Addressing the challenge of how the industry can navigate the shift to net zero emissions, Murphy told the Reuters Impact conference it had to strike a balance, for example cutting the use of plastic packaging without increasing the food waste that might follow.
Asked if customers were willing to pay higher prices for more sustainable goods, Murphy replied: "I think there is always a small proportion of very committed customers who are willing to pay a premium, but actually the vast majority are not is the honest truth.
"What our customers expect us to do is find ways to innovate, to make sustainable products for them."
Investors, he said, also insist that supermarkets increasingly focus on environmental goals but did not want to see a lower return on their investment as a consequence.
"So we're constantly juggling these priorities, and hopefully doing a decent job," he said.