The nutritional composition of agave flowers was determined and the following nutrients
were analysed: moisture (86.62%); energy (226 kJ/100 g); proteins (1.71 g/100 g); fat
(0.46 g/100 g); dietary fibre (2.12 g/100 g); K (207.77 mg/100 g); Mg (53.06 mg/100 g);
Ca (48.33 mg/100 g); P (32.12 mg/100 g); Na (1.27 mg/100 g); Fe (1.03 mg/100 g); Zn
(0.66 mg/100 g); Cu (0.04 mg/100 g); and Mn (0.15 mg/100 g). In contrast to many
vegetables, the flower samples contained sugars in the form of sucrose (0.52 g/100 g),
glucose (0.77 g/100 g), fructose (1.06 g/100 g) and maltose (0.69 g/100 g). The vitamin
C content was 1.03 mg /100 g, but no vitamin A was detected.
When compared to other flower vegetables, the agave flower had the lowest contents
for protein, P, K, Mn, Na, Cu and vitamin C, but the highest value for fat. The agave
flower and artichoke had similar values for energy, moisture and Mg, while the
cauliflower and agave compared well in regard to Ca and Zn contents. Broccoli had
similar contents for protein, fibre, P and Cu. The agave had higher values for energy,
and fat than cauliflower, and higher fat and Ca, Fe, Mg, P and Zn values than broccoli.
Artichokes had lower contents for moisture, fat, Ca and Zn than the agave flowers.
Broccoli and cauliflower were moister than the agaves.
Descriptive sensory analysis was used to investigate how various treatments would
influence the sensory properties of Agave americana flowers. Blanched and
unblanched flowers, subjected to three treatment methods (steaming, stir frying and
pickling), were analyzed by ten trained panelists, in three replications. The data was
analyzed using principle component analysis. A lexicon of 20 attributes was generated,
including 11 for the steamed treatment, an additional six for the stir fried treatment and
another four for the pickled treatment. Of these, three descriptors were for the attribute
aroma, six for mouthfeel, five for appearance, four for taste and one for aftertaste. The
unblanched pickled agave flowers were characterized by crunchy, fibrous and chewy mouthfeel, bitter taste, green pepper colour and cactus appearance, and a cucumber
odour. For the blanched pickled agave flowers, taste descriptors were prominent,
namely sweet, sour and sweet-sour, followed by a sweet aftertaste, combined with a
moist appearance. For all the unblanched flowers, regardless of treatment, some of the
descriptors had negative connections, like fibrous, bitter, cactus and rancid. Descriptors
for the blanched flowers, again regardless of treatment, were more favourable and
included sweet, sour and sweet-sour taste, and green bean and nutty odour.
Three panels of 50 members each participated in the consumer acceptance tests, one
each for the steamed breads and chocolate cakes, and one for the stew and deep fried
flowers. Apart from acceptability, aroma, taste and texture were also evaluated for the
baked products. The breads, cakes and stews were defrosted at 4 ºC overnight. The
breads and cakes were left at room temperature (22ºC) before serving, while the stews
were served heated. The breads, fritters and stews were prepared with blanched
flowers, while the cake was made with unblanched flour. All the products were
acceptable, but in different degrees. The scores were lower for aroma and final
acceptability of the bread, due to unfamiliar texture experienced by the consumer panel.
The agave cake scored lower for aroma and taste, but higher than the bread on texture.
The stews and battered agave fritters were liked by the consumer panels and scored
between 6.92 and 7.26 on the hedonic scale.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufs/oai:etd.uovs.ac.za:etd-08202014-151331 |
| Date | 20 August 2014 |
| Creators | Semuli, Makamohelo |
| Contributors | Prof G Osthoff, Dr C Bothma |
| Publisher | University of the Free State |
| Source Sets | South African National ETD Portal |
| Language | en-uk |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.uovs.ac.za//theses/available/etd-08202014-151331/restricted/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University Free State or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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