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How Coop tackled meat discolouration – with light

LUX magazine | posted: 11 March 2019

UK supermarket Coop had a particular problem: the pre-packed meats – including sliced hams, chicken, salami and chorizo – on the top shelves and close to the mullions started to discolour within 24 hours of shelf stacking.

EVEN WHEN stored and displayed in refrigerated cabinets, pre-packed meat discolours over time. It’s a major problem for grocery retailers.

It leads to high levels of food waste, as packs that look unattractive to customers have to be withdrawn from sale even when they’re perfectly safe to eat.

In its first trial, the retailer first changed the colour temperature of the LED lighting strips in the chiller cabinets from a cool 4000K to a warm 2700K, but this only gained a few extra hours of product shelf life.

It’s long been known that the factors that accelerate discolouration include light, temperature, the oxygen in sealed packaging and being left in the same shelf position for too long, but getting the mix right is difficult in practice.

UK supermarket Coop had a particular problem: the pre-packed meats – including sliced hams, chicken, salami and chorizo – on the top shelves and close to the mullions started to discolour within 24 hours of shelf stacking.

So the company set about tackling the problem and began experimenting with the lighting.

In its first trial, the retailer first changed the colour temperature of the LED lighting strips in the chiller cabinets from a cool 4000K to a warm 2700K, but this only gained a few extra hours of product shelf life.

Next it evaluated the lighting levels. It found that dimming the lighting to around 50 per cent significantly reduced the discolouration of the meat, but crucially it also reduced the product’s visual appeal.

The company then discussed the issues with both its refrigeration cabinet supplier Epta and Philips Lighting to try to find an alternative that could work.

Attention then turned to the light distribution. Could this be optimised to light the products attractively without overlighting?

Philips began exploring the the optics of the LEDs. Could modifying the light emitters could reduce the problem?

Philips installed a version of its InteGrade narrow beam fixxtures which use the latest generation low-powered LED chips in a 30-degree narrow beam arrangement. It appeared to reduce hotspots, increase the light uniformity and improve the presentation of the  chilled goods, with no canopy lighting required. But would it preserve the look of the meat over time?

After 24 hours, there were no visible signs of discolouration. So far, so good.

After five days, there was still no discolouration on the top shelf, and only early signs of discolouration on the meats closest to the mullions.

By the eighth day, the meats closest to the mullions showed minimal discolouration, though still at acceptable levels.

Only by the thirteenth day did increased levels of discolouration appear.

The experiment was a huge success, and now Coop is rolling out the solution in all new installations.

The narrow beam versions have extremely small dimensions and are easy to  integrate into the doors and mullions of the vertical chillers.

Better still, energy use was reduced. Compared to the 118W top-down lighting in a typical 2.5m cabinet, the narrow beam approach uses 87W an energy saving of around 30 per cent.