Structural, Physical, and Chemical Modifications Induced by Microwave Heating on Native Agar-like Galactans

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• 作者：Ana M. M. Sousa ; Simone Morais ; Maria H. Abreu ; Rui Pereira ; Isabel Sousa-Pinto ; Eurico J. Cabrita ; Cristina Delerue-Matos ; Maria Pilar Gon莽alves
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2012
• 出版时间：May 16, 2012
• 年：2012
• 卷：60
• 期：19
• 页码：4977-4985
• 全文大小：367K
• 年卷期：v.60,no.19(May 16, 2012)
• ISSN：1520-5118

文摘

Native agars from Gracilaria vermiculophylla produced in sustainable aquaculture systems (IMTA) were extracted under conventional (TWE) and microwave (MAE) heating. The optimal extracts from both processes were compared in terms of their properties. The agars鈥?structure was further investigated through Fourier transform infrared and NMR spectroscopy. Both samples showed a regular structure with an identical backbone, 尾-d-galactose (G) and 3,6-anhydro-伪-l-galactose (LA) units; a considerable degree of methylation was found at C6 of the G units and, to a lesser extent, at C2 of the LA residues. The methylation degree in the G units was lower for MAE^opt agar; the sulfate content was also reduced. MAE led to higher agar recoveries with drastic extraction time and solvent volume reductions. Two times lower values of [畏] and M_v obtained for the MAE^opt sample indicate substantial depolymerization of the polysaccharide backbone; this was reflected in its gelling properties; yet it was clearly appropriate for commercial application in soft-texture food products.

Keywords:

native agars; microwave irradiation; conventional heating; structural analysis; physicochemical properties; Gracilaria vermiculophylla