Effect of extrusion cooking on some quality attributes of full-fat soy flour and soy protein concentrate from locally grown Soybean (Glycine Max L.) varieties
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Date
2009-01
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Addis Ababa University
Abstract
Soybean (Glycine max L.) varieties, Clark 63K and SCS1 were obtained from Jimma
Agricultural Research Center. Their seed color and shape, seed density; hundred seed mass,
hydration and swelling capacities, hydration and swelling indices, hydration and swelling
coefficients were studied according to the standard procedures. The seeds were processed and
converted into full fat soy flour (FFSF) and soy protein concentrate (FF-SPC) to study the effect
of extrusion. The flours and concentrates from each variety were extruded at a barrel temperature
of 140 0C, screw speed of 120rpm, and feed moisture of 30%. The effect on extrudates expansion
ratio, specific length, proximate composition, flour and extrudate bulk density (BD), water
absorption index (WAI), water solubility index (WSI), oil absorption capacity (OAC), emulsion
activity (EA) and stability (ES), foaming capacity (FC) and stability (FS) was studied in
triplicate samples. The result of the seed analysis of both varieties showed no statistical
significant difference except in swelling coefficient. The bulk density of FFSF is significantly
higher than that of FF-SPC flour, while FFSF extrudates have lower bulk density than that of the
unprocessed flour. WAI of FF-SPC flour and extrudates of both varieties were found to be
significantly higher than that of FFSF. WSI of FFSF flour and extrudates of both varieties are
significantly higher than that of FF-SPC flour and extrudates. The OAC of FF-SPC flour is
significantly higher than that of FFSF in both varieties, while that of the extrudates is
significantly lower than that of their corresponding flours. EA and ES of extrudates of clark 63K
and SCS1showed significantly higher values than the corresponding unprocessed flours. In
general, the EA of SCS1 products are lower than that of Clark 63K, and the ES of Clark 63K and
SCS1 is closer. The FC of FFSF is significantly higher than that of all products of both varieties.
The FS of FFSF has been significantly higher than that of FF-SPC while the extrudates of SCS1
showed higher values of FS than that of Clark 63K. Generally, the present study showed that
both varieties are suitable for extrusion cooking, with SCS1 slightly better performance. Based
on the outcome of the study, the technology for developing an extruded product of soybean
varieties has been suggested.
Key words: Concentrate; extrusion cooking; flour; soybean
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Keywords
Concentrate, Extrusion Cooking, Flour, Soybean