Abstract ▼ AI-Helper

Marine algae are harvested or cultivated for the extraction of gelatinous materials such as carrageenan, alginate and agar collectively known as hydrocolloids or phycocolloids. Agar has a various application fields including the manufacture of foodstuff, pharmaceuticals, cosmetic products, and also ...

Marine algae are harvested or cultivated for the extraction of gelatinous materials such as carrageenan, alginate and agar collectively known as hydrocolloids or phycocolloids. Agar has a various application fields including the manufacture of foodstuff, pharmaceuticals, cosmetic products, and also in biological and medical research. Commercial grade agar and agarose are mainly obtained from the red algae, Gelidium and Gracrilaria species. Generally, Gelidium species have been exploited because of the high quality of their agarocolloids, while Gracilaria species produces agar with low quality due to their high sulphate concentrations. For this reason, the gel properties of many Gracilaria agar can be improved by alkali treatment.
The objective of this study was to investigate the influence of alkaline soaking using NaOH at different concentrations on yield and physicochemical properties of hydrogel from domestic non-edible G. verrucosa. Next, the alkaline soaking extraction and microwave thaw were applied to prepare agar with short process time and the development of simple production process. Then, the preparation of agarose from agar by further purification process was tried. First, mineral contents of the domestic algae were analyzed to find out its suitability for food. Proximate composition analysis showed a little fluctuation of carbohydrate contents with harvesting periods during March and May 2015. Agar extraction time was determined to be 120 min at 121℃ for a maximum yield. The yield of agar was maximum in 3% alkali concentration (34.8%) and minimum 1% alkali concentration (17%). Agar gel strengths fluctuated from 462 to 662 g cm-2. Algae to water ratio was optimum at 1:30 based on yield, gel strength, melting point, and gelling point. FT-IR and NMR analysis has been done to confirm the right structure of agar. The gel strength of the agar produced in this study showed rather comparable to commercial agar. The turbidity should be improved to be used in food and medical purposes. Agarose extraction was performed to produced much purified form of hydrogel. In summary, this study produced high value product of agr from cheap bioresource using alkali soaking extraction and microwave thawing method. Process time has been shortened and the process cost could be lower than the conventional method. For future works, some comprehensive analysis should be done to find out the mechanism of melting and gelling and a scale-up of the process will be studied before the pilot plant test of the process.