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Chemical Industry & Chemical Engineering Quarterly
Chem. Ind. Chem. Eng. Q. 21 (3) 441−446 (2015)
SHIFENG LI1,2
YANMING SHEN2
DONGBING LIU2
LIHUI FAN2
ZHE TAN2
ZHIGANG ZHANG1,2
WENXIU LI1,2
WENPENG LI2
1
Liaoning Provincial Key
Laboratory of Chemical Separation
Technology, Shenyang University
of Chemical Technology,
Shenyang, Liaoning, China
2
College of Chemical Engineering,
Shenyang University of Chemical
Technology, Shenyang, Liaoning,
China
SCIENTIFIC PAPER
UDC
DOI 10.2298/CICEQ140730046L
CI&CEQ
EXPERIMENTAL STUDY OF
CONCENTRATION OF TOMATO
JUICE BY CO2 HYDRATE FORMATION
Article Highlights
• Novel tomato juice concentration process using CO2 hydrate formation is presented
• Tomato juice has a small effect on CO2 hydrate formation
• The maximum dehydration ratio can reach 63.2% with feed pressure of 3.95 MPa
• The rate constant increased with increasing the feed pressure
Abstract
A new tomato juice concentration technology using CO2 hydrate formation is
presented. The CO2 hydrate equilibrium conditions were measured by the isochoric pressure search method and tomato juice concentration experiments
were carried out in a high-pressure stirred reactor. Moreover, the dehydration
ratio was defined and CO2 hydrate formation rate constants were calculated
with different feed pressures. The effects of feed pressure, temperature, and
juice volume on the dehydration ratio were investigated. The results show that
the tomato juice used in this work has almost no effect on CO2 hydrate phase
equilibrium conditions, but can accelerate CO2 hydrate formation. The dehydration ratio increased with increasing the feed pressure from 1.81 to 3.95 MPa;
the maximum dehydration ratio reached 63.2% at a feed pressure of 3.95
MPa, and the optimum tomato juice volume was 80 mL. These results demonstrated that removal of water with the help of CO2 hydrate is an efficient technology for tomato juice concentration.
Keywords: concentration, separation, clathrate hydrate, carbon dioxide,
tomato juice.
Fruit juice concentration is recognized wordwide
as a way to preserve fruit and reduce transport costs.
Despite recent advances in fruit juice concentration,
there remain numerous challenges. Evaporation,
membranes (ultrafiltration, reverse osmosis and
membrane distillation), and freeze concentration have
been developed for concentrated juice processing [1-4]. However, the evaporation process is usually carried out in evaporators at high temperature, which
causes valuable constituent losses (for example aroma
compounds) and decreases the final product quality.
Membrane concentration is regarded as a good alternative to the thermal methods of juice concentration,
Correspondence: S. Li, Liaoning Provincial Key Laboratory of
Chemical Separation Technology, Shenyang University of Chemical Technology, Shenyang, Liaoning, 110142, China.
E-mail: [email protected]
Paper received: 30 July, 2014
Paper revised: 23 November, 2014
Paper accepted: 22 December, 2014
but the membrane could get dirty as the product is
concentrated and the concentration process is costly
[2,3]. Regarding the third method, concentrate quality
is also satisfactory but it consumes a lot of energy, in
particular during the ice nucleation step [4].
Hydrate technology has received much recent
interest for its applications in the field of gas storage
[5-7], CO2 capture [8-15], desalination [16-18] and so
on. Hydrates are nonstoichiometric crystalline inclusion compounds formed through the combination of
water and suitably sized “guest” molecules, typically
under low temperature and elevated pressure conditions [19]. Recently, hydrate separation has been a
rapidly growing research area. The concentration process by gas hydrate formation is similar to freeze concentration. However, the difference is that the ice formation step is replaced by gas hydrate crystal formation during gas hydrate concentration. Since gas
hydrate can be formed above 0 °C, energy use
becomes smaller than that in freezing [9,13-15,19].
441
S. LI et al.: EXPERIMENTAL STUDY OF CONCENTRATION OF TOMATO JUICE…
Despite recent advances in hydrate separation technology, there are few reports on aqueous concentration via hydrate formation, especially in juice concentration [20-22]. In fact, as early as the 1960s,
Huang et al. [20] utilized CH3Br and CCl3F hydrate to
concentrate apple, tomato, and tomato juices. No difficulty was encountered in removing approximately
80% of the water from the substrates. Because the
hydrate formation gas is not environmental friendly,
the practical use of juice concentration by CH3Br and
CCl3F hydrate formation is limited. In the subsequent
40 years there had been no reports on on fruit juice
concentration via gas hydrate formation until 2001,
when Purwanto et al. [21] proposed concentration of
coffee solutions by use of xenon hydrate. They determined the induction time and size distribution of gas
hydrate and found that longer time was required for
higher concentration of solution to form xenon hydrate
and higher temperature and lower xenon pressure
yielded the larger size of xenon hydrate. Recently,
Andersen and Thomsen [22] investigated the possibility of using gas hydrates for concentration of sugar
juice. They found the process was not suitable for
sugar production, but could be interesting for concentration of heat sensitive, or high value products. Most
recently, Purwanto et al. [23] designed a novel higher
pressure container to concentrate coffee solution by
formation of Xe hydrate. The ingenious designs of the
higher pressure container could contribute to the
development of separation process continuously.
To our knowledge, there is no report on tomato
juice concentration via formation of CO2 hydrate.
Therefore, the purpose of this work is to develop a
novel tomato juice concentration method via CO2
hydrate formation and investigate the effect of feed
pressure, temperature, and volume of juice on the
concentration efficiency in order to establish the optimum operating conditions and explore practical applications of the technique in the future.
EXPERIMENTAL
Materials
CO2 gas (99.99%) was purchased from Beijing
AP BAIF Gases Industry CO., Ltd (China) and tomato
juice was supplied by Kagome (Taiwan). The contents of reducing sugars, total acid, vitamin C, soluble
solid and water content of tomato juice are listed in
Table 1.
Chem. Ind. Chem. Eng. Q. 21 (3) 441−446 (2015)
General procedure
CO2 hydrate phase equilibrium. The basic experimental setup was adopted from Li et al. [24] with
modifications made to facilitate the higher pressure
applications. It mainly consisted of a stainless-steel
reactor (volume 300 mL) equipped with a magnetic
stirrer (Nantong Feiyu Science and Technology exploitation Co., China). The reactor was designed to be
operated at pressure up to 25 MPa. The temperature
of the reactor was controlled by circulating the coolant
from a thermostat (Tianheng THCD-306) with a stability of ±0.01 K inside the jacket around the cell. Two
Pt100 resistance thermometers (Westzh WZ-PT100)
within 0.1 K in accuracy, placed in the middle and
bottom of the reactor, respectively, were used to
monitor the temperature of the reactor. A pressure
transducer (Senex DG-1300) within 0.01 MPa in
accuracy measured the pressure inside of the reactor.
The pressures and temperatures of the reactor were
recorded by data logger (Agilent 34972A). The hydrate equilibrium conditions were measured by the isochoric pressure search method [25]. The cell containing liquids (approximately 120 mL) was immersed into
the temperature-controlled bath. Carbon dioxide gas
was then supplied from a gas cylinder through a pressure-regulating vale into the evacuated cell until the
pressure inside the cell was increased to the desired
level. After the temperature and pressure were stabilized, the valve in the line connecting the cell and
cylinder was closed; then, the stirrer was started.
Subsequently, the temperature was gradually decreased to form the hydrate. Hydrate formation in the
cell can be detected by a decrease in pressure and
an increase in temperature. The temperature was
then increased with steps of 0.1 K. At every step, the
temperature was held constant for 4 h to achieve
equilibrium state in the cell. In this way, a P-T diagram was obtained for each experimental run, from
which the hydrate dissociation point was determined
[25]. Consequently, the point at which the slope of the
p-T curve plots sharply changed was considered as
the hydrate dissociation point at which all hydrate
crystals have dissociated.
Tomato juice hydrate concentration experiment.
After 100 mL tomato juice solution was introduced
into the evacuated reactor, the reactor was cooled to
the desired value (typically 275.8 K). When the cell
temperature was stabilized, the reactor was vacu-
Table 1. The contents of reducing sugars, total acid, vitamin C, soluble solid and water content of tomato juice used in this work
Component
Content
442
Reducing sugar, g/100 g
Total acid, g/kg
Vitamin C, mg/100 g
Soluble solid, %
Water content, %
2.51
3.31
16.85
5.5
94.2
S. LI et al.: EXPERIMENTAL STUDY OF CONCENTRATION OF TOMATO JUICE…
umed to ensure the absence of air, and then CO2 was
charged into cell until the given pressure. Then, the
CO2 intake valve was closed and the stirrer was
started to initiate hydrate formation (500 rpm). During
the experiment, the temperature and pressure were
recorded. After hydrate formation finished (the system
pressure was stable), the stirrer was stopped.
Calculation method
The moles of gas consumed. The number of
moles of CO2 gas that has been consumed during
hydrate formation can be calculated as [14]:
Δn = n f − n e =
pV
p eV g
f g
−
z fRT z eRT
(1)
where z is the compressibility factor of CO2 gas
calculated by the SRK equation of state, and subscripts f and e refer to component of the feed gas and
equilibrium gas. The volume of CO2 gas was assumed
constant throughout the hydrate formation process
(volume changes due to the phase transitions were
neglected).
Dehydration ratio. The content of water in hydrate phase is important for evaluating the dehydration
ratio of CO2 (defined as the ratio of water in the
hydrate phase and in the feed tomato juice). Because
it is difficult to determine the water cut in hydrate
phase in the presence of residual concentrated tomato juice, the following assumption and calculation
were adapted:
CO2 connects with water to form CO2 hydrate
based on the following reaction equations:
CO2 (g) + nH2O (l) → CO2 ⋅ nH2O (H)
n Δnw H2O
mf
1
K∗
=

∗
 = aK ( μ f − μe )

1
kf
−
1
kL
(4)
(5)
where a is the interfacial area, K ∗ is the overall
kinetic constant, μ f and μe are chemical potentials of
the guest molecule in the gas phase and in the
hydrate phase, respectively, k f is the crystal growth
constant, and k L is the mass transfer coefficient in
the liquid phase.
Under the conditions of this study, 1/ k L could
be eliminated by vigorous stirring (500 rpm) in the
reactor ( 1/ k f >> 1/ k L ). So the hydrate rate can be
expressed by:
ff
 dn 
rf =  −
 = ak f ( μ f − μe ) = ak fRT ln f
t
d


e
(6)
 Δn  V g (f f − f e )
rf = 
=
Δt
 Δt  RT
(7)
where f f and f e are the fugacity of the gas phase and
the hydrate phase at equilibrium condition, respectively, calculated by SRK equation of state. Vg is the
volume of the gas phase and Δt is the time to reach
equilibrium for hydrate separation process. Since it is
difficult to separate the terms a and k f from the
experimental results for the fugacity change, the hydrate rate constant is expressed as:
ak f =
Vg
(f f − f e )
(RT )2 Δt ln(f f / f e )
(8)
(2)
where n is the hydrate number of CO2 hydrate.
According to theoretical calculation result of Mckov
and Sinanoğlu [26] and Raman spectroscopic analyses data of Uchida et al. [27], the hydrate number of
CO2 hydrate in this work is approximately equal to
7.24. Therefore, the dehydration ratio (D) can be
calculated by the following formula:
D = 100
 dn
−
 dt
Chem. Ind. Chem. Eng. Q. 21 (3) 441−446 (2015)
(3)
where w H2O is molar mass of water, and m f is the
mass of water in feed tomato juice.
Hydrate formation rate constant. The hydrate
formation rate can be expressed in terms of fugacity
difference during formation and at equilibrium [28,29].
In this study, the chemical potential difference was
used as the driving force and the apparent gas uptake
rate (–dn/dt) is expressed as:
RESULTS AND DISCUSSION
Figure 1 shows the curve of CO2 gas-liquid
equilibrium and CO2 hydrate phase equilibrium. So,
the temperature and pressure conditions of tomato
juice concentration experiments were chosen in the
ellipse region between the two curves.
Firstly, to elucidate how the water cut of tomato
juice (94.2 wt%) affects CO2 hydrate phase equilibrium, hydrate phase equilibrium conditions for CO2 in
water and tomato juice systems were measured in the
presence of pure water and tomato juice by an isochoric pressure search method. The phase equilibrium data are given in Figure 2. From Figure 2, it is
apparent that the CO2 hydrate phase equilibrium
curve in the presence of tomato juice agrees roughly
with that in water. Therefore, it can be concluded that
the tomato juice has nearly no effect on CO2 hydrate
phase equilibrium conditions because the most of
tomato juice (94.2 wt.%) is water and the most of the
443
S. LI et al.: EXPERIMENTAL STUDY OF CONCENTRATION OF TOMATO JUICE…
residuals (fructose and soluble solid) have little effect
on equilibrium temperature and pressure of CO2
hydrate formation [22].
Chem. Ind. Chem. Eng. Q. 21 (3) 441−446 (2015)
the feed pressure of 3.46 MPa. As we can see, the
dehydration ratio increased with decreasing of temperature in the range of 274.8-279.8 K. Although lower
temperature is favorable for tomato juice concentration, the lower temperature would need higher refrigeration energy consumption. Comparing the results
in Figures 3 and 4, we can conclude that increasing
feed pressure is more efficient for tomato juice concentration than reducing temperature.
Figure 1. Schematic of hydrate formation regions.
Figure 3. Dehydration ratio as function of feed pressure.
Figure 2. Hydrate phase equilibrium conditions for CO2 in water
and tomato juice systems.
Then the tomato juice concentration experiments
were carried out with different feed pressure. In this
work, the feed pressure of CO2 gas varied from 1.80
to 3.95 MPa. As shown in Figure 3, the dehydration
ratio calculated using Eq. (3) increased with the feed
pressure increasing. The maximum dehydration ratio
can reach 63.2% with a feed pressure of 3.95 MPa.
The results clearly indicate that higher dehydration
ratio can be obtained with higher feed pressure
because of more hydrate formation. However,
although higher feed pressure was more beneficial for
concentration efficiency, the higher feed pressure
would need higher cost compression work.
The effect of hydrate formation temperature on
dehydration ratio was also studied. Figure 4 shows
the dehydration ratio as a function of temperature with
444
Figure 4. Dehydration ratio as function of temperature.
The effect of tomato juice volume on dehydration ratio was studied at 275.8 K and 3.46 MPa. As
shown in Figure 5, the dehydration ratio first increased up to 65.2% and then decreased when tomato
juice volume increased from 40 to 120 mL. With increasing tomato juice volume the mass of removed
water accordingly increased. The increase in tomato
juice volume from 40 to 120 mL will decrease the free
volume space in the reactor. With the same feeding
pressure, due to the different free volume space, the
amount of CO2 will be different. So when the volume
S. LI et al.: EXPERIMENTAL STUDY OF CONCENTRATION OF TOMATO JUICE…
of tomato juice is 40 mL, the liquid volume just
accounts for approximately one-thirteenth of the reactor. Because the stirrer stays in a fixed position, the
mix of CO2 gas and tomato juice could be insufficient,
which causes the dehydration ratio to decrease.
Therefore, considering the mass of removed water,
the optimum tomato juice volume is 80 mL.
Chem. Ind. Chem. Eng. Q. 21 (3) 441−446 (2015)
although the presence of tomato juice does not affect
the equilibrium conditions of CO2 hydrate, it can impact the kinetics of the hydrate formation due to the
texture in tomato juice. The solid particles in the mixture may serve as nuclei for initiating the hydrate
formation, which may accelerate the CO2 hydrate formation [19,29].
Table 2. Results for the hydrate formation rate constant
Pressure, MPa
akf×108 / J-1 mol2 s-1
1.81
0.94
2.40
1.36
3.10
1.65
3.46
1.82
3.95
2.01
CONCLUSIONS
Figure 5. Dehydration ratio as function of tomato juice volume.
To reveal the effect of feed pressure on hydrate
formation kinetics, the CO2 hydrate formation rate
constants were defined and calculated. As shown in
Table 2, the CO2 hydrate formation rate constants
calculated using Eq. (8) were 0.94×10-8, 1.36×10-8,
1.65×10-8, 1.82×10-8 and 2.01×10-8 J-1 mol2 s-1 with
feed pressure of 1.81, 2.40, 3.10, 3.46 and 3.95 MPa,
respectively. The results showed that the rate constant increased with increasing the feed pressure. It
can be explained by the higher feed pressure that a
larger driving force was achieved, which is consistent
with the two-film model for hydrate formation process
[28,29]. Several studies have reported the formation
rate of CO2 hydrate. For example, Uchida et al.
[30,31] observed CO2 hydrate formation process at
the interface between water and CO2 using microscopy and found that the rate-determining process is
mainly heat diffusion from the reaction sites. They
also studied the effect of addition of NaCl on lateral
growth rate of CO2 hydrate films, and their observations suggested that the hydrate formation rate in
NaCl solution is determined by not only the heat
transport, but also the mass transport of NaCl. Yang
et al. [32] concluded that vigorous inter-phase mixing
reduced heat and mass transfer resistances and the
global reaction rate may ultimately approached the
intrinsic CO2 hydrate formation rate. Tajma et al. [33]
also carried out CO2 hydrate formation experiments to
elucidate the effects of mixing functions of the static
mixer on CO2 hydrate formation. In conclusion,
A novel separation process was developed for
tomato juice concentration on the basis of CO2 hydrate formation. The CO2 hydrate equilibrium conditions in the presence tomato juice were measured by
the isochoric pressure search method. The tomato
juice concentration experiments were carried out in a
high-pressure stirred reactor under different conditions of feed pressure, temperature, juice volume, and
stirring speed. The hydrate equilibrium results show
that the tomato juice used in this work has little effect
on CO2 hydrate phase equilibrium conditions, but can
accelerate CO2 hydrate formation. The dehydration
ratio increased with increasing the feed pressure and
decreasing the temperature. The optimum tomato
juice volume was 80 mL and the stirring speed has
almost no effect on the dehydration ratio. The CO2
hydrate formation constants in tomato juice were the
same order of magnitude as the results of CH4 hydrate in the presence of surfactants.
Acknowledgement
The authors gratefully acknowledge the National
Natural Science Foundation of China (No. 21106085).
REFERENCES
[1]
B. Jiao, A. Cassano, E. Drioli, J. Food Eng. 63 (2009)
303-324
[2]
D.F. Jesus, M.F. Leite, L.F.M. Silva, R.D. Modesta, V.M.
Matta, L.M.C. Cabral, J. Food Eng. 81 (2007) 287-291
[3]
B. Guignon, C. Aparicio, P.D. Sanz, L. Otero, Food Res.
Inter. 46 (2012) 83-91
[4]
M. Aider, D. de Halleux, LWT-Food Sci. Technol. 41
(2008) 1768-1775
[5]
Y. Wang, X. Lang, S. Fan, J. Energy Chem. 22 (2013) 39-47
445
S. LI et al.: EXPERIMENTAL STUDY OF CONCENTRATION OF TOMATO JUICE…
Chem. Ind. Chem. Eng. Q. 21 (3) 441−446 (2015)
[6]
M. Ozaki, S. Tomure, R. Ohmura, Y.H. Mori, Int. J.
Hydrogen Energy 39 (2014) 3327-3341
[20]
C.P. Huang, O. Fennema, W.D. Powrie, Cryobiology 2
(1966) 240-245
[7]
J.W. Du, D.Q. Liang, X.X. Dai, D.L. Li, X.J. Li, J. Chem.
Thermodyn. 43 (2011) 617-621
[21]
Y.A. Purwanto, S. Oshita, Y. Seo, Y. Kawagoe, J. Food
Eng. 47 (2001) 133-138
[8]
D. Nguyen Hong, F. Chauvy, J.M. Herri, Energy Conv.
Manage. 48 (2007) 1313-1322
[22]
T.B. Andersen, K. Thomsen, Int. Sugar J. 111 (2009)
632-636
[9]
A. Eslamimanesh, A.H. Mohammadi, D. Richon, P.
Naidoo, D. Ramjugernath, J. Chem. Thermodyn. 46
(2012) 62-71
[23]
Y.A. Purwanto, S. Oshita, Y. Seo, Y. Kawagoe, Int. J.
Chem. Eng., 2014, Article ID 262968
[24]
[10]
P. Linga, A. Adeyemo, P. Englezos, Environ. Sci. Technol. 42 (2008) 315-320
S. Li, S. Fan, J. Wang, X. Lang, Y. Wang, J. Chem. Eng.
Data 55 (2010) 3212-3215
[25]
[11]
P. Babu, R. Kumar, P. Linga, Energy 50 (2013) 364-373
R. Ohmura, S. Takeya, T. Maekawa, T. Uchida, J. Chem.
Eng. Data 51 (2006) 161-163
[12]
S.P. Kang, H. Lee, Environ. Sci. Technol. 34 (2000)
43197-4400
[26]
V. Mckov, O. Sinanoğlu, J. Chem. Phys. 38 (1963) 2946-2956
[13]
S. Fan, S. Li, J. Wang, X. Lang, Y. Wang, Energy Fuels
23 (2009) 4202-4208
[27]
T. Uchida, A. Takagi, J. Kawabata, S. Mae, T. Hondoh,
Energy Conv. Manage. 36 (1995) 547-550
[14]
S. Li, S. Fan, J. Wang, X. Lang, D. Liang, J. Nat. Gas
Chem. 18 (2009) 15-20
[28]
P. Englezos, N. Kalogerakis, P.D. Dholabhaiand, P.R.
Bishnoi, Chem. Eng. Sci. 42 (1987) 2647-2658
[15]
C. Xu, S. Zhang, J. Cai, Z. Chen, X. Li, Energy 59 (2013)
719-725
[29]
T. Daimaru, A. Yamasaki, Y. Yanagisawa, J. Pet. Sci.
Eng. 56 (2007) 89-96
[16]
J. Javanmardi, M. Moshfeghian, Appl. Therm. Eng. 23
(2003) 845-857
[30]
T. Uchida, T. Ebinuma, J. Kawabata, H. Narita, J. Cryst.l
Growth 204 (1999) 348-356.
[17]
Y. Qi, W. Wu, Y. Liu, Y. Xie, X. Chen, Fluid Phase
Equilib. 325 (2012) 6-10
[31]
T. Uchida, I.Y. Ikeda, S. Takeya, T. Ebinuma, J. Nagao,
H. Narita, J. Cryst. Growth 237 (2002) 383-387
[18]
K. Park, S.Y. Hong, J.W. Lee, K.C. Kang, Y.C. Lee, M.
Ha, J.D. Lee, Desalination 274 (2011) 91-96
[32]
D. Yang, L. Le, R.J. Martinezb, R.P. Currier, D.F. Spencer, Chem. Eng. J. 172 (2011) 144-157
[19]
E.D. Sloan, C.A. Koh, Clathrate hydrates of natural
gases, CRC Press, Boca Raton, FL, 2008, pp. 1, 131.
[33]
H. Tajima, A. Yamasaki, F. Kiyono, Energy Fuels 19
(2005) 2364-2370.
1,2
SHIFENG LI
YANMING SHEN2
DONGBING LIU2
LIHUI FAN2
ZHE TAN2
ZHIGANG ZHANG1,2
WENXIU LI1,2
WENPENG LI2
1
Liaoning Provincial Key Laboratory of
Chemical Separation Technology,
Shenyang University of Chemical
Technology, Shenyang, Liaoning,
China
2
College of Chemical Engineering,
Shenyang University of Chemical
Technology, Shenyang, Liaoning,
China
NAUČNI RAD
446
EKSPERIMENTALNO PROUČAVANJE
KONCETRISANJE SOKA OD PARADAJZA
OBRAZOVANJEM CO2 HIDRATA
U radu je predstavljen nova tehnologija koncetrisanja soka od paradajza formiranjem CO2
hidrata. Ravnotežni uslovi CO2 hidrata su mereni metodom ispitivanja izohorskog pritiska.
Eksperimenti koncntrisanja soka od paradajza su sprovedeni u reaktoru sa mešanjem pod
visokim pritiskom. Štaviše, definisan je dehidratacioni odnos i određene su konstante
brzine formiranje CO2 hidrata pod različitim pritiscima. Analizirani su i efekti pritiska, temperature i zapremine soka na dehidratacioni odnos. Rezultati pokazuju da korišćeni sok od
paradajza skoro nema nikakav uticaj na ravnotežu CO2 hidrata, ali može da ubrza formiranje CO2 hidrata. Dehidratacioni odnos se povećava sa povećanjem pritiska od 1,81 do
3,95 MPa, a maksimalni dehidratacioni odnos može dostići vrednost od 63,2% pri pritisku
od 3.95 MPa i optimalnom količinom soka od paradajza od 80 ml. Ovi rezultati pokazuju da
uklanjanje vode uz pomoć CO2 hidrata predstavlja efikasnu tehnologiju koncentrisanja
soka od paradajza.
Ključne reči: koncentrisanje, odvajanje, klatratni hidrat, ugljen-dioksid, sok od
paradajza.