16
`
`Grasas y Aceites
`Vol. 50. Fase. 1 (1999), 16-22
`
`Determination of melting point of vegetable oils and fats by differentia!
`scanning calorimetry (DSC) technique
`
`By Renata Tieko Nassu* and Lireny Aparecida Guaraldo Gonçalves
`
`Laboratorio de Óleos e Gorduras - Faculdade de Engenharia de Alimentos (FEA) - Universidade
`Estadual de Campinas (UNIGAMP), Caixa Postal 6091 CEP 13081-970, Campinas, SP, Brazil.
`
`* To whom correspondence should be addressed. New address: Centro Nacional de Pesquisa da
`Agroindustria Tropical (CNPAT)/EMBRAPA- Rua Dra. Sara Mesquita, 2270. CEP 60511 -110, Fortaleza,
`CE, Brazil, e-mail: renata@cnpat.embrapa.br
`
`RESUMEN
`
`Determinación del punto de fusión de aceites y grasas
`vegetales por técnica de calorimetría diferencial de barri(cid:173)
`do (DSC).
`
`El punto de fusión de grasas es usado para caracterizar aceites y
`grasas, y está relacionado con sus propiedades físicas, tales como du(cid:173)
`reza y comportamiento térmico. El presente trabajo muestra la utiliza(cid:173)
`ción de la técnica de Calorimetría Diferencial de Barrido (DSC) en* la
`determinación del punto de fusión de grasas. En comparación con el
`punto de ablandamiento (AOCS método Ge 3-25), los valores de DSC
`fueron más altos que los obtenidos por los métodos de AOCS. Esto ha
`ocurrido debido al hecho que los valores obtenidos por la técnica de
`DSC fueron tomados cuando la grasa había fundido completamente.
`DSC fue también útil para determinar puntos de fusión de aceites líqui(cid:173)
`dos, tales como los de soya y algodón.
`
`PALABRAS-CLAVE: Calorimetría Diferencial de Barrido (DSC)
`-^ Grasa vegetal — Pur)to de ablandamiento — Punto de fusión.
`
`SUMMARY
`
`Determination of melting point of vegetable oils and
`fats by differential scanning calorimetry (DSC) technique.
`
`Melting point of fats is used to characterize oils and fats and is
`related to their physical properties, such as hardness and thermal
`behaviour. The present work shows the utilization of DSC
`technique on the determination of melting point of fats. In a
`comparison with softening point (AOCS method Cc 3-25), DSC
`values were higher than those obtained by AOCS method. It has
`occurred due to the fact that values obtained by DSC technique
`were taken when the fat had melted completely. DSC was also
`useful for determining melting point of liquid oils, such as soybean
`and cottonseed ones.
`
`KEY-WORDS: Differential Scanning Calorimetry (DSC) —
`Melting point — Softening point — Vegetable fat.
`
`1.
`
`INTRODUCTION
`
`Melting point of fats is measured by various
`methods.. These include Wiley melting point (AOCS
`
`Method Cc 2-38) (AOCS, 1988), open capillary slip
`point, softening point (AOCS method Cc 3-25)
`(AOCS, 1988), ring and ball methods and automated
`techniques such as Mettler dropping point and Elex
`apparatus. Several authors compared methods^
`usually applied with another ones, in relation to the
`methods themselves and temperature procedures.
`Kanematsu et al., (1979a and 1979b), used Mettler
`dropping point and tested conditions for measurement,
`comparing values obtained by Mettler dropping
`point, softening point from Japanese standard, clear
`point and Wiley melting point with various fats. Close
`correlations were found between these methods.
`Open-tube melting point using Elex automatic
`apparatus was compared with the conventional
`method by Kanematsu et al., (1981). Results showed
`that the values obtained did not show statistically
`significant differences. Deman etal., (1983) compared
`several methods for determination of melting point
`using various fats and tested the reproducibility of
`these methods. Reproducibilities of the Mettler
`dropping point and softening point were considered
`excellent and for slip point, poor. Kawada et al.,
`(1985) proposed melting point determination by
`another methods, such as ring and ball methods.
`
`Many melting point measurement methods can
`be grouped in different ways. As parameters for
`measuring it, some methods determine the point of
`complete melting of all crystalline material while
`others use a point farther removed from there and
`are called softening, slipping or dropping points.
`Subjective interpretation of the endpoint by the
`operator or objective indications are used. Some
`methods depend upon manual controls; others
`emply a certain degree of automation. In this group,
`modern instrumentation has shown the way for
`possible
`improvements. The use of automatic
`temperature control,
`linear heating
`rates and
`objective endpoint determinations promise an
`improvement in the precision of melting point tests
`(Mertens, 1973). Differential Scanning Calorimetry
`
`Merck 2008 Argentum
`v. Merck
`IPR2018-00423
`
`(c) Consejo Superior de Investigaciones Científicas
`Licencia Creative Commons 3.0 España (by-nc)
`
`http://grasasyaceites.revistas.csic.es
`
`

`

`Vol. 50. Faso. 1 (1999)
`
`17
`
`(DSC) is an alternative, being one of the most used
`techniques for studying thermal behaviour of various
`foods components. Melting point obtained by DSC is
`generally considered as the onset temperature, the
`inflection point of melting curve and solid line.
`Deman et al, (1991) consider melting point as the
`peak temperature calculated from a DSC melting
`curve. In this referred study, temperature measured
`at the end of melting curve obtained by DSC was
`considered as the real melting point, where the
`melting phenomenon finishes, when all crystals in
`solid state became liquid. Slew et ai, (1982) concluded
`that melting point is essentially determined by the
`hard fraction of stearins, indicated by the major peak.
`Chaisery & Dimick (1995), in a study of crystallization
`of cocoa butter, measured melting point by DSC of
`low and high melting fractions, considering onset
`melting temperature. In a study of effect of cooling
`and heating rates variation, Cebula & Smith (1991)
`measured melting point of pure triglycerides, also
`considering the onset temperature.
`In this study, final melting temperatures obtained
`by DSC technique were compared with softening
`point (AOCS method Cc 3-25) (AOCS, 1988) values
`for various vegetable oils and fats.
`
`2. EXPERIMENTAL
`
`2.1. Material
`
`Perkin Elmer DSC7 Differential Scanning Calorimeter.
`Nitrogen was the carrier gas and calibration was
`done with indium, after checking the operation with
`distilled, deionized water. 10-15mg of sample were
`enclosed in hermetically sealed aluminum pans and
`run against air (empty pan) as reference. DSC
`melting curves were obtained according to Dodd &
`Tonge (1987). Samples were heated to 80°C for 5
`minutes, cooled at 10°C/min to -50°C, holding at this
`temperature for 5 minutes to crystallize the sample.
`After this procedure, melting curves were recorded
`from initial temperature to 80°C at a heating rate of
`10°C/min. The resulting DSC data was analyzed by
`peak program and peak temperature, onset temperature
`and melting temperature were recorded. Melting
`temperature was considered as the temperature at
`the end of the curve, when melting has completed.
`
`3. RESULTS AND DISCUSSION
`
`Fatty acid composition of the samples can be
`seen in table I. Values showed the great variability of
`the samples, which influences melting point values
`and the shape of DSC melting curves.
`
`Table 1
`Fatty acid composition of
`
`vegetable oils
`
`Sanóle
`
`C8:0
`
`C10:0 C12;0 C14:0
`
`CI 6:0
`
`C16:1
`
`CI 8:0
`
`CI 8:1
`
`CI 8:2
`
`CI 8:3
`
`C20:0
`
`—
`
`—
`
`0.12
`
`11.41
`
`0.11
`
`9.51
`
`—
`
`—
`
`0.12
`
`11.16
`
`0.11
`
`13.04
`
`22.31
`49.21(a)
`
`2.05
`4.84(b)
`
`0.24
`
`0.18
`
`35.02
`36.28(a)
`
`0.91
`2.66(b)
`
`0.25
`
`0.44
`
`—
`
`—
`
`0.84
`
`23.31
`
`0.74
`
`3.36
`
`59.39
`
`1.12
`10.11(b)
`
`- ~
`
` —
`
`
`
`SON
`
`SOB
`
`AGH
`
`AGI
`
`5.34
`
`4.25 35.89 13.30
`
`11.06
`
`23.67
`
`3.77
`
`2.71
`
`PMD
`
`—
`
`0.46
`
`0.82
`
`38.23
`
`5.32
`
`42.47
`
`12.19
`
`0.01
`
`-
`0.10
`
`0.25
`0.86(c)
`-
`0.39
`
`6.59
`
`32.62
`
`9.28
`
`0.50
`
`0.37
`
`5.08
`
`44.53
`
`13.35
`
`0.59
`
`0.37
`
`- ----
`
`56.30
`
`2.07
`
`0.19
`0.52(b)
`
`0.01
`
`--_
`
`-
`
`
`
`2.34
`
`14.30
`
`2.47
`
`6.68
`
`2.22
`
`0.94
`
`3.51
`
`13.73
`
`2.43
`
`15.69
`
`2.02
`2.85(a)
`
`1.12
`
`----- ----
`
`—
`
`—
`
`—
`
`—
`
`—
`
`—
`
`0.80
`
`49.83
`
`0.63
`
`35.43
`
`0.68
`
`40.22
`
`----
`
`PME
`
`PMO
`
`PMH
`
`PKR
`
`4.35
`
`3.57 48.71 16.34
`
`8.15
`
`PKE
`
`2.62
`
`3.02 54.85 21.06
`
`8.35
`
`BBD
`
`6.01
`
`5.11 43.87 16.30
`
`9.04
`
`BBH
`
`5.90
`
`5.07 42.74 15.54
`
`9.08
`
`SON-hydrogenated soybean oil type «N»; SOB-hydrogenated soybean oil type «B»;
`AGH-hydrogenated cottonseed oil; AGI-interesterified cottoseed oil; PMD-deodorized
`palm oil; PME-palm stearin; PMO-palm olein; PMH-hydrogenated palm oil; PKR-refined
`palm kemel oil; PKE-palm kernel stearin; BBD-deodorized babassu oil; BBH-hydrogenated
`babassu oil.
`
`G8:0 - Caprilic acid
`C10:0-Capricacid
`C12:0-Laurie acid
`C14:0- Myristicacid
`C16:0-Palmitic acid
`016:1 - Palmitoleic acid
`
`018:0-Stearic acid
`018:1 -Oleic acid
`018:2 - Linoleic acid
`020:0 - Arachidic acid
`018:3 - Linolenic acid
`
`(a) Unidentified: probably trans isomer and/or positional of 018:1
`(b) Unidentified: probably trans isomer and/or positional of 018:2
`(c) Unidentified
`
`14 different types of oils and fats were used:
`soybean oil, cottonseed oil, palm oil, palm olein,
`palm stearin, babassu oil and hydrogenated oils
`(soybean, two types; palm oil, cottonseed oil and
`babassu oil), palm kernel oil, palm kernel stearin and
`intersterified cottonseed oil. The samples were
`gently supplied by Gessy Lever Ltda. (Valinhos, SP)
`and Refinadora de Óleos Brasil (Sao Caetano do
`Sul, SP).
`
`2.2. Fatty acid compositions of samples
`
`Fatty acid composition was done through analysis
`of methyl esters by gas-liquid chromatography. The
`instrument used was a Perkin Elmer Sigma 3B
`gas-liquid chromatograph with ionization detector
`and the results were obtained by a Perkin Elmer
`integrator LCI - 100. The methyl esters were
`obtained according to Hartman & Lago (1973).
`
`2.3. Melting point measurement of samples
`
`Melting point of samples were measured by
`Softening point [AOCS method Cc 3-25 (1988)] and
`by DSC, as described. The instrument used was a
`
`(c) Consejo Superior de Investigaciones Científicas
`Licencia Creative Commons 3.0 España (by-nc)
`
`http://grasasyaceites.revistas.csic.es
`
`

`

`18
`
`Grasas y Aceites
`
`Softening points varied from 20.1 °C to 58.4°C, for
`palm olein and hydrogenated palm oil, respectively.
`These values indicate a large range of melting point
`for the samples studied. This measurement was not
`done for soybean and cottonseed oils because this
`method does not apply to these samples due to their
`low melting points, -23 to -20°C for soybean oil and
`-2 to 2°C for cottonseed oil (Weiss, 1980)
`Figures 1 to 14 show DSC melting curves obtained.
`Melting range and DSC curve shape result from
`combined effects between fatty acid composition,
`polymorphism and thermal history (Kaisersberger,
`1989). Soybean oil has a characteristic curve about
`-25°C and its melting occurs at temperatures below 0°C
`(figure 1). In relation to hydrogenated soybean oils,
`there is a broadening of the curves and their moving to
`higher
`temperatures regions (figures 2 and 3).
`Formation of trans and positional isomers due to
`hydrogénation
`resulted
`in
`the
`formation of
`non-intersoluble triglycerides, increasing the melting
`range of the samples. The same phenomenon occurs
`with cottonseed oil and its hydrogenated and
`interesterified samples (figures 4, 5, and 6). Palm oil
`has a very characteristic curve, showing clearly its two
`component fractions, separated by an exothermic
`peak, (figure 7). Hydrogenated palm oil sample shows
`two peaks, corresponding to a and p polymorphic
`forms (figure 8). Palm olein (figure 9) shows only one
`peak, corresponding to the lowest temperature peak
`observed in palm oil while palm stearin (figure 10)
`shows a similar profile to that one of palm oil, showing
`two peaks. Palm kernel (figure 11) shows only one
`peak and a limited melting range. Palm kernel stearin
`(figure 12) has the same DSC profile of palm kernel,
`but its curve is sharper and is located at higher
`temperature, indicating a small melting range. Babassu
`oil (figure 13) has a similar profile of palm kernel oil, both
`with high concentrations of lauric acid (see table I).
`Hydrogenated babassu (figure 14) oil has a greater
`melting range, due to the formation of trans and
`positional isomers, as already commented about
`hydrogenated soybean and cottonseed oils.
`Onset, peak temperatures and melting point
`temperatures obtained by DSC melting curves and
`AOCS Softening point values are shown in table II.
`When comparing DSC melting point values with
`softening point ones, those obtained by DSC
`technique are always higher than softening point
`ones, with differences ranging from 2.2 to 9.3°C, with
`average values of 5.2°C. Correlationship between
`the temperatures obtained by the two techniques
`was calculated as 0.9856, considered high and
`indicating good
`relationship between
`the two
`techniques. These results agree with those obtained
`by Deman et al., (1983) which compared Mettler
`dropping point and DSC melting points. DSC melting
`points were generally considerably higher than the
`Mettler dropping points.
`
`• 5CUA OESOOmrZAOA
`
`•k.K
`
`- à .»
`
`-10.00
`
`lOô
`*ÔM
`I
`TaHparatura (C)
`
`30Ô
`
`3D.00
`
`«.oc
`
`Figure 1
`DSC melting curve for deodorized soybean oil
`
`Figure 2
`DSC melting curve for type «N» hydrogenated soybean oil
`
`- - SOJA HIQROeaiAOA E
`
`-30.00
`
`-ao.N
`
`- u .w
`
`10.00
`Q.09
`TMWsratura (C|
`
`ao.so
`
`ao.oo
`
`«.oo
`
`a.ec
`
`Figure 3
`DSC melting curve for type «B» hydrogenated soybean oil
`
`(c) Consejo Superior de Investigaciones Científicas
`Licencia Creative Commons 3.0 España (by-nc)
`
`http://grasasyaceites.revistas.csic.es
`
`

`

`Vol.50. Fase. 1 (1999)
`
`19
`
`Figure 4
`DSC melting curve for deodorized cottonseed oil
`
`Figure 7
`DSC melting curve for deodorized palm oil
`
`- - PALMA HIOROKNAOA
`
`Figure 5
`DSC melting curve for hydrogenated cottonseed oil
`
`Figure 8
`DSC melting curve for hydrogenated palm oil
`
`• ALSQDAO IKTERESTBUPICAOO
`
`• OLECKA OE PALMA
`
`ïlôi
`
`-&.00
`
`'o.«
`
`ia.oo
`ÎOÔ
`Taaparatura (¡c)
`
`íü
`
`«loi
`
`51ô
`
`BOÔ TÔ.OC
`
`5 1.3
`
`-hM
`
`-áo.oo
`
`-laM
`
`lo.oi
`'ôM
`TsfipwMtuce dc]
`
`S;;»
`
`Sîw
`
`30fl
`
`A.K
`
`-30.08
`
`-ao.oo
`
`-tO.OO
`
`20.00
`1.00 M.OS
`Teniwaturalcj
`
`30.00
`
`40.00
`
`SB.»
`
`GO.OC
`
`Figuré 6
`DSC melting curve for interesterified cottonseed oil
`
`Figure 9
`DSC melting curve for palm oil
`
`(c) Consejo Superior de Investigaciones Científicas
`Licencia Creative Commons 3.0 España (by-nc)
`
`http://grasasyaceites.revistas.csic.es
`
`

`

`20
`
`Grasas y Aceites
`
`r_:
`
`BABASSU DeSOOOfllZAOO
`
`^'^v^
`
`V.
`
`•
`
`-io.M
`
`-km
`
`-io.oo
`
`koo
`'o.»
`TsBpBrature CC)
`
`km
`
`JS.OO
`
`JO.OO
`
`SO.OC
`
`Figure 10
`DSC melting curve for palm stearin
`
`Figure 13
`DSC melting curve for deodorized babassu oil
`
`- - PALMISTE nCFINADQ
`
`-io.oo
`
`-á).eo
`
`-{b.oo
`
`zôSo
`loTôi
`ï lô
`Teaperature (Cl
`
`S iô
`
`30ô
`
`5Iôô
`
`li.oc
`
`Figure 14
`DSC melting curve for hydrogenated babassu oil
`
`¿1.(10
`T«Bperatura (C)
`
`Figure 11
`DSC melting curve for refined palm kernel oil
`
`- - ESTEARINA DE PALMISTE
`
`-jo.eo
`
`4).eQ
`
`-io.oo
`
`â lô
`SIS
`olü
`TaHp«patur« (C)
`
`£lw
`
`Ï IM
`
`SU «.O<
`
`Figure 12
`DSC melting curve for palm kernel stearin
`
`Figure 15 shows a graphical comparison between
`differences of melting points and other characteristic
`temperatures obtained by DSC melting curves and
`softening point values. If onset temperatures were
`considered, differences between these temperatures
`and softening point ones are bigger, because onset
`temperatures were recorded when the fat began to
`melt, while in softening point they had melt more
`than this point recorded by DSC. When comparing
`peak temperatures obtained by DSC with softening
`points, we can observe that the former are higher
`than
`those obtained by DSC, except
`for
`hydrogenated palm sample. Big differences can be
`seen between deodorized palm oil and palm olein.
`This fact occurs because peak temperature is
`recorded as the temperature of the main peak, when
`curve shows more than one. In this case, main peak
`of both samples was located in a region where
`temperature was not sufficient to melt the sample in
`the same point of that recorded by softening point.
`
`(c) Consejo Superior de Investigaciones Científicas
`Licencia Creative Commons 3.0 España (by-nc)
`
`http://grasasyaceites.revistas.csic.es
`
`

`

`Vol. 50. Fasc.1 (1999)
`
`21
`
`Sample
`
`Table II
`Characteristic temperatures obtained by DSC
`melting curves and AOCS softening point values
`Onset
`Peak
`Melting
`Softening
`temperature
`temperature
`point
`point
`fC)
`(°C)
`(°C)
`(°C)
`—
`SOD
`-28.6
`-26.1
`-5.8
`SON
`6.9
`19.8
`36.8
`32.0
`SOB
`15.0
`42.7
`32.5
`37.3
`—
`AGD
`-9.9
`- -4.5
`-0.5
`AGH
`10.9
`27.8
`38.4
`32.7
`AGI
`15.5
`32.7
`42.8
`36.4
`PMD
`-18.6
`0.2
`36.2
`41.3
`PME
`2.3
`46.2
`54.5
`49.8
`PMO
`-15.5
`4.0
`29.4
`20.1
`PMH
`54.4
`59.7
`64.9
`58.4
`PKR
`13.6
`25.8
`30.6
`28.4
`PKE
`24.2
`31.3
`34.8
`31.7
`BBD
`13.8
`24.4
`24.4
`28.9
`BBH
`12.3
`27.3
`40.4
`35.5
`SOD - deodorized soybean oil; SON - hydrogenated soybean oil
`type «N»; SOB - hydrogenated soybean oil type «B»; AGD -
`deodorized cottonseed oil; AGH - hydrogenated cottonseed oil;
`AGI - interesterified cottonseed oil; PMD - deodorized palm oil;
`PME - palm stearin; PMO - palm olein; PMH - hydrogenated
`palm oil; PKR - refined palm kernel oil; PKE - palm kernel stearin;
`BBD - deodorized babassu oil; BBH - hydrogenated babassu oil.
`
`ACKNOWLEDGEMENTS
`
`The authors acknowledge the financial support
`given by CNPq (Conselho Nacional de Desenvolvimento
`Científico e Tecnológico, Brasilia, Brasil) and FAPESP
`(Fundaçao de Amparo à Pesquisa do Estado de Sao
`Paulo, Sao Paulo, Brasil).
`
`REFERENCES
`
`AOCS (1988).—«Official Methods and Recomnaended
`Practices of the American Oil Chenriists' Society». 3rd.
`éd., Champaign.
`Cebula, D.J.; Smith, K.W. (1991).—«Differential Scanning
`Calorimetry of Confectionery Fats. Pure triglycerides:
`effects of cooling and heating rate variation».—J. Am.
`Oil Chem. Soc. 68: 591-595.
`Chaiseri, S.; Dimick, P.S. (1995).—«Dynamic crystallization
`of cocoa butter. II Morphological, thermal and chemical
`characteristics during crystal growth.».—J. Am. Oil
`Chem. Soc. 82: 1497-1504.
`Deman, J.M.; Deman, L; Blackman, B. (1983).—
`«Melting-point determination of fat products».—J. Am.
`Oil Chem. Soc. 60:15-18
`Deman, L; Deman, J.M.; Blackman, B. (1991).— «Physical
`and textural characteristics of some North American
`shortenings».—xJ. Am. Oil Chem. Soc. 68: 63-69.
`Dodd, J.W.; Tonge, K.H. (1987).—«Thermal methods».—
`John Wiley and Sons, London.
`Hartman, L& Lago, R. C. (1973).—«Rapid determination
`of fatty acid methyl esters from lipids».—Lab. Practice
`22(8): 475-476, 494.
`Kaisersberger, E (1989).—«DSC investigations of the
`thermal characterization of edible fats and oils».—
`Thermochim. Acta 151: 83-90.
`Kanematsu, H.; Kinoshita, Y; Niiya, I.; Matsumoto, T.
`(1979a).—«Automatic melting point determination of
`edible solid fats. IV. Mettler softening points of solid
`fats».-^. Japan Oil Chem. Soc. (Yukagaku) 28:180-184
`Kanematsu, H.; Kinoshita, Y; Niiya,
`I.; Matsumoto,
`T.(1979b).—«Automatic melting point determination of
`edible solid fats. V. Melting point of mixed fats and
`plastic fat products».—J. Japan Oil Chem. Soc.
`(Yukagaku) 28:344-347
`Kanematsu, H.; Kinoshita, Y; Niiya, I.; Matsumoto, T.
`(1981).—«Automatic melting point determination of
`edible solid fats. VI. Open-tubed melting point using
`the Elex apparatus».—J. Japan Oil Chem. Soc.
`(Yukagaku) 30: 881-883.
`Kawada-T; Suzuki-K; Yokomizo-K; Kanematsu-H;
`Hirata-Y; Shikama-T; Sakata-M; Mori-Hi Takeya-K;
`Abeshima-T (1985).—«Softening point determination
`by the ring and ball method».—J. Japan Oil Chem.
`Soc. (Yukagaku) 34: 952-956.
`Mertens, W.G. (1973).—«Fat melting point determinations:
`a review».—J. Am. Oil Chem. Soc. 50: 115-119
`Siew, W.L; Ong, A.S.H.; Oh, FC.H.; Berger, K.G. (1982).—
`«Critical aspects of slip melting point measurements».—
`PORIMBull.4: 1-18.
`Weiss, T.J. (1980).—«Food oils and their uses».—2nd.
`Ed.—The AVI Publishinjg Company Inc., Westport,
`(Connecticut), p.27-28.
`
`Recibido: Noviembre 1997
`Aceptado: Abril 1998
`
`u
`
`"
`UJ
`
`1
`
`If 20 4-
`u.
`a
`
`A III y y
`
`1
`
`i
`
`1
`
`Bdif. DSC onset temp, x S.P.
`lodif. DSC peak temp, x S.P.
`
`1 1 A
`î 1
`L i i ll
`f^
`
`SON SOB AGH AGI PMD Ptm PMO PMH PKR PKE BBO BBH
`
`DSC - Differential Scanning Calorimetry; M.P. - melting point; S.P.
`- softening point.
`SOD - deodorized soybean oil; SON - hydrogenated soybean oil
`type «N»; SOB - hydrogenated soybean oil type «B>>; AGD -
`deodorized cottonseed oil; AGH - hydrogenated cottonseed oil;
`AGI - interesterified cottonseed oil; PMD - deodorized palm oil;
`PME - palm stearin; PMO - palm olein; PMH - hydrogenated
`palm oil; PKR - refined palm kernel oil; PKE - palm kernel stearin;
`BBD - deodorized babassu oil; BBH - hydrogenated babassu oil.
`Figure 15
`Comparative graphic of differences between temperatures
`obtained by DSC technique and AOCS softening point values
`
`4. CONCLUSIONS
`is a accurate
`that DSC
`These
`results show
`technique, which can measure the temperature when
`fat is completely in the liquid state. When measuring by
`softening point technique, an empirical method, in the
`point of measurement crystals are not melted
`completely, leading to lower values. Besides, by DSC
`technique it is possible to determine melting point of
`liquid oils such as soybean and cottonseed oils. DSC
`melting curves are also obtained, which is very useful
`to observe the melting range of the sample.
`
`(c) Consejo Superior de Investigaciones Científicas
`Licencia Creative Commons 3.0 España (by-nc)
`
`http://grasasyaceites.revistas.csic.es
`
`