- Teks
- Sejarah
(Fig. 11). The cisconfiguration pro
(Fig. 11). The cisconfiguration produces a bend in the
molecule, whereas thetrans configuration resembles
more the straight chain of saturated fatty acids.
During partial hydrogenation, some double bonds are
isomerized into transfatty acids from theircisconfiguration (Scholfield et al., 1967). Transfatty acids have
similar melting points to that of the corresponding
saturated fatty acids and are very important contributors to the functional properties of hydrogenated
products. This has recently become a controversial
health issue. Many studies have been done on the biological effects of trans-fatty acids in animal and human
subjects (Anderson, Grande, & Keys, 1961; Anderson
and Coots, 1967; Beveridge & Connel, 1962; Coots,
1964a, 1964b; Emken, Rohwedder, Dutton, Dejarlais, &
Adolf, 1979; Erickson, Coots, Mattson, & Kligman,
1964; Johnston, Johnson, & Kummerow, 1957; Kummerow, Mizuguchi, Arima, Cho, & Hunang, 1978;
Mavis & Vegelos, 1972). However, some controversial
results were reported regarding their effect on the metabolism and vital organs of the respective subjects under
experimental conditions. Kummerow and coworkers
(Kummerow et al., 1978) reported the adverse effects of
hydrogenated fat on the development of atherosclerotic
lesions in swine. In human subjects, it has been found
that diet containing trans acids cause an elevation of
plasma cholesterols, triacylglycerides and phospholipids
(Anderson et al., 1961). These results are supported by
Vergrosen (1972)and Houtsmuller (1978). However,
Vergrosen (1972)also reported that trans acids are less
hypercholesterolemic (increase in plasma cholestrol
level) than the shorter-chain saturates, lauric and myristic, but more hypercholesterolemic than either palmitic
or oleic. The fact thattrans fatty acids have a higher
Fig. 11. Molecular structure ofcisandtransisomers of C18:1.
Table 14
Summary: hydrogenation
Influence of process conditions
Increase in Parameter affected
Degree of selectivity Trans-isomer formation
H2pressure Decreases Decreases
Temperature Increases Increases
Agitation Decreases Decreases
Table 15
Summary: factors affecting selectivity of a hydrogenation process
Hydrogenation conditions affecting selectivity
Reaction parameter Selective
hydrogenation
Non-selective
hydrogenation
Temperature High Low
H2 Low High
Agitation Low High
Catalyst concentration High Low (spent)
Trans-isomer formed High amount Low amount
SFC curve shape (Fig. 3) Steep Flat
Crystal stability Beta prime or mixture
of beta-prime and beta
Beta only
1038 B.S. Ghotra et al. / Food Research International 35 (2002) 1015–1048
melting point than their correspondingcis-isomers suggests that the incorporation of thetransfatty acids into
cellular membranes may affect the properties of the
membrane and its function (Chapman, Owens et al.,
1966). High levels of trans fatty acids are considered to
be a risk factor for cardiovascular diseases (Reddy &
Jeyarani, 2001). Industry and regulatory agencies are
beginning to work together to ensure that the manufacture of shortenings do not amplify TFA intake. It is
expected that USA Food and Drug Administration
(FDA) will establish regulations governing the percentage of allowed TFAs in edible oil products in 2002.
Specialty oils such as Trisun and Sunola oils (based on
sunflower seed oil) do not require hydrogenation for
good stability and performance (Mag, 1994). These
have potential uses in manufacturingtrans-free shortenings. Recently, it has been reported that it is possible
to prepare TFA-free bakery shortening (puff/cake/biscuit) using Mango and Mahua fats and their fractions
(Reddy & Jeyarani, 2001). Reddy and Jeyrani (2001)
and Kok and coworkers (Kok, Fehr, Hammond, &,
White, 1999), have successfully prepared a shortening
without any hydrogenation treatment. They also
demonstrated that such a product has functional
properties comparable to most of the commercial
shortenings.
Further research is required in the following important
areas:
1. Improvements in the hydrogenation process for
use in the manufacture oftrans-free shortenings.
2. Effects oftransfatty acids on the physiology and
biochemistry of vital organs such as the heart.
3. Manipulations of the processing conditions
under which shortenings/margarines are produced to deliver comparable functional properties without needing to hydrogenate.
Within our laboratory, our efforts are concentrated
around understanding relationships between molecular
ensembles, processing conditions, crystalline and
microstructural structure of the shortening network,
and between all levels of structure of the network and
physical functionality of the shortening. In this manner, we
hope to build a comprehensive understanding of the ways
in which the starting materials and processing conditions
affect the functional properties of the final network.
10.2. Manufacturing
There are number of factors that influence the final
physical functionality of shortenings and margarines:
1. proportions of solids to liquids;
2. viscosity of the liquid;
3. temperature treatment;
4. mechanical working;
5. super cooling;
6. polymorphism;
7. properties of the crystals: size, number, and
composition; and
8. spatial distribution, size, and shape of the
microstructure.
Processing, therefore, is as equally important as the
design of the oil blend; in the determination of the physical properties and performance of shortenings. For
example, whipping of margarines up to fifty percent
overrun. (Overrun is defined as incorporation of air into
the product that results in decreasing the bulk density,
increasing hardness, and in allowing the use of softer
(unsaturated) oil blends, (Gorman, Bluff, Christie, &
Glenview Kraft, 1960). Formulation of the blend and
subsequent processing conditions regulates the type of
crystal formation and subsequent network formation.
The type of crystals formed has a direct influence on the
morphology of the solid structure (microstructure) that
traps the liquid phase of the shortening/margarine
(Haighton, 1976; Thomas, III 1978; Wiedermann,
1978).Haighton (1959, 1976)reported that the hardness
of margarine in terms of yield value has a strong correlation to the solid content. The manufacturing process
itself can have significant impact on the solid content of
the finished margarine. Margarines are typically manufactured by quick chilling of the fat blend using a swept
surface heat exchanger (Unit A, Fig. 12), followed by
holding in crystallization tubes before molding or
forming. Depending on the rate of cooling, the relative
time spent in the heat exchanger and crystallization
tubes, whether the fat is ‘worked’ in the crystallization
tubes, and the temperature of the crystallization tube,
the solid content, and the crystal type and microstructure of the resulting network is greatly affected.
The temperature in the crystallization tube is usually
2
C higher than the temperature in Unit A, due to the
liberation of heat during crystallization (Haighton,
1976). If the rate of crystallization is low, the margarine
is typically very soft (Haighton, 1976). The fat continues
to crystallize in the holding tubes and usually needs
hours to reach complete crystallization. Various
arrangements of Unit A and crystallization tubes are
applied for different kind of shortening manufacturing,
as shown inFig. 12. For stick margarines, the supercooled fat is allowed to solidify without agitation. This
post crystallization, in the absence of agitation, favors
the formation of strong networks characterized by sintering between network structures and the product
demonstrates a narrow plastic range. When a specific
characteristic is desired, the use of an additional working unit, after super cooling in the scraped surface heat
exchanger, is required.
molecule, whereas thetrans configuration resembles
more the straight chain of saturated fatty acids.
During partial hydrogenation, some double bonds are
isomerized into transfatty acids from theircisconfiguration (Scholfield et al., 1967). Transfatty acids have
similar melting points to that of the corresponding
saturated fatty acids and are very important contributors to the functional properties of hydrogenated
products. This has recently become a controversial
health issue. Many studies have been done on the biological effects of trans-fatty acids in animal and human
subjects (Anderson, Grande, & Keys, 1961; Anderson
and Coots, 1967; Beveridge & Connel, 1962; Coots,
1964a, 1964b; Emken, Rohwedder, Dutton, Dejarlais, &
Adolf, 1979; Erickson, Coots, Mattson, & Kligman,
1964; Johnston, Johnson, & Kummerow, 1957; Kummerow, Mizuguchi, Arima, Cho, & Hunang, 1978;
Mavis & Vegelos, 1972). However, some controversial
results were reported regarding their effect on the metabolism and vital organs of the respective subjects under
experimental conditions. Kummerow and coworkers
(Kummerow et al., 1978) reported the adverse effects of
hydrogenated fat on the development of atherosclerotic
lesions in swine. In human subjects, it has been found
that diet containing trans acids cause an elevation of
plasma cholesterols, triacylglycerides and phospholipids
(Anderson et al., 1961). These results are supported by
Vergrosen (1972)and Houtsmuller (1978). However,
Vergrosen (1972)also reported that trans acids are less
hypercholesterolemic (increase in plasma cholestrol
level) than the shorter-chain saturates, lauric and myristic, but more hypercholesterolemic than either palmitic
or oleic. The fact thattrans fatty acids have a higher
Fig. 11. Molecular structure ofcisandtransisomers of C18:1.
Table 14
Summary: hydrogenation
Influence of process conditions
Increase in Parameter affected
Degree of selectivity Trans-isomer formation
H2pressure Decreases Decreases
Temperature Increases Increases
Agitation Decreases Decreases
Table 15
Summary: factors affecting selectivity of a hydrogenation process
Hydrogenation conditions affecting selectivity
Reaction parameter Selective
hydrogenation
Non-selective
hydrogenation
Temperature High Low
H2 Low High
Agitation Low High
Catalyst concentration High Low (spent)
Trans-isomer formed High amount Low amount
SFC curve shape (Fig. 3) Steep Flat
Crystal stability Beta prime or mixture
of beta-prime and beta
Beta only
1038 B.S. Ghotra et al. / Food Research International 35 (2002) 1015–1048
melting point than their correspondingcis-isomers suggests that the incorporation of thetransfatty acids into
cellular membranes may affect the properties of the
membrane and its function (Chapman, Owens et al.,
1966). High levels of trans fatty acids are considered to
be a risk factor for cardiovascular diseases (Reddy &
Jeyarani, 2001). Industry and regulatory agencies are
beginning to work together to ensure that the manufacture of shortenings do not amplify TFA intake. It is
expected that USA Food and Drug Administration
(FDA) will establish regulations governing the percentage of allowed TFAs in edible oil products in 2002.
Specialty oils such as Trisun and Sunola oils (based on
sunflower seed oil) do not require hydrogenation for
good stability and performance (Mag, 1994). These
have potential uses in manufacturingtrans-free shortenings. Recently, it has been reported that it is possible
to prepare TFA-free bakery shortening (puff/cake/biscuit) using Mango and Mahua fats and their fractions
(Reddy & Jeyarani, 2001). Reddy and Jeyrani (2001)
and Kok and coworkers (Kok, Fehr, Hammond, &,
White, 1999), have successfully prepared a shortening
without any hydrogenation treatment. They also
demonstrated that such a product has functional
properties comparable to most of the commercial
shortenings.
Further research is required in the following important
areas:
1. Improvements in the hydrogenation process for
use in the manufacture oftrans-free shortenings.
2. Effects oftransfatty acids on the physiology and
biochemistry of vital organs such as the heart.
3. Manipulations of the processing conditions
under which shortenings/margarines are produced to deliver comparable functional properties without needing to hydrogenate.
Within our laboratory, our efforts are concentrated
around understanding relationships between molecular
ensembles, processing conditions, crystalline and
microstructural structure of the shortening network,
and between all levels of structure of the network and
physical functionality of the shortening. In this manner, we
hope to build a comprehensive understanding of the ways
in which the starting materials and processing conditions
affect the functional properties of the final network.
10.2. Manufacturing
There are number of factors that influence the final
physical functionality of shortenings and margarines:
1. proportions of solids to liquids;
2. viscosity of the liquid;
3. temperature treatment;
4. mechanical working;
5. super cooling;
6. polymorphism;
7. properties of the crystals: size, number, and
composition; and
8. spatial distribution, size, and shape of the
microstructure.
Processing, therefore, is as equally important as the
design of the oil blend; in the determination of the physical properties and performance of shortenings. For
example, whipping of margarines up to fifty percent
overrun. (Overrun is defined as incorporation of air into
the product that results in decreasing the bulk density,
increasing hardness, and in allowing the use of softer
(unsaturated) oil blends, (Gorman, Bluff, Christie, &
Glenview Kraft, 1960). Formulation of the blend and
subsequent processing conditions regulates the type of
crystal formation and subsequent network formation.
The type of crystals formed has a direct influence on the
morphology of the solid structure (microstructure) that
traps the liquid phase of the shortening/margarine
(Haighton, 1976; Thomas, III 1978; Wiedermann,
1978).Haighton (1959, 1976)reported that the hardness
of margarine in terms of yield value has a strong correlation to the solid content. The manufacturing process
itself can have significant impact on the solid content of
the finished margarine. Margarines are typically manufactured by quick chilling of the fat blend using a swept
surface heat exchanger (Unit A, Fig. 12), followed by
holding in crystallization tubes before molding or
forming. Depending on the rate of cooling, the relative
time spent in the heat exchanger and crystallization
tubes, whether the fat is ‘worked’ in the crystallization
tubes, and the temperature of the crystallization tube,
the solid content, and the crystal type and microstructure of the resulting network is greatly affected.
The temperature in the crystallization tube is usually
2
C higher than the temperature in Unit A, due to the
liberation of heat during crystallization (Haighton,
1976). If the rate of crystallization is low, the margarine
is typically very soft (Haighton, 1976). The fat continues
to crystallize in the holding tubes and usually needs
hours to reach complete crystallization. Various
arrangements of Unit A and crystallization tubes are
applied for different kind of shortening manufacturing,
as shown inFig. 12. For stick margarines, the supercooled fat is allowed to solidify without agitation. This
post crystallization, in the absence of agitation, favors
the formation of strong networks characterized by sintering between network structures and the product
demonstrates a narrow plastic range. When a specific
characteristic is desired, the use of an additional working unit, after super cooling in the scraped surface heat
exchanger, is required.
0/5000
(Fig. 11). The cisconfiguration produces a bend in themolecule, whereas thetrans configuration resemblesmore the straight chain of saturated fatty acids.During partial hydrogenation, some double bonds areisomerized into transfatty acids from theircisconfiguration (Scholfield et al., 1967). Transfatty acids havesimilar melting points to that of the correspondingsaturated fatty acids and are very important contributors to the functional properties of hydrogenatedproducts. This has recently become a controversialhealth issue. Many studies have been done on the biological effects of trans-fatty acids in animal and humansubjects (Anderson, Grande, & Keys, 1961; Andersonand Coots, 1967; Beveridge & Connel, 1962; Coots,1964a, 1964b; Emken, Rohwedder, Dutton, Dejarlais, &Adolf, 1979; Erickson, Coots, Mattson, & Kligman,1964; Johnston, Johnson, & Kummerow, 1957; Kummerow, Mizuguchi, Arima, Cho, & Hunang, 1978;Mavis & Vegelos, 1972). However, some controversialresults were reported regarding their effect on the metabolism and vital organs of the respective subjects underexperimental conditions. Kummerow and coworkers(Kummerow et al., 1978) reported the adverse effects ofhydrogenated fat on the development of atheroscleroticlesions in swine. In human subjects, it has been foundthat diet containing trans acids cause an elevation ofplasma cholesterols, triacylglycerides and phospholipids(Anderson et al., 1961). These results are supported byVergrosen (1972)and Houtsmuller (1978). However,Vergrosen (1972)also reported that trans acids are lesshypercholesterolemic (increase in plasma cholestrollevel) than the shorter-chain saturates, lauric and myristic, but more hypercholesterolemic than either palmiticor oleic. The fact thattrans fatty acids have a higherFig. 11. Molecular structure ofcisandtransisomers of C18:1.Table 14Summary: hydrogenationInfluence of process conditionsIncrease in Parameter affectedDegree of selectivity Trans-isomer formationH2pressure Decreases DecreasesTemperature Increases IncreasesAgitation Decreases DecreasesTable 15Summary: factors affecting selectivity of a hydrogenation processHydrogenation conditions affecting selectivityReaction parameter SelectivehydrogenationNon-selectivehydrogenationTemperature High LowH2 Low HighAgitation Low HighCatalyst concentration High Low (spent)Trans-isomer formed High amount Low amountSFC curve shape (Fig. 3) Steep FlatCrystal stability Beta prime or mixtureof beta-prime and betaBeta only1038 B.S. Ghotra et al. / Food Research International 35 (2002) 1015–1048melting point than their correspondingcis-isomers suggests that the incorporation of thetransfatty acids intocellular membranes may affect the properties of themembrane and its function (Chapman, Owens et al.,1966). High levels of trans fatty acids are considered tobe a risk factor for cardiovascular diseases (Reddy &Jeyarani, 2001). Industry and regulatory agencies arebeginning to work together to ensure that the manufacture of shortenings do not amplify TFA intake. It isexpected that USA Food and Drug Administration(FDA) will establish regulations governing the percentage of allowed TFAs in edible oil products in 2002.Specialty oils such as Trisun and Sunola oils (based onsunflower seed oil) do not require hydrogenation forgood stability and performance (Mag, 1994). Thesehave potential uses in manufacturingtrans-free shortenings. Recently, it has been reported that it is possibleto prepare TFA-free bakery shortening (puff/cake/biscuit) using Mango and Mahua fats and their fractions(Reddy & Jeyarani, 2001). Reddy and Jeyrani (2001)and Kok and coworkers (Kok, Fehr, Hammond, &,White, 1999), have successfully prepared a shorteningwithout any hydrogenation treatment. They alsodemonstrated that such a product has functionalproperties comparable to most of the commercialshortenings.Further research is required in the following importantareas:1. Improvements in the hydrogenation process foruse in the manufacture oftrans-free shortenings.2. Effects oftransfatty acids on the physiology andbiochemistry of vital organs such as the heart.3. Manipulations of the processing conditionsunder which shortenings/margarines are produced to deliver comparable functional properties without needing to hydrogenate.Within our laboratory, our efforts are concentratedaround understanding relationships between molecularensembles, processing conditions, crystalline andmicrostructural structure of the shortening network,and between all levels of structure of the network andphysical functionality of the shortening. In this manner, wehope to build a comprehensive understanding of the waysin which the starting materials and processing conditionsaffect the functional properties of the final network.10.2. ManufacturingThere are number of factors that influence the finalphysical functionality of shortenings and margarines:1. proportions of solids to liquids;2. viscosity of the liquid;3. temperature treatment;4. mechanical working;5. super cooling;6. polymorphism;7. properties of the crystals: size, number, andcomposition; and8. spatial distribution, size, and shape of themicrostructure.Processing, therefore, is as equally important as thedesign of the oil blend; in the determination of the physical properties and performance of shortenings. Forexample, whipping of margarines up to fifty percentoverrun. (Overrun is defined as incorporation of air intothe product that results in decreasing the bulk density,increasing hardness, and in allowing the use of softer(unsaturated) oil blends, (Gorman, Bluff, Christie, &Glenview Kraft, 1960). Formulation of the blend andsubsequent processing conditions regulates the type ofcrystal formation and subsequent network formation.The type of crystals formed has a direct influence on themorphology of the solid structure (microstructure) thattraps the liquid phase of the shortening/margarine(Haighton, 1976; Thomas, III 1978; Wiedermann,1978).Haighton (1959, 1976)reported that the hardnessof margarine in terms of yield value has a strong correlation to the solid content. The manufacturing processitself can have significant impact on the solid content ofthe finished margarine. Margarines are typically manufactured by quick chilling of the fat blend using a sweptsurface heat exchanger (Unit A, Fig. 12), followed byholding in crystallization tubes before molding orforming. Depending on the rate of cooling, the relativetime spent in the heat exchanger and crystallizationtubes, whether the fat is ‘worked’ in the crystallizationtubes, and the temperature of the crystallization tube,the solid content, and the crystal type and microstructure of the resulting network is greatly affected.The temperature in the crystallization tube is usually2C higher than the temperature in Unit A, due to theliberation of heat during crystallization (Haighton,1976). If the rate of crystallization is low, the margarineis typically very soft (Haighton, 1976). The fat continuesto crystallize in the holding tubes and usually needshours to reach complete crystallization. Variousarrangements of Unit A and crystallization tubes areapplied for different kind of shortening manufacturing,as shown inFig. 12. For stick margarines, the supercooled fat is allowed to solidify without agitation. Thispost crystallization, in the absence of agitation, favorsthe formation of strong networks characterized by sintering between network structures and the productdemonstrates a narrow plastic range. When a specificcharacteristic is desired, the use of an additional working unit, after super cooling in the scraped surface heatexchanger, is required.
Sedang diterjemahkan, harap tunggu..
(Gbr. 11). Cisconfiguration menghasilkan sebuah tikungan di
molekul, sedangkan konfigurasi theTrans menyerupai
lebih rantai lurus dari asam lemak jenuh.
Selama hidrogenasi parsial, beberapa ikatan ganda yang
diisomerisasi menjadi asam trans dari theircisconfiguration (Scholfield et al., 1967). Asam transfatty memiliki
titik leleh yang sama dengan yang sesuai
asam lemak jenuh dan merupakan kontributor yang sangat penting terhadap sifat fungsional terhidrogenasi
produk. Ini baru-baru ini menjadi kontroversial
masalah kesehatan. Banyak penelitian telah dilakukan pada efek biologis asam trans-lemak pada hewan dan manusia
mata pelajaran (Anderson, Grande, & Keys, 1961; Anderson
dan Coots, 1967; Beveridge & Connel, 1962; Coots,
1964a, 1964b; Emken, Rohwedder , Dutton, Dejarlais, &
Adolf, 1979; Erickson, Coots, Mattson, & Kligman,
1964; Johnston, Johnson, & Kummerow, 1957; Kummerow, Mizuguchi, Arima, Cho, & Hunang, 1978;
Mavis & Vegelos, 1972). Namun, beberapa kontroversial
hasilnya dilaporkan mengenai efeknya pada metabolisme dan organ-organ vital dari mata pelajaran masing-masing di bawah
kondisi percobaan. Kummerow dan rekan kerja
(Kummerow et al., 1978) melaporkan efek buruk
lemak terhidrogenasi pada pengembangan aterosklerosis
lesi pada babi. Dalam subyek manusia, telah ditemukan
bahwa diet yang mengandung asam trans menyebabkan ketinggian
kolesterol plasma, triacylglycerides dan fosfolipid
(Anderson et al., 1961). Hasil ini didukung oleh
Vergrosen (1972) dan Houtsmuller (1978). Namun,
Vergrosen (1972) juga melaporkan bahwa asam trans kurang
hiperkolesterolemia (peningkatan kolesterol plasma
tingkat) daripada jenuh pendek rantai, laurat dan miristat, tetapi lebih hiperkolesterolemia dari baik palmitat
atau oleat. Asam lemak fakta thattrans memiliki tinggi
Gambar. 11. ofcisandtransisomers struktur molekul dari C18: 1.
Tabel 14
Ringkasan: hidrogenasi
Pengaruh kondisi proses
Kenaikan Parameter terpengaruh
Tingkat selektivitas pembentukan Trans-isomer
H2pressure Turun Mengurangi
Meningkatkan Suhu Meningkatkan
Agitasi Turun Mengurangi
Tabel 15
Ringkasan: faktor yang mempengaruhi selektivitas proses hidrogenasi
kondisi hidrogenasi yang mempengaruhi selektivitas
Reaksi parameter Selektif
hidrogenasi
Non-selektif
hidrogenasi
Suhu Tinggi Rendah
H2 Rendah Tinggi
Rendah Tinggi Agitasi
konsentrasi Catalyst Tinggi Rendah (menghabiskan)
Trans-isomer yang terbentuk jumlah yang tinggi jumlah Rendah
kurva SFC bentuk (Gambar 3.) Steep datar
stabilitas kristal perdana Beta atau campuran
dari beta-prime dan beta
Beta hanya
1038 BS Ghotra et al. / Food Research International 35 (2002) 1015-1048
titik leleh dari mereka correspondingcis-isomer menunjukkan bahwa penggabungan thetransfatty asam ke dalam
membran sel dapat mempengaruhi sifat-sifat
membran dan fungsinya (Chapman, Owens et al.,
1966). Tingginya kadar asam lemak trans dianggap
menjadi faktor risiko untuk penyakit kardiovaskular (Reddy &
Jeyarani, 2001). Industri dan badan pengatur yang
mulai bekerja sama untuk memastikan bahwa pembuatan shortening tidak memperkuat asupan TFA. Hal ini
diharapkan USA Food and Drug Administration
(FDA) akan mendirikan peraturan yang mengatur persentase diperbolehkan TFA dalam produk minyak goreng pada tahun 2002.
Khusus minyak seperti Trisun dan Sunola minyak (berdasarkan
minyak biji bunga matahari) tidak memerlukan hidrogenasi untuk
stabilitas yang baik dan kinerja (Mag, 1994). Ini
memiliki kegunaan potensial dalam manufacturingtrans bebas shortening. Baru-baru ini, telah dilaporkan bahwa adalah mungkin
untuk mempersiapkan roti pemendekan TFA bebas (engah / kue / biskuit) menggunakan Mango dan lemak Mahua dan fraksinya
(Reddy & Jeyarani, 2001). Reddy dan Jeyrani (2001)
dan Kok dan rekan kerja (Kok, Fehr, Hammond, &,
Putih, 1999), telah berhasil menyiapkan shortening sebuah
tanpa perawatan hidrogenasi. Mereka juga
menunjukkan bahwa produk tersebut memiliki fungsional
sifat sebanding dengan sebagian besar komersial
shortening.
Penelitian lebih lanjut diperlukan dalam penting berikut
bidang:
1. Perbaikan dalam proses hidrogenasi untuk
digunakan dalam pembuatan shortening oftrans bebas.
2. Efek oftransfatty asam pada fisiologi dan
biokimia dari organ-organ vital seperti jantung.
3. Manipulasi kondisi pengolahan
di mana shortening / margarin diproduksi untuk memberikan sifat fungsional yang sebanding tanpa perlu hydrogenate.
Dalam laboratorium kami, usaha kita terkonsentrasi
di sekitar hubungan pengertian antara molekul
ansambel, kondisi pengolahan, kristal dan
struktur mikro dari jaringan pemendekan,
dan antara semua tingkat struktur jaringan dan
fungsi fisik mentega. Dengan cara ini, kita
berharap untuk membangun pemahaman yang komprehensif tentang cara
di mana bahan awal dan kondisi pengolahan
mempengaruhi sifat fungsional dari jaringan akhir.
10.2. Manufaktur
Ada sejumlah faktor yang mempengaruhi akhir
fungsi fisik shortening dan margarin:
1. proporsi padatan cairan;
2. viskositas cairan;
3. perlakuan suhu;
4. kerja mekanik;
5. Super pendinginan;
6. polimorfisme;
7. sifat kristal: ukuran, jumlah, dan
komposisi; dan
8. distribusi spasial, ukuran, dan bentuk
. mikro
Processing, oleh karena itu, sama-sama pentingnya dengan
desain campuran minyak; dalam penentuan sifat fisik dan kinerja shortening. Sebagai
contoh, mencambuk dari margarin hingga lima puluh persen
overrun. (Overrun didefinisikan sebagai penggabungan udara ke
produk yang menghasilkan penurunan berat isi,
meningkatkan kekerasan, dan memungkinkan penggunaan lebih lembut
(campuran jenuh) minyak, (Gorman, Bluff, Christie, &
Glenview Kraft, 1960). Formulasi dari campuran dan
kondisi pengolahan selanjutnya mengatur jenis
pembentukan kristal dan pembentukan jaringan selanjutnya.
Jenis kristal yang terbentuk memiliki pengaruh langsung terhadap
morfologi struktur padat (mikro) yang
memerangkap fasa cair dari pemendekan / margarin
(Haighton, 1976; Thomas, III 1978; Wiedermann,
1978) .Haighton (1959, 1976) melaporkan bahwa kekerasan
margarin dalam hal nilai hasil memiliki korelasi yang kuat dengan isi padat Proses manufaktur.
itu sendiri dapat memiliki dampak yang signifikan terhadap kandungan padatan dari
margarin selesai. Margarin biasanya diproduksi oleh cepat dingin dari campuran lemak menggunakan menyapu
penukar panas permukaan (Unit A, Gambar. 12), diikuti dengan
memegang di tabung kristalisasi sebelum molding atau
membentuk. Tergantung pada tingkat pendinginan, relatif
waktu yang dihabiskan dalam penukar panas dan kristalisasi
tabung, apakah lemak adalah 'bekerja' dalam kristalisasi
tabung, dan suhu tabung kristalisasi,
isi padat, dan jenis kristal dan mikro jaringan yang dihasilkan sangat dipengaruhi.
Suhu di dalam tabung kristalisasi biasanya
2
?
C lebih tinggi dari suhu di Unit A, karena
pembebasan panas selama kristalisasi (Haighton,
1976). Jika tingkat kristalisasi rendah, margarin
biasanya sangat lembut (Haighton, 1976). Lemak terus
mengkristal dalam tabung memegang dan biasanya membutuhkan
jam untuk mencapai kristalisasi. Berbagai
pengaturan Unit A dan tabung kristalisasi yang
diterapkan untuk berbagai jenis memperpendek manufaktur,
seperti yang ditunjukkan inFig. 12. Untuk tongkat margarin, lemak superdingin diperbolehkan untuk memperkuat tanpa agitasi. Ini
posting kristalisasi, dengan tidak adanya agitasi, nikmat
pembentukan jaringan yang kuat ditandai dengan sintering antara struktur jaringan dan produk
menunjukkan berbagai plastik yang sempit. Ketika tertentu
karakteristik yang diinginkan, penggunaan unit kerja tambahan, setelah Super pendinginan di panas permukaan tergores
penukar, diperlukan.
molekul, sedangkan konfigurasi theTrans menyerupai
lebih rantai lurus dari asam lemak jenuh.
Selama hidrogenasi parsial, beberapa ikatan ganda yang
diisomerisasi menjadi asam trans dari theircisconfiguration (Scholfield et al., 1967). Asam transfatty memiliki
titik leleh yang sama dengan yang sesuai
asam lemak jenuh dan merupakan kontributor yang sangat penting terhadap sifat fungsional terhidrogenasi
produk. Ini baru-baru ini menjadi kontroversial
masalah kesehatan. Banyak penelitian telah dilakukan pada efek biologis asam trans-lemak pada hewan dan manusia
mata pelajaran (Anderson, Grande, & Keys, 1961; Anderson
dan Coots, 1967; Beveridge & Connel, 1962; Coots,
1964a, 1964b; Emken, Rohwedder , Dutton, Dejarlais, &
Adolf, 1979; Erickson, Coots, Mattson, & Kligman,
1964; Johnston, Johnson, & Kummerow, 1957; Kummerow, Mizuguchi, Arima, Cho, & Hunang, 1978;
Mavis & Vegelos, 1972). Namun, beberapa kontroversial
hasilnya dilaporkan mengenai efeknya pada metabolisme dan organ-organ vital dari mata pelajaran masing-masing di bawah
kondisi percobaan. Kummerow dan rekan kerja
(Kummerow et al., 1978) melaporkan efek buruk
lemak terhidrogenasi pada pengembangan aterosklerosis
lesi pada babi. Dalam subyek manusia, telah ditemukan
bahwa diet yang mengandung asam trans menyebabkan ketinggian
kolesterol plasma, triacylglycerides dan fosfolipid
(Anderson et al., 1961). Hasil ini didukung oleh
Vergrosen (1972) dan Houtsmuller (1978). Namun,
Vergrosen (1972) juga melaporkan bahwa asam trans kurang
hiperkolesterolemia (peningkatan kolesterol plasma
tingkat) daripada jenuh pendek rantai, laurat dan miristat, tetapi lebih hiperkolesterolemia dari baik palmitat
atau oleat. Asam lemak fakta thattrans memiliki tinggi
Gambar. 11. ofcisandtransisomers struktur molekul dari C18: 1.
Tabel 14
Ringkasan: hidrogenasi
Pengaruh kondisi proses
Kenaikan Parameter terpengaruh
Tingkat selektivitas pembentukan Trans-isomer
H2pressure Turun Mengurangi
Meningkatkan Suhu Meningkatkan
Agitasi Turun Mengurangi
Tabel 15
Ringkasan: faktor yang mempengaruhi selektivitas proses hidrogenasi
kondisi hidrogenasi yang mempengaruhi selektivitas
Reaksi parameter Selektif
hidrogenasi
Non-selektif
hidrogenasi
Suhu Tinggi Rendah
H2 Rendah Tinggi
Rendah Tinggi Agitasi
konsentrasi Catalyst Tinggi Rendah (menghabiskan)
Trans-isomer yang terbentuk jumlah yang tinggi jumlah Rendah
kurva SFC bentuk (Gambar 3.) Steep datar
stabilitas kristal perdana Beta atau campuran
dari beta-prime dan beta
Beta hanya
1038 BS Ghotra et al. / Food Research International 35 (2002) 1015-1048
titik leleh dari mereka correspondingcis-isomer menunjukkan bahwa penggabungan thetransfatty asam ke dalam
membran sel dapat mempengaruhi sifat-sifat
membran dan fungsinya (Chapman, Owens et al.,
1966). Tingginya kadar asam lemak trans dianggap
menjadi faktor risiko untuk penyakit kardiovaskular (Reddy &
Jeyarani, 2001). Industri dan badan pengatur yang
mulai bekerja sama untuk memastikan bahwa pembuatan shortening tidak memperkuat asupan TFA. Hal ini
diharapkan USA Food and Drug Administration
(FDA) akan mendirikan peraturan yang mengatur persentase diperbolehkan TFA dalam produk minyak goreng pada tahun 2002.
Khusus minyak seperti Trisun dan Sunola minyak (berdasarkan
minyak biji bunga matahari) tidak memerlukan hidrogenasi untuk
stabilitas yang baik dan kinerja (Mag, 1994). Ini
memiliki kegunaan potensial dalam manufacturingtrans bebas shortening. Baru-baru ini, telah dilaporkan bahwa adalah mungkin
untuk mempersiapkan roti pemendekan TFA bebas (engah / kue / biskuit) menggunakan Mango dan lemak Mahua dan fraksinya
(Reddy & Jeyarani, 2001). Reddy dan Jeyrani (2001)
dan Kok dan rekan kerja (Kok, Fehr, Hammond, &,
Putih, 1999), telah berhasil menyiapkan shortening sebuah
tanpa perawatan hidrogenasi. Mereka juga
menunjukkan bahwa produk tersebut memiliki fungsional
sifat sebanding dengan sebagian besar komersial
shortening.
Penelitian lebih lanjut diperlukan dalam penting berikut
bidang:
1. Perbaikan dalam proses hidrogenasi untuk
digunakan dalam pembuatan shortening oftrans bebas.
2. Efek oftransfatty asam pada fisiologi dan
biokimia dari organ-organ vital seperti jantung.
3. Manipulasi kondisi pengolahan
di mana shortening / margarin diproduksi untuk memberikan sifat fungsional yang sebanding tanpa perlu hydrogenate.
Dalam laboratorium kami, usaha kita terkonsentrasi
di sekitar hubungan pengertian antara molekul
ansambel, kondisi pengolahan, kristal dan
struktur mikro dari jaringan pemendekan,
dan antara semua tingkat struktur jaringan dan
fungsi fisik mentega. Dengan cara ini, kita
berharap untuk membangun pemahaman yang komprehensif tentang cara
di mana bahan awal dan kondisi pengolahan
mempengaruhi sifat fungsional dari jaringan akhir.
10.2. Manufaktur
Ada sejumlah faktor yang mempengaruhi akhir
fungsi fisik shortening dan margarin:
1. proporsi padatan cairan;
2. viskositas cairan;
3. perlakuan suhu;
4. kerja mekanik;
5. Super pendinginan;
6. polimorfisme;
7. sifat kristal: ukuran, jumlah, dan
komposisi; dan
8. distribusi spasial, ukuran, dan bentuk
. mikro
Processing, oleh karena itu, sama-sama pentingnya dengan
desain campuran minyak; dalam penentuan sifat fisik dan kinerja shortening. Sebagai
contoh, mencambuk dari margarin hingga lima puluh persen
overrun. (Overrun didefinisikan sebagai penggabungan udara ke
produk yang menghasilkan penurunan berat isi,
meningkatkan kekerasan, dan memungkinkan penggunaan lebih lembut
(campuran jenuh) minyak, (Gorman, Bluff, Christie, &
Glenview Kraft, 1960). Formulasi dari campuran dan
kondisi pengolahan selanjutnya mengatur jenis
pembentukan kristal dan pembentukan jaringan selanjutnya.
Jenis kristal yang terbentuk memiliki pengaruh langsung terhadap
morfologi struktur padat (mikro) yang
memerangkap fasa cair dari pemendekan / margarin
(Haighton, 1976; Thomas, III 1978; Wiedermann,
1978) .Haighton (1959, 1976) melaporkan bahwa kekerasan
margarin dalam hal nilai hasil memiliki korelasi yang kuat dengan isi padat Proses manufaktur.
itu sendiri dapat memiliki dampak yang signifikan terhadap kandungan padatan dari
margarin selesai. Margarin biasanya diproduksi oleh cepat dingin dari campuran lemak menggunakan menyapu
penukar panas permukaan (Unit A, Gambar. 12), diikuti dengan
memegang di tabung kristalisasi sebelum molding atau
membentuk. Tergantung pada tingkat pendinginan, relatif
waktu yang dihabiskan dalam penukar panas dan kristalisasi
tabung, apakah lemak adalah 'bekerja' dalam kristalisasi
tabung, dan suhu tabung kristalisasi,
isi padat, dan jenis kristal dan mikro jaringan yang dihasilkan sangat dipengaruhi.
Suhu di dalam tabung kristalisasi biasanya
2
?
C lebih tinggi dari suhu di Unit A, karena
pembebasan panas selama kristalisasi (Haighton,
1976). Jika tingkat kristalisasi rendah, margarin
biasanya sangat lembut (Haighton, 1976). Lemak terus
mengkristal dalam tabung memegang dan biasanya membutuhkan
jam untuk mencapai kristalisasi. Berbagai
pengaturan Unit A dan tabung kristalisasi yang
diterapkan untuk berbagai jenis memperpendek manufaktur,
seperti yang ditunjukkan inFig. 12. Untuk tongkat margarin, lemak superdingin diperbolehkan untuk memperkuat tanpa agitasi. Ini
posting kristalisasi, dengan tidak adanya agitasi, nikmat
pembentukan jaringan yang kuat ditandai dengan sintering antara struktur jaringan dan produk
menunjukkan berbagai plastik yang sempit. Ketika tertentu
karakteristik yang diinginkan, penggunaan unit kerja tambahan, setelah Super pendinginan di panas permukaan tergores
penukar, diperlukan.
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