very much affect the commercial sam

very much affect the commercial samples, whereas the laboratory-prepared
sample showed a more narrow gelatinization temperature range.
10.4 RETROGRADATION OF STARCH
The changes that occur in gelatinized starch, from initially an amorphous
state to a more ordered or crystalline state, are referred to as retrogradation.
These changes occur because gelatinized starch is not in thermodynamic
equilibrium. The rheological properties will change, as evidenced by an
increase in firmness or rigidity.
Loss of water-holding capacity and restoration of crystallinity will also
become evident and increase on aging. These processes exert a major and
usually not acceptable influence on the texture of foods rich in starch. Starch
retrogradation is the main factor in the staling of bread and other baked
products [132–135], although other factors are also involved [136].
Because the processes of recrystallization and increased firmness are both
referred to as retrogradation and different techniques are used to measure them,
the evaluation of retrogradation becomes complicated. Different techniques
are not necessarily measuring the same process. The kinetics of retrogradation
has been studied to elucidate the molecular mechanism behind the phenomenon but is still not completely known [132,133,135–139]. Retrogradation
would not take place without a certain minimum amount of water, and the
water content together with the storage temperatures are very important
because they control the rate and the extent of retrogradation. Many substances
can interfere with the retrogradation process. Most important among them are
lipids and surfactants. The retrogradation tendency of starches of various
botanical origins varies greatly and does not seem to depend simply on the
amylose-to-amylopectin ratios of the starches.
10.4.1 METHODS FORESTIMATINGRETROGRADATION
AND THEFEATURESMEASURED
The most common methods for measuring retrogradation (i.e., rate and extent
of recrystallization on aging) are x-ray diffraction analysis [133,140,141],
thermal methods such as DSC [91,134,142–145], and rheological techniques
[138,146–148]. Because the retrogradation is to a large extent a recrystallization process, it can be followed by changes in x-ray diffraction patterns. In
cereal starches, the A-pattern is lost during gelatinization and only the Vpattern is obtained due to the formation of an amylose–lipid complex. On
aging, the B-pattern will develop, superimposed on the V-pattern [140]. The
intensity of the B-pattern increases with time. X-ray diffraction analysis gives,
therefore, both the type and degree of crystallinity.
© 2006 by Taylor & Francis Group, LLC
Starch: Physicochemical and Functional Aspects 417
Thermal methods (e.g., DSC) are well suited for following the rate and
extent of retrogradation as the starch molecules progressively reassociate on
aging. Aged gels and stale bread show a characteristic melting endotherm
around 55 to 60°C, which is absent in fresh gels and breads immediately after
gelatinization. This transition enthalpy increases progressively in magnitude
with storage time until a certain limit is reached and remains constant on
further storage. The calorimetry provides, therefore, a means to follow the
formation of recrystallized starch gels through the melting endotherm of the
B-crystals. The endotherm measured is the melting of recrystallized amylopectin [91]. Rheological techniques, especially fundamental viscoelastic measurements, are also well suited to monitoring gel firmness (rigidity) on aging.
Other methods, such as enzymatic digestion [149], quantitative centrifugation
[150], Raman spectrometry [137], and the NMR technique [151] have been
used to evaluate the retrogradation process.
10.4.2 COMPONENTS OFSTARCH
It was first suggested by Schoch and French [132] that the staling of bread
essentially involves the retrogradation of the amylopectin but not the amylose
fraction. Since then, many investigations have been carried out to determine
the respective roles of amylopectin and amylose and their combined effects
in the retrogradation of starch gels and staling of baked products. The composite nature of starch gels, in which swollen gelatinized starch granules are
embedded in an interpenetrating amylose–gel matrix, to a large extent determines the roles of both amylose and amylopectin [152–155].
When gels that are made of amylose or amylopectin (without granules)
are compared to starch gels, some important features emerge that explain the
roles of the two starch polymers in retrogradation. Early x-ray diffraction
studies on aged starch gels showed that the B-type diffraction pattern developed slowly [140]. Amylose gels in storage and amylose precipitated from
aqueous solution give weak x-ray diffraction patterns of the B-type [156].
Amylopectin gels also show the characteristic B-type pattern upon storage
[157,158]. Both amylose and amylopectin gels, then, show the B-pattern upon
storage. Sarko and Wu [40] proposed that the retrogradation is due to crosslinking of chains by double-helical gel junction zones. One possible mechanism
involved in the gelling of amylose is phase separation into polymer-rich and
polymer-deficient regions [146,147]. Crystallinity, as detected by x-ray diffraction, is a slower process than gel network formation (i.e., phase separation)
and was proposed to occur in the polymer-rich regions of the gel [146,147].
For both amylose and the starch gel, the initial development of crystallinity
was found to occur at similar rates. The crystallization of amylose reached a
limit after 2 days, whereas the crystallinity of the starch gel continued to
increase [147]. The amylopectin gels increase slowly in crystallinity with time
© 2006 by Taylor & Francis Group, LLC
418 Carbohydrates in Food
and approach a limiting value after 30 to 40 days [158]. It was found that
about 70% of the crystallinity of fully retrograded starch gels was lost after
heating to 90°C, whereas the crystallinity of the amylose gel was reduced by
only 25% [146]. The crystallinity of amylopectin gels is fully reversible by
heating [157]. The residual crystallinity of starch gels after heating is therefore
solely due to the amylose fraction. Isolated gelatinized starch granules that
are mostly made of amylopectin and washed free from all exuded amylose
give no x-ray diffraction pattern immediately after cooling. After 2 weeks of
storage, the B-type pattern is obtained, which completely disappears upon
heating to 70°C [146].
Differential scanning calorimetry studies on retrogradation also suggest
that long-term changes are due to the amylopectin fraction [91,142,146]. Aged
bread, starch, and amylopectin gels show a melting endotherm that slowly
increases with time, whereas no melting endotherm is obtained for amylose
gels in the temperature interval of 10 to 130°C. The crystallinity of the amylose
fraction can be seen as an endothermic peak at 145 to 153°C [142,159], a
temperature rarely reached in connection with starch-based foods. The melting
endotherm of starch gels and stale breads is completely reversible; no endotherm is obtained immediately after the heating of an aged starch gel. In a
DSC study on amylose chain association in lipid-depleted starches and amylose, an exothermic peak appeared on cooling immediately after the samples
had been heated to 180°C [159]. This shows that the amylose reassociates
very quickly, as waxy maize starch or amylopectins did not show this exothermic peak. The different recrystallization rates of amylose and amylopectin
have been confirmed by microcalorimetry, where the exothermic heat evolved
during crystallization is measured [159a].

Hasil (Bahasa Indonesia) 1:

very much affect the commercial samples, whereas the laboratory-preparedsample showed a more narrow gelatinization temperature range.10.4 RETROGRADATION OF STARCHThe changes that occur in gelatinized starch, from initially an amorphousstate to a more ordered or crystalline state, are referred to as retrogradation.These changes occur because gelatinized starch is not in thermodynamicequilibrium. The rheological properties will change, as evidenced by anincrease in firmness or rigidity. Loss of water-holding capacity and restoration of crystallinity will alsobecome evident and increase on aging. These processes exert a major andusually not acceptable influence on the texture of foods rich in starch. Starchretrogradation is the main factor in the staling of bread and other bakedproducts [132–135], although other factors are also involved [136].Because the processes of recrystallization and increased firmness are bothreferred to as retrogradation and different techniques are used to measure them,the evaluation of retrogradation becomes complicated. Different techniquesare not necessarily measuring the same process. The kinetics of retrogradationhas been studied to elucidate the molecular mechanism behind the phenomenon but is still not completely known [132,133,135–139]. Retrogradationwould not take place without a certain minimum amount of water, and thewater content together with the storage temperatures are very importantkarena mereka mengontrol tingkat dan tingkat retrogradation. Banyak zatdapat mengganggu proses retrogradation. Terpenting di antara mereka yanglipid dan surfaktan. Kecenderungan retrogradation Pati berbagaiasal-usul botani sangat bervariasi dan tampaknya tidak tergantung hanya padarasio amilosa di-amilopektin Pati.10.4.1 METODE FORESTIMATINGRETROGRADATIONDAN THEFEATURESMEASUREDMetode yang paling umum untuk mengukur retrogradation (yaitu, tingkat dan tingkatrekristalisasi pada penuaan) adalah analisis Difraksi sinar x [133,140,141],termal metode seperti DSC [91,134,142-145], dan teknik rheological[138,146-148]. Karena retrogradation adalah untuk sebagian besar proses rekristalisasi, ini dapat diikuti oleh perubahan dalam pola-pola Difraksi sinar x. DalamPati sereal, A-pola hilang selama gelatinization dan hanya Vpattern diperoleh karena pembentukan sebuah kompleks amilosa – lipid. Padapenuaan, B-pola akan mengembangkan, ditumpangkan ke V-pola [140]. Theintensitas dari B-pola meningkatkan dengan waktu. Memberikan analisis Difraksi sinar x,oleh karena itu, jenis dan tingkat bagian kristalinitas.© 2006 oleh Taylor & Francis Group, LLCPati: Secara fisikokimia maupun fungsional aspek 417Metode termal (misalnya, DSC) sangat cocok untuk mengikuti tingkat dantingkat retrogradation sebagai Pati molekul semakin reassociate padapenuaan. Umur gel dan roti basi menunjukkan karakteristik mencair endothermaround 55 to 60°C, which is absent in fresh gels and breads immediately aftergelatinization. This transition enthalpy increases progressively in magnitudewith storage time until a certain limit is reached and remains constant onfurther storage. The calorimetry provides, therefore, a means to follow theformation of recrystallized starch gels through the melting endotherm of theB-crystals. The endotherm measured is the melting of recrystallized amylopectin [91]. Rheological techniques, especially fundamental viscoelastic measurements, are also well suited to monitoring gel firmness (rigidity) on aging.Other methods, such as enzymatic digestion [149], quantitative centrifugation[150], Raman spectrometry [137], and the NMR technique [151] have beenused to evaluate the retrogradation process.10.4.2 COMPONENTS OFSTARCHIt was first suggested by Schoch and French [132] that the staling of breadessentially involves the retrogradation of the amylopectin but not the amylosefraction. Since then, many investigations have been carried out to determinethe respective roles of amylopectin and amylose and their combined effectsin the retrogradation of starch gels and staling of baked products. The composite nature of starch gels, in which swollen gelatinized starch granules areembedded in an interpenetrating amylose–gel matrix, to a large extent determines the roles of both amylose and amylopectin [152–155].When gels that are made of amylose or amylopectin (without granules)are compared to starch gels, some important features emerge that explain theroles of the two starch polymers in retrogradation. Early x-ray diffractionstudies on aged starch gels showed that the B-type diffraction pattern developed slowly [140]. Amylose gels in storage and amylose precipitated fromaqueous solution give weak x-ray diffraction patterns of the B-type [156].Amylopectin gels also show the characteristic B-type pattern upon storage[157,158]. Both amylose and amylopectin gels, then, show the B-pattern uponstorage. Sarko and Wu [40] proposed that the retrogradation is due to crosslinking of chains by double-helical gel junction zones. One possible mechanisminvolved in the gelling of amylose is phase separation into polymer-rich andpolymer-deficient regions [146,147]. Crystallinity, as detected by x-ray diffraction, is a slower process than gel network formation (i.e., phase separation)and was proposed to occur in the polymer-rich regions of the gel [146,147].For both amylose and the starch gel, the initial development of crystallinitywas found to occur at similar rates. The crystallization of amylose reached alimit after 2 days, whereas the crystallinity of the starch gel continued toincrease [147]. The amylopectin gels increase slowly in crystallinity with time© 2006 by Taylor & Francis Group, LLC418 Carbohydrates in Foodand approach a limiting value after 30 to 40 days [158]. It was found thatabout 70% of the crystallinity of fully retrograded starch gels was lost afterheating to 90°C, whereas the crystallinity of the amylose gel was reduced byonly 25% [146]. The crystallinity of amylopectin gels is fully reversible byheating [157]. The residual crystallinity of starch gels after heating is thereforesolely due to the amylose fraction. Isolated gelatinized starch granules thatare mostly made of amylopectin and washed free from all exuded amylosegive no x-ray diffraction pattern immediately after cooling. After 2 weeks ofstorage, the B-type pattern is obtained, which completely disappears uponheating to 70°C [146].Differential scanning calorimetry studies on retrogradation also suggestthat long-term changes are due to the amylopectin fraction [91,142,146]. Agedbread, starch, and amylopectin gels show a melting endotherm that slowlyincreases with time, whereas no melting endotherm is obtained for amylosegels in the temperature interval of 10 to 130°C. The crystallinity of the amylosefraction can be seen as an endothermic peak at 145 to 153°C [142,159], atemperature rarely reached in connection with starch-based foods. The meltingendotherm of starch gels and stale breads is completely reversible; no endotherm is obtained immediately after the heating of an aged starch gel. In aDSC study on amylose chain association in lipid-depleted starches and amylose, an exothermic peak appeared on cooling immediately after the sampleshad been heated to 180°C [159]. This shows that the amylose reassociatesvery quickly, as waxy maize starch or amylopectins did not show this exothermic peak. The different recrystallization rates of amylose and amylopectinhave been confirmed by microcalorimetry, where the exothermic heat evolvedduring crystallization is measured [159a].

Hasil (Bahasa Indonesia) 2:

sangat mempengaruhi sampel komersial, sedangkan laboratorium disiapkan
sampel menunjukkan kisaran suhu gelatinisasi lebih sempit.
10.4 retrogradasi DARI PATI
Perubahan yang terjadi pada pati gelatinized, dari semula amorf
negara atau negara kristal lebih teratur, yang disebut sebagai retrogradasi.
Perubahan ini terjadi karena gelatinized pati tidak dalam termodinamika
ekuilibrium. Sifat reologi akan berubah, yang dibuktikan dengan
peningkatan ketegasan atau kekakuan.
Hilangnya kapasitas retensi air dan pemulihan kristalinitas juga akan
menjadi jelas dan meningkatkan penuaan. Proses ini mengerahkan utama dan
tidak berpengaruh diterima biasanya pada tekstur makanan kaya pati. Pati
retrogradasi adalah faktor utama dalam staling roti dan panggang lainnya
produk [132-135], meskipun faktor-faktor lain juga terlibat [136].
Karena proses rekristalisasi dan peningkatan ketegasan keduanya
disebut sebagai retrogradasi dan teknik yang berbeda digunakan untuk mengukur mereka,
evaluasi retrogradasi menjadi rumit. Teknik yang berbeda
tidak selalu mengukur proses yang sama. Kinetika retrogradasi
telah dipelajari untuk menjelaskan mekanisme molekuler di balik fenomena tetapi masih belum sepenuhnya diketahui [132,133,135-139]. Retrogradasi
tidak akan berlangsung tanpa jumlah minimum tertentu air, dan
kadar air bersama-sama dengan suhu penyimpanan sangat penting
karena mereka mengontrol laju dan tingkat retrogradasi. Banyak zat
dapat mengganggu proses retrogradasi. Paling penting di antara mereka adalah
lipid dan surfaktan. The retrogradasi kecenderungan pati dari berbagai
asal-usul botani sangat bervariasi dan tampaknya tidak tergantung hanya pada
amilosa-to-amilopektin rasio pati.
10.4.1 METODE FORESTIMATINGRETROGRADATION
DAN THEFEATURESMEASURED
Metode yang paling umum untuk mengukur retrogradasi (yaitu, tingkat dan luasnya
rekristalisasi pada penuaan) adalah x-ray analisis difraksi [133140141],
metode termal seperti DSC [91,134,142-145], dan teknik rheologi
[138,146-148]. Karena retrogradasi adalah untuk sebagian besar proses rekristalisasi, dapat diikuti dengan perubahan x-ray pola difraksi. Dalam
pati sereal, A-pola hilang selama gelatinisasi dan hanya Vpattern diperoleh karena pembentukan kompleks amilosa-lipid. Pada
penuaan, B-pola akan mengembangkan, ditumpangkan pada V-pola [140]. The
Intensitas B-pola meningkat seiring dengan waktu. Analisis difraksi sinar-X memberikan,
karena itu, baik jenis dan derajat kristalinitas.
© 2006 oleh Taylor & Francis Group, LLC
Pati: fisiko dan Aspek Fungsional 417
metode Thermal (misalnya, DSC) sangat cocok untuk mengikuti laju dan
luasnya retrogradasi sebagai molekul pati semakin reassociate pada
penuaan. Gel Berumur dan roti basi menunjukkan endoterm leleh karakteristik
sekitar 55 hingga 60 ° C, yang tidak hadir dalam gel segar dan roti segera setelah
gelatinisasi. Entalpi transisi ini meningkat secara progresif dalam besarnya
dengan waktu penyimpanan sampai batas tertentu tercapai dan tetap konstan pada
penyimpanan lebih lanjut. Kalorimetri yang menyediakan, oleh karena itu, sarana untuk mengikuti
pembentukan rekristalisasi pati gel melalui endoterm leleh
B-kristal. The endoterm diukur adalah mencairnya rekristalisasi amilopektin [91]. Teknik rheologi, terutama mendasar pengukuran viskoelastik, juga cocok untuk pemantauan gel ketegasan (kekakuan) dari penuaan.
Metode lain, seperti enzimatik pencernaan [149], sentrifugasi kuantitatif
[150], Raman spektrometri [137], dan teknik NMR [ 151] telah
digunakan untuk mengevaluasi proses retrogradasi.
10.4.2 KOMPONEN OFSTARCH
Ini pertama kali diusulkan oleh Schoch dan Perancis [132] bahwa staling roti
dasarnya melibatkan retrogradasi amilopektin namun tidak amilosa
fraksi. Sejak itu, banyak penelitian telah dilakukan untuk menentukan
peran masing-masing dari amilopektin dan amilosa dan efek gabungan mereka
di retrogradasi pati gel dan staling produk panggang. Sifat komposit dari gel pati, di mana bengkak granula pati gelatinized yang
tertanam dalam matriks amilosa-gel yang saling, untuk sebagian besar menentukan peran kedua amilosa dan amilopektin [152-155].
Ketika gel yang terbuat dari amilosa atau amilopektin (tanpa butiran)
dibandingkan dengan pati gel, beberapa fitur penting muncul yang menjelaskan
peran dari dua polimer pati dalam retrogradasi. Awal difraksi x-ray
studi tentang umur gel pati menunjukkan bahwa pola difraksi B-jenis berkembang dengan lambat [140]. Gel amilosa dalam penyimpanan dan amilosa diendapkan dari
larutan berair memberikan pola difraksi sinar-x lemah dari tipe B [156].
amilopektin gel juga menunjukkan pola B-tipe karakteristik pada penyimpanan
[157158]. Kedua amilosa dan amilopektin gel, kemudian, menunjukkan B-pola pada
penyimpanan. Sarko dan Wu [40] mengusulkan bahwa retrogradasi adalah karena silang rantai dengan double-heliks zona gel persimpangan. Salah satu mekanisme yang mungkin
terlibat dalam pembentuk gel amilosa adalah pemisahan fase ke-polimer yang kaya dan
polimer-kekurangan daerah [146147]. Kristalinitas, seperti yang terdeteksi oleh difraksi sinar-x, adalah proses yang lebih lambat daripada pembentukan jaringan gel (yaitu, pemisahan fasa)
dan diusulkan terjadi di daerah yang kaya polimer gel [146147].
Untuk kedua amilosa dan gel pati, pengembangan awal kristalinitas
ditemukan terjadi pada tingkat yang sama. Kristalisasi amilosa mencapai
batas setelah 2 hari, sedangkan kristalinitas gel pati terus
meningkat [147]. Gel amilopektin meningkat secara perlahan dalam kristalinitas dengan waktu
© 2006 oleh Taylor & Francis Group, LLC
418 Karbohidrat dalam makanan
dan mendekati nilai batas setelah 30 sampai 40 hari [158]. Ditemukan bahwa
sekitar 70% dari kristalinitas sepenuhnya retrograded pati gel hilang setelah
pemanasan sampai 90 ° C, sedangkan kristalinitas gel amilosa berkurang
hanya 25% [146]. Kristalinitas amilopektin gel sepenuhnya reversibel dengan
pemanasan [157]. Oleh karena itu, kristalinitas sisa pati gel setelah pemanasan
semata-mata karena fraksi amilosa. Terisolasi gelatinized granula pati yang
sebagian besar terbuat dari amilopektin dan dicuci bebas dari segala amilosa memancarkan
tidak memberikan pola difraksi sinar-x segera setelah pendinginan. Setelah 2 minggu
penyimpanan, pola B-jenis diperoleh, yang benar-benar menghilang pada
pemanasan sampai 70 ° C [146].
studi kalorimetri pemindaian Diferensial pada retrogradasi juga menyarankan
bahwa perubahan jangka panjang yang disebabkan oleh fraksi amilopektin [91142146]. Berumur
roti, pati, dan amilopektin gel menunjukkan endoterm leleh yang perlahan-lahan
meningkat seiring dengan waktu, sedangkan tidak ada endoterm leleh diperoleh untuk amilosa
gel dalam interval suhu 10 sampai 130 ° C. Kristalinitas amilosa
fraksi dapat dilihat sebagai puncak endotermik pada 145-153 ° C [142159], seorang
suhu jarang mencapai sehubungan dengan makanan berbasis tepung. The mencair
endoterm gel pati dan roti basi benar-benar reversibel; ada endoterm diperoleh segera setelah pemanasan dari pati gel umur. Dalam sebuah
studi DSC pada asosiasi rantai amilosa dalam pati-habis lipid dan amilosa, puncak eksotermis muncul di segera pendinginan setelah sampel
telah dipanaskan sampai 180 ° C [159]. Hal ini menunjukkan bahwa amilosa yang reassociates
sangat cepat, seperti lilin pati jagung atau amylopectins tidak menunjukkan puncak eksotermik ini. Tingkat rekristalisasi berbeda amilosa dan amilopektin
telah dikonfirmasi oleh microcalorimetry, dimana panas eksotermis berevolusi
selama kristalisasi diukur [159a].