dc.contributor.advisor |
O'Connor, Charmian J. |
en |
dc.contributor.author |
Lal, Shane Norishma Devi |
en |
dc.date.accessioned |
2020-07-08T04:49:53Z |
en |
dc.date.available |
2020-07-08T04:49:53Z |
en |
dc.date.issued |
2008 |
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dc.identifier.uri |
http://hdl.handle.net/2292/51969 |
en |
dc.description |
Full text is available to authenticated members of The University of Auckland only. |
en |
dc.description.abstract |
Since Iast century, food products have been fortified and enriched by addition of essential
nutrients to satisfy needs of specific populations. A wide variety of dairy products is
currently available, as a result of continued advances and improvements in the dairy industry
over the past decade. Plant sterols have been recognised as a functional food ingredient due
to their ability to lower systemic cholesterol levels. This current research was directed to the
preparation of dairy products - milk, yoghurt and spread - with added plant sterols. The final
plant sterol content of each of the formulated milk and yoghurt was 1% and of the spread
5%. Plant sterols interfere with the absorption of cholesterol in the gut but the exact details of
how they do this are not yet well understood. Further research has thus been carried out in
order to investigate the role of bile salts in assisting plant sterols inhibit the solubilisation of
cholesterol and, in particular, whether the suppression of cholesterol absorption results from
the lowering of the relative amount of cholesterol solubilised by bile salt micelles when plant
sterols coexist with cholesterol. Bile salts are a family of steroidal compounds synthesized in
the liver and they have a number of potential roles in the human body. Bile salt micelles have
the ability to solubilise water-insoluble components in bile and lipolytic products, forming
tiny water soluble packets called dietary mixed micelles in the small intestine. When the
micelles make contact with the intestinal cell wall, they deliver their content. Since the
cholesterol content of the mixed micelles is not water soluble, it forms a complex with
proteins and triglycerides inside the intestinal cells before moving in to the body as
chylomicrons. In this study, therefore, different types of bile salts and a mixture of bile salts
which mimics that present in bile have been used in the presence of cholesterol, β-sitosterol
and/or Stigmasterol. Increased hydrophobicity of the bile salts is a key factor in their ability
to solubilise cholesterol and plant sterols. A solution of mixed bile salts which mimics that
present in bile is very effective in this role. Subtle changes in sterol structure are also
important, with β-sitosterol being much more effective than Stigmasterol in decreasing
cholesterol solubilisation. Nutritional analysis of the formulated dairy products, performed using analytical techniques such as Kjeldahl digestion for protein content and high performance liquid chromatography
for total sugar content, yielded reproducible results. The total lipid content was obtained
through simple extraction procedures which yielded 1%, 1.4% and 15.5% of fat in the
formulated milk, yoghurt and spread, respectively. The fatty acid profiles of the formulated
dairy products were altered by an increase in monounsaturated and polyunsaturated fatty
acids of approximately 50%. A serving size (200 mL) of milk or a standard punnet (150 g) of
yoghurt and a serving of spread (10 g) would contribute 1.6 g, 1.4 g or 0.5 g of plant sterols,
respectively, towards the amount required (2 g/day) to reduce cholesterol absorption. |
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dc.publisher |
ResearchSpace@Auckland |
en |
dc.relation.ispartof |
PhD Thesis - University of Auckland |
en |
dc.relation.isreferencedby |
UoA99182616714002091 |
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dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
en |
dc.rights |
Restricted Item. Full text is available to authenticated members of The University of Auckland only. |
en |
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
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dc.title |
The application of plant sterols as functional ingredients in dairy products |
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dc.type |
Thesis |
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thesis.degree.discipline |
Food Science |
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thesis.degree.grantor |
The University of Auckland |
en |
thesis.degree.level |
Doctoral |
en |
thesis.degree.name |
PhD |
en |
dc.rights.holder |
Copyright: The author |
en |
dc.identifier.wikidata |
Q112877711 |
|