As an entree to Michael Moss’s excellent new book, try this experiment. Imagine or place two bowls in front of you: One with potato chips; the other with whole walnuts. Make sure they are both good quality brands and fresh from a never-opened bag. Sample a walnut first. Enjoy how its initial slightly bitter crunch transforms into something soft, buttery, faintly woodsy. Next munch a potato chip. Its flavour is less complex than the walnut’s, but every chip instantly delivers an intense combination of salt, sugar and fat. They are so crispy you can hear them snap between your teeth, and then they miraculously dissolve into nothingness on your tongue, making you want another. And another. And another.