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Does Unwrapped Sandwich Meat Really Go Bad After Seven Days of Opening the Package?

how long is deli meat good for in the fridge

The time in which lunch meat spoils will surprise people. In some instances in less than seven days the lunch meat you leave unwrapped can harbor listeria in 7 days.


Lunch meat and other ready-to-eat food left unsealed in the refrigerator only remains usable for seven days before acquiring strange coloring and odor. Does lunch meat really go bad after seven days of opening the package?

Hypothesis: Lunch meat left exposed to the environment of the refrigerator will spoil and become inedible in seven days because of growth of cold-resistant bacteria.

How long is deli meat good for in the fridge?

Prediction: If lunch meat is left in the original unsealed container will then show signs of spoilage after a period of seven days while sealed lunch meat will not. These results will occur providing the environment of the refrigerator is kept at a constant temperature throughout the experiment.

Background Research

Food safety is an ongoing problem facing households every day. While most spoiled lunch meat will not cause dire illness, there is a concern that the organism Listeria could be present and this illness can even cause death (Refrigeration and Food Safety, 2015). In order to have accurate results from the experiment, information was sought in regards to the impact of temperature in the refrigerator on the lunch meat. The Centers for Disease Control and Prevention (CDC) say that temperature in the refrigerator should be no higher than 40˚F in order to reduce the formation of cold resistant bacteria and is actually better if the temperature is closer to 32˚F (Reddy, 1981; Sparu, Scarano, Ibba, Pala, Sparu, and DeSantis, 2014). According to the CDC, 1600 people get sick from Listeria each year, it is the third leading cause of death from food poisoning, of these people 90% are pregnant, 65 years or older or those who have impaired immune systems. This organism can lead to miscarriage, newborn death or severe illness upon birth, and meningitis (Recipe for Food Safety, 2013; Food Safety for Pregnant Women, 2015).

The United States Department of Agriculture (USDA) has identified two types of change that occurs to refrigerated foods like lunch meat. One kind is pathogenic. This is the type that leads to most foodborne illnesses. The other one is spoilage. These organisms can grow even in low temperatures (Reddy, 1981). These are also the ones that eventually lead to bad taste or smell in refrigerated foods. While most of this type will not do more than cause diarrhea, there is one that can be very deadly-Listeria (Refrigeration and Food Safety,2015; Special Handing, 2016).

Also see: How To Store You Tomatoes Not To Kill The Flavor of Your Sandwich.

USDA and Food Safety and Inspection Service (FSIS) both recommend not only using refrigeration temperature of more than 40˚F and to make use of the meat drawer if available. However, even with use of the meat drawer storage of lunch meat should be only 2 weeks if package unopened and three to five days once the package has been opened (Control of Listeria, 2003). This fact was an even shorter time span being addressed with the proposed experiment. Another important place to look for predicting the outcome of this experiment is a date found on all packaged lunch meat. Manufacturers of ready to eat food like lunch meat or hot dogs are required by the USDA and FSIS to place use by dates on their products (Food Product Dating, 2007). With this information in mind, special care will be taken to insure the sample used for testing is freshest available. There are two types of dating used by manufacturers to help protect the public from ingesting tainted food. One is open dating or the use of an actual calendar date placed on refrigerated foods that are more immediately perishable such as meat, poultry, dairy, or eggs and ready to eat foods including lunch meat. The other type is closed or coded dating. This type is mostly used on items such as canned foods or boxed foods and are items with a longer shelf life. Sometimes these items also include a calendar date but for the most part it is just a code of letters and numbers used by the company to track batches of items produced by their companies (Food Product Dating, 2007; Boyer & McKinney, 2013). Unfortunately either form of dating is meant only for gauging shelf life not how long it will stay fresh once it is brought home (Food Product Dating, 2007).

In January of 2011, the president signed into law the Food Safety Modernization Act. This act gives the Food and Drug Administration (FDA) the power to hold processing facilities for inspection of risk for contamination. It also gives the FDA the ability to monitor food products coming to the United States from other countries (Hamburg, 2011).
Experimental Design: In this proposed exercise the experimental group will be two slices of a newly opened package of bologna. Care will be taken to have a product that has between three and four weeks of future freshness according to the use by date (Food Product Dating, 2007). As a control group, the remaining bologna will be placed in a zip-loc type bag and resealed removing as much air as humanly possible. For this experiment, the independent variable will be the temperature of the refrigerator. For this experiment, the dependent variable will be the condition of the bologna left exposed to the environment of the refrigerator.

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1. One 12 ounce package of bologna with a use by date of at least three to four weeks into the future from the date of starting the experiment.

2. One sandwich sized zip-loc type bag.

3. One digital thermometer that registers both indoors and outdoors temperatures. Use of this instrument will allow for monitoring of temperature without opening the door of the refrigerator. This monitoring will be done each day at the same time prior to opening the refrigerator door to check on the appearance and odor of the bologna.

4. One refrigerator in good working order. The temperature will be taken before the experiment is started to ensure the refrigerator is within the guidelines of proper temperature put forth by USDA and FSIS of below 40˚F (Control of Listeria, 2003; Refrigeration and Food Safety, 2015). Adjustments will be made to make sure the temperature is correct prior to the beginning of the experiment.

5. One cleaned meat drawer for the experiment to be conducted in. This will be cleaned using a chlorine impregnated cloth commercially available for removing as much bacteria as possible.


1. Making use of the indoor/outdoor thermometer, the base temperature will be obtained before opening and dividing the bologna up. Temperature can be adjusted until within the proper level put forth by USDA and FSIS as the proper level prior to starting the experiment (Refrigeration and Food Safety, 2015; Recipe for Food Safety, 2013).

2. Once accomplished remove bologna from the refrigerator, open the package and place all but two slices into the zip-loc type bag and seal it removing as much air as possible.

3. Then place both packages in the cleaned meat drawer. It is important that the drawer be as clean as possible prior to the start of the experiment to ensure the bacteria in the refrigerator environment is as minimal as possible. Utilizing a commercially available chlorine impregnated cloth will accomplish this step. Rinse drawer prior to replacing in refrigerator to remove any residual chlorine as that could alter the results by inhibiting bacterial growth.

4. Each day at a predetermined time, the condition of the bologna in both the opened package and the sealed package will be assessed after the temperature has been documented. This assessment includes comparing color of both samples, checking for odor from both samples, looking for any foreign growth on the bologna of both samples, and documenting the temperature from inside refrigerator. This assessment will be the same throughout the entire time of the experiment. At the end of the seven days a final determination will be made as to how the results of the experiment proved the prediction was true or false and the hypothesis was proven or disproven. If all steps are carried out as listed this experiment should have the expected results every time it is conducted. For the purpose of replicating the results the procedure should be done at least two additional times with new samples of 12 oz packages of bologna being used for each time and the drawer cleaned as before with the chlorine impregnated cloth and rinsed.

Discussion of Results: If this experiment was to be conducted as specified above, the results would be expected to prove the prediction was indeed true. The results to prove this would include no odor or change in color of the sealed bologna as well as change in color and odor of the unsealed bologna possibly even including appearance of actual bacterial growth on the unsealed meat. Results expected to disprove the prediction would include the two specimens would be identical after the period of seven days and would not have any changes in appearance or odor.


  1. Boyce, Rene, and Julie McKinney. "Food Storage Guidelines for Consumers." Virginia Cooperative Extension. College of Agriculture and Life Sciences, Virginia Polytechnic Institute and State University of Virginia, 2013. Web. 12 Oct. 2016.
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  4. "Food Safety for Pregnant Women" Food Safety Choose My Plate, United States Department of Agriculture, 30 June 2015.
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  6. "Recipe for Food Safety." CDC Vital Signs. Centers for Disease Control and Prevention (CDC), June 2013. Web. 15 Oct. 2016.
  7. Reddy, Kuruganti Venkatakrishna. Effect of method of freezing, processing and packaging variables on microbiological and other quality characteristics of beef and poultry." Retrospective Theses and Dissertations. Iowa State University Digital Repository, 1981. Web. 22 Nov. 2016.
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  9. Spanu, Carlo, Christian Scarano, Michela Ibba, Carlo Pala, Vincenzo Spanu, and Enrico Pietro Luigi DeSantis. "Microbiological Challenge Testing for Listeria Monocytogenes in Ready-to-Eat Food: A Practical Approach." Italian Journal of Food Safety 9 Dec. 2014: 231-37. Italian Journal of Food Safety. Pubmed Central, 10 Dec. 2014. Web. 22 Nov. 2016. doi: 10.4081/ijfs.2014.4518
  10. "Special Handling of Ready-to-Eat, Refrigerated Foods." United States Food and Drug Administration, United States Department of Health and Human Services, 7 Jan. 2016.