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The influence of lipid changes in bran and offall on the baking properties of wheaten flour

Thesis (Masters Diploma (Food Technology)) -- Cape Technikon, Cape Town,1991 / Bread is an important commodity in South Africa for its nutritional value and
contribution to the economy. As such anything that enhances consumption of bread
is of economic importance.

Variation in bread volumen influences its utility value aand consumer acceptance of
the product- The variation of brown bread volume is much greater than that of
white bread. Bakers will benefit if they could control the variation in brown bread
volume since consumer studies indicate that brown bread sales could surpass that of
white bread in the near future.
The baking industry uses an automated, continuous baking process that is difficult to alter. Variance of flour thus causes variance in bread volume. Flour variance is caused by the availability of suitable wheat cultivars to blend the grist, the
sxtraction rate of the flour, the amount of bran and germ materials inclusionan and the
amount of cake flour divided off. Although millers strive to control variation in
flour quality, they must operate their mills within constraints of profitability and
wheat availability.
Deregulation is only applied to bread and excludes the raw material. Since the total
deregulation of bread, the fixed price structure has been abolished. Bakers can now
use more expensive additives to negate any shortfalls in floUT quality. This could
ensure standard bread quality at a slightly higher price. The problem at this stage is
that very little is known about the factors that cause variable bread volume. In
most cases decreased volumes are attributed to shortfalls in protein quality and
quantity and bran content. Baking quality of brown bread flour deteriorates during storage. The deterioration
is mor pronounced in flour blended with bran before storage. This study centres
around the effects of changing lipid composition during storage on the baking
quality of the flour.
A review of the literature, with respect to the formation of gluten and the lipidprotein
interactions during this process) shows that the various authors have
contradictory opinions. The effects of bran and its contribution to the baking
process led to even more contradictions.
The research approach of this study differed from the approach published in the
literature where the researchers use a specific sample of wheat and then generalise
for wheat in total. fn this study the samples were selected such that variation
between samples are as high as possible. The lipids were extracted as total lipid,
and were not separated into various fractions. This allowed the determination of
the effect of the changed total lipid content on bread volume. The separation of the
different flour samples, that was necessary in the analysis of the results, indicates
that one or more important parameters were absent in the design.
With this approach it was shown that the changes in total lipids are caused by
enzymatic action and that total lipid profIles correlate with bread volumes. It was
however impossible to generalise for all the different samples of flour.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/821
Date January 1991
CreatorsRobberts, Theunis Christoffel
ContributorsVenter, I., Mie, Rautenbach, Fanie, Theunis Co, Benade, Spinnie, Prlipid
PublisherCape Technikon
Source SetsSouth African National ETD Portal
LanguageEnglish
Detected LanguageEnglish
TypeThesis
Rightshttp://creativecommons.org/licenses/by-nc-sa/3.0/za/

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