as added lipids. These lipids are either on the surface or inside the terjemahan - as added lipids. These lipids are either on the surface or inside the Bahasa Indonesia Bagaimana mengatakan

as added lipids. These lipids are e

as added lipids. These lipids are either on the surface or inside the granules
[242,243] and consist mainly of phospholipids or free fatty acids [244]. Ionic
surfactants interact in a similar way with starch as monoacyl lipids by complex
formation, but their being charged complicates their effects [236,245]. When
amylose leaches out of the granules during gelatinization, the lipids, either
native or added, form complexes with the exuded amylose, probably on the
surface of the granules, and retard their swelling [246,247]; as a result, the
gelatinization temperature is somewhat increased. Because the complex formation is an exothermic process that probably takes place during gelatinization, the enthalpy of the gelatinization measured via DSC could be observed
to be lower than it really is [5,232a,235,236]. Certain surfactants (i.e., sodium
dodecyl sulfate [SDS]) have been observed to decrease the gelatinization
temperature of starches [245,247,248].
10.6.1.4.3 Rheological Properties
Monoacyl lipids and surfactants affect the rheological properties of the
starches. They do so probably by changing the swelling and solubility of the
starch granules. Previous studies on various lipids and surfactants have shown
that they increase or decrease the starch viscosity, depending on the type of
lipid and source of starch as well as experimental conditions [192,249–251].
The monoacyl lipids and ionic surfactants have a similar interaction mechanism, except that the ionic surfactants have an additional effect due to their
charged nature [201,236,245]. Furthermore, when the lipids are introduced,
whether they are heated with the starch suspension from the beginning or
added at later stages (e.g., after the gelatinization), is a critical factor.
The volume occupied by the swollen granules is a dominant factor at low
starch concentrations, as discussed in Section 10.5. In a system of low starch
concentration, the effect of the lipids should be decreased viscosity because of
the retarded swelling and solubility; however, a decrease in viscosity is only
obtained as long as the lipids or surfactants can retard the swelling and solubility
of the granules. At high temperatures (e.g., above 95°C), starches with added
lipids or surfactants can have higher viscosity than starch pastes without added
lipids [236]. At 95°C in systems with excess or intermediate water contents,
many amylose–lipid complexes begin to melt [201,232,252], allowing for rearrangement of the complex [252], and the retardation effects disappear. At lower
temperatures (e.g., 85°C), the lipids effectively retard the swelling and decrease
the viscosity compared to starches without added lipids [236]. If the lipids or
surfactants are added at later stages, when the starch has already been heated,
smaller effects should be seen because the granules have swelled unrestricted.
Ionic surfactants have somewhat different effects, as they destabilize the
starch granule; for example, increased swelling and solubility are observed
when starch is heated in their presence [253]. This could be the result of an
amylose extraction effect of the ionic surfactants, because of the charged and
highly hydrophilic head group [109,192,245]. The viscosity should therefore
© 2006 by Taylor & Francis Group, LLC
Starch: Physicochemical and Functional Aspects 439
increase in their presence, and the charged head group further stabilizes the
starch paste because of electrostatic repulsive forces. At 85°C, the viscosity
increase is only due to the charged nature of the ionic surfactants, as their
effect can be completely canceled by the addition of salt before heating. At
95°C, the addition of salt makes the ionic surfactants behave similarly to
nonionic surfactants [236].
At high concentrations the situation is different. Granule-to-granule contact, and thus granule deformability, is the most important factor. The lipids
or surfactants make the starch granules more rigid until a certain temperature
is reached; therefore, starch pastes should become more viscous when lipids
or surfactants are added, and gels should be firmer than starch pastes or gels
without added lipids or surfactants. Lipids and surfactants that are added at
later stages could be expected to affect only the continuous amylose phase.
Other rheological properties (e.g., stickiness) are also affected when lipids are
added because the complex on the surface of the starch granule reduces
stickiness by decreasing the hydrogen bonds available.
10.6.1.4.4 Retrogradation
Monoglycerides and other related compounds are known to have an antistaling effect on bread and to extend its shelf-life [241,255,256]. It is believed
that the retarding mechanism of lipids and surfactants on retrogradation is
related to their ability to form complexes with the amylose fraction
[140,241,255,256]. The effects of added lipids or surfactants on retrogradation can be measured with many different techniques, such as x-ray diffraction, DSC, or various rheological methods. The effect of lipids added to bread
is an increase in V-type x-ray pattern compared to control bread without such
an addition. The V-type pattern is virtually unchanged with time but is superimposed by a B-type x-ray diffraction pattern that increases on aging [140].
The effect of lipids or surfactants on retrogradation as observed with DSC
is a decreased melting endotherm of recrystallized amylopectin, as well as an
increased size of the endotherm associated with the amylose–lipid complex
transition [143,144]. Rheological measurements (mostly firmness measurements) usually show that added lipids decrease the firmness of breads on aging
compared to breads without added lipids [257]. Other rheological measurements have shown that surfactants can have varied effects on the rheological
properties of starch gels depending on the type of surfactant [236,241]. The
presence of emulsifiers in concentrated starch gels (40%, w/w) slows down
the increase in firmness during aging, although the elasticity modulus initially
is higher than for the control without emulsifiers [256a].
As discussed in Section 10.4, the amylopectin fraction is responsible for
retrogradation [132], and the long-term effects associated with retrogradation
are related to the amylopectin fraction. The obvious question then arises as to
how lipids or surfactants can affect retrogradation, as they are believed to form
complexes with the amylose molecule [140,255,258]. The possible alternatives
© 2006 by Taylor & Francis Group, LLC
440 Carbohydrates in Food
are that either the lipids act through an amylose–lipid complex in various ways
or the lipids interact directly with the amylopectin.
Three possibilities exist with regard to the amylose–lipid complex and
retrogradation. First, it could be that the intact complex (i.e., as one entity)
interferes with the crystallization of amylopectin and retards the retrogradation
[259]. Second, the amylose–lipid complex could change or retard the water
distribution and hence the retrogradation [260]. Third, a cocrystallization of
amylose and amylopectin is possible to some extent, and substances that
complex with amylose eliminate the contribution of amylose in the recrystallizing process [161]. On the other hand, the interaction of amylopectin and
lipids means that lipids interact directly with the amylopectin fraction, at least
to a small extent, and retard retrogradation through the formation of an amylopectin–lipid complex [6,160,171,172,236,261,262].
The possibility of retarding the retrogradation of some starches (maize,
potato, and waxy maize) and nongranular amylopectin by adding an intact
cetyltrimethylammonium bromide (CTAB)–amylose complex has been
explored [259]. It was found that CTAB–amylose complexes added to a cooled
gelatinized starch gel or to starch suspensions that were heated to temperatures
below the transition temperature of the CTAB–amylose complex had little
effect on retrogradation; however, starch gels or starch suspensions with added
CTAB–amylose complexes that were heated to temperatures above the transition temperature (i.e., the complex melted) showed a decreased retrogradation. This mechanism is therefore unlikely.
Because lipids and some surfactants retard or delay gelatinization, probably by complexing with leached amylose on the surface of the starch granules,
it is possible that lipids or surfactants also retard the retrogradation by a similar
mechanism (i.e., by acting as a barrier against water transport) [260]. This
mechanism could be involved in retarding the retrogradation of normal starches
because it is known that the water content is very important for recrystallization; however, it does not explain the effect of lipids and surfactants on
decreasing the retrogradation of waxy starches, unless they are able to interact
with the surface molecules of the waxy starch granules. Furthermore, nongranular amylopectin gels have also been shown to decrease in retrogradation
when surfactants and monoglycerides are added [160,261], which shows that
the granule form is not a limiting factor. If lipids and surfactants are added
after the gelatinization is concluded, such a barrier effect should not be
obtained and the retrogradation should progress in a way similar to that for
starch gels without additives; however, pregelatinization of the starches before
the addition of a surfactant was found to decrease retrogradation compared to
starch gels without such an addition [171,172]. This indicates that lipids or
surfactants affect the retrogradation even after the starch suspensions are fully
gelatinized. This alternative, therefore, has only limited value as an explanation
of the effects of lipids or surfactants on retrogradation.
© 2006 by Taylor & Francis Group, LLC
Starch: Physicochemical and Functional Aspects 441
Russell [161] has suggested that a possible cocrystallization of amylose
and amylopectin contributes to retrogradation, and the role of l
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Hasil (Bahasa Indonesia) 1: [Salinan]
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sebagai menambahkan lipid. Lipid ini yang baik pada permukaan atau di dalam butiran[242,243] dan terdiri terutama dari fosfolipid atau asam lemak bebas [244]. Ioniksurfaktan berinteraksi dalam cara yang mirip dengan pati sebagai lipid monoacyl oleh komplekspembentukan, tetapi mereka dikenakan merumitkan efek mereka [236,245]. Kapanamilosa leaches dari butiran selama gelatinization, lipid, baikasli atau ditambahkan, membentuk kompleks dengan amilosa exuded, mungkin padapermukaan granul, dan menghambat mereka pembengkakan [246,247]; Akibatnya,gelatinization suhu agak meningkat. Karena formasi kompleks adalah proses eksotermik yang mungkin terjadi selama gelatinization, entalpi gelatinization diukur melalui DSC dapat dilihatuntuk lebih rendah daripada benar-benar adalah [5, 232a, 235, 236]. Surfaktan tertentu (yakni, natriumlauryl sulfate [SDS]) telah diamati untuk mengurangi gelatinizationsuhu Pati [245,247,248].10.6.1.4.3 rheological padaMonoacyl lipid dan surfaktan mempengaruhi rheological padaPati. Mereka melakukan jadi mungkin dengan mengubah pembengkakan dan kelarutanbutiran Pati. Studi sebelumnya pada berbagai lipid dan surfaktan telah menunjukkanbahwa mereka menambah atau mengurangi viskositas Pati, tergantung pada jenislipid dan sumber Pati serta kondisi eksperimental [192,249-251].Monoacyl lipid dan ionik surfaktan memiliki mekanisme interaksi mirip, kecuali bahwa surfaktan ionik memiliki efek tambahan karena merekadibebankan alam [201,236,245]. Selain itu, Kapan lipid diperkenalkan,Apakah mereka yang dipanaskan dengan suspensi Pati dari awal atauditambahkan pada tahap selanjutnya (misalnya, setelah gelatinization), merupakan faktor penting.Volume yang ditempati oleh butiran bengkak adalah faktor dominan di rendahPati konsentrasi, seperti yang dibahas dalam bagian 10.5. Dalam sistem rendah Patikonsentrasi, efek lipid harus penurunan viskositas karenapembengkakan terbelakang dan kelarutan; Namun, penurunan viskositas adalah hanyaDiperoleh selama lipid atau surfaktan dapat menghambat pembengkakan dan kelarutanbutiran. Pada suhu tinggi (misalnya, di atas 95° C), Pati dengan ditambahkanlipid atau surfaktan dapat memiliki kekentalan tinggi dari Pati pasta tanpa ditambahkanlipid [236]. Di 95° C dalam sistem dengan isi air kelebihan atau menengah,banyak kompleks amilosa – lipid mulai mencair [201,232,252], memungkinkan untuk penataan ulang kompleks [252], dan efek keterbelakangan menghilang. Lebih rendahsuhu (misalnya, 85° C), lipid efektif menghambat pembengkakan dan penurunanviskositas dibandingkan Pati tanpa ditambahkan lipid [236]. Jika lipid atausurfaktan ditambahkan pada tahap selanjutnya, ketika Pati sudah dipanaskan,efek kecil harus dilihat karena butiran telah membengkak terbatas.Ionik surfaktan memiliki efek yang agak berbeda, karena mereka mengacaukangranula Pati; sebagai contoh, peningkatan pembengkakan dan kelarutan diamatiKapan Pati dipanaskan dalam kehadiran mereka [253]. Ini bisa menjadi hasil dariamilosa ekstraksi efek surfaktan ionik, karena biaya dansangat hidrofil kepala kelompok [109,192,245]. Viskositas harus karena itu© 2006 oleh Taylor & Francis Group, LLCPati: Secara fisikokimia maupun fungsional aspek 439peningkatan kehadiran mereka, dan kelompok kepala dikenakan biaya tambahan untuk menstabilkanPati pasta karena pasukan menjijikkan elektrostatik. Pada 85° C, viskositasPeningkatan ini hanya karena sifat bermuatan surfaktan ionik, sebagai merekaefek dapat benar-benar dibatalkan oleh garam sebelum Penghangat Ruangan. Di95° C, penambahan garam membuat surfaktan ionik berperilaku demikian pula untuksurfaktan Nonionic sekaligus [236].Pada konsentrasi tinggi dalam situasi berbeda. Hubungi granul-untuk-granul, dan dengan demikian deformability granul, adalah faktor yang paling penting. Lipidatau surfaktan membuat butiran Pati lebih kaku sampai suhu tertentutercapai; oleh karena itu, Pati pasta harus menjadi lebih kental ketika lipidatau surfaktan ditambahkan, dan gel harus lebih kencang dari Pati pasta atau geltanpa ditambahkan lipid atau surfaktan. Lipid dan surfaktan yang ditambahkan padatahap selanjutnya dapat diharapkan untuk mempengaruhi hanya tahap amilosa terus-menerus.Lain rheological pada (misalnya, lengket) juga dipengaruhi ketika lipidditambahkan karena mengurangi kompleks pada permukaan granula Patilengket dengan mengurangi ikatan hidrogen yang tersedia.10.6.1.4.4 retrogradationMonoglycerides dan lain terkait senyawa yang dikenal untuk memiliki efek antistaling pada roti dan memperpanjang kehidupannya rak [241,255,256]. Hal ini diyakinimekanisme retarding lipid dan surfaktan di retrogradation yangberkaitan dengan kemampuan mereka untuk membentuk kompleks dengan fraksi amilosa[140,241,255,256]. efek ditambahkan lipid atau surfaktan di retrogradation dapat diukur dengan berbagai teknik, seperti Difraksi sinar x, DSC, atau berbagai metode rheological. Efek lipid ditambahkan ke rotipeningkatan V-jenis x-ray pola dibandingkan dengan kontrol roti tanpa sepertitambahan. Pola V-jenis ini hampir tidak berubah dengan waktu tetapi melapiskan oleh pola Difraksi sinar x B-type yang meningkat pada penuaan [140].Efek lipid atau surfaktan di retrogradation seperti yang diamati dengan DSCadalah endotherm mencair menurun dari recrystallized amilopektin, sertapeningkatan ukuran endotherm yang terkait dengan kompleks amilosa-lemaktransisi [143,144]. Rheological pengukuran (kebanyakan ketegasan pengukuran) biasanya menunjukkan bahwa menambahkan lipid mengurangi ketegasan roti pada penuaandibandingkan dengan roti tanpa ditambahkan lipid [257]. Pengukuran rheological lain telah menunjukkan bahwa surfaktan dapat bervariasi efek pada rheologicalsifat gel Pati tergantung pada jenis surfaktan [236,241]. Thekehadiran emulsifiers di gel terkonsentrasi Pati (40%, w/w) melambatpeningkatan ketegasan selama penuaan, meskipun modulus elastisitas awalnyalebih tinggi dibandingkan untuk kontrol tanpa emulsifiers [256a].Seperti dibahas dalam bagian 10.4, fraksi amilopektin bertanggung jawab untukretrogradation [132], dan efek jangka panjang yang terkait dengan retrogradationyang berhubungan dengan fraksi amilopektin. Pertanyaan jelas yang kemudian muncul sebagaiBagaimana lipid atau surfaktan dapat mempengaruhi retrogradation, seperti yang mereka percaya untuk membentukkompleks dengan molekul amilosa [140,255,258]. Kemungkinan alternatif© 2006 oleh Taylor & Francis Group, LLC440 karbohidrat dalam makananadalah bahwa baik lipid bertindak melalui sebuah kompleks amilosa – lipid dalam berbagai caraatau lipid berinteraksi secara langsung dengan amilopektin.Ada tiga kemungkinan berkaitan dengan kompleks amilosa – lipid danretrogradation. Pertama, bisa jadi yang kompleks utuh (yaitu, sebagai satu kesatuan)mengganggu kristalisasi amilopektin dan menghambat retrogradation[259]. kedua, kompleks amilosa – lipid dapat mengubah atau menghambat airdistribusi dan karenanya retrogradation [260]. Ketiga, cocrystallization dariamilosa dan amilopektin adalah mungkin untuk batas tertentu, dan zat yangkompleks dengan amilosa menghilangkan kontribusi amilosa dalam proses recrystallizing [161]. Di sisi lain, interaksi amilopektin danlipid berarti bahwa lipid berinteraksi langsung dengan fraksi amilopektin, setidaknyasebagian kecil, dan retard retrogradation melalui pembentukan sebuah kompleks amilopektin – lipid [6,160,171,172,236,261,262].Kemungkinan penghambat retrogradation beberapa Pati (jagung,kentang, dan lilin jagung) dan nongranular amilopektin dengan menambahkan utuhcetyltrimethylammonium bromida (CTAB) – amilosa kompleks telahdieksplorasi [259]. Ternyata bahwa kompleks CTAB – amilosa ditambahkan ke didinginkangelatinized Pati gel atau Pati suspensi yang dipanaskan suhudi bawah suhu transisi CTAB-amilosa kompleks memiliki sedikitefek pada retrogradation; Namun, Pati gel atau Pati suspensi dengan ditambahkanCTAB – amilosa kompleks yang dipanaskan suhu di atas suhu transisi (yaitu, kompleks mencair) menunjukkan penurunan retrogradation. Mekanisme ini karena itu tidak mungkin.Karena lipid dan beberapa surfaktan retard atau penundaan gelatinization, mungkin dengan kompleksasi dengan kehabisan amilosa pada permukaan butiran Pati,dimungkinkan bahwa lipid atau surfaktan juga menghambat retrogradation oleh serupamekanisme (yaitu, dengan bertindak sebagai penghalang terhadap transportasi air) [260]. Inimekanisme dapat terlibat dalam penghambat retrogradation normal Patikarena itu dikenal bahwa kandungan air sangat penting untuk rekristalisasi; Namun, tidak menjelaskan efek lipid dan surfaktan padapenurunan retrogradation lilin Pati, kecuali mereka dapat berinteraksidengan molekul permukaan butiran lilin Pati. Selain itu, nongranular amilopektin gel juga telah ditunjukkan untuk mengurangi retrogradationKapan surfaktan dan monoglycerides ditambahkan [160,261], yang menunjukkan bahwabentuk granul bukanlah faktor pembatas. Jika lipid dan surfaktan ditambahkansetelah gelatinization menyimpulkan, seperti efek penghalang yang tidak bolehDiperoleh dan retrogradation harus kemajuan dalam cara yang mirip dengan yang untukPati gel tanpa aditif; Namun, pregelatinization Pati sebelumPenambahan surfaktan ditemukan untuk penurunan dibandingkan dengan retrogradationPati gel tanpa penambahan tersebut [171,172]. Ini menunjukkan bahwa lipid atausurfaktan mempengaruhi retrogradation bahkan setelah suspensi Pati sepenuhnyagelatinized. Alternatif ini, oleh karena itu, memiliki hanya terbatas pada nilai sebagai penjelasanefek dari lipid atau surfaktan di retrogradation.© 2006 oleh Taylor & Francis Group, LLCPati: Secara fisikokimia maupun fungsional aspek 441Russell [161] telah menyarankan mungkin cocrystallization dari amilosadan amilopektin berkontribusi retrogradation, dan peran l
Sedang diterjemahkan, harap tunggu..
Hasil (Bahasa Indonesia) 2:[Salinan]
Disalin!
as added lipids. These lipids are either on the surface or inside the granules
[242,243] and consist mainly of phospholipids or free fatty acids [244]. Ionic
surfactants interact in a similar way with starch as monoacyl lipids by complex
formation, but their being charged complicates their effects [236,245]. When
amylose leaches out of the granules during gelatinization, the lipids, either
native or added, form complexes with the exuded amylose, probably on the
surface of the granules, and retard their swelling [246,247]; as a result, the
gelatinization temperature is somewhat increased. Because the complex formation is an exothermic process that probably takes place during gelatinization, the enthalpy of the gelatinization measured via DSC could be observed
to be lower than it really is [5,232a,235,236]. Certain surfactants (i.e., sodium
dodecyl sulfate [SDS]) have been observed to decrease the gelatinization
temperature of starches [245,247,248].
10.6.1.4.3 Rheological Properties
Monoacyl lipids and surfactants affect the rheological properties of the
starches. They do so probably by changing the swelling and solubility of the
starch granules. Previous studies on various lipids and surfactants have shown
that they increase or decrease the starch viscosity, depending on the type of
lipid and source of starch as well as experimental conditions [192,249–251].
The monoacyl lipids and ionic surfactants have a similar interaction mechanism, except that the ionic surfactants have an additional effect due to their
charged nature [201,236,245]. Furthermore, when the lipids are introduced,
whether they are heated with the starch suspension from the beginning or
added at later stages (e.g., after the gelatinization), is a critical factor.
The volume occupied by the swollen granules is a dominant factor at low
starch concentrations, as discussed in Section 10.5. In a system of low starch
concentration, the effect of the lipids should be decreased viscosity because of
the retarded swelling and solubility; however, a decrease in viscosity is only
obtained as long as the lipids or surfactants can retard the swelling and solubility
of the granules. At high temperatures (e.g., above 95°C), starches with added
lipids or surfactants can have higher viscosity than starch pastes without added
lipids [236]. At 95°C in systems with excess or intermediate water contents,
many amylose–lipid complexes begin to melt [201,232,252], allowing for rearrangement of the complex [252], and the retardation effects disappear. At lower
temperatures (e.g., 85°C), the lipids effectively retard the swelling and decrease
the viscosity compared to starches without added lipids [236]. If the lipids or
surfactants are added at later stages, when the starch has already been heated,
smaller effects should be seen because the granules have swelled unrestricted.
Ionic surfactants have somewhat different effects, as they destabilize the
starch granule; for example, increased swelling and solubility are observed
when starch is heated in their presence [253]. This could be the result of an
amylose extraction effect of the ionic surfactants, because of the charged and
highly hydrophilic head group [109,192,245]. The viscosity should therefore
© 2006 by Taylor & Francis Group, LLC
Starch: Physicochemical and Functional Aspects 439
increase in their presence, and the charged head group further stabilizes the
starch paste because of electrostatic repulsive forces. At 85°C, the viscosity
increase is only due to the charged nature of the ionic surfactants, as their
effect can be completely canceled by the addition of salt before heating. At
95°C, the addition of salt makes the ionic surfactants behave similarly to
nonionic surfactants [236].
At high concentrations the situation is different. Granule-to-granule contact, and thus granule deformability, is the most important factor. The lipids
or surfactants make the starch granules more rigid until a certain temperature
is reached; therefore, starch pastes should become more viscous when lipids
or surfactants are added, and gels should be firmer than starch pastes or gels
without added lipids or surfactants. Lipids and surfactants that are added at
later stages could be expected to affect only the continuous amylose phase.
Other rheological properties (e.g., stickiness) are also affected when lipids are
added because the complex on the surface of the starch granule reduces
stickiness by decreasing the hydrogen bonds available.
10.6.1.4.4 Retrogradation
Monoglycerides and other related compounds are known to have an antistaling effect on bread and to extend its shelf-life [241,255,256]. It is believed
that the retarding mechanism of lipids and surfactants on retrogradation is
related to their ability to form complexes with the amylose fraction
[140,241,255,256]. The effects of added lipids or surfactants on retrogradation can be measured with many different techniques, such as x-ray diffraction, DSC, or various rheological methods. The effect of lipids added to bread
is an increase in V-type x-ray pattern compared to control bread without such
an addition. The V-type pattern is virtually unchanged with time but is superimposed by a B-type x-ray diffraction pattern that increases on aging [140].
The effect of lipids or surfactants on retrogradation as observed with DSC
is a decreased melting endotherm of recrystallized amylopectin, as well as an
increased size of the endotherm associated with the amylose–lipid complex
transition [143,144]. Rheological measurements (mostly firmness measurements) usually show that added lipids decrease the firmness of breads on aging
compared to breads without added lipids [257]. Other rheological measurements have shown that surfactants can have varied effects on the rheological
properties of starch gels depending on the type of surfactant [236,241]. The
presence of emulsifiers in concentrated starch gels (40%, w/w) slows down
the increase in firmness during aging, although the elasticity modulus initially
is higher than for the control without emulsifiers [256a].
As discussed in Section 10.4, the amylopectin fraction is responsible for
retrogradation [132], and the long-term effects associated with retrogradation
are related to the amylopectin fraction. The obvious question then arises as to
how lipids or surfactants can affect retrogradation, as they are believed to form
complexes with the amylose molecule [140,255,258]. The possible alternatives
© 2006 by Taylor & Francis Group, LLC
440 Carbohydrates in Food
are that either the lipids act through an amylose–lipid complex in various ways
or the lipids interact directly with the amylopectin.
Three possibilities exist with regard to the amylose–lipid complex and
retrogradation. First, it could be that the intact complex (i.e., as one entity)
interferes with the crystallization of amylopectin and retards the retrogradation
[259]. Second, the amylose–lipid complex could change or retard the water
distribution and hence the retrogradation [260]. Third, a cocrystallization of
amylose and amylopectin is possible to some extent, and substances that
complex with amylose eliminate the contribution of amylose in the recrystallizing process [161]. On the other hand, the interaction of amylopectin and
lipids means that lipids interact directly with the amylopectin fraction, at least
to a small extent, and retard retrogradation through the formation of an amylopectin–lipid complex [6,160,171,172,236,261,262].
The possibility of retarding the retrogradation of some starches (maize,
potato, and waxy maize) and nongranular amylopectin by adding an intact
cetyltrimethylammonium bromide (CTAB)–amylose complex has been
explored [259]. It was found that CTAB–amylose complexes added to a cooled
gelatinized starch gel or to starch suspensions that were heated to temperatures
below the transition temperature of the CTAB–amylose complex had little
effect on retrogradation; however, starch gels or starch suspensions with added
CTAB–amylose complexes that were heated to temperatures above the transition temperature (i.e., the complex melted) showed a decreased retrogradation. This mechanism is therefore unlikely.
Because lipids and some surfactants retard or delay gelatinization, probably by complexing with leached amylose on the surface of the starch granules,
it is possible that lipids or surfactants also retard the retrogradation by a similar
mechanism (i.e., by acting as a barrier against water transport) [260]. This
mechanism could be involved in retarding the retrogradation of normal starches
because it is known that the water content is very important for recrystallization; however, it does not explain the effect of lipids and surfactants on
decreasing the retrogradation of waxy starches, unless they are able to interact
with the surface molecules of the waxy starch granules. Furthermore, nongranular amylopectin gels have also been shown to decrease in retrogradation
when surfactants and monoglycerides are added [160,261], which shows that
the granule form is not a limiting factor. If lipids and surfactants are added
after the gelatinization is concluded, such a barrier effect should not be
obtained and the retrogradation should progress in a way similar to that for
starch gels without additives; however, pregelatinization of the starches before
the addition of a surfactant was found to decrease retrogradation compared to
starch gels without such an addition [171,172]. This indicates that lipids or
surfactants affect the retrogradation even after the starch suspensions are fully
gelatinized. This alternative, therefore, has only limited value as an explanation
of the effects of lipids or surfactants on retrogradation.
© 2006 by Taylor & Francis Group, LLC
Starch: Physicochemical and Functional Aspects 441
Russell [161] has suggested that a possible cocrystallization of amylose
and amylopectin contributes to retrogradation, and the role of l
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