QUINOA'S tricky pronunciation (keen-wah) has not stopped it from taking over salads in kitchens, cafés and supermarkets. The grain used to be the preserve of Andean peasants, but is now hailed for its high protein content by opinion-formers from Oprah Winfrey to the United Nations. Some even celebrated 2013 as the International Year of Quinoa. But since 2014 the price of quinoa has been plunging. Why?
