Texture and sensory properties of starch solutions or gels, resp., can be influenced by regulating the visco-elastic properties that cannot be adjusted by simply varying the waxy rice starch concentration. Therefore, the hydrocolloid galactomannans guar gum and locust bean gum were used for addition. A total polymer concentration of c = 5% was maintained through all tests, the hydrocolloid fractions varied (cHK = O.S%, 1%, 2%). The mixtures were entirely decomposed in an autoclave at 13OOC resulting in an almost complete destruction of the granular starch structure. With rheomechanical oscillation measurements in the linear-visco-elastic range the influence of the galactomannans onto viscosity yield and visco-elasticity was determined quantitatively. It was found that the influence on the viscosity is depending on the deformation rate. At low frequencies and with increasing galactomannan fraction the viscosity decreases, while above a critical frequency mkr an increase in viscosity could be detected compared to pure starch. The mixtures also displayed an increase in viscous fractions versus elastic fractions compared to pure starch. With increasing galactomannan fraction, the ratio storage modulus/loss modulus is reduced continuously from G:G"> 10 (definitely mainly elastic) to G : G = 1 with simultaneously decreasing influence of the frequency. Based on the presented data and knowledge on solution structure of the individual components, a model for describing network structures in mixtures was developed. Changes in viscous-elastic properties are based on a thermodynamic incompatibility between starch and galactomannan fractions. The mixtures contain mixed network structures, with waxy rice starch (permanent network points) and galactomannans (temporary network points) contributing individually and characteristically to the resulting flow behaviour. Regulierung viskoelastischer Eigenschaften vonWachsreisstarke in Mischungen mit Galaktornannanen. Die Textur und das sensorische Empfinden von Starkelosungen bzw. Gelen werden durch die Regulierung der viskoelastischen Eigenschaften, deren Einstellung nicht durch eine einfache Variation der Wachsreisstarkekonzentration gelingt, beeinfluDt. Es wurden daher Hydrokolloidadditivierungen mit den Galaktomannanen Guar und Johannisbrotkernmehl durchgefuhrt. Eingesetzt wurden unterschiedliche Hydrokolloid-Anteile (cflK = 0,5%, I%, 2%) bei einer konstant gehaltenen Gesamtpolymerkonzentration von c = 5%. Hierzu wurden die Mischungen in einem Autoklaven bei 130°C aufgeschlossen, so daD die granulare Struktur der Starke nahezu vollstandig zerstort werden konnte. Mit Hilfe rheomechanischer Schwingungsmessungen im linear-viskoelastischen Bereich wurde der Ein-fluS der Galaktomannane auf die Viskositatsergiebigkeit und die Viskoelastizitat quantitativ erfaDt. Es konnte gezeigt werden, daD der EinfluB auf die Viskositat von der Deformationsrate abhangt. Mit zunehmendem Galaktomannan-Anteil ist bei kleinen Frequenzen eine Erniedrigung, ab einer kritischen Frequenz mkr eine Erhohung der...
378 starch/stiirke 47 (1995) Nr 10. S . 378-384 0 VCH Ve rlagsgeaellschat't mbH, D-69451 Weinheim, 1995 0038-9056/95/1010-0378$05.00+.25/0
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.