Perishable Food Delivered through Mail Carrier: Concerns of Spoilage

February 2, 2019 - 11 minutes read

Convenience, avoiding long lines at the grocery store, or giving your loved ones’ an edible gift for Valentine’s Day are a few of the many reasons why Americans order perishable foods directly to their home through online vendors. Most of the time the perishable foods are delivered by a mail carrier, such as the United States Postal Service, FedEx, or UPS. Mail carriers do not take responsibility of spoiled food or have a vested interest in preventing spoilage. Because of this, not only are perishable products being transported, stored, and delivered using the same methods as non-perishable items, but sometimes packages are left on doorsteps where they are exposed to high temperatures.6 Doulgeraki et al. (2012) states, “Condition of storage, packaging, and temperature can affect the rate of spoilage with temperature being the most important factor affecting meat spoilage”. Leaving food out too long at room temperature can cause bacteria (e.g. Staphylococcus aureus, Salmonella enteritidis, Escherichia coli O157:H7, and Campylobacter) to grow to dangerous levels, which can cause illness. 12 Estrada-Flores and Tanner (2005) found food spoilage of product when delivered by a multi-temperature van. With the increase in loading and delivery time, and no proper temperature control, the number of generations of pseudomonads and E. coli increased significantly.3  

A survey from the International Food Information Council and AARP Foundation (2018) found that one major problem with online grocery shopping for Americans 50 and older who get groceries delivered are produce and meat spoilage. Scallan et al. (2011) estimates that each year 31 major pathogens acquired in the United States cause 9.4 million foodborne illnesses, of which 3.6 million (39%) were caused by bacteria: of these, nontyphoidal Salmonella spp. (1.0 million, 11%), Clostridium perfringens (1.0 million, 10%), and Campylobacter spp. (0.8 million, 9%) caused the most illnesses. According to the CDC (2018), one of the actions that needs to happen to greatly decrease the burden of foodborne illness is further research on understanding how food becomes contaminated during production, packaging, transporting, and/or preparing processes. Implementation of the Sanitation Food Transportation Act (SFTA) provisions was included in the FDA Food Safety Modernization Act (FSMA) to prevent practices during transportation that create food safety risk, such as failure to properly refrigerate and protect food and inadequate cleaning of vehicles between loads. 4 The Sanitation Transportation rule applies to carriers who physically transport the food, but does not include parcel services.8 Because mail carriers do not monitor or control the temperatures of perishable packages, it is important that consumers who receive a food item marked “Keep Refrigerated,” open it immediately and check its state (frozen or partially frozen with ice crystals still visible) or temperature with a food thermometer (below 40 °F).12, 13

Since mail carriers cannot ensure the safety of perishable foods, companies must take steps to prevent food from spoiling in uncontrolled temperature environments. The shipper is responsible for appropriately packing and making sure there is enough refrigerant to ensure that their perishable goods reach their customer safely.6 One necessary step includes choosing the right preservation techniques suitable for the company’s product. By combining chemical and physical preservation techniques with low temperature storage (5 °C) the rate of spoilage of meat and meat products can be controlled.7

Chemical preservatives include antimicrobials, antioxidants, enzyme inhibitors, and chelating agents. Physical preservation techniques include, but are not limited to drying, freezing, pasteurization, and irradiation (Figure 1).1, 9 Irradiation of food has a range of effects including killing bacteria, molds, and insect pest and is sometimes called “cold pasteurization” because the product is not heated and instead exposes food to ionizing radiation1. However, the irradiation of food has not been widely accepted by the American public. Antimicrobial preservatives prevent microbial spoilage due to bacteria, yeast, and mold. For example, calcium propionate and other propionates are used to inhibit molds in baked goods; and sodium and other benzoates are used to prevent fungal growth in many products, such as beverages, fruit preserves, cheeses, and pickles.14 More examples of antimicrobial preservatives include sulfites, sulfur dioxide, sorbic acid, sodium salts, and nitrates (Figure 1).14, 9 Antioxidants are chemicals that help prevent rancidity in food (oxidative spoilage), especially food with unsaturated fats, by slowing or stopping oxidation. Examples of antioxidant preservatives are sulfites, ascorbic acid, phenols (e.g. TBHQ (tertiary butylhydroquinone), and propyl gallate (Figure 1). They are used in a variety of foods, such as in potato chips, nuts, cereals, and crackers.14 Enzyme inhibitors prevent enzymatic degradation of food. Ascorbic acid and citric acid in lemon or other citrus juices deactivate enzymes, including the enzyme phenolase, which turns surfaces of cut apples and potatoes brown.14, 1 Chelating agents prevent discoloration, flavor changes, and rancidity by removing atoms of trace metals such as iron and copper that are responsible for catalyzing oxidation reactions. EDTA (ethylenediaminetetraacetic acid) and citric acid are commonly used chelating agent (Figure 1).14

However, chemical preservatives are not always able to inhibit the physical growth of bacteria on their own. Physical preservation techniques are used in combination with chemical preservatives to inhibit food spoilage. Also, the combination of chemical preservatives can inhibit food spoilage and in some cases, be more effective than using one preservative.7 For example, sodium chloride and sodium lactate in combination was more effective than lactates alone in delaying the onset of meat spoilage.11 Since oxidative spoilage cannot be prevented by freezing (if it is in contact with the air), a combination of antimicrobial and antioxidant preservatives can be an effective strategy for controlling spoilage meat.7.

FIGURE 1. Physical and chemical food preservation examples
(adapted from Wolke, 2005; Samal et al., 2017)

Because of the lack of regulations on mail carriers in regard to preventing food spoilage, suppliers of perishable food should not rely on mail carriers to ensure the safety of their product. Adding chemical preservatives to food in combination with physical preservation techniques, such as low temperature storage, is one way to prevent food spoilage. Different foods require specific types of physical and chemical preservation techniques and some combinations of preservation techniques are more effective than others. Burdock Group can help companies determine what their ingredients need for safe shipment and the most effective way for implementing preservation strategies for their budgetary needs.


  1. Abdulmumeen, H.A.; Risikat, A.N. and Sururah, A.R. (2012) Food: its preservatives, additives and applications. Ijcbs 1:36–47.
  2. Center for Disease Control and Prevention (CDC) (2008) Burden of Foodborne Illness: Questions and Answers(site visted on January 21, 2019)
  3. Estrada-Flores, S. and Tanner, D. (2005) Temperature variability and prediction of food spoilage during urban delivery of food products. Acta Horticulturae 674:63–69.
  4. FDA (2017) Sanitary Transportation Rule: Implementation. U.S. Food and Drug Administration (FDA). (site visited on January 21, 2019)
  5. International Food Information Council and AARP Foundation (2018) Grocery Delivery For Older Americans. (site visted on  January 21, 2019)
  6.  Hallman, W.K.; Senger-Mersich, A. and Godwin, S.L. (2015) Online purveyors of raw meat, poultry, and seafood products: Delivery policies and available consumer food safety information. Food Protection Trends 35:80–88.
  7. Mutwakil, D.; Ghaly, A.E.; Dave, D. and Ghaly, A.E. (2011) Meat Spoilage Mechanisms and Preservation Techniques: A Critical Review. American Journal of Agricultural and Biological Sciences 6:486–510.
  8. Safe Food Alliance (2017) Food Logistics Operations: How Does FSMA Apply? Safe Food Alliance. (site visited on January 14, 2019)`
  9. Samal, D.; Gouda, S. and Patra, J. (2017) Food preservatives and their uses: a short report. Asian Journal of Biology 4:1–4.
  10. Scallan, E.; Hoekstra, R.M.; Angulo, F.J.; Tauxe, R. V.; Widdowson, M.A.; Roy, S.L.; Jones, J.L. and Griffin, P.M. (2011) Foodborne illness acquired in the United States-major pathogens. Emerging Infectious Diseases 17:7–15.
  11. Tan, W. and Shelef, L.A. (2002) Effects of sodium chloride and lactates on chemical and microbiological changes in refrigerated and frozen fresh ground pork. Meat Science 62:27–32.
  12. USDA (2013) How Temperatures Affect Food. Mail Order Food Safety. United States Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS). (site visited on January 14, 2019)
  13. USDA (2015) Mail Order Food Safety. United States Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS). (site visted on  January 21, 2019)
  14. Wolke, R.L. (2005) What Einstein Told His Cook 2: The Sequel: Further Adventures In Kitchen Science. W. W. Norton & Company, New York, NY p. 374-375.
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