Experimental cultivation of <em>Gelidium pusillum</em> in open sea along the south east Indian coast

336-345Experimental cultivation of Gelidium pusillum was attempted in the south east coast of India with three different cultivation methods to enhance the biomass production for obtaining superior quality agar with high gel strength. The maximum biomass yield (0.465 ± 0.34 kg.fr.wt m-2) was recorded in net bag method whereas minimum biomass yield (0.144 ±0.03 kg.fr.wt m-2) was recorded by net pouch method. Similarly, Daily Growth Rate (DGR) was more in net bag method (1.05 ± 0.529 %) than raft (0.679 ± 0.13 %) and net pouch (0.56 ± 0.256 %).  Furthermore, best quality agar was obtained by net bag method [high gel strength: 2100 ± 50 g cm-2 in 1.5 % gel; gelling temperature: 35 ± 1 oC; ash content: ≤1 %; sulphate content: ≤0.34 %] essential for potential superior quality agar applications

Factors affecting yield and gelling properties of agar

Agar, a gelatinous polysaccharide in the cell wall of many red algal species, is widely used as a gelling, thickening and stabilizing agent. The commercial value of seaweed is judged by their agar content and gel quality. Seaweed materials with higher agar yield and better gelling properties are desired due to the growing demand for agar in the global market. Agar biosynthesis in seaweeds is affected by genetic variations, developmental stages and environmental conditions, while different agar extraction techniques can also affect the yield and quality of agar. In this paper, the effects of different physiological states of seaweed, abiotic and biotic factors, seaweed storage and agar extraction techniques on the agar yield and gelling characteristics, are reviewed. This information is important as a guide for marine aquaculture of potential agarophytes and the possible effects of climate change on the stock of this natural resource