Consumers place a high level of importance on flavour when assessing the acceptability of
food. The flavour of dairy products can be affected by heating both during processing and
by consumers during food preparation. Of particular importance to the flavour of heated
dairy products is the highly complex network of Maillard reactions. Previously, emphasis has
been placed on undesirable flavours generated through the Maillard reaction in dairy
products and efforts have been made to minimise the formation of these flavours. However,
beneficial flavours are also formed by the Maillard reaction. Dairy products such as ghee are
formed by heating and are characterised by their unique flavours; these flavours are
generated by the Maillard reaction.
The objective of this thesis was to unravel the factors that influence the Maillard and
caramelisation reactions that occur during the cooking of ghee. Particular focus was placed
on the impact that the structure of the cream had on the reaction, and how manipulation of
these parameters could provide an avenue for the control of the Maillard reaction.
The development and validation of model reaction systems for the Maillard and
caramelisation reactions involved the variation of parameters including cooking time,
temperature, pH, phosphate buffers and salt. A group of eleven compounds including acetic
acid, furfural, 2-acetylfuran, butyrolactone, 2(5H)-furanone, furfuryl alcohol, maltol, 2-
acetylpyrrole, hydroxymaltol, hydroxymethylfurfural (HMF) and dihydro-4-hydroxy-2(3H)-
furanone (DHHF) were monitored to determine the impact of these parameter changes.
These results provided a starting point to assess the impact of food structure on these
reactions. To assess the impact of food structure a series of matrix structures were designed
starting from an aqueous matrix. The first component that was added to the aqueous matrix
was fat to generate a two phase structure. Emulsion structures were then formed from the
two phase structure using emulsifiers and high pressure homogenisation.
Analysis of the volatile compounds formed as the matrix structures were altered was carried
out using headspace solid phase microextraction/ gas chromatography mass spectrometry
(SPME/GCMS). Results indicated that fat is a key structural component in flavour generation
via the Maillard reaction. This could have implications for low fat foods where the flavour
developed during cooking is important. The addition of fat indicated a significant impact on
the Maillard reaction with a less significant impact seen on the caramelisation reaction.
The formation of two emulsions with inverted structures provided a means to alter the ratio
of volatile compounds in the cooked samples. The oil in water emulsion generated a volatile
compound profile similar to that of the fat containing matrix, whereas the water in oil
emulsion produced a different ratio of these same compounds.
The results reported in this thesis shed some light on the relationship between food
structure and flavour formation during the cooking of milk fat emulsions. These structures
will create future opportunities to manipulate the structure of food to control flavour
formation.
| Identifer | oai:union.ndltd.org:canterbury.ac.nz/oai:ir.canterbury.ac.nz:10092/9276 |
| Date | January 2014 |
| Creators | Newton, Angela |
| Publisher | University of Canterbury. Biology |
| Source Sets | University of Canterbury |
| Language | English |
| Detected Language | English |
| Type | Electronic thesis or dissertation, Text |
| Rights | Copyright Angela Newton, http://library.canterbury.ac.nz/thesis/etheses_copyright.shtml |
| Relation | NZCU |
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