Paper Title:Effects of Season on the Yield and Properties of Agar from GRACILARIA CORTICATA


Agars are well-known as water-soluble, gel-forming polysaccharide extracts from agarophyte members of red seaweeds. Gracilaria corticata is one of the naturally occurring agarophytes of Indian waters. Seasonal changes in the yield and properties of agar were studied from Gracilaria corticata growing at Tuticorin coast, Gulf of Mannar. Plants were collected during the seasons of premonsoon, monsoon and postmonsoon. Agar yield, gel strength, gelling and melting temperatures, sulphate and 3,6 anhydrogalactose content were determined. Carbohydrate content was measured from algal tissue. There was a clear seasonality in the yield and properties of agar. Agar yield of Gracilaria corticata ranged between 6.9% and 33.5%. Agar yield increased from premonsoon to monsoon season and lowest yield was found in the postmonsoon season. Gel strength ranged between 42 and 69 g cm-2. Gel strength decreased from premonsoon to monsoon and was highest during the postmonsoon season. An inverse relationship was found between agar yield and gel strength. The gelling and melting temperature ranged from 35oC to 38oC and 56.5oC to 70.5oC respectively. Maximum content of 3,6 anhydrogalactose and sulphate were observed in monsoon season. The result indicates clear seasonal variations in yield and properties of agar from Gracilaria corticata.

Keywords:Agar yield, Gel strength, Melting and gelling temperatures, 3,6-anhydrogalactose.