Aspartic proteases from thistle flowers: Traditional coagulants used in the modern cheese industry

Abstract

Thistle flowers are traditional coagulants that have been used for many years in southern Europe and northern Africa for cheese production. The flowers contain aspartic proteases (APs) with high milk-clotting and cheeses produced with the vegetable coagulants tend to have a creamier and softer texture and more intense odour and flavour compared with those made with commercial chymosin or calf rennet. This review provides an overview of structural characteristics of the APs and their functional properties such as pH and temperature-dependence of their enzyme activity, substrate specificities, and technological applications, with a focus on cheese manufacturing. The review also refers to recent achievements on in vitro production of the APs present in thistle flowers using recombinant enzyme technologies. These techniques could be considered as promising strategies to scale up the production of plant APs to strengthen the industrial applications of the vegetable enzymes.