Safe Food Practices During Refrigeration

Refrigeration is one of the most common means of food preservation and little can we fathom life without it. From tucking out lemon to start the mornings to the end-of-day hustle to accommodate food leftovers, the refrigerator humbly caters to our daily food regimen. The sweltering heat of summer additionally demands chilled drinks, desserts, and fruits to name a few. Small fridges have now metamorphosed into large stainless-steel wall-cabinet-like structures. Within this increasing coexistence, how often do we reflect upon our refrigerator handling practices and their impact on heath?

During refrigeration, food quality can be challenged by issues related to poor hygiene, overloading, cross-contamination and power failure. This may manifest as nausea, discomfort, to even severe gastrointestinal disorders. The impact on immunocompromised people may be more adverse.  As the globe gears up to celebrate World Food Safety Day on June 7th, it’s time we reflect on these pertinent questions. True to this year’s theme, “Food Safety: Science in Action”, achieving food safety has always been an amalgamation of efforts centered on identifying and controlling risks. Hence, as we hone our food-accommodating skills, we also need to enhance awareness regarding issues that challenge food safety during refrigeration.

Refrigerate to preserve  

The credit for modern refrigeration is often given to Jacob Perkins, the Father of the Refrigerator, after his 1834 AD patent on Vapor Compression Cycle. Technically, the refrigeration cycle is a trail followed by a refrigerant as it traverses through various units in a refrigerator. Low-pressure liquid refrigerant passes through evaporator coils and, in the process, cools the food. The refrigerant, now in gaseous form, is then compressed before it is condensed. Refrigerant pressure is then released. This low-pressure liquid refrigerant is now ready to extract heat from food once again and the cycle continues. 

The United States Food and Drug Administration (USFDA) recommends refrigerators to be set at 4 degrees Celsius and freezers at minus 18 degrees Celsius. Low temperature retards microbial activity and chemical reactions in food thereby extending its shelf life. Handling practices, however, can impact the quality and safety of stored food. Published research papers infer the predominance of bacterial genera like Bacillus, Acinetobacter and fungal genera like Candida and Saccharomyces in domestic refrigerators. This suggests the need for regular cleaning and disinfection. Likewise, many pathogenic bacteria like Staphylococcus aureus, Salmonella typhi, Escherichia coli and Shigella species have also been detected. Listeria, notoriously labelled as “Refrigerator Killer”, accounts for a large part of foodborne illnesses. 

Poor hygiene is by far the most common deterrent to food quality. Food spillage harbours contamination, especially when there is a power outage. The aesthetic appeal of stored food is impacted. Uncovered food could imbibe the mixed odors circulating within the closed space. Any ready-to-eat food, including green chillies and pieces of lemon, should not be placed in the egg storage section, as egg shells are a big source of microbial contamination. Raw and cooked food are often stored alongside. Overstuffing could obstruct air flow and delay the cooling of food. The use of thick plastic containers for storage delays food cooling. Similarly, frequent opening of refrigerator doors could impact refrigerator temperature.  

Precautions  

Ensuring food safety in a refrigerator would require consistency in mindful handling practices. Provision of an uninterrupted power supply and voltage stabilisers is are crucial prerequisite. Refrigerator temperatures should be regularly monitored. Despite this, psychotropic bacteria may flourish at low temperatures. Hence, cleanliness should be stringently maintained to prevent it from turning into a potential breeding ground for microbes. Use of mild detergents is advised for cleaning. Vinegar water solution is useful for removing food odors. Any carryover of dirt, especially in vegetables, should be avoided. 

Stock rotation based on the First-In First-Out system is crucial here. In an industrial setting, proper labelling of stocks is essential. Meat and fish are normally stored in the deep freeze section. In case of intermittent storage, the lower sections should be used to prevent any spillover of its drippings. Thawing should be done within a refrigerator or a microwave oven could be used. Refreezing of thawed food should be avoided. Perishable foods should not be stored in the refrigerator door, as the temperature fluctuates more often here. Minimal door openings should be planned. 

Leftover food should be promptly refrigerated to avoid its exposure to the danger zone (between 4.4 to 60 degrees Celsius), where microbial growth is rapid. It is advisable to use a storage container made of materials that cool faster. The use of 304 SS (Stainless Steel) containers is recommended here. Preventive maintenance of the refrigerator is another aspect that needs to be considered. Generally, home refrigerators are not considered for servicing until a breakdown occurs. It is important to ensure proper functioning of evaporator coils, compressor, expansion valves and condenser units. The condenser coils located at the back of the refrigerator should be unobstructed to facilitate effective dissipation of heat. 

Way ahead

As refrigeration outgrows domestic units to be a part of mobile transport systems, maintaining the cold chain of food is now a reality. While the conveniences of refrigeration fuel its rising dependency, we need to be mindful of the coexisting challenges. Temperature abuse and ingress of contaminants profoundly affect food safety. The impact on vulnerable groups like infants, children, the diseased and the aged may be harsher. 

It's time to converge efforts towards improving food handling practices during refrigeration. A strategic way ahead is to monitor temperature and adopt food hygiene and sanitation practices. As we acknowledge this valuable innovation that upholds the sanctity of food, we need to be mindful of its judicious use and try to enhance our knowledge around pertinent risks. 

(The author is a Food Technologist: monicakpg@yahoo.com).