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Physical
properties of Tylosemia esculentum and the effect of
roasting on the functional properties of its flour
V. A. Jideani, J. Van Wyk and M. H. Cruywagen
Department of Food Technology, Cape Peninsula
University of Technology, P.O. Box 652, Cape Town 8000,
South Africa
*Corresponding
author. E-mail:
JideaniV@cput.ac.za.
Accepted 7 September, 2009 |
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The physical properties of two varieties of morama
beans and the effect of roasting on the functional
properties of their flours were studied. Majority (65, 92.5,
79%) of the seeds has medium dimensions (17.0 - 19.99, 14.0
- 19.99, 12.0 - 14.99 mm) of length, width and thickness
respectively. The size of the morama bean (MB) follows a
normal distribution, being much heavier than most other oil
seeds and legumes with 1000-seed weight of 2.2 - 2.3 kg.
Significantly higher angle of repose was observed for the
cement surface (9.76o). MB sphericity
(85.7-86.8%) and aspect ratio (91.9 - 92.5%) indicates that
the bean will roll rather than slide. Morama flour (MF) is
rich in protein (31.7 - 33.1%), fat (36.4 - 39.0%) and ash
(2.9%). Roasting significantly increased the protein and
ash. Roasting increased the water absorption capacity of MF
significantly (P < 0.05) (211% increase). Roasting
significantly increased the oil absorption capacity (112%
increases). Emulsifying activity ranged from 37.90 - 38.20%
respectively for light- and dark-brown morama flour.
Emulsion stability ranged from 70.62% (light brown) to
72.18% (dark brown). The colour of unroasted MF is light
yellow (L = 82.71, Hue angle = 88.05, Chroma = 26.21),
turning darker and less saturated on roasting.
Key words:
Morama bean, physical properties, functional properties,
lightness, hue, chroma. |
