Colors can change shade, or metamerize, under different light sources, so when Harfouch hits on a perfect match he has to be sure it looks the same under sunlight as it does under artificial, supermarket light.

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But some in the food industry, including Kellogg's, a cereals manufacturer, and Tesco, a supermarket, say that traffic-light labelling is too simplistic.

ECONOMIST: Junk food

Supermarket giant Tesco has recently been given a green light to build Britain's first ever straw-powered Combined Heat and Power (CHP) plant to meet the electricity and heating needs of one of its distribution centres.

BBC: Time to encourage biomass growth