ISSN:
1573-5176
Keywords:
steam explosion
;
agar
;
Gracilaria dura
;
Gracilariaceae
;
Rhodophyta
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Steam explosion was investigated as a pretreatment step in the isolation of agar from the macroalgaGracilaria dura. As compared to conventional procedures, the yield of agar obtained using this method on alkali (Na2CO3) conditioned algal material was higher. Extractions performed first at 95 °C and then at 121 °C showed that the major fraction of the agar was extracted at 95 °C, independently of the pretreatment. The efficiency of sulphate hydrolysis during steam explosion ofG. dura previously conditioned in Na2CO3, was similar to that of a NaOH based alkali pretreatment. Except for a lower nitrogen content of the sample obtained after NaOH based alkali pretreatment and a higher 6-O-methyl-β-d-galactose content in the agar after steam explosion, the chemical composition of the agars showed no significant difference. Agars extracted after steam explosion had melting temperature, gel strength and apparent modulus of elasticity lower than those of corresponding ‘native’ and alkali (NaOH) pretreated samples, but comparable to those of a commercial sample.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02182734
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