Citric acid: emerging applications of key biotechnology industrial product.

Owing to new biotechnological production units mostly located in China, global supply of citric acid in the course of the last two decades rose from less than 0.5 to more than 2 million tonnes becoming the single largest chemical obtained via biomass fermentation and the most widely employed organic acid. Critically reviewing selected research achievements and production trends, we identify the reasons for which this polycarboxylic acid will become a key chemical in the emerging bioeconomy.Graphical abstractPalermo's Fabbrica Chimica Italiana Goldenberg today. In 1930 it was Europe's largest citric acid plant (photo courtesy of Aldo Ferrande).