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Title: Functionality of new xanthan gums
Author: Janin, Marie
ISNI:       0000 0004 6496 2516
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2015
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As controversies between studies have arisen over the properties and characteristics of the xanthan for the last decades, the current work aimed to establish the role of the xanthan molecular fine structure on its rheological and thermal properties in various conditions. Different xanthan gums were first characterised in order to understand the relationship between the structure and rheological and thermal properties before studying more complex systems such as xanthan and particulate materials (cellulosic materials and starch) or konjac glucomannan (KM); all this being the basis of the investigation of the xanthan-KM system in a yeast-raised product. Thanks to a range of xanthans with diverse acetate and pyruvate content coming from two different strains, it was demonstrated that the xanthan structure, especially the pyruvate groups, influences the rheological and thermal properties of xanthan. New findings showed that different master curves (viscosity vs c[rd) were obtained depending on the rigidity of the xanthan and ionic environment as well as the pyruvate groups being the driving force determining the xanthan viscosity and transition temperature. The pyruvate groups and their distribution also influence its interaction with konjac mannan leading to two types of interactions (with ordered and disordered form of xanthan) within a single xanthan sample. However, the optimum ratio of xanthan:KM present in aqueous solutions is not present in a food product (bread), but the different effect of xanthan and KM is noticeable: dough strength, and open structure of the breadcrumb for xanthan and dough extensibility and dryness for KM. The mixture of these hydrocolloids produced more acceptable breads than those made with only xanthan or KM.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available