Research Article Kinetic Study on the Isothermal and...

Research ArticleKinetic Study on the Isothermal and NonisothermalCrystallization of Monoglyceride Organogels

Zong Meng1 Lijun Yang1 Wenxin Geng1 Yubo Yao2 Xingguo Wang1 and Yuanfa Liu1

1 State Key Laboratory of Food Science and Technology Synergetic Innovation Center of Food Safety and NutritionSchool of Food Science and Technology Jiangnan University 1800 Lihu Road Wuxi Jiangsu 214122 China

2 Patent Examination Cooperation Center of the Patent Office No 3 Building No 11 Gaoliangqiaoxie Street Haidian DistrictBeijing 100081 China

Correspondence should be addressed to Yuanfa Liu foodscilyf163com

Received 25 August 2013 Accepted 30 October 2013 Published 19 February 2014

Academic Editors I E Pavel and C Wu

Copyright copy 2014 Zong Meng et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

The isothermal and nonisothermal crystallization kinetics of monoglyceride (MAG) organogels were studied by pulsed nuclearmagnetic resonance (pNMR) and differential scanning calorimetry (DSC) respectively The Avrami equation was used to describethe isothermal crystallization kinetics and experimental data fitted the equation fairly well Results showed that the crystal growthof MAG organogels was a rod-like growth of instantaneous nuclei at higher degrees of supercooling and a plate-like form withhigh nucleation rate at lower degrees of supercoolingThe exothermic peak in nonisothermal DSC curves for the MAG organogelsbecame wider and shifted to lower temperature when the cooling rate increased and nonisothermal crystallization was analyzed byMo equation Results indicated that at the same crystallization time to get a higher degree of relative crystallinity a higher coolingrate was necessaryThe activation energy of nonisothermal crystallizationwas calculated as 73959 kJmol according to theKissingermethod Therefore as the results of the isothermal and nonisothermal crystallization kinetics for the MAG organogels obtainedthe crystallization rate crystal nucleation and growth during the crystallization process could be preliminarily monitored throughtemperature and cooling rate regulation which laid the foundation for the real industrial manufacture and application of the MAGorganogels

1 Introduction

Repeated consumption of a large number of saturated andtrans fats in the solid fat products such as shorteningsmargarines fat spreads and chocolate leads to a negativeimpact on human health by increasing the risk of metabolicsyndrome and cardiovascular diseases (CVD) [1ndash3] It is esti-mated that by replacing 5 of energy intake from saturatedfats with that from carbohydrates or monounsaturated fatsthe associated risk of CVD would reduce 22 and 37respectively [4] So new methods are required to producesolid fat alternatives

In recent years organogels have attracted much researchattention which can be defined as lipophilic liquid andsolid mixtures of bulk liquid vegetable oil entrapped withina thermoreversible three-dimensional gel network A largenumber of various types of oleogelators which should be of

food-grade economic and efficient used to structure liquidoil have been reported such as triacylglycerides (TAGs)[5] diacylglycerides (DAGs) monoglycerides (MAGs) [6 7]food-grade waxes [8 9] protein walls [10] mixtures of 120573-sitosterol and 120574-oryzanol [11 12] mixtures of long-chainfatty acids and fatty alcohols [13] and mixtures of lecithinand sorbitan tristearate [14] Among these gelators saturatedMAGs are regarded as one of those with a great potential fora wide range of application Concentrated mixtures of liquidoils andMAGs can form semisolid stable network structuresupon cooling from the melted state and the MAGoilmixtures could be served as healthy substitutes of the mar-garine or butter without the attendant high levels of transand saturated fatty acids The MAG molecules can build athree-dimensional network structure by self-organization vianoncovalent interactions for example van der Waals inter-actions hydrogen bonding 120587-stacking and coordination

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 149753 7 pageshttpdxdoiorg1011552014149753

2 The Scientific World Journal

bonds [15] Physicochemical properties and crystallizationbehavior of MAG organogels have been investigated byseveral groups [16ndash19] Da Pieve et al used saturated MAGsto gelate cod liver oil the results showed that shear processingduring crystallization led to the formation of a weak gelnetwork with a low oil binding capacity while the oppositesituation was obtained under static crystallization and alsodemonstrated double effects on the oxidation of cod liveroil which was ineffective on the first step of oxidation buthindered the formation of the secondary oxidation product[16 17] Ojijo et al investigated the effects of MAG contentcooling rate and shear on the temperature ramp mechanicalspectra and hardness of olive oilMAG gel networks theresults showed that the onset temperature of structure forma-tion final values of elastic modulus and network hardness ofthe system all increased with the increasing content of MAGs[18] Compared to the polarizing light microscopy polarizingnear-field scanning optical microscopy provided additionalinformation on the structural organization of olive oilMAGcoagels at the micro- and submicron scale [19] Accordingto these studies however a fundamental question on howthe organogels formed through structuring liquid vegetableoil on the molecular scale were connected with the theirphysicochemical properties on the macroscopic scale is stillunclear Moreover to date attempts have not yet been maderegarding the comparative analysis of the isothermal andnonisothermal crystallization kinetics of organogels Similarto the traditional fat products the crystallization behaviorof the system profoundly influences the final structure oforganogels

In the present research the isothermal and nonisother-mal crystallization kinetics of MAG organogels were exam-ined systematically in a comparative study The isothermalcrystallization behavior is analyzed by pulsed nuclear mag-netic resonance (pNMR) and the isothermal crystallizationkinetic is described by the Avrami equation [20 21] Whilein the real industrial production and transportation of fatproducts the crystallization behavior usually occurs underthe nonisothermal conditions (crystallization temperaturechange over time) the research of the nonisothermal crys-tallization process can guide the manufacture and applica-tion of related products The nonisothermal crystallizationbehavior is analyzed using differential scanning calorimetry(DSC) [22] and the nonisothermal crystallization kinetic isinvestigated using the Mo equation

2 Experimental Section

21 Materials Dimodan HS K-A saturated MAGs (fattyacid composition 120 C

140 5963 C

160 3848 C

180

and 068 C181

melting point 6705 plusmn 05∘C) supplied byDanisco (Shanghai China) were used due to their commonapplication as an ingredient in the food industry Canolaoil (CaO) was generously provided by Kerry Specialty FatsLtd (Shanghai China) which was chosen as the target lipidmatrix to prepare the organogels because it contains thelowest level of long-chain saturated fatty acids such as 412C160

and 181 C180

among common dietary fats and oils

22 Preparation of MAG Organogels Appropriate amountof CaO was weighed in a 100mL beaker and heated on amagnetic stirrer heating plate to a temperature of 75 plusmn 5∘CThen 8 (ww) of MAGs was added to the hot oil and themixture stirred until the MAGs were melted completely Thesamples were then crystallized until reaching 20∘C at a rate of15∘Cminminus1 The organogels were stored at 20∘C under staticconditions for 24 h to ensure that adequate time was givento anneal the network giving the maximum structure Allprocesses were duplicated

23 pNMR Solid fat content (SFC) was measured by pNMRusing a AM4000 MQC NMR analyzer (Oxford InstrumentsAbingdon UK) The water bath based cooling used in thepNMR experiments also offered rapid cooling and accuratetemperature control Instrumentwas automatically calibratedusing three standards (supplied by Oxford Instruments)containing 0 293 and 697 solid Samples were runin triplicate and the values were averaged The SFC ofthe samples was determined using the following thermaltreatment NMR tubes were filled with the melted sample(about 25 g) kept at 80∘C for 30min and then placed in athermostated water bath at 20 25 30 and 35∘C and SFCreadings were obtained at appropriate time intervals

24 DSC Calorimetric analyses of theMAGorganogels weremade using a TA Q2000 DSC instrument (TA InstrumentsNew Castle USA) Samples (sim08mg) were hermeticallysealed in an aluminum pan with an empty pan servingas a reference The samples were heated to 70∘C and heldfor 5min to eliminate previous thermal history and thenthe nonisothermal crystallization profiles were obtained bycooling to 10∘C at the cooling rate of 1 5 10 and 20∘Cminrespectively

25 Avrami Model pNMR data were fitted to the Avramiequation for isothermal crystallizationThe Avrami equationcan be used to quantify crystallization kinetics and givean indication of the nature of the crystallization processincluding nucleation and growth [23] It has the form

1 minus 119883119905= exp (minus119870

119905119905119899) (1)

where119883119905is the relative degree of crystallinity at the time 119905119870

119905

is crystallization rate constant which depends primarily oncrystallization temperature and 119899 the Avrami exponent is aconstant relating to the dimensionality of the transformationThe values of 119870

119905and 119899 are calculated from the intercept and

slope respectively by the linear form of the Avrami equationas follows

ln [minus ln (1 minus 119883119905)] = 119899 ln 119905 + ln119870

119905 (2)

The numerical value of 119870119905is directly related to the half-

time of crystallization 11990512

and therefore the overall rate ofcrystallization [24] which is given by the following equation

(11990512

)119899

=0693

119870119905

(3)

The Scientific World Journal 3

26 Mo Model Considering that the nonisothermal is anature of the crystallization process Ozawa [25] had mod-ified the Avrami equation by the way of assuming that thenonisothermal process is the result of an infinite numberof small isothermal steps According to the Ozawa theorytherefore the relative crystallinity (119883

119905) can be written as

follows

119883119905= 1 minus exp(

minus119870119879

120593119898) (4)

where 119870119879

and 119898 represent cooling crystallizationtemperature-dependent function and Ozawa exponentrespectively 119870

119879is referred to the crystallization rate (it

indicates how fast crystallization occurs) 119898 depends onthe crystal dimension and 120593 is the cooling rate (∘Cmin)However the Ozawa analysis when applied in certainfields (eg the polymer system) failed to describe theirnonisothermal crystallization behavior [26]

For the purpose of finding a convenient approach todescribe the nonisothermal crystallization process exactlythe research team of Mo combined the Avrami equationand Ozawa equation together a method modified has beensuccessfully applied to describe the nonisothermal crystal-lization kinetics of various polymers [26ndash31] The final formof modified equation is shown as follows

lg120593 = lg(119870119879

119870119905

)1119898

minus (119899

119898) lg 119905 (5)

lg120593 = lg119865 (119879) minus 119886 lg 119905 (6)

where the parameter119865(119879) = (119870119879119870119905)1119898 refers to the value of

the cooling rate which has to be chosen at unit crystallizationtime when the measured system amounts to a certain degreeof crystallinity 119886 = (119899119898) is the ratio of the Avrami exponent119899 to the Ozawa exponent 119898 According to (6) at a givendegree of crystallinity the plot of lg120593 versus lg 119905 will give astraight line and the value of 119865(119879) and 119886 could be obtainedby the intercept and the slope of the line respectively

In the study of nonisothermal crystallization using DSCthe energy released during the crystallization process appearsto be a function of temperature As a result the relativecrystallinity 119883(119879) as a function of temperature can beformulated as

119883 (119879) =int119879

1198790

(119889119867119888119889119879) 119889119879

Δ119867119888

(7)

where 1198790and 119879 represent the onset and an arbitrary tem-

perature respectively 119889119867119888is the enthalpy of crystallization

released during an infinitesimal temperature interval 119889119879 andΔ119867119888refers to the total enthalpy of crystallization at a certain

cooling rate During nonisothermal crystallization processesthe crystallization time domain can be transformed fromthe horizontal temperature scale the crystallization time iscalculated by the following equation

119905 =

10038161003816100381610038161198790 minus 1198791003816100381610038161003816

120593 (8)

Table 1 Avrami exponent (119899) Avrami constant (119870119905) and half-time

of crystallization (11990512) for MAG organogels at 20 25 30 and 35∘C

respectively

Temperature (∘C) 119899 119870119905

11990512

(min) 1198772

20 1340 4823 0235 096525 1533 4400 0300 098930 1571 4105 0322 098335 1772 3988 0372 0978

where 119879 is the temperature at the crystallization time 119905 and 120593is the cooling rate (∘Cmin)

27 Nonisothermal Crystallization Activation EnergyDetailed kinetic analysis can provide us more informationwith the thermal transition about the MAG organogelsKissinger [32] developed a method to calculate the activationenergy (Δ119864) of the nonisothermal crystallization processwhich can be formulated as

119889 [ln (1205931198792119901)]

119889 (1119879119901)

= minusΔ119864

119877 (9)

where 119877 and 120593 represent the ideal gas constant(8314 Jsdotmolminus1 kminus1) and the cooling rate respectivelyand Δ119864 is the effective activation energy ln(1205931198792

119901) versus

1119879119901can be obtained as a linear relationship the slope of

which shows the value of minusΔ119864119877 Then the value of Δ119864 canbe derived from the slope

3 Results and Discussion

31 Isothermal Crystallization Kinetics The crystallizationbehavior of organogels profoundly influences the final struc-ture of related application products and is intrinsically relatedto their macroscopic properties Isothermal crystallizationcurves of MAG organogels at different temperatures areshown in Figure 1(a) Crystallization showed hyperbolicpatterns against time and an equilibrium value in SFC wasclearly visible in all curves The equilibrium SFC and theslope of crystallization curves decreased as the crystallizationtemperature increased from 20∘C to 35∘C indicating that thecrystallization rate slowed down gradually

The Avrami model is the one most prevalently usedto study the crystallization of fats and may be used toevaluate the crystallization kinetics and suggest the nature ofcrystal growth To quantify differences in the crystallizationbehaviors of MAG organogels at different temperaturesrespectively the SFC crystallization kinetic data were fittedseparately by Avrami equations According to (2) the valueof ln[minus ln(1 minus 119883

119905)] against ln 119905 gives a linear regression line

of the MAG organogels at different crystallization temper-ature the slope stands for 119899 and the intercept for ln119870

119905 as

shown in Figure 1(b) The equation fitted the data very wellover the entire range of fractional crystallization shown inTable 1 (1198772 gt 096 in all cases) The Avrami exponents (119899)Avrami constants (119870

119905) and half-times of crystallization (119905

12)

determined from the curve fits are also shown in Table 1


0 2 4 6 8 100

2

4

6

8

10SF

C (

)

Time (min)

20∘C25∘C

30∘C35∘C

(a)

minus20 minus18 minus16 minus14 minus12 minus10 minus08 minus06 minus04 minus02 00

minus20

minus15

minus10

minus05

00

05

10

15

ln[minus

ln(1minusX

t)]

ln t

20∘C25∘C

30∘C35∘C

(b)

Figure 1 (a) SFC versus time of crystallization for MAG organogels at 20 25 30 and 35∘C (b) Plots of ln[minus ln(1 minus 119883119905)] versus ln 119905 for

isothermal crystallization of MAG organogels at 20 25 30 and 35∘C respectively

As previously introduced crystallization temperature hasa very strong influence on the crystallization rate constant(119870119905) which decreaseswith increasing temperature indicating

that crystallization proceededmore rapidly at a higher degreeof supercooling (lower temperature)The declining119870

119905values

also indicated a change in the nucleation andor growthrate in MAG organogels under different temperatures notedabove Since 119870

119905is a combined function of nucleation and

growth as well as a strong function of temperature thedeclines of which ineluctably induce changes in crystalmorphology such as crystal size and type [23] Besides theparameter 119870

119905 the increase in 119905

12for the MAG organogels

as a function of increasing crystallization temperature alsoreflected the decrease in119870

119905at higher temperatures As shown

in Table 1 the Avrami exponent 119899 for MAG organogelswas increased with increasing crystallization temperatureThe change in 119899 could indicate differences in crystal growthgeometry and the type of nucleation because it is a functionof the number of dimensions in which growth takes placeit reflects the details of fat crystal nucleation and growthmechanisms Christian [33] has tabulated values for theAvrami exponent 119899 for various types of nucleation andgrowth For example an 119899 of 1 indicates rod-like growth frominstantaneous nuclei an 119899 of 2 represents high nucleationrate and plate-like growth where growth is primarily alongtwo dimensions an 119899 of 3 indicates spherulitic growthfrom instantaneous nuclei whereas an 119899 of 4 representsheterogeneous nucleation and spherulitic growth from spo-radic nuclei For MAG organogels an increase in Avramiexponents from sim1 to sim2 with increasing temperature ispossibly also due to the type of fat crystal growth fromrod-like form at higher degrees of supercooling to plate-like form at lower degrees of supercooling Generally lowvalues of 119899 and high values of 119870

119905are associated with an

increased rate of crystallization and a more instantaneous

30 40 50 60 70minus1

0

1

2

3

4

5

6

7

8

Hea

t flow

(wg

) (en

do u

p)

Temperature (∘C)

1∘Cmin

5∘Cmin

10∘Cmin

20∘Cmin

Figure 2 Nonisothermal melt crystallization exotherms for MAGorganogels at four different cooling rates (1 5 10 and 20∘Cminresp)

nucleation process with a shorter induction time whichin turn would yield smaller and more numerous crystalsTherefore as the parameters of the isothermal crystallizationkinetics for the MAG organogels are discussed above thecrystallization rate crystal nucleation and growth duringthe crystallization process could be preliminarily monitoredthrough temperature regulation

32 Nonisothermal Crystallization Kinetics Figure 2 showsDSC curves of heat flow as a function of temperature atdifferent cooling rates of 1 5 10 and 20∘Cmin for MAGorganogels It can be seen that the MAG organogels showa single peak from 70∘C to 30∘C under four differentcooling rates mentionedabove Clearly when the coolingrate increased the exothermic peak of the MAG organogelsbecame wider and shifted to lower temperature as would be


32 34 36 38 40 42 44 46 48 50 52 54 56

0

20

40

60

80

100X

(T) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Temperature (∘C)

(a)

0 2 4 6 8 10 12 14 16 18 200

20

40

60

80

100

X(t

) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Time (min)

(b)

Figure 3 Plots of119883(119879) versus temperature (a) and plots of119883(119905) versus time (b) for crystallization ofMAGorganogels at four different coolingrates (1 5 10 and 20∘Cmin resp)

Table 2 Characteristic data of non-isothermal melt crystallizationexotherms for MAG organogels

120593 (∘Cmin) 1198790(∘C) 119879

119901(∘C) Δ119867

119888(Jg)

1 5339 5203 55745 5229 5019 707710 5150 4940 740720 5089 4845 7730

expected for crystallization in a nucleation-controlled regionThis was probably because of the fact that under the lowercooling rate MAG organogels crystallization could maintaina longer time at a higher temperature the time was sufficientfor the nucleation and crystal growth so it could crystallize ina higher and narrower temperature range In contrast whenthe cooling rate was faster the time was not sufficient fornucleation and the crystal formation was incomplete so thatthe crystallization temperature range was wider Based onthese curves some kinetic data such as the crystallizationpeak temperature (119879

119901) the onset temperature (119879

0) and the

enthalpy of crystallization (Δ119867) for MAG organogels can betaken and the values of these parameters are summarized inTable 2 It could be seen that all the crystallization parametersof MAG organogels were directly affected by the cooling rateThe values of 119879

0and 119879

119901decreased while the Δ119867 increased

gradually for the sample with increasing cooling rateIn order to obtain the kinetic information the exper-

imental data such as those shown in Figure 2 need to beconverted to the relative crystallinity function of temperature119883(119879) using (7) The converted 119883(119879) curves are illustrated inFigure 3(a) Apparently all curves showed an approximatelyreversed sigmoidal shape which showed a fast primarycrystallization in the early stage and a slow secondary crys-tallization at the later stage When the cooling rate increased

Table 3 Values of119865 (119879) and 119886 for crystallization ofMAGorganogelsat the given degree of crystallinity

119883 () 119865 (119879) 119886

20 4875 084140 5598 079960 7129 078980 9727 0783

from the start to the end of the crystallization the desiredtemperature range became broader which was in accordancewith the result obtained from Figure 2 The data can befurther analyzed by converting the temperature scale of the119883(119879) function into the time scale using (8) to get the relativecrystallinity function of time 119883(119905) The converted curves areshown in Figure 3(b) It could be seen that all these curvesshowed similar sigmoidal shapes That is there appeared aninitial lag period where no sample was crystallized followedby a period of rapid crystallization Clearly it is also noticedthat the time for complete crystallization time increasedas cooling rate decreased Specifically when the coolingrate reduced to 1∘Cmin crystallization time was increasedsignificantly

33 Mo Analysis At a given degree of crystallinity the plotsof lg120593 versus lg 119905 for MAG organogels based on the Moequation are shown in Figure 4 and the values of 119865(119879) and119886 are obtained by the intercepts and the slopes of these linesrespectively which are shown in Table 3 It showed that 119865(119879)systematically increased from 4875 to 9727 with the risingrelative degree of crystallinity119865(119879)has a definite physical andpractical significance for a given degree of crystallinity Thatis the higher value of 119865(119879) the higher cooling rate necessarywithin the unit crystallization time indicating the difficulty of


minus02 00 02 04 06 08 10 12 14

minus04

minus02

00

02

04

06

08

10

X = 40X = 60X = 80

lg 120593

lg tX = 20

Figure 4 Plots of lg120593 versus lg 119905 for MAG organogels at thecrystallinity of 20 40 60 and 80 respectively

307 308 309 310 311minus120

minus115

minus110

minus105

minus100

minus95

minus90

minus85

1Tp (10minus3Kminus1)

ln(120593T

2 p)

Figure 5The plot of ln(1205931198792119901) versus 1119879

119901for theMAG organogels

crystallization behavior The parameter 119886 shows only a smalldecrease with the increasing relative degree of crystallinityranging from 0841 to 0783 indicating that the ratio of 119899 to119898 almost remained constant at different crystallinity

Generally the Kissinger activation energy characterizesthe difficulty of the lipid crystallization process The plot ofln(1205931198792

119901) versus 1119879

119901for the MAG organogels was shown in

Figure 5 which fitted the Kissing equation quite well (1198772 gt099) The activation energy Δ119864 was obtained from the slopeof the line and calculated as 73959 kJmol

4 Conclusions

In the present study various classical models namely theAvrami Mo and Kissinger models were applied to describethe isothermal and nonisothermal crystallization process ofMAG organogels respectively The Avrami the Mo and theKissinger models were found to describe the experimental

data fairly well The results of isothermal crystallizationkinetics of the MAG organogels showed that the values of 119899increased from 1340 to 1772 with the increasing temperaturerange from 20∘C to 35∘C indicating the transition of crystalgrowth from a rod-like form of instantaneous nuclei to aplate-like form with high nucleation rate The exothermicpeak in nonisothermal DSC curves for the MAG organogelsbecamewider and shifted to lower temperature as the coolingrate increased All curves of relative crystallinity versuscrystallization temperature for the MAG organogels at thedifferent cooling rate showed a reversed sigmoidal profilewhich showed a fast primary crystallization in the early stageand a slow secondary crystallization at the later stage Thecurves of relative crystallinity versus time showed similarsigmoidal shapes namely there appeared an initial lag periodwhere no sample crystallized followed by a period of rapidcrystallization The values of 119865(119879) were increased from 4875to 9727 with the increasing relative crystallization rangingbetween 20 and 80 meaning that a higher cooling ratewas required to reach a higher degree of relative crystallinityat the same crystallization time The activation energy ofnonisothermal crystallizationwas calculated as 73959 kJmolaccording to the Kissinger method Therefore according tothe results obtained in this study the crystallization ratecrystal nucleation and growth during the isothermal andnonisothermal crystallization process could be preliminarilymonitored through temperature and cooling rate regulationwhich are very useful for guiding the real industrial manufac-ture and application of the MAG organogels

Conflict of Interests

The authors declare that they have no competing interestsAll authors have no financial relation with the commercialidentities mentioned in the paper

Acknowledgments

This research was supported by the National Natural ScienceFoundation of China (31201382) National Twelve-Five planfor Science amp Technology Support (2011BAD02B04) and theprogram for New Century Excellent Talents in University ofChina (NCET-10-0457)

References

[1] RHUnger GO Clark P E Scherer and LOrci ldquoLipid home-ostasis lipotoxicity and the metabolic syndromerdquo Biochimica etBiophysica Acta vol 1801 no 3 pp 209ndash214 2010

[2] J E Hunter J Zhang P M Kris-Etherton and L ChildsldquoCardiovascular disease risk of dietary stearic acid comparedwith trans other saturated and unsaturated fatty acids asystematic reviewrdquo American Journal of Clinical Nutrition vol91 no 1 pp 46ndash63 2010

[3] A-L Tardy B Morio J-M Chardigny and C Malpuech-Brugere ldquoRuminant and industrial sources of trans-fat and car-diovascular and diabetic diseasesrdquo Nutrition Research Reviewsvol 24 no 1 pp 111ndash117 2011


[4] H M Roche ldquoFatty acids and the metabolic syndromerdquoProceedings of the Nutrition Society vol 64 no 1 pp 23ndash292005

[5] K Higaki T Koyano I Hachiya K Sato and K Suzuki ldquoRheo-logical properties of 120573-fat gel made of binary mixtures of high-melting and low-melting fatsrdquo Food Research International vol37 no 8 pp 799ndash804 2004

[6] N K O Ojijo E Kesselman V Shuster et al ldquoChanges inmicrostructural thermal and rheological properties of oliveoilmonoglyceride networks during storagerdquo Food ResearchInternational vol 37 no 4 pp 385ndash393 2004

[7] A Sein J A Verheij and W G M Agterof ldquoRheologi-cal characterization crystallization and gelation behavior ofmonoglyceride gelsrdquo Journal of Colloid and Interface Sciencevol 249 no 2 pp 412ndash422 2002

[8] L S K Dassanayake D R Kodali S Ueno and K SatoldquoPhysical properties of rice bran wax in bulk and organogelsrdquoJournal of the American Oil Chemistsrsquo Society vol 86 no 12 pp1163ndash1173 2009

[9] J F Toro-Vazquez J A Morales-Rueda E Dibildox-AlvaradoM Charo-Alonso M Alonzo-Macias and M M Gonzalez-Chavez ldquoThermal and textural properties of organogels devel-oped by candelilla wax in safflower oilrdquo Journal of the AmericanOil Chemistsrsquo Society vol 84 no 11 pp 989ndash1000 2007

[10] A I Romoscanu and R Mezzenga ldquoEmulsion-templated fullyreversible protein-in-oil gelsrdquo Langmuir vol 22 no 18 pp7812ndash7818 2006

[11] H Sawalha G Margry R den Adel et al ldquoThe influence of thetype of oil phase on the self-assembly process of 120574-oryzanol +120573-sitosterol tubules in organogel systemsrdquo European Journal ofLipid Science and Technology vol 115 no 3 pp 295ndash300 2013

[12] A Bot andW G M Agterof ldquoStructuring of edible oils by mix-tures of 120574-oryzanol with 120573-sitosterol or related phytosterolsrdquoJournal of the American Oil Chemistsrsquo Society vol 83 no 6 pp513ndash521 2006

[13] F G Gandolfo A Bot and E Floter ldquoStructuring of edible oilsby long-chain FA fatty alcohols and their mixturesrdquo Journal ofthe American Oil Chemistsrsquo Society vol 81 no 1 pp 1ndash6 2004

[14] M Pernetti K van Malssen D Kalnin and E Floter ldquoStruc-turing edible oil with lecithin and sorbitan tri-stearaterdquo FoodHydrocolloids vol 21 no 5-6 pp 855ndash861 2007

[15] M Suzuki Y Nakajima M Yumoto M Kimura H Shirai andK Hanabusa ldquoEffects of hydrogen bonding and van der Waalsinteractions on organogelation using designed low-molecular-weight gelators and gel formation at room temperaturerdquo Lang-muir vol 19 no 21 pp 8622ndash8624 2003

[16] S Da Pieve S Calligaris E Co M C Nicoli and AG Marangoni ldquoShear Nanostructuring of monoglycerideorganogelsrdquo Food Biophysics vol 5 no 3 pp 211ndash217 2010

[17] S Da Pieve S Calligaris A Panozzo G Arrighetti and MC Nicoli ldquoEffect of monoglyceride organogel structure on codliver oil stabilityrdquo Food Research International vol 44 no 9 pp2978ndash2983 2011

[18] N K O Ojijo I Neeman S Eger and E Shimoni ldquoEffectsof monoglyceride content cooling rate and shear on therheological properties of olive oilmonoglyceride gel networksrdquoJournal of the Science of Food and Agriculture vol 84 no 12 pp1585ndash1593 2004

[19] E Kesselman and E Shimoni ldquoImaging of oilmonoglyceridenetworks by polarizing near-field scanning optical microscopyrdquoFood Biophysics vol 2 no 2-3 pp 117ndash123 2007

[20] ZMeng Y-F Liu Q-Z Jin et al ldquoComparative analysis of lipidcomposition and thermal polymorphic and crystallizationbehaviors of granular crystals formed in beef tallow and palmoilrdquo Journal of Agricultural and Food Chemistry vol 59 no 4pp 1432ndash1441 2011

[21] M C Puppo S Martini R W Hartel and M L HerreraldquoEffects of sucrose esters on isothermal crystallization andrheological behavior of blends of milk-fat fraction sunfloweroilrdquo Journal of Food Science vol 67 no 9 pp 3419ndash3426 2002

[22] E Chiavaro L Cerretani M Paciulli and S Vecchio ldquoKineticevaluation of non-isothermal crystallization of oxidized extravirgin olive oilrdquo Journal of Thermal Analysis and Calorimetryvol 108 no 2 pp 799ndash806 2012

[23] M Avrami ldquoKinetics of phase change II transformation-timerelations for random distribution of nucleirdquo The Journal ofChemical Physics vol 8 no 2 pp 212ndash224 1940

[24] A P Singh C Bertoli P R Rousset and A G MarangonildquoMatching avrami indices achieves similar hardnesses in palmoil-based fatsrdquo Journal of Agricultural and Food Chemistry vol52 no 6 pp 1551ndash1557 2004

[25] T Ozawa ldquoKinetics of non-isothermal crystallizationrdquo Polymervol 12 no 3 pp 150ndash158 1971

[26] T Liu Z Mo S Wang and H Zhang ldquoNonisothermal meltand cold crystallization kinetics of poly(aryl ether ether ketoneketone)rdquo Polymer Engineering and Science vol 37 no 3 pp568ndash575 1997

[27] M Ren Z Mo Q Chen et al ldquoCrystallization kinetics andmorphology of nylon 1212rdquo Polymer vol 45 no 10 pp 3511ndash3518 2004

[28] Y Tao Y Pan Z Zhang and K Mai ldquoNon-isothermal crystal-lization melting behavior and polymorphism of polypropylenein 120573-nucleated polypropylenerecycled poly(ethylene tereph-thalate) blendsrdquo European Polymer Journal vol 44 no 4 pp1165ndash1174 2008

[29] J-W Huang Y-L Wen C-C Kang W-J Tseng and M-YYen ldquoNonisothermal crystallization of high density polyethy-lene and nanoscale calcium carbonate compositesrdquo PolymerEngineering and Science vol 48 no 7 pp 1268ndash1278 2008

[30] Y Liu and G Yang ldquoNon-isothermal crystallization kinetics ofpolyamide-6graphite oxide nanocompositesrdquo ThermochimicaActa vol 500 no 1-2 pp 13ndash20 2010

[31] H J Wu M Liang and C Lu ldquoNon-isothermal crystallizationkinetics of peroxide-crosslinked polyethylene effect of solidstate mechanochemical millingrdquoThermochimica Acta vol 545pp 148ndash156 2012

[32] H E Kissinger ldquoVariation of peak temperature with heatingrate in differential thermal analysisrdquo Journal of Research of theNational Bureau of Standards vol 57 no 4 pp 217ndash221 1956

[33] J W Christian The Theory of Transformations in Metals andAlloys Part I EquilibriumandGeneral KineticTheory PergamonPress Oxford UK 2nd edition 1975

Submit your manuscripts athttpwwwhindawicom

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Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Analytical ChemistryInternational Journal of


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bonds [15] Physicochemical properties and crystallizationbehavior of MAG organogels have been investigated byseveral groups [16ndash19] Da Pieve et al used saturated MAGsto gelate cod liver oil the results showed that shear processingduring crystallization led to the formation of a weak gelnetwork with a low oil binding capacity while the oppositesituation was obtained under static crystallization and alsodemonstrated double effects on the oxidation of cod liveroil which was ineffective on the first step of oxidation buthindered the formation of the secondary oxidation product[16 17] Ojijo et al investigated the effects of MAG contentcooling rate and shear on the temperature ramp mechanicalspectra and hardness of olive oilMAG gel networks theresults showed that the onset temperature of structure forma-tion final values of elastic modulus and network hardness ofthe system all increased with the increasing content of MAGs[18] Compared to the polarizing light microscopy polarizingnear-field scanning optical microscopy provided additionalinformation on the structural organization of olive oilMAGcoagels at the micro- and submicron scale [19] Accordingto these studies however a fundamental question on howthe organogels formed through structuring liquid vegetableoil on the molecular scale were connected with the theirphysicochemical properties on the macroscopic scale is stillunclear Moreover to date attempts have not yet been maderegarding the comparative analysis of the isothermal andnonisothermal crystallization kinetics of organogels Similarto the traditional fat products the crystallization behaviorof the system profoundly influences the final structure oforganogels

In the present research the isothermal and nonisother-mal crystallization kinetics of MAG organogels were exam-ined systematically in a comparative study The isothermalcrystallization behavior is analyzed by pulsed nuclear mag-netic resonance (pNMR) and the isothermal crystallizationkinetic is described by the Avrami equation [20 21] Whilein the real industrial production and transportation of fatproducts the crystallization behavior usually occurs underthe nonisothermal conditions (crystallization temperaturechange over time) the research of the nonisothermal crys-tallization process can guide the manufacture and applica-tion of related products The nonisothermal crystallizationbehavior is analyzed using differential scanning calorimetry(DSC) [22] and the nonisothermal crystallization kinetic isinvestigated using the Mo equation

2 Experimental Section

21 Materials Dimodan HS K-A saturated MAGs (fattyacid composition 120 C

140 5963 C

160 3848 C

180

and 068 C181

melting point 6705 plusmn 05∘C) supplied byDanisco (Shanghai China) were used due to their commonapplication as an ingredient in the food industry Canolaoil (CaO) was generously provided by Kerry Specialty FatsLtd (Shanghai China) which was chosen as the target lipidmatrix to prepare the organogels because it contains thelowest level of long-chain saturated fatty acids such as 412C160

and 181 C180

among common dietary fats and oils

22 Preparation of MAG Organogels Appropriate amountof CaO was weighed in a 100mL beaker and heated on amagnetic stirrer heating plate to a temperature of 75 plusmn 5∘CThen 8 (ww) of MAGs was added to the hot oil and themixture stirred until the MAGs were melted completely Thesamples were then crystallized until reaching 20∘C at a rate of15∘Cminminus1 The organogels were stored at 20∘C under staticconditions for 24 h to ensure that adequate time was givento anneal the network giving the maximum structure Allprocesses were duplicated

23 pNMR Solid fat content (SFC) was measured by pNMRusing a AM4000 MQC NMR analyzer (Oxford InstrumentsAbingdon UK) The water bath based cooling used in thepNMR experiments also offered rapid cooling and accuratetemperature control Instrumentwas automatically calibratedusing three standards (supplied by Oxford Instruments)containing 0 293 and 697 solid Samples were runin triplicate and the values were averaged The SFC ofthe samples was determined using the following thermaltreatment NMR tubes were filled with the melted sample(about 25 g) kept at 80∘C for 30min and then placed in athermostated water bath at 20 25 30 and 35∘C and SFCreadings were obtained at appropriate time intervals

24 DSC Calorimetric analyses of theMAGorganogels weremade using a TA Q2000 DSC instrument (TA InstrumentsNew Castle USA) Samples (sim08mg) were hermeticallysealed in an aluminum pan with an empty pan servingas a reference The samples were heated to 70∘C and heldfor 5min to eliminate previous thermal history and thenthe nonisothermal crystallization profiles were obtained bycooling to 10∘C at the cooling rate of 1 5 10 and 20∘Cminrespectively

25 Avrami Model pNMR data were fitted to the Avramiequation for isothermal crystallizationThe Avrami equationcan be used to quantify crystallization kinetics and givean indication of the nature of the crystallization processincluding nucleation and growth [23] It has the form

1 minus 119883119905= exp (minus119870

119905119905119899) (1)

where119883119905is the relative degree of crystallinity at the time 119905119870

119905

is crystallization rate constant which depends primarily oncrystallization temperature and 119899 the Avrami exponent is aconstant relating to the dimensionality of the transformationThe values of 119870

119905and 119899 are calculated from the intercept and

slope respectively by the linear form of the Avrami equationas follows

ln [minus ln (1 minus 119883119905)] = 119899 ln 119905 + ln119870

119905 (2)

The numerical value of 119870119905is directly related to the half-

time of crystallization 11990512

and therefore the overall rate ofcrystallization [24] which is given by the following equation

(11990512

)119899

=0693

119870119905

(3)




follows

119883119905= 1 minus exp(

minus119870119879

120593119898) (4)

where 119870119879





lg120593 = lg(119870119879

119870119905

)1119898

minus (119899

119898) lg 119905 (5)

lg120593 = lg119865 (119879) minus 119886 lg 119905 (6)




119883 (119879) =int119879

1198790

(119889119867119888119889119879) 119889119879

Δ119867119888

(7)





119905 =

10038161003816100381610038161198790 minus 1198791003816100381610038161003816

120593 (8)



respectively

Temperature (∘C) 119899 119870119905

11990512

(min) 1198772

20 1340 4823 0235 096525 1533 4400 0300 098930 1571 4105 0322 098335 1772 3988 0372 0978



119889 [ln (1205931198792119901)]

119889 (1119879119901)

= minusΔ119864

119877 (9)


119901) versus








119905 as



12)



0 2 4 6 8 100

2

4

6

8

10SF

C (

)

Time (min)

20∘C25∘C

30∘C35∘C

(a)


minus20

minus15

minus10

minus05

00

05

10

15

ln[minus

ln(1minusX

t)]

ln t

20∘C25∘C

30∘C35∘C

(b)





119905values











30 40 50 60 70minus1

0

1

2

3

4

5

6

7

8

Hea

t flow

(wg

) (en

do u

p)

Temperature (∘C)

1∘Cmin

5∘Cmin

10∘Cmin

20∘Cmin





32 34 36 38 40 42 44 46 48 50 52 54 56

0

20

40

60

80

100X

(T) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Temperature (∘C)

(a)

0 2 4 6 8 10 12 14 16 18 200

20

40

60

80

100

X(t

) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Time (min)

(b)



120593 (∘Cmin) 1198790(∘C) 119879

119901(∘C) Δ119867

119888(Jg)

1 5339 5203 55745 5229 5019 707710 5150 4940 740720 5089 4845 7730



0) and the


0and 119879





119883 () 119865 (119879) 119886

20 4875 084140 5598 079960 7129 078980 9727 0783




minus02 00 02 04 06 08 10 12 14

minus04

minus02

00

02

04

06

08

10

X = 40X = 60X = 80

lg 120593

lg tX = 20


307 308 309 310 311minus120

minus115

minus110

minus105

minus100

minus95

minus90

minus85


ln(120593T

2 p)





119901) versus 1119879



4 Conclusions





Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




follows

119883119905= 1 minus exp(

minus119870119879

120593119898) (4)

where 119870119879





lg120593 = lg(119870119879

119870119905

)1119898

minus (119899

119898) lg 119905 (5)

lg120593 = lg119865 (119879) minus 119886 lg 119905 (6)




119883 (119879) =int119879

1198790

(119889119867119888119889119879) 119889119879

Δ119867119888

(7)





119905 =

10038161003816100381610038161198790 minus 1198791003816100381610038161003816

120593 (8)



respectively

Temperature (∘C) 119899 119870119905

11990512

(min) 1198772

20 1340 4823 0235 096525 1533 4400 0300 098930 1571 4105 0322 098335 1772 3988 0372 0978



119889 [ln (1205931198792119901)]

119889 (1119879119901)

= minusΔ119864

119877 (9)


119901) versus








119905 as



12)



0 2 4 6 8 100

2

4

6

8

10SF

C (

)

Time (min)

20∘C25∘C

30∘C35∘C

(a)


minus20

minus15

minus10

minus05

00

05

10

15

ln[minus

ln(1minusX

t)]

ln t

20∘C25∘C

30∘C35∘C

(b)





119905values











30 40 50 60 70minus1

0

1

2

3

4

5

6

7

8

Hea

t flow

(wg

) (en

do u

p)

Temperature (∘C)

1∘Cmin

5∘Cmin

10∘Cmin

20∘Cmin





32 34 36 38 40 42 44 46 48 50 52 54 56

0

20

40

60

80

100X

(T) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Temperature (∘C)

(a)

0 2 4 6 8 10 12 14 16 18 200

20

40

60

80

100

X(t

) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Time (min)

(b)



120593 (∘Cmin) 1198790(∘C) 119879

119901(∘C) Δ119867

119888(Jg)

1 5339 5203 55745 5229 5019 707710 5150 4940 740720 5089 4845 7730



0) and the


0and 119879





119883 () 119865 (119879) 119886

20 4875 084140 5598 079960 7129 078980 9727 0783




minus02 00 02 04 06 08 10 12 14

minus04

minus02

00

02

04

06

08

10

X = 40X = 60X = 80

lg 120593

lg tX = 20


307 308 309 310 311minus120

minus115

minus110

minus105

minus100

minus95

minus90

minus85


ln(120593T

2 p)





119901) versus 1119879



4 Conclusions





Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0 2 4 6 8 100

2

4

6

8

10SF

C (

)

Time (min)

20∘C25∘C

30∘C35∘C

(a)


minus20

minus15

minus10

minus05

00

05

10

15

ln[minus

ln(1minusX

t)]

ln t

20∘C25∘C

30∘C35∘C

(b)





119905values











30 40 50 60 70minus1

0

1

2

3

4

5

6

7

8

Hea

t flow

(wg

) (en

do u

p)

Temperature (∘C)

1∘Cmin

5∘Cmin

10∘Cmin

20∘Cmin





32 34 36 38 40 42 44 46 48 50 52 54 56

0

20

40

60

80

100X

(T) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Temperature (∘C)

(a)

0 2 4 6 8 10 12 14 16 18 200

20

40

60

80

100

X(t

) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Time (min)

(b)



120593 (∘Cmin) 1198790(∘C) 119879

119901(∘C) Δ119867

119888(Jg)

1 5339 5203 55745 5229 5019 707710 5150 4940 740720 5089 4845 7730



0) and the


0and 119879





119883 () 119865 (119879) 119886

20 4875 084140 5598 079960 7129 078980 9727 0783




minus02 00 02 04 06 08 10 12 14

minus04

minus02

00

02

04

06

08

10

X = 40X = 60X = 80

lg 120593

lg tX = 20


307 308 309 310 311minus120

minus115

minus110

minus105

minus100

minus95

minus90

minus85


ln(120593T

2 p)





119901) versus 1119879



4 Conclusions





Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


32 34 36 38 40 42 44 46 48 50 52 54 56

0

20

40

60

80

100X

(T) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Temperature (∘C)

(a)

0 2 4 6 8 10 12 14 16 18 200

20

40

60

80

100

X(t

) (

)

1∘Cmin5∘Cmin

10∘Cmin20∘Cmin

Time (min)

(b)



120593 (∘Cmin) 1198790(∘C) 119879

119901(∘C) Δ119867

119888(Jg)

1 5339 5203 55745 5229 5019 707710 5150 4940 740720 5089 4845 7730



0) and the


0and 119879





119883 () 119865 (119879) 119886

20 4875 084140 5598 079960 7129 078980 9727 0783




minus02 00 02 04 06 08 10 12 14

minus04

minus02

00

02

04

06

08

10

X = 40X = 60X = 80

lg 120593

lg tX = 20


307 308 309 310 311minus120

minus115

minus110

minus105

minus100

minus95

minus90

minus85


ln(120593T

2 p)





119901) versus 1119879



4 Conclusions





Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


minus02 00 02 04 06 08 10 12 14

minus04

minus02

00

02

04

06

08

10

X = 40X = 60X = 80

lg 120593

lg tX = 20


307 308 309 310 311minus120

minus115

minus110

minus105

minus100

minus95

minus90

minus85


ln(120593T

2 p)





119901) versus 1119879



4 Conclusions





Acknowledgments


References












































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of









































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Research Article Kinetic Study on the Isothermal and...

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