Thesis (MTech (Consumer Science: Food and Nutrition))--Cape Peninsula University of Technology, 2011.Includes bibliographical references (leaves 139-156). / Oxidative stress has been implicated in the development of a number of chronic
degenerative diseases. These diseases can often be prevented by dietary and
lifestyle changes. One major dietary aspect is increasing the intake of plant
foods, such as fruit and vegetables as they are rich in the major nutrient and nonnutrient
antioxidants. The South African population does not have an adequate
intake of fruit and vegetables and many barriers have been noted against
increasing the intake of these foods. Other avenues should therefore be sought
to increase the antioxidant intake. One such avenue is to use a basic food item
consumed often as an antioxidant carrier to increase the antioxidant intake.
Much interest has developed in functional foods and their therapeutic effects as
well as the use of nutraceuticals in food product development and food
fortification. Tea and its polyphenols, due to the antioxidant properties, is a
potentially viable option for nutraceutical and functional food use. Rooibos and
honeybush herbal teas, native to South Africa, can be potential nutraceutical
sources to increase antioxidant levels of food due to their unique polyphenol
content.
The objective of the study was to increase the total antioxidant capacity (TAC) of
a basic food item consumed regularly by most South Africans, such as brown
bread through fluid manipulation using rooibos, honeybush and black teas
respectively, as the replacement fluid for water in a standardised bread recipe
formulation. The TAC of these experimental breads were compared to the TAC
of the bread produced with no fluid manipulation (control bread) and a
commercially processed bread (reference bread). The experimental breads were
prepared using 2% weight per volume (w/v) and 5% (w/v) concentration levels for
rooibos, honeybush and black tea respectively. To ascertain the TAC of the
experimental breads, the fluorescein(FL)-based oxygen radical absorbance
capacity (ORACFL) method was used. The hydrophilic (H)-ORACFL assay was
used as the teas contain polyphenols which favour a water environment. The
results indicated that the H-ORACFL of the control bread using water as the fluid
and the commercial reference bread was significantly different (p < 0.05 for each)
to all the experimental bread formulations besides for the 2% (w/v) honeybush
experimental bread formulation. The 2% (w/v) honeybush experimental bread
formulation was therefore not considered for the consumer acceptance testing.
There was no significant difference (p > 0.05) in the H-ORACFL of the 2% (w/v)
rooibos and black tea experimental bread formulations, but the H-ORACFL of the
5% (w/v) black tea experimental bread formulation was significantly (p < 0.05)
higher than that of the 5% (w/v) rooibos experimental bread formulation. This
particular experimental bread formulation had a “golden-orange” colour with a
pungent smell due to the increase in rooibos concentration. The 5% (w/v) black
tea experimental bread formulation, however, had noted negative sensory
attributes of being densely textured with a very dark colour and a pungent and
overpowering taste of black tea. These sensory attributes and TAC results lead
to the rooibos experimental breads containing 5% (w/v) (as bread A) and 2%
(w/v) (as bread B) chosen for the consumer acceptance testing and rooibos
being a proudly South African product.
The participants (n = 85) of the consumer acceptance testing participated
voluntarily and were regular bread consumers. The sample was mostly female
(57.6%), in the age group of 18 to 24 years (54.1%), with an education level of
between three to four years post-matric/-grade 12 (71.7%) and single, living on
their own without children (76.4%). They also represented a sample which had
characteristics of a healthy lifestyle. Most participants perceived themselves as
being of an optimal body weight (55.2%) and the majority was non-smokers
(74.1%), physically active (63.5%), having no family history of chronic disease
(69.4%) and not consuming dietary supplements (70.5%).
Three sensory attributes of the experimental breads were rated for the
acceptance testing and included appearance/colour, flavour/taste and
texture/mouthfeel. Both the experimental bread formulations was accepted
favourably regarding the above-mentioned sensory attributes. The three liking
acceptance categories, ‘neither like nor dislike’ (neutral response), ‘like’ and ‘like
very much’ were the most commonly indicated by the participants which also
resulted in the experimental breads being rated as fair, good and very good
according to the development scores. Although both breads were very similarly
scored, there was a trend for bread A to be rated slightly higher regarding the
above-mentioned sensory attributes. The acceptance category, ‘like’/good was
scored the highest for bread A according to the sensory attributes of
appearance/colour (56.5%), flavour/taste (55.3%) and texture/mouthfeel (50.6%).
There was no significant association/difference (p > 0.05 for each) between the
participants’ demographic characteristics and their overall acceptance of the
experimental breads. Most of the participant biographic characteristics also had
no significant (p > 0.05 for each) impact on the sensory attribute acceptance of
the experimental breads. Although the majority (75%) of the participants
consumed rooibos, there was no significant (p > 0.05) association/difference
between the participants’ tea consumption and their acceptance of the
experimental breads. Although most participants (64%) had no awareness of
functional foods, most indicated willingness to purchase foods with added health
benefits (93%) and to pay more for foods with added health benefits (73%).
These results indicated a general acceptance of bread with functional food
characteristics and the possibility of purchasing such products with added health
benefits and even at a higher price premium.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/769 |
| Date | January 2011 |
| Creators | Septoe, Nina Lee |
| Contributors | Venter, I., Mrs, Marnewick, J., Prof |
| Publisher | Cape Peninsula University of Technology |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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