More than ever, with a heatwave in most parts of the country and an unstable power supply, retailers and other food businesses face an uphill battle to keep their foods at the correct thermal reading. Should they lose control over the cold chain, in particular, the food that they prepare and sell is likely to become spoiled and even unsafe to eat — surprisingly quickly. 

Disease-causing bacteria contaminating our food supply are a frequent reminder that even though we might be high up on the food chain, microorganisms pose a massive threat.

Experts have warned that fluctuations in power supply endanger the cold chain, which is a risk to food safety as noticeable increases in ambient temperature speed up spoilage in perishable foods.

Beyond a stomach upset, fever and nausea, foodborne illness can manifest in far worse symptoms and even be fatal, especially in young children, pregnant women, the elderly and immunocompromised people, as we learnt from the listeriosis crisis of 2017-18: during that outbreak, there were 1,060 confirmed cases of listeriosis and 216 deaths.

As suppliers, retailers have a particular responsibility to ensure that the food they sell to consumers is fit for consumption. The key to this is in maintaining the cold chain, which involves the entire supply side — from preparation, to packaging, distribution, retail, display and purchase — because once a prescribed temperature has been reached, it should be strictly maintained as far as possible, with minimal fluctuations in temperature tolerated, depending on the product type. 

With rolling blackouts ramped up, stores now have additional processes to review food quality during outages, because for every 10 minutes that stock is out of the cold chain, temperatures rise by 1ºC.

Interruption of that cold chain happens when a step of that cold chain is compromised at any time, explained food safety expert Prof Lucia Anelich. 

“How long it will take for there to be a problem is dependent on several factors, including the type of food product, whether it is frozen or refrigerated [frozen food will take longer to reach an undesirable temperature than a refrigerated product], whether there are any preservatives in the product that extend its shelf-life, whether it is a ready-to-eat food, ie food that does not need any cooking before consumption, whether it is raw and still needs to be cooked before consumption and, of course, the duration in the break of the cold chain.”

Not apparent to the naked eye

Spoilt food is visibly blighted but unsafe food is not obviously dangerous, she warned: “Spoilage usually manifests as visible microbial growth, like undesirable mould on cheese, slimy bacterial growth or colour and texture changes — one can see these changes and there is most often a bad smell as well. So the chances of eating those foods are minimal as they are off-putting and will taste bad.

“Unsafe food, on the other hand, cannot be seen, smelled, felt or tasted.  So, one may eat this food without even knowing that it is unsafe.”

Some foods, like preserved meats and chicken, become particularly dangerous when they spoil. Keeping food cold (ie at below 5ºC), is designed to slow down the growth of these microorganisms in food, but the moment that temperature is increased because of a cold chain interruption, those microorganisms will grow faster and reach levels that either spoil the product or make it unsafe for consumption quite quickly.

“This is true for all foods that are dependent on the cold chain for their stability — just think of supermarket shelves and the vast array of foods in those refrigerators.”

Anelich said the shelf-life (or lifespan) of a perishable product is greatly reduced when temperatures rise, so the consumer may buy a product that will not last as long as the date label states, but when it comes to food safety, retailers cannot take chances with food.

Consumers must be vigilant and always check the display fridges before purchasing.

“Considering that we have four-hour load shedding periods at a time, [consumers] must determine whether the cabinets and refrigerators feel cold enough. If there is a temperature gauge on the cabinet or refrigerator, check that. If it is not cold enough, they should raise the issue with the manager of the store and insist that something is done about it.”

What retailers do to secure the cold chain

Last week’s generator failure at the Plattekloof Woolworths highlighted how seriously some retailers take the importance of managing the cold chain to ensure that perishable products are not only safe, but also of high quality at the point of consumption. 

During that incident, according to social media reports, Woolworths was said to have destroyed a significant amount of refrigerated food. The retailer failed to respond to repeated requests for comment on this particular incident, but its press office did offer this:

“Most of our Woolworths stores have standby generator power supplies, enabling them to continue to trade despite Eskom’s capacity and maintenance issues.

“The store’s emergency back-up generator keeps equipment like refrigeration units and tills, up and running, and provides adequate lighting. 

“If the generator fails, the store will attempt to save the stock by moving cold chain products into the walk-in cooler / and frozen products into the walk-in freezers at the back of the store. Any cold chain products that go above 5ºC and frozen products above -18ºC would be isolated and will not be sold.”

Woolworths said they had focused on energy measurement, management and efficiency initiatives across their facilities, which has resulted in about a 40% relative reduction over the past decade. However, the impact on consumer and business confidence is significant.  

“We are also [affected] when shopping centres within which we trade are unable to trade during load shedding.”

Spar has its own particular battles, as not all franchises are similarly equipped: many have full back-up during blackouts, but some stores prioritise refrigeration, freezers, basic lighting and till operation to reduce costs of running generators.

“The power outages are certainly causing havoc with refrigeration and other appliances, as well as backup batteries and other alternative power sources, coming under increasing strain in the retail sector and across many other industries,” a Spar spokesperson said.

“However, it is imperative that alternative solutions are found, which sadly may result in some wastage of products.

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“Excessive power cuts should never be an excuse for not ensuring the highest safety standards and protocols are maintained,” the spokesperson said, adding that they had ensured “zero interruption” to the cold chain in its distribution centres through operational solar plants and standby diesel generators. The trucks that transport perishables are refrigerated.

At a distribution level, the impact of rolling blackouts has been mitigated by generators and solar, but at retail level they cannot quantify lost stock, as their stores are independently run.

“Our retailers assess load shedding hours in advance and plan around load shedding accordingly.”

Shoprite/Checkers, which has invested heavily in going off-grid, said it was confident it had taken sufficient steps to mitigate damage from the blackouts: 

“The Shoprite Group has made substantial investments over the years to equip all its supermarkets with alternative power solutions to enable uninterrupted operations, including keeping refrigerators and freezers running to protect perishable products during intermittent power cuts. It has become a standard specification for new stores,” a spokesperson said.

All Shoprite and Checkers stores have diesel generators and, in some locations, generators are used alongside solar power to help reduce diesel dependency. Stores also have UPS (uninterruptible power supply) equipment to keep tills going during power outages. 

Last year, the group increased solar PV systems by 82% and finalised sustainability-linked loans of R3.5-billion. 

The group’s current fleet includes 903 trucks and 1,360 trailers, of which 1,041 are fitted with solar PV panels, which allows the refrigeration and tailgate lift to continue to run on solar power even when the trucks are switched off and waiting to make a store delivery.

Pick n Pay’s chief business transformation officer, David North, said all their stores had backup power. 

“However, severe load shedding creates severe challenges for everyone.  Customers are inconvenienced when travelling, or shopping in centres where not everyone has backup power, and worry about whether they can keep products fresh when they get home. 

“Load shedding disrupts the production of food and creates stock challenges. Backup power is very expensive, and generators are not always designed to run for many hours on end.” 

Expressing frustrations widely shared in the industry, North said the country rapidly needed a sustainable solution to this crisis.

“In the meantime, Pick n Pay is fully focused on assuring customers that it is business as usual in our stores.” BM/DM