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Phylum Class Order Family Genus Species Rhodophyta Florideophyceae Gelidiales Gelidiaceae Gelidium Gelidium sesquipedale Gelidium amansii Gelidium robustum Gelidium pristoides Gelidium canariense Gelidium rex Gelidium chilense Gelidiella Gelidiella Pterocladia Pterocladia capillacea Pterocladia lucida Gracilariales Gracilariaceae Gracilaria Gracilaria chilense Gracilaria gigas Gracilaria edulis Gracilaria gracilis Gracilaria tenuistipitata Gracilariopsis Gracilariopsis lamaneiformis Gracilariopsis sjostedtii Ahnfeltisles Ahnfeltiaceae Ahnfeltia Ahnfeltia plycata

5.3 Agar Manufacturing

      Japanese used to called agar, Kanten, ‘frozen sky’, based on its origin of site. In 1658 Tarazaemon Minoya recorded that Japanese freeze and thaw extracted agar in open fields during winters and observed that agar is insoluble when it is cold. This traditional technique described by Minoya is even now in trends in natural oriental craft industries to produce natural agar worldwide. The agar produced by this technique is called strip agar and square agar [10]. In this procedure G. amansii was washed carefully using the same devices which were used in washing the tea-leaves. After leaves were washed using fresh water, they were handpicked to avoid any foreign contamination like unrelated agarophyte algae then agar was extorted by water (100 °C) and with balanced pH by using vinegar or sake. The extract was filtered with muslin cloth bags and then it was made to dry on timber trays. The dried extract was then cut into squares or into strips and later allowed to gel by freezing throughout a night or two in open fields. Later this agar was thawed and moistened using water sprinklers and dried again in sun and stored. Till 1960 there were approximately 400 artisan operating plants in production which used to produce eight to twenty-two pounds per day, depending upon the weather throughout the year.

      In modern time, industrial agars are produced in very controlled conditions. The best industrial plant setups follow ISO-9000 norms, assuring quality of the product as well its traceability. Like availability of the raw materials to the shipped finished product.

      5.3.1 Types of Agar Manufacturing

       5.3.1.1 Freeze–Thaw Method

      Freezing–thawing method was the oldest traditional method for agar production globally until 1939. In 1939 an American company named, American Agar & Co. (San Diego, USA) began manufacturing it in chilling containers like ice blocks. After World War-II, Japan started to use same technique and built new plant. Other countries like Portugal, Spain and Morocco followed the same. The extracted seaweed, which traditionally contained 1–1.2% of agar, was concentrated by thawing and straining and making it 10–12%, which was tenfold increase. All the oligomers, organic and inorganic salts and other seaweed proteins like phycoerytrins (a protein that gives red color to Rhodophyceae family) washes away with eluted water.

       5.3.1.2 Syneresis Method

      In this process, the gelling

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