Biblid: 1821-4487 (2014) 18; 3; p 119-122
UDK: 582.661.15
Original Scientific Paper
Originalni naučni rad
THE EFFECT OF CALCIUM SULPHATE, ALUMINIUM SULPHATE
AND POLYELECTROLYTE ON SEPARATION OF PECTIN
FROM THE SUGAR BEET JUICE
UTICAJ KALCIJUM SULFATA, ALUMINIJUM SULFATA I
POLIELEKTROLITA NA IZDVAJANJE
PEKTINA SOKA ŠEĆERNE REPE
Tatjana KULJANIN*, Biljana LONČAR*, Milica NIĆETIN*, Vladimir FILIPOVIĆ*, Violeta KNEŽEVIĆ*, Jasna GRBIĆ**
*
University of Novi Sad, Faculty of Technology, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia
**
University of Novi Sad, Institute for Food Technology, Bulevar Cara Lazara 1,
21000 Novi Sad, Serbia
e-mail: [email protected]
ABSTRACT
In the sugar industry, calcium ions (in the form of CaO) that are commonly used to eliminate the pectin from beet juice have a
relatively low binding affinity. The quantities of used lime are very large (15 g/100 g juice). The precipitation of pectin could be
achieved by the charge neutralization. Compounds with bi- and trivalent cations such as CaSO4 and Al2(SO4)3 could be used to extract pectin from colloidal systems. Application of polyelectrolyte previously referred to the improvement of flocculation in water
treatment and sugar cane juice.Model - pectin solutions (50 cm3 and 0.1 % wt.) were treated with different concentration of CaSO4
and Al2(SO4). Optimal amounts of applied coagulants, determined using measurements of zeta potential were: 410 mg/dm 3 for CaSO4
and 110 mg/dm3 for Al2(SO4)3.By adding a cationic polyelectrolyte (1, 3 and 5 mg/dm3), the most efficient separation of pectin was
achieved with polyelectrolyte concentration 3 mg/dm3. Adding this type polyelectrolyte, amounts of applied coagulants required for
charge neutralization (zero zeta potential) were reduced. These amounts were 460 mg CaSO4 and 128 mg Al2( SO4)3/g pectin and significantly less than the amount of CaO used in the conventional process of sugar beet juice clarification (9 g/g pectin).
Key words: calcium and aluminium sulphate, pectin, sugar beet, zeta potential.
REZIME
U industriji šećera, kalcijumovi joni (u vidu CaO) koji se najčešće koriste za ukljanjanje pektina iz soka šećerne repe imaju relativno mali afinitet vezivanja. Količine kreča upotrebljene u tu svrhu su vrlo velike (oko 15 g CaO/100 g soka). Taloženje pektina moglo
bi se izvoditi procesom razelektrisanja pektinskih čestica hemiskim putem. Naime, jedinjenja sa dvo- i trovalentnim katjonima kao što
su CaSO4 i Al2(SO4)3 mogla bi se upotebiti za izdvajanje pektina iz koloidnih sistema. Aluminijum sulfat se najčešće koristi u obradi
otpadnih voda dok se primena polielektrolita (katjonskih i anjonskih) dosad odnosila na poboljšanje flokulacije u obradi otpadnih
voda i soka šećerne trske.Model-rastvori pektina (zapremine 50 cm3 i koncentracije 0,1 % mas.) tretirani su sa 7 različitih
koncentracija rastvora CaSO4 i Al2(SO4)3. Optimalne količine primenjenih koagulanata, određivane metodom merenja Zeta
potencijala iznosile su: 410 mg/dm3 rastvora (CaSO4) i 110 mg/dm3 rastvora (Al2(SO4)3 .Dodavanjem katjonskog polielektrolita
(MAGNAFLOC LT-24, koncentracije 1, 3 i 5 mg/dm3) u pektinske rastvore, najveća efikasnost izdvajanja pektina postignuta je sa
koncentracijom polielektrolita 3 mg/dm3. Dodavanjem ovog tipa polielektrolita, smanjile su se optimalne količine primenjenih
koagulanata neophodnih za razelektrisanje pektinskih čestica (nulti Zeta potencijal). Ove količine su iznosile 460 mg/gpektina (CaSO4) i
128 mg/gpektina (Al2(SO4)3) i značajno su manje od prosečne količine CaO koji se upotrebljava u klasičnom procesu čišćenja soka
šećerne repe (oko 9 g/gpektina).
Ključne reči: kalcijum i aluminijum sulfat, pektini, šećerna repa, zeta potencijal
INTRODUCTION
Separation of non-sucrose compounds, above all pectin, from
sugar beet juice is mostly done by CaO in form of Ca(OH)2.
However, in sugar industry, great amounts of this compound are
needed, but this can have a negative consequence on surrounding
soil and lead to its alkalization (Haapala et al., 1996). It is well
known that pectin, proteins and other colloidal particles in
solution like sugar beet juice are negatively charged which
prevents their coagulation and precipitation. Addition of
oppositely charged ions with higher valence would lead to
neutralization of these macromolecules. In this way stabilization
of the system would be disturbed and conditions for coagulation
and precipitation would occur (Lević et al., 2007; Schneider et
al., 2011, Kuljanin et al., 2013). The most efficient method for
Journal on Processing and Energy in Agriculture 18 (2014) 3
monitoring the process of colloidal particles neutralization is
zeta potential measurement. It is know that every particle in
colloidal solution is surrounded with double electrical layer
consisting of static and diffusion layer. Zeta or electrokinetical
potential is easily measurable size and represents the difference
between the potential of diffusion and stationary layer (Koper,
2007; Kuljanin et al., 2010, Kuljanin et al., 2013).
Addition of Ca2+ ions leads to charge neutralization when
electrostatic interactions occur between these ions and
negatively charged side chains of polysaccharides in pectins.
Presence of Ca2+ ions, in hydrophilic macromolecules (such as
pectin and proteins) causes significant decrease of hydration
which is, in addition to the charge neutralization, a precondition
for more rapid coagulation and precipitation of these
macromolecules (Garnier et al., 1994). In the article of Kuljanin
119
Kuljanin, Tatjana et al./The Effect of Ca-Sulphate, Al-Sulphate and Polyelectrolyte on separation of Pectin from the Sugar Beet Juice
et al. 2014, the effect of calcium compounds, CaSO4 and
Ca(OH)2 under the same experimental conditions was studied. It
was found that Ca2+ ions attached to SO4- anions show higher
binding affinity for the polysaccharide pectin than Ca2+ ions
associated with (OH)1- anions which are used in the traditional
processing of sugar beet juice. In a previous paper (Lević et al.,
2007), negligible differences were reported in the strength of
CaSO4 and CaCl2 binding with pectin macromolecules.
Aluminium salts, in the form of hydrolysed salt Al2(SO4)3,
are commonly used for purification of fresh and waste water
(Duan and Gregory, 2003; Duan et, al., 2002). Lipets and Oleinik in 1972 in Russia examined aluminum sulfate and aluminum
chloride as sugar beet extract clarificants. They reported on the
use of aluminum salts in sucrose extraction and juice clarification in the sugar factory extensively.
By studying the bonding strength of various metal ions with
humic materials in water, it was found that Al3+ ions are 6 – 7
times more efficient than Ca2+ ions (Kinniburgh et al., 1999).
Al2(SO4)3 was also proved to be effective in the chemical
processing of molasses (Lević et al., 2005). In this paper,
optimal amounts of Al2(SO4)3 were determined by zeta potential
measurement method.
Coagulation
and
precipitation
of
undesirable
macromolecules (such as pectin of sugar beet juice) can be
improved by using high molecular weight polyelectrolyte. They
act by inter-particle bridging mechanism when the particles are
adsorbed within the polymer chains of polyelectrolyte (Kuljanin
et al., 2012a; Hilal et al., 2008; Pattabi et al., 2000).
Polyelectrolyte (cationic and anionic), are commonly used for
purification of waste water (Baraniak & Walerianczyk, 2003,
Pattabi et al., 2000) as well as for improvement of the
flocculation in sugar cane juice processing (Doherty et al., 2003;
Gorjian et al., 2001). In previous work (Kuljanin et al., 2012.a;
Kuljanin et al., 2012.b), it was found that separation of the
protein and pectin of sugar beet juice is more efficient, when the
cationic polyelectrolyte is used in combination with Al2(SO4)3
and CuSO4.
The aim of this study was to compare effects of CaSO4 with
Al2(SO4)3 in combination with cationic polyelectrolyte, on the
efficiency of pectin extraction from sugar beet juice. The
measurements were performed using electrophoretic method
(measurement of zeta potential) which showed an advantage
over the method of measuring the residual turbidity of the
solution (Kuljanin et al., 2013).
MATERIAL AND METHOD
Pectin preparation was extracted from the pressed sugar beet
cuttings obtained in industrial processing of sugar beet (sugar
factory from Žabalj, Serbia). The dry matter content of the
pressed sugar beet cuttings was 20 % (mass). For pectin
extraction calcium and aluminium sulphate were used in a
crystal- hydrated form (CaSO4 x 7H2O and Al2(SO4)3 x 18H2O)
in the form of aqueous solutions, (manufacturer's ''Zorka
Pharma'', Šabac, Serbia). To correct the pH value in presence of
Al2(SO4)3, an equivalent amount of Na2CO3 was used. In
addition to these coagulants, the cationic polyelectrolyte
(MAGNAFLOC LT-24) high-purity (99%), production of "Low
Moor," Bradford, England was also used.
Pectin preparation was isolated by extraction in acidic
condition by standard laboratory procedure AOAC (2000).
Previously, multiple washing of fresh-prepared sugar beet
cuttings with distilled water slightly acidified with HCl (pH 5.5)
120
was done. Thereafter, extraction was carried out discontinuously
by aqueous HCl solution in the extractor with volume of 2 dm3.
The mass ratio of sugar beet cuttings to solvent was 1:10.
Extraction was performed at pH 3.5 and 85°C during 2.5 h. High
molecular colloidal fraction was isolated from extract by
multistage precipitation with 70% ethanol solution. The
precipitated colloids were left over night to deposit and obtained
sediment was washed out with 70% ethanol solution. Pectin
preparation, at the end was dried in a vacuum drier for 12 hours
at 70 °C. Procedure was repeated several times and basic
parameters of pectin preparation were determined according to
standard methods of AOAC (2000).
The degree of esterification of pectin preparation was
calculated over the equivalents of free (X) and the esterified
carboxyl groups (Y), using equation:
DE 
Y
100
XY
(1)
Mean molar mass of the protein and the pectin preparation
was determined using spectrophotometry and the refractometer,
by the method Kar-a i Arslan-a (Kuljanin et al., 2010).
The experiment has tested the model-solutions of pectin
preparations concentrations of 0.1 % (mass). Working solutions
were prepared by dissolving 1 g of pectin preparation in 250 cm3
of distilled water and left over night to swallow. After that,
distilled water was added up to 1 dm3, and for every
measurement 50 cm3 was separated. After dissolution of 1 g
Al2(SO4)3 and CaSO4 in 200 cm3 of distilled water, an
appropriate amount was collected by pipette and added to 50
cm3 of pectin solution (0.1 mass. %). The obtained
concentrations of CaSO4 were in the range of 50 to 450 mg/dm3
while concentrations of Al2(SO4)3, were in range 50 – 200
mg/dm3 (figure1 and 2). All measurements were performed at
pH = 7. At this pH, Al3+ and Ca2+ ions have limited solubility
and hidrolized cationic forms are dominate (Duan and Gregory,
2003; Duan et, al., 2002). To obtained desired solution alcality
(pH=7), Na2CO3 was added to Al2(SO4)3 (mass ratio of Na2CO3
to Al2(SO4)3 was 1:1.07, calculated on pure Al2(SO4)3) (Kuljanin
et al., 2012.b).
After the coagulants CaSO4 and Al2(SO4)3 were added to the
tested preparation, pH was adjusted and the solution was stirred
for 30 min on a high-speed magnetic stirrer, (stirring speed 500
o/min). After aging the solution for 5 min, zeta potential of clear
part of the solution was measured. The measurements were
performed at room temperature.
In the second phase of the experiment, in addition to
coagulation, a
cationic
polyelectrolyte
was
added
(MAGNAFLOC LT-24). The starting solution was prepared by
dissolving 0.5 g of polyelectrolyte in 100 cm3 of distilled water
and left overnight at room temperature to swell. Using this
solution, the concentrations of solutions were prepared: 1, 3 and
5 mg/dm3. These solutions were added to a solution of pectin
preparation as described by Kuljanin et al., 2012.b.
Zeta potential was determined by electrophoretic method
using a commercial apparatus ZETA-METER ZM 77 (Riddick,
1975). On a stereoscopic microscope was read the time for
which solution particle exceeds one standard micrometre
division. An average value of 20 readings was used to derive the
zeta potential of colloidal particles in the tested solutions using a
diagram (based on the Helmoltz-Smoluchowski equation for
electrophoretic mobility of colloidal particles). Results represent
an average value of 3 measurements. Experiments were
performed at 6-fold magnitude on stereoscopic microscope with
Journal on Processing and Energy in Agriculture 18 (2014) 3
Kuljanin, Tatjana et al./The Effect of Ca-Sulphate, Al-Sulphate and Polyelectrolyte on separation of Pectin from the Sugar Beet Juice
voltage adjusted at 150 V. Immediately before zeta potential
measurements, solution temperatures were measured. Zeta potential was read from the diagram and multiplied by correction
factor for given temperature.
and higher ions charge, with smaller amounts lower the zeta potential to zero
20
RESULTS AND DISCUSSION
Table 1. Physical-chemical properties of pectin preparations
Solid Equivalent Equivalent Content of
Degree of
Mean
content of free
of ester. galacturonic esterification molar
SC
COOH
COOH
acid (%)
DE
mass,
(g/100g)
groups,
groups
MWsr
X · 105
Y · 105
(kg/kmol)
80.35
24.58
16.05
72.24
39.50
87 720
The content of galacturonic acid (degree of purity) and the
degree of esterification in the test preparation corresponds to the
mean value of the pectin contents and the degree of esterification
in sugar beet raw juice. The obtained preparation belongs to the
group of less esterified pectin (DE < 50). This means a greater
ability to bind cations to macromolecules of sugar beet juice, due
to the greater presence of the free carboxyl groups (COO-). More
favourable for removal process are pectins with low degree of
esterification (< 25 %) since they include a number of free functional groups in its structure. Also advantageous for the removal
are pectins with larger molar mass as in the presence of the
cation, there is greater possibility for crosslinking chains in galacturonic acid.
Influence of CaSO4 amount to change the zeta potential of
pectin preparations solution without the addition of polyelectrolyte and with a cationic polyelectrolyte at 1, 3 and 5 mg/dm3
concentration, is shown in Figure 1. Influence of Al2(SO4)3 to
change the zeta potential of pectin solution using the same type
of polyelectrolyte (concentrations 1, 3 and 5 mg/dm3), was studied in previous works (Kuljanin et al., 2012.a; Kuljanin et al.,
2012.b) and it is shown in Figure 2.
10
Zeta potential (mV)
5
0
-5
50
100
150
200
250
300
350
400
450
-10
-15
-20
-25
Concentration of Ca-sulphate (mg/dm3)
Pectin solution without electrolyte
Pectin solution with 1 mg/dm3 polyelectrolyte
Pectin solution with 3 mg/dm3 polyelectrolyte
Pectin solution with 5 mg/dm3 polyelectrolyte
Fig. 1. Influence of CaSO4 on change in the zeta potential pectin
solution without the addition of polyelectrolyte and cationic
polyelectrolyte concentration of 1, 3 and 5 mg/dm3
Substitution of zeta potential sign from "-" to "+" in the
range of tested concentrations of CaSO4 and Al2(SO4)3 showed
that the total charge carried by Ca+2, and Al+3 ions (as well as H+
ions from the solution) became greater by absolute value of the
negative charge on the surface of the macromolecule. According
to Schulce-Hardy-s rule, Al+3 ions, due to the higher valence,
Journal on Processing and Energy in Agriculture 18 (2014) 3
0
50
75
100
125
150
175
200
-10
-20
-30
Concentration of Al-sulphate (mg/dm3)
Pectin solution without polielectrolyte
Pectin solution with 1 mg/dm3 polyelectrolyte
Pectin solution with 3 mg/dm3 polyelectrolyte
Pectin solution with 5 mg/dm3 polyelectrolyte
Fig. 2. Influence of Al2(SO4)3 amount on the change in zeta
potential pectin solution without polyelectrolyte and with the
addition of cationic polyelectrolyte concentration 1, 3 and 5
mg/dm3 (Kuljanin et al., 2012.a)
450
Optimal concentration of Ca /
Al sulphate (mg/dm3)
Results of measuring pectin preparations composition are
given in table 1.
Zeta potential (mV)
10
Ca-sulphate
Al-sulphate
400
350
300
250
200
150
100
50
0
1
2
3
4
1 – pectin solution without polyelectrolyte
2 - pectin solution with 1 mg/dm3 polyelectrolyte
3 - pectin solution with 3 mg/dm3 polyelectrolyte
4 - pectin solution with 5 mg/dm3 polyelectrolyte
Fig. 3. Optimal concentrations of Ca and Al-sulphate to achieve
zero zeta potential values of pectin solution without and with the
addition of polyelectrolyte
The higher affinity of Al3+ ions to sugar beet pectin can be
explained by hydrolysis of Al2 (SO4)3 when products of hydrolysis of a large positive charge are created. They are binding to the
COO- groups of pectin macromolecules forming surface complexes. The amounts of Ca2+ ions originating from CaSO4 were
compared with the amounts of Al3+ ions from Al2(SO4)3 to
achieve zero zeta potential values. It takes about 3.5 times as
much of Ca2+ ions in comparison with Al3+ ions for zeta potential to reach zero value (410 mg/dm3 CaSO4 and 110 mg/dm3
Al2(SO4)3). This is explained by the smaller electric charge of
these ions and the last place that is on a scale binding affinity of
divalent ions, is occupied by Ca2+ ions (Kuljanin et al., 2010;
Kuljanin et al., 2012.b). This means that Ca2+ ions with COOgroups of pectin macromolecules bind only with weak electrostatic forces.
By adding a cationic polyelectrolyte (MAGNAFLOC LT-24)
at 1 mg/dm3, zeta potential changes are negligible. By adding a
cationic polyelectrolyte at 3 and 5 mg/dm3, the required amount
of CaSO4 and Al2(SO4)3 for achieving zero zeta potential value,
were reduced in the interval of 15 up to 130 mg/dm3. Concentrations of polyelectrolyte at 3 and 5 mg/dm3, showed a similar effect on the change of zeta potential (Figure 3). Using polyelec-
121
Kuljanin, Tatjana et al./The Effect of Ca-Sulphate, Al-Sulphate and Polyelectrolyte on separation of Pectin from the Sugar Beet Juice
trolyte concentration at 3 mg/dm3, the required amount of coagulant CaSO4 for achieving zero zeta potential value is 280 mg/dm3
(460 mg/gpectin), while for Al2(SO4)3, that amount is 95 mg/dm3
(128 mg/gpectin) (Figures 1 and 2). Based on this, it can be concluded that cationic polyelectrolytes probably besides interparticle bridging mechanism, provide additional charge neutralization. This means that the cationic polyelectrolytes have a function of coagulant (via charge neutralization) and flocculants (via
inter-particle bridging).
The amounts of both examined coagulants were substantially
less than the average amount of CaO used in the conventional
process of sugar beet juice clarification (about 9 g/gpectin).
It is known that aluminum salts may have unfavorable effect
in the nutrition. For example, in 1965, animal experiments suggested a possible connection between aluminium and Alzheimer’s disease. Analysis of aluminium content of a number of
foods and food products was undertaken in order to evaluate the
nutritional intake of aluminium (Stahl et, al., 2011). FAO/WHO
Expert Committee on Food Additives reduced the provisional
tolerable weekly intake value for aluminium from 7 mg/kg body
weight/week to 1 mg/ kg body weight/week.
For this reason, CaSO4 is recommended as a partial or total
replacement for the traditional coagulant in the process of sugar
beet juice clarification. By adequate dosing of CaSO4 and cationic polyelectrolyte as well as controlling zeta potential, greater
efficiency of pectin separation in the phase of clarification of
sugar beet juice would be achieved.
CONCLUSION
The amounts of CaSO4 were compared with the amounts of
Al2(SO4)3 in combination with a cationic polyelectrolyte to
achieve zero zeta potential values when creating the optimal
conditions for extracting pectin from solution. Al3+ ions possess
a greater bonding strength with sugar beet pectin compared to
Ca2+ ions. However, CaSO4 would be more suitable for any industrial application because of acceptable prices and favourable
solubility in water. In the presence of cationic polyelectrolyte
(MAGNAFLOC LT-24) concentrations of 3 mg/dm3, CaSO4
showed the highest efficiency for pectin extraction from solution. Cationic polyelectrolyte, in this case, has a dual functioncoagulant (via charge neutralization mechanism) and flocculants
(via inter-particle bridging mechanism).
The quantity of CaSO4 using cationic polyelectrolyte are up
to 25 times smaller than the average amount of traditional coagulant CaO which is commonly used in the process of sugar beet
juice clarification.
ACKNOWLEDGMENT: This research is part of the project
supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia, Project
III 46005.
REFERENCES
AOAC (2000). Methods of Analysis of Official Analytical
Chemists, Washington, USA.
Baraniak, B. M., Walerianczyk, E. (2003). Flocculation.
Encyclopaedia of Food Sciences and Nutrition (Second
Edition), 2531-2535.
Doherty, W. O. S., Fellows, C. M., Gorjian, S., Senogles, E.,
Cheung, W. H. (2003). Flocculation and sedimentation of cane
sugar juice particles with cationic homo- and copolymers.
Journal of Applied Polymer Science, 90 (1), 316-325.
Duan, J., Wang, J., Graham, N., Wilson, F. (2002). Coagulation
of humic acid by aluminum sulphate in saline water conditions.
Desalination, 150, 1-14.
Garnier, C., Axelos, M. A. V., Thibault, J. F. (1994). Selectivity
and cooperativity in the binding of calcium ions by pectins.
Carbohydrate Research, 256, 71.
122
Gorjian, S., Fellows, C. M., Doherty, W. O. S., Cheung, W. H.
(2001). Zuckerindustrie, 126 (4), 259-263.
Haapala, H., Goltsova, N., Pitulko, V., Lodenius, M. (1996). The
effects of simultaneous large acid and alkaline airborne
pollutants on forest soil. Environmental Pollution, 94, 159168.
Hilal, N., Al-Abri, M., Moran, A., Al-Hinai, H. (2008). Effect of
heavy metals and polyelectrolytes in humic substance
coagulation under saline conditions. Desalination, 220, 85-95.
Kinniburgh, D. G., Riemsdijk, W. H., Koopal, L. K., Borkovec,
M., Benedetti, M. F., Avena, M. J. (1999). Ion binding to
natural
organic
matter:
competition,
heterogeneity,
stoichiometry and thermodynamic consistency. Colloids and
Surfaces, A: Physicochem. Eng. Aspects, P 151, 147-166.
Koper, G. J. M. (2007). An Introduction to Interfacial
Engineering, VSSD, Delft.
Kuljanin, Tatjana, Mišljenović, Nevena, Koprivica, Gordana,
Lević Lj., Filipčev, Bojana (2010). Influence of Cu2+ and Al3+
ions on Zeta potential change of pectin and protein
preparations extracted from sugar beet. Journal on Processing
and Energy in Agriculture, 14 (3), 141-144.
Kuljanin, Тatjana, Mišljenović, Nevena, Koprivica, Gordana,
Jevrić, Lidija, Grbić, Jasna, Jevtić-Mučibabić, Rada (2012).
Effect of aluminium salts, copper salts and polyelectrolytes on
sharge neutralization of pectin macromolecules. 6th Central
European Congress on Food, Novi Sad, Serbia, 518-522.
Kuljanin, Tatjana, Koprivica, Gordana, Jevrić, Lidija, JevtićMučibabić, Rada, Filipčev, Bojana, Grbić, Jasna (2012).
Binding Al3+, Cu2+ ions and polyelectrolytes with
macromolecules in sugar beet juice. Journal on Processing and
Energy in Agriculture, 16 (2), 71-74.
Kuljanin, Tatjana, Jevtić-Mučibabić, Rada, Ćurčić, Biljana,
Nićetin, Milica, Filipović, V., Knežević, Violeta (2013).
Clarification of sugar beet juice using Cu2+ and Al3+ ions –
method of measurement residual solution turbidity and Zeta
potential. Journal on Processing and Energy in Agriculture, 17
(2), 76-79.
Kuljanin, Tatjana, Jevrić, Lidija, Ćurčić, Biljana, Nićetin,
Milica, Filipović, V., Grbić Jasna (2014). Aluminium and calcium ions binding to pectin in sugar beet juice: Model of electrical double layer. Hemijska industrija, OnLine-First (00): 3232., DOI:10.2298/HEMIND 121214032K
Lević, Lj., Gyura, Julijana, Đurić, Mirjana, Kuljanin, Tatjana
(2005). Optimization of pH value and aluminum sulphate
quantity in the chemical treatment of molasses. European Food
Research. Technology, 220, 70-73.
Lević, Lj., Tekić, M., Djurić, Mirjana, Kuljanin, Tatjana (2007).
CaCl2, CuSO4 and AlCl3 & NaHCO3 as possible pectin
precipitants in sugar juice clarification. International Journal of
Food Science and Technology, 42, 609-614.
Lipets, A. A., and Oleinik, I. A. (1972). Use of aluminum salts.
In Russian. Sakhar Promyshlennost 46, 47-48.
Pattabi, S., Ramasami, K., Selvam, K., Swaminathan (2000).
Influence of polyelectrolytes on sewage water treatment using
inorganic coagulants. Indian Journal of Environmental Protection, 20, 499-507.
Riddick, M. T. (1975). Zeta-Meter Manual (third ed.), New
York.
Schneider, C., Hanisch, M., Wedel, B., Jusufi, A., Ballauff, M.
(2011). Experimental study of electrostatically stabilized
colloidal particles: Colloidal stability and charge reversal,
Journal of Colloid and Interface Science, 358, 62-67.
Stahl, T., Taschan, H., Brunn, H. (2011). Aluminium content of
selected foods and food Products. Environmental Sciences
Europe 23:37.
Received: 04. 03. 2014.
Accepted: 25. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3