Fractionation of Starch by Selective Precipitation with Butanol

Schoch, Thomas John

doi:10.1021/ja01264a065

Cited by 309 publications

(105 citation statements)

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“…This mutual enhancement of adsorption by guar gum and xanthate is suggestive of an association between them. Evidence for similar association between surfactants and starch has been reported and a non-polar type of bonding has been suggested with the surfactant molecules occupying a position inside the starch helix with their long axes parallel to the helix axis [34][35][36][37]. Such a mechanism with the xanthate held inside the guar gum can also explain the observed enhanced adsorption of xanthate at the chalcopyrite-solution interface in the presence of guar gum without rendering the chalcopyrite surface hydrophobic.…”

Section: Depression Mechanismssupporting

confidence: 58%

Studies on the Interaction of Guar Gum With Chalcopyrite

Rath¹,

Subramanian²,

Sivanandam³

et al. 2001

Canadian Metallurgical Quarterly

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-Adsorption, electrokinetic and flotation studies have been carried out to investigate the interaction of guar gum with chalcopyrite. The adsorption density of guar gum onto chalcopyrite shows a weak adsorption maximum at pH 9.5. The adsorption isotherms exhibit Langmuirian behaviour. The electrophoretic mobilities of chalcopyrite are decreased in proportion to the added concentration of guar gum. Flotation tests reveal that guar gum depresses chalcopyrite in agreement with the adsorption data. Dissolution experiments indicate release of lattice metal ions from chalcopyrite, while co-precipitation and conductivity tests confirm guar gum-metal ion interaction in the bulk solution. The pH of maximum co-precipitation between guar gum and copper species is observed in the range 9-9.5. The adsorption process is governed primarily by chemical interaction between the hydroxyl groups of guar gum and hydroxylated chalcopyrite apart from hydrogen bonding. Fourier Transform Infrared Spectrometer (FTIR) and X-ray Photoelectron Spectroscopic Studies (XPS) provide evidence in support of the interaction mechanisms proposed.Résumé -On a exécuté des études d'adsorption, d'électrocinétique et de flottation afin d'examiner -l'interaction de la gomme de guar avec la chalcopyrite. La densité d'adsorption de la gomme de guar sur la chalcopyrite montre un maximum d'adsorption faible à un pH de 9.5. Les isothermes d'adsorption exhibent un comportement langmuirien. Les mobilités électrophorétiques de la chalcopyrite diminuent en proportion de la concentration de gomme de guar. Les tests de flottation révélent que la gomme de guar déprime la chalcopyrit, en accord avec les données d'adsorption. Les expériences de dissolution indiquent un reléchement des ions métalliques du réseau de la chalcopyrite, alors que des tests de co-pré-cipitation et de conductivité confirment l'interaction gomme de guar -ion métallique dans la solution en vrac. Le pH de co-précipitation maximum entre la gomme de guar et les espéces de cuivre se trouve entre 9 et 9.5. Le procédé d'adsorption est gouverné principalement par l'interaction chimique entre les groupes hydroxyles de la gomme de guar et la chalcopyrite hydroxylée, à l'écart des liens hydrogénes. Les études par FTIR et XPS fournissent l'évidence supportant les mécanismes d'interaction propoés.

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Section: Depression Mechanismssupporting

confidence: 58%

Studies on the Interaction of Guar Gum With Chalcopyrite

Rath¹,

Subramanian²,

Sivanandam³

et al. 2001

Canadian Metallurgical Quarterly

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“…As the reported amylose contents of potato and maize starches are of the order of 22 per cent. (Schoch 1942b), the results are consistent with the view that the amylose fraction accounts for the activity of natural starches. As the butanol-soluble fractions were not free from amylose, it is possible that such activity as they had was due to their amylose content.…”

Section: (C) Experiments On the Mode Of Action Of Starchsupporting

confidence: 90%

“…(iv) Comparison of Amylose and Amylopectin Fractions.-Samples of potato and maize starches were fractionated by the butanol solubility method of Schoch (1942b), the maize starch being first extracted with methanol. The activity of the butanol-insoluble (amylose) and butanol-soluble (amylopectin) fractions was compared with the parent starch.…”

Section: (C) Experiments On the Mode Of Action Of Starchmentioning

confidence: 99%

The Enumeration of Heated Bacterial Spores

Olsen¹,

Scont²

1950

Aust. Jnl. Of Bio. Sci.

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SummaryExperiments with 13 strains of types A and B Cl. botulinum have shown that the detection and enumeration of spores surviving lethal heating become increasingly difficult as the period of heating is increased. Media which are very satisfactory for enumerating unheated spores may be unsatisfactory for enumerating spores which survive the heat treatment. By comparison with unheated spores the numerical estimates of spores surviving severe heat treatments were more dependent on thioglycollate in the medium and on the pH and temperature during incubation. As the amount of heating was increased, the surviving spores became progressively more sensitive to inhibitors· in the medium. These inhibitory substances were present in all media used, and their effects were counteracted under a wide range of conditions by the incorporation of approximately 0.1 per cent. starch in the medium. The starch supplement produced no significant effect on the estimates of unheated spores. The effects of starch are a feature of the amylose portion of the undegraded starch molecule which, like charcoal or serum albumin, acts by adsorbing inhibitors from the medium. The probability that at least part of the inhibition is due to unsaturated fatty acids is discussed.The heated spores of several other species of Clostridium show a similar response to the inclusion of starch in the medium.

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“…The method of amylose purification was based on that of Schoch (1942). Starch (1.33 g) was heated in 100 mL of distilled water at 100ЊC until gelatinized.…”

Section: Partial Purification Of Amylose Using Butanolmentioning

confidence: 99%

Discrete Forms of Amylose Are Synthesized by Isoforms of GBSSI in Pea[W]

Edwards

Vincken²,

Suurs³

et al. 2002

The Plant Cell

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Amyloses with distinct molecular masses are found in the starch of pea embryos compared with the starch of pea leaves. In pea embryos, a granule-bound starch synthase protein (GBSSIa) is required for the synthesis of a significant portion of the amylose. However, this protein seems to be insignificant in the synthesis of amylose in pea leaves. cDNA clones encoding a second isoform of GBSSI, GBSSIb, have been isolated from pea leaves. Comparison of GBSSIa and GBSSIb activities shows them to have distinct properties. These differences have been confirmed by the expression of GBSSIa and GBSSIb in the amylose-free mutant of potato. GBSSIa and GBSSIb make distinct forms of amylose that differ in their molecular mass. These differences in product specificity, coupled with differences in the tissues in which GBSSIa and GBSSIb are most active, explain the distinct forms of amylose found in different tissues of pea. The shorter form of amylose formed by GBSSIa confers less susceptibility to the retrogradation of starch pastes than the amylose formed by GBSSIb. The product specificity of GBSSIa could provide beneficial attributes to starches for food and nonfood uses.

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Fractionation of Starch by Selective Precipitation with Butanol

Cited by 309 publications

References 0 publications

Studies on the Interaction of Guar Gum With Chalcopyrite

Studies on the Interaction of Guar Gum With Chalcopyrite

The Enumeration of Heated Bacterial Spores

Discrete Forms of Amylose Are Synthesized by Isoforms of GBSSI in Pea[W]

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