adhesion between the dispersed phas

adhesion between the dispersed phase (the starch granules) and the continuous
phase can also be affected when another macromolecule is introduced.
10.6.1.5.1 Proteins
The influence of proteins on the gelatinization of starch has been studied with
the DSC, but in most systems the interpretation is difficult because the protein
denaturation endotherm and the starch gelatinization endotherm overlap
[265,266]; however, gluten is one protein for which it is possible to investigate
the interaction [267]. Gluten by itself shows no, or at least very minor, transitions [268,269]. When gluten was added to wheat starch, an increase in To
with increasing amounts of gluten was measured [267]. The thermal transitions
in a mixture of starch and fish protein were found to proceed independently
of each other [265], and in a surmi system the Tofor starch was shifted to a
higher temperature compared with the starch–water system [270].
The influence of gluten on the rheological properties of starch gels has
been investigated, and it was found that the effect of adding gluten depends
on the type of starch to which it is added [119]. For mixtures of gluten and
wheat starch, a weakening of the starch paste or gel in the presence of gluten
was observed [270a]. The rheological behavior of starch–caseinate mixtures
was studied in steady shear [271]. The mixed gel showed a shear-thinning
behavior, as did the starch. A synergistic effect was found, as the starch–caseinate mixed gel showed higher apparent viscosities than did the single component. For mixtures of pea starch and egg white heated together, the modulus
at small deformations increased for the mixtures compared with any of the
components alone [272]. This was also the case for mixtures of amylose and
egg white. Microscopic examination revealed a phase-separated structure in
both systems. For mixed protein–starch gels (potato starch, annealed potato
starch, pregelatinized potato starch, or cassava starch and bovine serum albumin [BSA] or gelatin) it was found that both the transition temperature and
the rates of gelation of the components were critical for the behavior of the
complex system [266]. When the starch gel was formed before the protein gel
(e.g., BSA and cassava), G′ and G″of the complex system could be predicted
by the simple addition of the moduli of the components at corresponding
concentrations. When the gelation occurred in the reverse order (e.g., BSA
and annealed potato starch), the gels were considerably stronger than predicted
by simple addition. When starch is present in surmi, the rigidity of the mixture
at increasing temperature is higher for the surmi without starch [270].
Another aspect of the gel formation of starch and starch components is
the influence on diffusion of molecules in the gels. This effect was studied for
the diffusion of BSA in amylose and amylopectin gels [273]. The diffusion
coefficient of BSA in amylose and amylopectin gels was found to decrease
with increasing polysaccharide concentration. No difference between amylose
and amylopectin gels was observed.
© 2006 by Taylor & Francis Group, LLC
444 Carbohydrates in Food
Because starch is present as particles in most products, a starch interface
exists and the starch can be regarded as a solid phase. The adsorption of
proteins on starch has been studied, and it was found that BSA is adsorbed to
a very low extent and wheat storage proteins are adsorbed to a much higher
extent [78]. Differences between starches were also observed; for example,
the adsorption of wheat storage proteins was much higher on potato starch
than on wheat or maize starch.
It has been suggested that the interaction between starch and protein
determines the endosperm hardness in cereals [39,274]. The phenomenon has
even been attributed to a single protein, friabilin [69], which has been suggested to influence the desorption of protein from starch during the starch
preparation procedure [275]. Interactions between amylose or amylopectin and
the protein oryzin were found to decrease during storage and were related to
the stickiness of cooked rice [276]. The binding of oryzin to the starch components had a positive influence on the stickiness of cooked rice.
The presence of glass transition temperatures when heating 1:1 mixtures
of amylopectin and gluten or amylopectin and casein was used to study the
miscibility of these polymers [277]. It was evident from the presence of two
separate Tgvalues that amylopectin and gluten are immiscible, whereas the
results were not as conclusive in the case of amylopectin and casein due to
their similar Tg
values.
The molecular interaction between amylose or amylopectin and protein in
solution has not been investigated to a great extent, except for some studies
that have used the iodine-binding property of starch for detecting interactions
[278,279]. It was concluded that the association between wheat starch and
wheat proteins occurs at neutral and acidic pH values. When starch, proteins,
and lipids are all present, many interactions are possible. Three-component
interactions were demonstrated in sorghum starch, whey proteins, and free
fatty acids [279a]. This was observed as a cooling stage viscosity when all
three components were present in the RVA. Certain proteins are lipid binding
(e.g., whey proteins). The expected interactions between the starch and the
lipids might then be cancelled because the lipids are bound by the protein and
thus not available for complexation with amylose or amylopectin [279b,c].

Hasil (Bahasa Indonesia) 2:

adhesi antara fasa terdispersi (butiran pati) dan terus menerus
fase juga dapat dipengaruhi ketika makromolekul lain diperkenalkan.
10.6.1.5.1 Protein
Pengaruh protein pada gelatinisasi pati telah dipelajari dengan
DSC, tetapi dalam kebanyakan sistem interpretasi sulit karena protein
endoterm denaturasi dan gelatinisasi pati endoterm tumpang tindih
[265266]; Namun, gluten adalah salah satu protein yang dimungkinkan untuk menyelidiki
interaksi [267]. Gluten dengan sendirinya tidak menunjukkan, atau setidaknya sangat kecil, transisi [268269]. Ketika gluten telah ditambahkan ke tepung gandum, peningkatan Untuk
dengan meningkatnya jumlah gluten diukur [267]. Transisi termal
dalam campuran tepung dan ikan protein yang ditemukan untuk melanjutkan independen
dari satu sama lain [265], dan dalam sistem surmi pati tofor dialihkan ke
suhu yang lebih tinggi dibandingkan dengan sistem pati-air [270].
Pengaruh gluten pada sifat reologi pati gel telah
diteliti, dan ditemukan bahwa pengaruh penambahan gluten tergantung
pada jenis pati yang ditambahkan [119]. Untuk campuran gluten dan
pati gandum, melemahnya pasta pati atau gel dengan adanya gluten
diamati [270a]. Perilaku reologi campuran pati-caseinate
dipelajari di geser mantap [271]. Campuran gel menunjukkan geser-menipis
perilaku, seperti halnya pati. Sebuah efek sinergis ditemukan, sebagai pati-caseinate campuran gel menunjukkan viskositas jelas lebih tinggi daripada komponen tunggal. Untuk campuran pati kacang dan putih telur dipanaskan bersama-sama, modulus
pada deformasi kecil meningkat untuk campuran dibandingkan dengan salah satu
komponen saja [272]. Hal ini juga terjadi untuk campuran amilosa dan
putih telur. Pemeriksaan mikroskopis mengungkapkan struktur fase dipisahkan dalam
kedua sistem. Untuk campuran gel protein-pati (pati kentang, anil kentang
pati, pregelatinized tepung kentang, atau pati singkong dan albumin serum bovine [BSA] atau gelatin) ditemukan bahwa kedua suhu transisi dan
tingkat gelasi komponen yang penting untuk perilaku
sistem yang kompleks [266]. Ketika gel pati dibentuk sebelum gel protein
(misalnya, BSA dan singkong), G 'dan G "dari sistem yang kompleks dapat diprediksi
dengan penambahan sederhana dari modulus komponen di sesuai
konsentrasi. Ketika gelasi terjadi dalam urutan terbalik (misalnya, BSA
dan anil tepung kentang), gel yang jauh lebih kuat dari yang diperkirakan
oleh penambahan sederhana. Ketika pati hadir dalam surmi, kekakuan campuran
untuk meningkatkan suhu lebih tinggi untuk surmi tanpa pati [270].
Aspek lain dari pembentukan gel pati dan pati komponen adalah
pengaruh pada difusi molekul dalam gel. Efek ini dipelajari untuk
difusi BSA di amilosa dan amilopektin gel [273]. Difusi
koefisien BSA di amilosa dan amilopektin gel ditemukan menurun
dengan meningkatnya konsentrasi polisakarida. Tidak ada perbedaan antara amilosa
dan amilopektin gel diamati.
© 2006 oleh Taylor & Francis Group, LLC
444 Karbohidrat dalam makanan
Karena pati hadir sebagai partikel di sebagian besar produk, antarmuka pati
ada dan pati dapat dianggap sebagai fase padat. Adsorpsi
protein pada pati telah dipelajari, dan ditemukan bahwa BSA diserap ke
tingkat dan penyimpanan gandum protein sangat rendah teradsorpsi ke jauh lebih tinggi
tingkat [78]. Perbedaan antara pati juga diamati; misalnya,
adsorpsi protein penyimpanan gandum jauh lebih tinggi pada pati kentang
dari pada gandum atau tepung jagung.
Ia telah mengemukakan bahwa interaksi antara pati dan protein
menentukan kekerasan endosperm dalam sereal [39274]. Fenomena ini
bahkan telah dikaitkan dengan protein tunggal, friabilin [69], yang telah disarankan untuk mempengaruhi desorpsi protein dari pati selama pati
prosedur persiapan [275]. Interaksi antara amilosa atau amilopektin dan
protein oryzin ditemukan menurun selama penyimpanan dan terkait dengan
kekakuan nasi [276]. Pengikatan oryzin ke komponen pati telah berpengaruh positif terhadap kelengketan nasi.
Kehadiran suhu transisi gelas saat pemanasan 1: 1 campuran
dari amilopektin dan gluten atau amilopektin dan kasein digunakan untuk mempelajari
miscibility polimer ini [277 ]. Itu terbukti dari kehadiran dua
Tgvalues ​​terpisah yang amilopektin dan gluten yang bercampur, sedangkan
hasilnya tidak seperti yang konklusif dalam kasus amilopektin dan kasein karena
Tg serupa mereka
nilai.
Interaksi molekul antara amilosa atau amilopektin dan protein dalam
larutan memiliki belum diteliti untuk sebagian besar, kecuali untuk beberapa studi
yang telah menggunakan properti yodium-mengikat pati untuk mendeteksi interaksi
[278279]. Disimpulkan bahwa hubungan antara pati gandum dan
protein gandum terjadi pada pH netral dan asam. Ketika pati, protein,
dan lipid semua hadir, banyak interaksi yang mungkin. Tiga-komponen
interaksi yang ditunjukkan dalam pati sorghum, protein whey, dan bebas
asam lemak [279a]. Hal ini diamati sebagai tahap viskositas pendinginan ketika semua
tiga komponen yang hadir di RVA tersebut. Protein tertentu lipid mengikat
(misalnya, protein whey). Interaksi yang diharapkan antara pati dan
lipid mungkin kemudian dibatalkan karena lipid terikat oleh protein dan
dengan demikian tidak tersedia untuk kompleksasi dengan amilosa atau amilopektin [279b, c].