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Title: Effects of sucrose replacement by polydextrose on structure development of cakes.
Author: Pateras, Irene.
ISNI:       0000 0001 3476 5157
Awarding Body: Oxford Polytechnic
Current Institution: Oxford Brookes University
Date of Award: 1991
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Full and partial substitution of sucrose with polydextrose, and its effects on properties of batters and structure development of cakes were studied. Although substitution levels around 25% did not alter the properties of the system, higher levels of replacement resulted in significant changes in batter and cake properties. The effects of sucrose replacement by polydextrose on starch gelatinization and egg protein denaturation temperatures were studied by differential scanning calorimetry in model systems. Experiments showed that polydextrose raises gelatinization temperature more than sucrose. No significant difference was found between the two solutes with respect to their effect on egg protein denaturation. Dynamic oscillatory experiments showed that the viscoelastic profile of cake batters is altered when polydextrose is used to replace sucrose. A clear tendency towards permanent deformation and fluid-like behaviour was observed with increasing levels of replacement by polydextrose. Changes in rheological properties of batters with increasing polydextrose concentration were related to bubble size and distribution of cake batters. Microscopical techniques were developed to assess the foam characteristics of batters, before and during heating. Increasing level of replacement increased the mean size of bubbles and introduced large variation in bubble size distribution. The lack of uniformity in bubble distribution of polydextrose batters increased the rate of gas diffusion from the small bubbles to larger ones. During heating, bubble population of conventional batters expanded more than that of polydextrose substituted batters. Changes in bubble expansion rates resulted in cakes of lower volume with increasing levels of replacement. Assessment of textural properties of cakes indicated that sucrose replacement at levels around 50% or greater contributes to weakening the mechanical strength of crumb structure. Scanning electron microscopy of crumb samples demonstrated changes on the degree of starch granules swelling, cell wall structure and matrix development, as a result of sucrose replacement by polydextrose
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Low-calorie cake-making processes Food