World-wide use and importance of Gracilaria

Abstract

The world's first source of agar, from the middle of the seventeenth century, was Gelidium from Japan, but by the beginning of the twentieth century demand for the phycocolloid exceeded of the supply of this alga. Since then Gracilaria has played an important role in the production of agar. Currently agars are obtained from five genera in three orders of red algae and marketed as ‘natural agar’ in squares or strips or as ‘industrial agar’ in powder form. The development of production processes through alkaline hydrolysis of sulphates has allowed a good quality food agar to be obtained from Gracilaria. This does not show the synergistic reaction with locust bean gum apparent with Gelidium agar. The term ‘agaroids’ is applied to Gracilaria agars produced without alkaline hydrolysis of sulphates, with greater sulphate content and much less gel strength. Unlike Gelidium, Gracilaria has to be processed in a short period of time and cannot be allowed to remain in storage for use during years of lower availability. Statistics of imports of agarophytes to Japan during the last 10 years give an indication of the state of the market. During this period there was a marked reduction in Gracilaria imports, mainly from Chile, but also the Philippines, Indonesia and South Africa, mainly due to the overall increase in the capacity of agar production in Gracilaria-producing countries.