Foo, Wan Teck
(2013)
Textural And Rheological Properties Of
Gelatin Or Gellan In Maize Starch – Egg
White Composite Gels.
PhD thesis, Universiti Sains Malaysia.
Abstract
Gellan (Gll) has been suggested as one of the gelatin (Glt) alternatives as the
Gll gels could provide ‘melt-in-mouth’ sensory perception that is similar to Glt gels.
However, the application of Gll as a Glt replacer in composite systems has not been
sufficiently explored. The purpose of this study was to elucidate the effects of
ingredient proportions on the texture, rheology and structural properties of Glt or Gll
composite gels consisted of maize starch (MS) and egg white (EW). These main
ingredients were chosen to yield gels based on their practical importance in the food
industry. Mixture design experiment was applied as a tool in exploring the
interaction effects of different proportions of the components. Textural properties
and breakdown behaviour of single component gels were determined by using
texture profile analysis (TPA) and multiple extrusion cell analysis (MEC),
respectively. Rheological properties of composite gels under compression were
determined by using stress relaxation test (linear deformation) and fracture analysis.
The structural properties of gels were revealed through the gel formations that were
determined by using rheometer. The morphologies of selected gels obtained from
scanning electron microscopy images further revealed the structures of gels. The
relationships of structure, rheology and texture of the gels were then assessed and
compared between Glt and Gll systems. From TPA results, Glt gel was strong and
elastic while Gll gel was weak and brittle. However, Glt and Gll gels showed similar
decay patterns and rates in MEC test. This tentatively supports the notion of Gll as a
Glt replacer in food products.
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