeccable job lecturing the basics of germ theory to us poor 19-22 year old mold-able minds. One lecture was spent discussing the amazing work performed by a genius named Louis Pasteur, a hero to many microbiologists. Among his outstanding advancements include an experiment involving a swan neck flask and broth. With a hefty load of basic microbiology knowledge, 200 years of advancement in the field, and a handy set of crayons for the extra credit question, we should have been prepared to answer this question.

From a young age, we're educated with the knowledge gained by our ancestors over thousands of years. While most people conjure up images of high school teachers, coaches, professors or primary investigators when the word "teacher" or "mentor" is dropped in a conversation, it's important to recognize that the majority of our education is likely based on our home life. What we learn as children tends to stick with us for life because "I say so." We want to grow up to be like our parents, hanging on their every word and mimicking their behavior. We do as we're told, even when we think differently than what we're being told (with obvious exceptions during those rebellious teenage years).

So, what would you do? Mom knows best, right? Well I'm sorry Kay, but we've established that statement isn't always true. The refrigerator similar to what we now know was invented in 1913, so what we do prior to 1913 to preserve food? Well, building on knowledge gained over hundreds of years of experience, we canned. So why did we replace scientific knowledge the instant the fridge showed up? The principle in canning is to kill bacteria in a high pressure, high temperature apparatus (alternatively open boiling systems may only use a high temperature water bath). When the minimal remaining gas in the container cools, it loses energy and compresses, pulling down on the lid creating a sealed, anaerobic environment. Louis experiment worked on a similar principle: eliminate bacteria & prevent them from contacting nutrient rich sources. Louis and Dr Robson were probably disappointed in the answers of many of my classmates that day. Sure chicken noodle soup is a delicious concoction of basic amino acids and more complex proteins, carbohydrates, fats, minerals and vitamins. Everything we and bacteria need to grow and thrive. So why dont bacteria spoil that soup that I decided to leave out on the stove top overnight? That little s curve that the hypothetical question highlights works exactly like the delicate swan neck s curve in Louis flask. After boiling away any bacteria the only way to for bacteria to spoil our delightful soup is by contamination from an exterior source. That s curve traps any bacteria just like that plumbing under your sink traps heavy objects and debris that you flush down. Without a push from the outside environment, the bacteria are never exposed to the soup and soup remains sterile. The question posed after this lengthy scenario brings into question why do you do what you do in everyday life. How much of life is dictated by social convention? How much do you do simply because thats the way I was raised" or "when I was a kid we…”

In this blog, we propose the science behind the photo. What we take for granted in everyday life, what were taught is right simply by social convention or how emotions dictate our decision making process are brought into question in a scientific light. Please read with an open mind and consider how your life is impacted by the simple science in everyday life. I still put my soup in the refrigerator at the end of the evening, but sometimes I think about the hundreds of years of scientific progress that made making that soup a safe and delicious meal, even days after I cooked it. 



  1. Chicken soup is also a common, delicious and famous dish in China! As a developing country, meat was very expensive for common people 30 years ago. A lot of families raised some chicken or duck at the backyard. These chickens are not for meat but eggs. Chicken is not a darly food for most family. However, when festivals came, the family would harvest a hen to celebrate. In my family, I remember chicken soup was always one indispensable dish in spring festival which is Chinese new year. What's more, traditional Chinese medicine makes chicken soup with medicine materials as a tonic for patients. I still remember when I got cold or sick, my family used to prepared chicken soup for me and I got better afterwards. It is so sad, for some reasons, I just can't make the chicken soup with the same flavor in America. I missed it so much.

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  3. This is a fun topic and one that I occasionally like to "goad" people about if the right situation presents itself. Although you used chicken soup as an example, with really neat scientific fun facts to back it up, you could use the same argument about some other food spoilage scenarios. I must offer a disclaimer here...there are few things that irritate me as much as a "germaphobe". Usually because the rational for their fears is so completely unfounded it's impossible to even have a logical discussion about it. I.e....your groceries will not instantly spoil if they are left out on the counter for a bit (although your ice cream may melt), you can eat leftovers that have been in the fridge for a week and not get sick (in most cases!) and eating raw produce does not mean you are going to get food poisoning from e.coli! It's true that many crops are fertilized with manure, which definitely contains e.coli, so this may be motivation to wash and/or cook your veggies but the bacteria are not growing inside the vegetable. Along those lines...."washing" raw chicken, an old wives recommendation if you will, is completely false in its pretense of cleaning the meat and actually increases risk of getting sick. Salmonella and Campylobacter are extremely common poultry pathogens that frequently end up on the surface of the raw bird, no matter how stringent the processors are about cleaning, and washing off the chicken merely splashes them all over the sink and counter. Adequate cooking will be sufficient protection.

    But I digress. I guess my feeling is that our society as a whole has become hypersensitive to germs but much of that fear is based on rumor and speculation, not fact! And the irony is, all the people I know that are the biggest germaphobes are usually the ones that end up being sick. I could make a very unscientific statement suggesting that they never challenge their immune systems and thus have weak defenses....but I guess that is just my educated opinion. :-)