In recent years, due to the impact of the COVID-19 pandemic, ongoing home isolation and prevention requirements have disrupted people’s previously convenient lifestyles of takeout and dining out, leading many families to regret not purchasing larger-capacity refrigerators. Many households have included large refrigerators and freezers in their purchasing plans to have enough space to stockpile more food and extend its freshness as much as possible, preparing for unforeseen circumstances. However, in recent years, food poisoning safety incidents caused by consuming food taken from refrigerators have occurred frequently. Investigations show that the causes of these incidents, in addition to the mixing of raw and cooked foods, are also related to the long-term lack of cleaning of refrigerators. Many “cooks” believe that since ingredients need to be washed before cooking, cleaning the inside of the refrigerator is unnecessary and that taking all the food out is time-consuming and troublesome; cleaning pots and pans is essential, while the refrigerator only needs to maintain temperature and does not require frequent cleaning. In this issue, we will discuss the cleaning and maintenance of refrigerators.
In fact, a wide variety of microorganisms live in household refrigerators. Recent investigations in certain areas have shown that the bacteria found in household refrigerators mainly include Bacillus, Staphylococcus, Listeria, and Pseudomonas species; the fungi mainly include Aspergillus, Penicillium, and other molds; the pathogenic bacteria mainly belong to the Staphylococcus genus, including hemolytic Staphylococcus, human Staphylococcus, and epidermal Staphylococcus. Additionally, some refrigerators have a high detection rate of Yersinia enterocolitica, a pathogenic bacterium that produces heat-resistant enterotoxins (which easily grow in low-temperature environments) and is a significant pathogen for modern “refrigerator disease.” A survey of nearly 400 household refrigerators showed that 17% of refrigerators had a refrigeration compartment temperature exceeding 8°C. When grouped by different parts of the refrigerator, it was found that the detection rate of Bacillus cereus on the back of the refrigerator’s storage box was significantly higher than in other areas, the total bacterial count at the air outlet was higher than in other parts, and bacterial contamination was also present in the circulating air of frost-free refrigerators. These strains are pathogenic to humans or animals, and the diseases they may cause are often very broad, not limited to the digestive system but also affecting the respiratory and urinary systems. The survey also found that many households had visible food debris, soup, cake crumbs, etc., on the glass shelves inside the refrigerator; the drawers in the refrigeration compartment contained rotting leaves and spoiled fruits; there was often a strange smell, especially in summer and autumn; the folds of the seal harbored various foreign substances, such as milk stains, grease, and other food residues; additionally, the refrigerator door handle could become a hotspot for bacterial proliferation, especially in summer when grease and stains quickly spoil… All of these provide a nutrient source for various microorganisms. The refrigerator is not a “food insurance box.” Although these microorganisms reproduce relatively slowly at low temperatures, psychrophilic bacteria and the varying freshness periods of different foods cannot be ignored.
Pathways of Refrigerator Contamination
For working professionals, balancing work and cooking presents a challenge, as “cooks” face heavy cooking tasks and tight schedules. During the preliminary preparation or cooking process, “cooks” often handle ingredients while repeatedly opening the refrigerator to take the needed food, leaving various fingerprints on the refrigerator door afterward. Residues from external packaging of milk, juice, etc., can easily become nutrient sources for various microorganisms inside the refrigerator; food residues in the refrigerator’s seal can mold during the rainy season and summer, and grease and soup residues that have not been cleaned for a long time can deform the seal, reducing its sealing effectiveness, leading to decreased cooling efficiency and increased power consumption.
Optimizing Cleaning Procedures to Reduce Food Safety Risks
Indeed, there are many factors influencing microbial contamination in the refrigerator’s refrigeration compartment, including the initial contamination of items, the handling of items before placing them in the refrigerator, the usage time of the refrigerator, and the cleaning frequency and methods. Ingredients such as meat, eggs, and fish are prone to spoilage and may contain pathogenic microorganisms; if not handled properly, these microorganisms can enter the refrigerator, increasing the risk of foodborne diseases in the household. Refrigerators should always be kept clean; otherwise, they will become the best breeding ground for bacteria, spreading throughout the refrigerator, and long-term neglect will increase the risk of foodborne disease infections. Additionally, cleaning the refrigerator door handle is a key factor in reducing cross-contamination risk, preventing household members, especially children, from directly accessing food in the refrigerator and becoming infected by bacteria.
- Cleaning Aids for Refrigerators
Typically, people use kitchen paper, detergents, cloths, discarded toothbrushes, toothpaste, and sterilizing deodorizers to clean refrigerators. Currently, there are no specific national or industry standards for refrigerator cleaning agents. The product standards related to refrigerator cleaning agents include the “National Food Safety Standard for Detergents” (GB14930.1-2015) and the “Safety Technical Specification for Cleaning Products” (GB/T6396-2011). The sterilizing deodorizers sold on the market claim to have functions such as sterilization, deodorization, and pesticide residue removal, and provide testing reports from third-party testing agencies. Their working principle is to use ozone to sterilize and inhibit various psychrophilic bacteria, molds, and pathogenic bacteria in the refrigerator. The results show that they can increase the freshness of stored fruits and vegetables and eliminate odors.
- Timely Cleaning
Based on actual conditions, people should promptly clean refrigerator door handles to avoid cross-contamination risks for household members. When cleaning, a small amount of detergent can be used to remove grease, followed by rinsing with warm water. The rainy season is the best time for various molds to grow, and refrigerator door handles and seals are more susceptible to contamination and mold growth, so people should check and organize food every 1-2 weeks and clean it as mentioned above.
The overall frequency of cleaning the refrigerator is not absolute; it is closely related to the user’s habits. Paying attention to the cleanliness of the exterior of all food containers and ensuring they are sealed can significantly reduce the risk of cross-contamination while extending the cleaning cycle. Sterilizing deodorizers should not be used for extended periods, as their high ozone concentration can lead to ozone pollution, ultimately affecting the user’s health.
After cleaning the refrigerator, when putting food back, people should check the freshness of the food to adjust the cooking order, ensuring food safety. Refrigerators need regular cleaning and maintenance to ensure dietary safety, which requires attention to detail.