Seasonal variation of the agar quality and chemical composition of Gracilaria veleroae and Gracilaria vermiculophylla (Rhodophyceae, Gracilariaceae) from Baja California Sur, Mexico

Yield and physico-chemical properties of agar from Gracilaria veleroaeE.Y. Dawson and Gracilaria vermiculophylla (Ohmi) Papenfuss were studied and the chemical composition of the two seaweeds was determined. Samples were collected seasonally from summer 2003 to spring 2005. The agar yield did not vary significantly between seasons for both species. The lowest agar gel strength was obtained from G.veleroae (207.5gcm^-2) in summer 2003 and the highest from G.vermiculophylla (793.1gcm^-2) in winter 2004. Melting temperatures and hysteresis were higher in G.vermiculophylla, whereas gelling temperatures and 3,6-anhydrogalactose content were higher for G.veleroae. Moisture, ash, crude fiber, and ether extract showed no significant seasonal variation for G.veleroae. The chemical composition of G.vermiculophylla showed significant seasonal variation. G.vermiculophylla possesses a better agar quality than G.veleroae and is a species that could be considered as a source of agar for commercial use.