Kinetics and thermodynamics of sucrose crystallization from pure solution at different initial supersaturations

Khaddour, Issam; Bento, Luís; Ferreira, António; Rocha, Fernando

doi:10.1016/j.susc.2010.04.005

Cited by 25 publications

(13 citation statements)

References 25 publications

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“…Two more experiments at the same initial relative supersaturation σ in = 0.185 and agitation speeds of 400 and 550 rpm were performed. °Brix vs. time plots for all the experiments were consistent and in a good agreement with the corresponding plots of other work [12], which was performed under the same experimental conditions, and at very similar www.crt-journal.org © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim initial supersaturations to the used ones in this work. Also overlapping of the °Brix vs. time plots of replicates for three runs was found, i.e.…”

Section: Methodssupporting

confidence: 89%

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Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Khaddour¹,

Rocha²

2011

Cryst. Res. Technol.

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Key words metastable zone width, interfacial free energy, nucleation, growth from solution.This study presents an evaluation of a new method, called zero growth activation free energy, used to determine the metastable zone width for the secondary nucleation case. It predicts the metastable zone width with a maximum error of 5-10%. Estimation of the metastable zone width for different isothermal crystallization conditions can be modeled according to a chosen reference set of growth experiments carried out in the volume diffusion regime at different initial supersaturations, using seed crystals of a certain characteristic size. Moreover, the activation free energy of the secondary nucleation was estimated. The role of the enthalpy of immersion in the formation of secondary nucleation events inside the metastable zone was pointed out, as well as its effect in causing extra-fast growth rate. Furthermore, sucrose crystal surface free energy was estimated.

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Section: Methodssupporting

confidence: 89%

“…Distinguishing between volume diffusion regime and surface integration regime is based on growth activation free energy values, as shown elsewhere [12]. Plotting the application of Birth and Spread model, for the experiments with initial relative supersaturations 0.133, 0.152.…”

Section: Resultsmentioning

confidence: 96%

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Khaddour¹,

Rocha²

2011

Cryst. Res. Technol.

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“…Furthermore, Faria et al [27] found, at 40 1C, negligible effects of the dextrans of molecular weights of range 5 Â 10 6 -40 Â 10 6 Da on the shape of sucrose crystal at concentrations of 0.5% and 1% (on a weight basis). As a conclusion, the same values of the shape factors of the pure sucrose crystals [22,28] are considered, and applied to estimate the growth rate of the sucrose from dextran-doped solutions, as this procedure does not change the final conclusions of the work. One reasonable support for this assumption comes from the analysis of the dextran content in the final sucrose crystals, using FPLC system, where the incorporated concentrations of the used dextrans in the final crystals were not detectable.…”

Section: Shape Factor Problemmentioning

confidence: 99%

“…At 40 1C, slight growth-enhancing effects due to the different dextrans were found. These general enhancing effects can be understood applying birth and spread model [28], which is applied in the form:…”

Section: Growth Rate Curvesmentioning

confidence: 99%

Sucrose crystal growth in the presence of dextran of different molecular weights

Khaddour

Ferreira

Bento

et al. 2012

Journal of Crystal Growth

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“…The type of elongation most commonly observed in cane sugar is in the C axis direction [23]. Sucrose crystallizes in supersaturated aqueous solutions [24]. The complete process of crystallization of sucrose consists of the formation of crystalline nuclei and their subsequent growth.…”

Section: Sucrose Crystallizationmentioning

confidence: 99%

Interferences of Sugarcane Glycoproteins on the Formation of Commercial Sucrose Crystals

Sánchez-Elordi¹,

Bałanda²,

Vicente³

et al. 2017

AFSE

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Abstract:The aim of the present work is to study the way in which defense glycoproteins, produced by sugar cane plants, retard and modify the crystallization pattern of sucrose. The effect of defense glycoproteins against smut on the crystallization of sucrose has been studied with preference. In general, these glycoproteins delay the appearance of the first nuclei, hinder the association of individual crystals to form agglomerates or star-like nuclei, and increase the degree of surface erosion of the formed crystals. Using defense glycoproteins labeled with fluorescein isothiocyanate, it has been observed that the adhesion of these glycoproteins to the sucrose crystals is carried out mainly on the edges thereof, never on their flat faces, and never penetrates inside them, although they may move along its outer surface. The fluorescence diffuses in the zones of rupture or abrasion, indicating that the appearance of such accidents releases the proteins adhered to the free solution.Key words: Crystallization, glycoproteins, impurities, sucrose, sugar cane. IntroductionWithin the large family of Poaceae, the genus Saccharum comprises six species characterized by different degrees of polyploidy. One of them, S. officinarum, is used in extensive cultures mainly to produce sucrose. Sugar metabolism in S. officinarum is directed to the synthesis and accumulation of sucrose in the parenchyma of the stems. Sugarcane produces sucrose in leaves from a part of the pool of hexose-P that are produced during photosynthesis. Sucrose-P synthase transfers a glucose moiety from UDPG to fructose-6-P to form sucrose phosphate, which is then dephosphorylated to sucrose by the corresponding phosphatase [1]. The sucrose formed will then be transported to the stem to be stored in their internodes or used, after its hydrolysis, in respiratory processes. During the ripening stage, any remaining glucose, fructose and other soluble carbon are converted back into sucrose for storage [2]. Secondarily, some soluble polysaccharides may transiently accumulate along with sucrose [3][4][5]. These polysaccharides can be naturally produced by the plant, such as starch [6] or to appear as a defense response against pathogens [7][8]. Anyway, they can interfere with the industrial process of crystallization of sugar, reducing the yield of its production and giving rise to obtain a product whose appearance and properties produce the rejection of the consumer. Therefore, knowing the origin of these polysaccharides and their attachment mechanisms to the sucrose crystals during the purification process is of vital importance in order to avoid irreversible economic losses. 2The Manufacture of Sucrose from Sugar Cane for Food IndustryThe manufacture of sugar for food industry can be summarized as follows [9]. To extract the juice, the cane stalks are crushed with rotary blades and a shredder before grinding to facilitate the extraction of the juice in the mills. Generally, between four and seven mills are used, passing the bagasse from one to another by mean...

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Kinetics and thermodynamics of sucrose crystallization from pure solution at different initial supersaturations

Cited by 25 publications

References 25 publications

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Metastable zone width for secondary nucleation and secondary nucleation inside the metastable zone

Sucrose crystal growth in the presence of dextran of different molecular weights

Interferences of Sugarcane Glycoproteins on the Formation of Commercial Sucrose Crystals

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