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adhesi antara fase tersebar (pati butiran) dan terus-menerusfase juga akan terpengaruh ketika makromolekul lain diperkenalkan.10.6.1.5.1 proteinPengaruh protein pada gelatinization Pati telah diteliti denganDSC, tetapi pada kebanyakan sistem interpretasi sulit karena proteinDenaturasi endotherm dan endotherm gelatinization Pati tumpang tindih[265,266]; Namun, gluten adalah sebuah unsur protein yang dimungkinkan untuk menyelidikiinteraksi [267]. Perekat dengan sendirinya menunjukkan tidak ada, atau setidaknya sangat kecil, transisi [268,269]. Kapan gluten ditambahkan ke Pati gandum, peningkatan untukdengan meningkatnya jumlah gluten adalah diukur [267]. Transisi termaldalam campuran pati dan ikan protein yang ditemukan untuk melanjutkan independensatu sama lain [265], dan sistem surmi Tofor Pati bergeser kesuhu yang lebih tinggi dibandingkan dengan sistem Pati-air [270]. Memiliki pengaruh gluten pada rheological Pada pati geltelah diselidiki, dan ternyata bahwa efek menambahkan gluten tergantungpada jenis pati yang itu ditambahkan [119]. Untuk campuran gluten dantepung gandum, melemahnya pasta tepung atau gel hadapan perekatdiamati [270a]. Perilaku rheological campuran pati-caseinatedipelajari di mantap geser [271]. Gel campuran menunjukkan penipisan geserbehavior, 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 modulusat small deformations increased for the mixtures compared with any of thecomponents alone [272]. This was also the case for mixtures of amylose andegg white. Microscopic examination revealed a phase-separated structure inboth systems. For mixed protein–starch gels (potato starch, annealed potatostarch, pregelatinized potato starch, or cassava starch and bovine serum albumin [BSA] or gelatin) it was found that both the transition temperature andthe rates of gelation of the components were critical for the behavior of thecomplex 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 predictedby the simple addition of the moduli of the components at correspondingconcentrations. When the gelation occurred in the reverse order (e.g., BSAand annealed potato starch), the gels were considerably stronger than predictedby simple addition. When starch is present in surmi, the rigidity of the mixtureat increasing temperature is higher for the surmi without starch [270].Another aspect of the gel formation of starch and starch components isthe influence on diffusion of molecules in the gels. This effect was studied forthe diffusion of BSA in amylose and amylopectin gels [273]. The diffusioncoefficient of BSA in amylose and amylopectin gels was found to decreasewith increasing polysaccharide concentration. No difference between amyloseand amylopectin gels was observed.© 2006 by Taylor & Francis Group, LLC444 Carbohydrates in FoodBecause starch is present as particles in most products, a starch interfaceexists and the starch can be regarded as a solid phase. The adsorption ofproteins on starch has been studied, and it was found that BSA is adsorbed toa very low extent and wheat storage proteins are adsorbed to a much higherextent [78]. Differences between starches were also observed; for example,the adsorption of wheat storage proteins was much higher on potato starchthan on wheat or maize starch.It has been suggested that the interaction between starch and proteindetermines the endosperm hardness in cereals [39,274]. The phenomenon haseven been attributed to a single protein, friabilin [69], which has been suggested to influence the desorption of protein from starch during the starchpreparation procedure [275]. Interactions between amylose or amylopectin andthe protein oryzin were found to decrease during storage and were related tothe 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 mixturesof amylopectin and gluten or amylopectin and casein was used to study themiscibility of these polymers [277]. It was evident from the presence of twoseparate Tgvalues that amylopectin and gluten are immiscible, whereas theresults were not as conclusive in the case of amylopectin and casein due totheir similar Tgvalues.The molecular interaction between amylose or amylopectin and protein insolution has not been investigated to a great extent, except for some studiesthat have used the iodine-binding property of starch for detecting interactions[278,279]. It was concluded that the association between wheat starch andwheat proteins occurs at neutral and acidic pH values. When starch, proteins,and lipids are all present, many interactions are possible. Three-componentinteractions were demonstrated in sorghum starch, whey proteins, and freefatty acids [279a]. This was observed as a cooling stage viscosity when allthree components were present in the RVA. Certain proteins are lipid binding(e.g., whey proteins). The expected interactions between the starch and thelipids might then be cancelled because the lipids are bound by the protein andthus not available for complexation with amylose or amylopectin [279b,c].
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