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Effect of alkali treatment of red algae Gracilaria blodgettii and Gracilaria verrucosa (Rhodophyta) on agar quality

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Title Effect of alkali treatment of red algae Gracilaria blodgettii and Gracilaria verrucosa (Rhodophyta) on agar quality
 
Creator Sasikumar, C.
Rao, V.N.R.
Rengasamy, R.
 
Description 191-194
The agarophytes Gracilaria blodgettii(Harvey) and G. verrucosa(Huds.)Papenfus from the Madras coast, were analyzed with and without pre-alkaline treatment(0.5, I, 2, 4, 6 and 8 N of NaOH) for the physical and chemical properties of their agar. Prealkaline treatment of both algae increased the gelling potential of the agar but reduced the yield. The yield of agar under various treatments ranged from 6.0-21% and 7.0-24% of dry weight in G. blodgettii and G. verrucosa respectively. The highest gel strength in 1.5% agar (414 g cm(-2)) was obtained when samples were treated with strong alkali [8 N] and the lowest (42 g cm(-2)) in untreated samples of G. blodgettii. Alkali treatment increased the melting and the gelling temperatures from 87 degrees C to 101 degrees C and 38 degrees C to 49 degrees C respectively. Of the two algae, G. blodgettii showed high values of 3,6-anhydrogalactose (49.0% dry wt) and galactose (34.7% dry wt) at 8 N and 0.5 N alkali treatment respectively. The amount of sulphate in the agar samples of both species showed an inverse relationship to alkali treatment. Shade dried samples showed a higher agar yield and gel quality compared with sun dried samples. The get strength of agar from G. blodgettii when treated with mild alkali (0.5 N NaOH) at 80 degrees C for 1 h was similar to that of bacteriological grade (Hi Media) agar. Proving that G. blodgettii and G. verrucosa could also be a good source material for commercial production of agar.
 
Date 2016-10-26T10:03:33Z
2016-10-26T10:03:33Z
1997-06
 
Type Article
 
Identifier 0975-1033 (Online); 0379-5136 (Print)
http://nopr.niscair.res.in/handle/123456789/36254
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJMS Vol.26(2) [June 1997]