The major high-street food multiples may be paying more attention than ever to the environmental impact of their packaging, but as their individual messages to consumers become clearer, so too do the differences between them.
Marks & Spencer (M&S) and Sainsbury are among those chains to have made significant advances in reducing packaging, especially transit and back-of-store systems. They have also increased their use of recycled materials and simplified packs to make them more readily recyclable. The M&S board sandwich pack actually features in a high-profile corporate social responsibility campaign.
But even in this sample of just two retailers, there is divergence in some major policy areas. While M&S took the decision years ago to exclude polyvinyl chloride (PVC), it does not discriminate against any other plastics, says packaging manager Helene Roberts.
Sainsbury, on the other hand, is explicitly favouring high density polyethylene (HDPE) and polyethylene terephthalate (PET), since there are established collection and recycling routes for these polymers.
New on-pack messages effectively tell the consumer that other plastics are unrecyclable. Roberts at M&S objects: "We should be asking how we can drive forward the market for these other materials."
In more general terms, she says: "By using recycled board and, increasingly, plastics, we're trying to close the loop." But for Sainsbury, in plastics at least, much more importance is being given to the 'recyclable' than the 'recycled' side of this equation.
In biodegradable plastics, Sainsbury recycling resource manager James McKechnie says: "We use the term 'compostable'. Our aim is for people to be able to compost at home." But for M&S, Roberts says: "We use polylactide (PLA) purely on the basis that it's from a renewable resource." Many packs which are biodegradable in certain environments are not home-compostable.
Both retailers have worked with the government-funded Waste & Resources Action Programme (WRAP) over recent months. Among other projects, M&S trialled closed loop PET recycling for its single-serve juices, and Sainsbury ran a similar trial with salad bowls.
WRAP special adviser Mark Barthel notes that Sainsbury and M&S were among 13 grocery retailers to undertake last summer's so-called Courtauld Commitment to cut food and packaging waste.
Of the two chains' approaches, he says: "It would be wrong to assume that they offer two fundamentally different views of retail packaging." He underlines Sainsbury's concern over recyclability in the post-consumer waste stream, and explains: "In the short to medium term this will probably mean a switch to PET and HDPE from materials like PVC and polypropylene."