Crisper humidity and warm load response

Thanks to your feedback, we pilot test two new criteria.

Testing for the real world

We're always asking what's important to you when it comes to products, and fridges are no exception. You recently told us that how well a crisper works and how a fridge responded to a warm load of groceries were at the top of the list of what you want to know before buying a new fridge.

We put aside some time to pilot a couple of new tests to see if we can introduce these criteria into our overall fridge testing. The trick is to balance what's important to you and what we can consistently repeat across all fridges, and come up with something useful for you to assess when shopping for a fridge. We tried each of the following tests on two fridge samples we had in-house.

Crisper humidity

Most fridges have a crisper; some have more than one. But do they do what they're supposed to? The idea of a crisper is to keep your fruit and vegetables fresher than they'd be in the main food compartment of the fridge. This means maintaining suitable temperature and humidity. If you take a look at recommendations for fresh fruit and vegetables, this can range from 0–3°C, and 85–100% humidity.

We used humidity sensors to test what happens inside of crispers, with interesting results. When sliders on the crisper drawers were opened mid-testing, even if they were only open for a short period, the humidity in the crisper would decrease to the fridge's ambient humidity, and the temperature would drop as well.

Both fridges we tested on showed similar responses, though at different rates.

Warm load response

What happens when you put that load of car boot-temperature shopping into the fridge? We found it brings the temperature of all the surrounding food up to hazardous temperatures. We put thermocouples into temperature packs to simulate food in the fridge, then when the fridge was at a stable temperature, we put 1L of 32°C water into the centre of the fridge to simulate mildly warm leftovers. Within minutes it had brought the temperatures of the surrounding 'food' up to above 4°C, or outside of the minimum safety food temperature zone, and kept it there for up to eight hours. Needless to say, depending on the food affected, this might result in a sore tummy or worse.

Scoring would depend on how quickly the fridge reacts to the warm load. A fridge that drops its temperature to minimise the fluctuations, and therefore is safer for food storage, would score better than one that doesn't. 

CHOICE verdict

So what's next? We'll need to keep on testing to see whether the small sample results we've found so far can be repeated and are consistent across a greater range of fridges. Then we'll work on a way of communicating which fridges have effective crispers and which cool fast without lowering the surrounding temperatures.

We'll do this preferably with scoring so it's a simple process to look and see at a glance which fridges perform well for these functions. We'll add these into our overall score, suitably weighted, but disclose the individual scores as well so that if these elements are very important to you, you can use them to make your decision rather than just our weighted score.

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