Chemical composition of agars from a newly reported Japanese agarophyte, Gracilariopsis lemaneiformis

Abstract

The chemical composition of agars from Gracilariopsis lemaneiformis, newly reported from Japan, was investigated. Native agars were isolated by a sequential extraction of plants in water at 22 °C and 100 °C, and in boiling 20, 40 and 60% ethanol. Agars in each extract were analyzed by chemical methods, H, 3 C NMR; and IR spectroscopy. The highest yield of agar (total carbohydrate) was obtained from the 40% ethanol extract (55%). Highest sulfate content was attained in non-alkali treated agars extracted with hot water (4.81 %, DS 0.2). The 3,6-anhydrogalactose content was highest in the 40% ethanol extract (36.1% in non-alkali treatment, 40.3% in alkali treatment). The highest methoxyl content (6.51%, DS 0.66) was obtained in the 60% ethanol extract. The G. lemaneiformis agar is composed of the biological precursor to agarobiose repeating units and agarobiose containing 6-0-methyl agarobiose and a small amount of 2-0-methyl-a-L-galactopyranose residues. Alkali treatment improved the chemical quality of the agar fractions, which was comparable with Japanese commercial agar and agarose.

Microstructure and mechanical properties of soy protein/agar blend films: Effect of composition and processing methods

“…The peaks at 2890 cm À1 associated with methoxyl groups (Armisén and Galatas, 1987), 1641 cm À1 caused by stretching of the conjugated peptide bond formed by amine (NH) and acetone (CO) groups (Cristiaen and Bodard, 1983), 1376 cm À1 attributed to ester sulfate (Armisén and Galatas, 1987), and 890 cm À1 attributed to the CAH of residual carbons of b-galactose were also observed (Matsuhiro, 1996). However, differences were found from the characteristics agar bands between 1070 and 930 cm À1 (associated with the CAO of 3, 6-anhydro-galactose bridges) (Chirapart et al, 1995). Characteristics bands at 1074, 1051 and 932 cm À1 of NAG slightly red-shifted to 1070, 1046, 929 cm À1 after plasticizing with glycerol, indicating certain interactions (hydrogen-bonding) existed.…”

Elastic and macroporous agarose–gelatin cryogels with isotropic and anisotropic porosity for tissue engineering

“…The viscosity of agarose can be controlled by the partial acid hydrolysis using acetic acid solutions in different concentration and using different time periods of heating. Normally, partial acid hydrolysis of agarose showed significant effect on the physical properties like reduced mechanical strength of the gel 48. However, the gel synthesized in acetic acid solution showed better gel strength in comparison with the gel treated with other acid solutions (i.e., sulfuric acid, oxalic acid, and citric acid) of same normality 48…”

Preparation and application of agar/alginate/collagen ternary blend functional food packaging films

“…An intense peak at 1610 cm −1 was corresponding to C O stretching of amide I peak [30]. The peak at 1373 cm −1 was assigned to ester sulfate and the bands at 1070 and 960 cm −1 were associated with the 3,6-anhydro-galactose bridges [31]. The band at 1149 cm −1 was due to vibration mode of ester-sulfate link vibrations and the small signal at 854 cm −1 was assigned to the sulfate in C-4 from galactose [32,33].…”