ISBN 9783843942522

978-3-8439-4252-2, Reihe Verfahrenstechnik

Valerie Louise Pietsch
High moisture extrusion: Investigations on the reaction behavior of plant proteins

238 Seiten, Dissertation Karlsruher Institut für Technologie (2019), Softcover, A5

Zusammenfassung / Abstract

High moisture extrusion processing can be applied to impart a muscle meat-like texture to plant proteins. Herein, the reaction behavior of plant proteins upon thermomechanical treatment plays an important role, as it affects the rheological properties and subsequently the formation of various product textures. During extrusion processing, however, thermomechanical stresses are widely distributed and difficult to determine. For this reason, knowledge on the reaction behavior of plant proteins during extrusion processing is currently not well understood.

To deal with this complexity, a model system was used to investigate the reaction behavior of wheat gluten in a defined manner and at extrusion-like conditions. Change in reaction behavior was characterized by polymerization reactions involving the formation of disulfide bonds. From these results, a kinetic model was proposed describing the polymerization behavior of wheat gluten as function of thermal and mechanical stresses. To transfer this model to the extrusion process, local process conditions were characterized. At certain conditions, polymerization predicted at various process parameter settings showed the same tendencies compared to measured values. The deviations observed between absolute values, however, indicate that the methods applied were not entirely captured by the methods used to describe non-isothermal conditions. Moreover, it is necessary to consider the influence of higher mechanical stresses on the reaction behavior of wheat gluten in future studies.

Finally, the applicability of the approach developed to investigate the reaction behavior of wheat gluten to other plant protein sources was demonstrated using soy protein concentrate. The findings underline that the approach developed in the scope of this thesis not only offers an access to investigate the reaction behavior of a wide range of plant protein sources.