Chemical characteristics and gelling properties of agar from two Philippine Gracilaria spp. (Gracilariales, Rhodophyta)

Montaño, N. E.; Villanueva, Ronald D.; Romero, Jumelita B.

doi:10.1007/978-94-011-4449-0_67

Cited by 14 publications

(15 citation statements)

References 18 publications

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“…In addition, melting point was similar to G. tenuistipitata (Montaño, Villanueva, & Romero, 1999), G. arcuata (Montaño et al, 1999), G. corticate (Oyieke, 1993), G. crassa (Oyieke, 1993), G. millardetii (Oyieke, 1993) and G. salicornia (Oyieke, 1993). Melting point is reported to be positively correlated to pyruvic acid content of agar (Young et al, 1971), however further investigation is required as this factor was not analysed in present study.…”

Section: Alkali Treatmentmentioning

confidence: 42%

Agar extraction process for Gracilaria cliftonii (Withell, Millar, & Kraft, 1994)

Kumar

Fotedar

2009

Carbohydrate Polymers

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Section: Alkali Treatmentmentioning

confidence: 42%

Agar extraction process for Gracilaria cliftonii (Withell, Millar, & Kraft, 1994)

Kumar

Fotedar

2009

Carbohydrate Polymers

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“…For example, the highest gel strength for G. gracilis was in autumn-winter and for and G. bursa-pastori was in spring-summer even when the samples were collected in the same site and season (Marinho-Soriano and Bourret 2003). It is well documented that the increase in gel strength after alkaline treatment is related to the presence of an ester sulfate in the C-6 oxygen of the galactose unit linked in C-4, and these residues with this kind of substitution in the C-6 are precursors of 3,6-AG, and also that agars with high content of 3,6-AG produce strong gels and, vice versa, agars poor in 3,6-AG produce weak gels (Armisén 1995;Duckworth et al 1971;Montaño et al 1999). …”

Section: Discussionmentioning

confidence: 98%

Seasonal variation of agar from Gracilaria vermiculophylla, effect of alkali treatment time, and stability of its Colagar

Vergara-Rodarte¹,

Hernández‐Carmona²,

Rodríguez-Montesinos³

et al. 2010

J Appl Phycol

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Gracilaria vermiculophylla, from Baja California Sur, Mexico, was studied in order to determine the seasonal variation of yield and quality of native and alkaline agar during 2007-2008. The highest alkaline agar yield was obtained in summer (17%) and the highest gel strength in spring (1,132 gcm −2 ). The highest melting temperature was 98°C (winter). The highest gelling temperature was 68°C (summer). The values obtained are within the range of the most important Gracilaria species harvested worldwide. During the agar extraction step, the best results were obtained after 30 min of alkali treatment with sodium hydroxide (7%), after which the quality decreased significantly. We produced Colagar from G. vermiculophylla which consists of the seaweeds treated with sodium hydroxide and dried. The yield and quality of the agar obtained from the Colagar shows stability in both yield and quality during 1 year of storage, suggesting that alkali treatment is a good method of avoiding agar hydrolysis during storage.

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“…To the contrary, high 3,6-AG content has been previously reported to increase gel strength. Alkali treatment of either algal plants or agar has been shown to reduce sulphate, increase 3,6-AG content and hence increase gel strength in some Gracilaria species (Yenigül, 1993;Chirapart & Ohno, 1993;Givernaud et al, 1999;Montaño et al, 1999). It therefore appears that gel strength is not solely dependent on the 3,6-AG content.…”

Section: Seasonal Variation In Agar Qualitymentioning

confidence: 99%

Standing Stock, Agar Yield and Properties of <i>Gracilaria salicornia</i> Harvested along the Tanzanian Coast

Buriyo

Kivaisi

2004

West Ind. Oc. J Mar. Sci.

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Abstract-Seasonal biomass variation and agar yield of G. salicornia (C. Ag.) Dawson from Oyster Bay, Dar es Salaam, and Chwaka Bay, Zanzibar, were determined, and some properties of the agar examined. Mean biomass and canopy cover values ranged from 21-60 g/m 2 and 7-20 %, respectively. The highest mean biomass and cover values were obtained during the SE monsoon. Agar yield varied from 13.7 to 30.2 % (dry weight) and was highest during the dry NE monsoon period. Alkali treatment generally reduced agar yield by 25-56 %. Gel strength of the agar gels ranged between 118 and 251 g/cm 2 and was significantly higher during the NE monsoon period (t = 2.2; P = 0.04 and t = 8.9; P << 0.05) for samples collected from Oyster Bay and Chwaka Bay respectively). Mean gel strengths of native agar samples (205 ± 45 g/cm 2 ) was about 42 % of that of the standard agar used. The 3,6-anhydrogalactose content was highest during the rainy season (37.4-44.3 %) and tended to coincide with low gel strengths. Sulphate content varied between 0.5 and 2.8 % in both populations. It was concluded that the best period for harvesting G. salicornia for agar production in Tanzania is the dry (NE monsoon) period.

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Chemical characteristics and gelling properties of agar from two Philippine Gracilaria spp. (Gracilariales, Rhodophyta)

Cited by 14 publications

References 18 publications

Agar extraction process for Gracilaria cliftonii (Withell, Millar, & Kraft, 1994)

Agar extraction process for Gracilaria cliftonii (Withell, Millar, & Kraft, 1994)

Seasonal variation of agar from Gracilaria vermiculophylla, effect of alkali treatment time, and stability of its Colagar

Standing Stock, Agar Yield and Properties of <i>Gracilaria salicornia</i> Harvested along the Tanzanian Coast

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