TECHNOLOGICAL-SCALE DEHULLING PROCESS TO IMPROVE THE NUTRITIONAL-VALUE OF FABA BEANS

A technological process for dehulling faba beans to improve the nutrit ional value for pigs was studied. The process consisted of three stage s: the beans were first broken, then sifted, and finally air classifie d. The best dehulling results were achieved when the beans were broken in a roller mill at two different roller distances, 3.0 mm for the wh ole beans and 2.0 mm for the broken beans which were not sufficiently broken. Drying the beans proved to be unnecessary as the dehulling eff iciency was not improved by drying. When the non-dried beans were only broken and sifted, almost 100% of the cotyledons remained and 34-55% of the hulls could be removed by this treatment. Introduction of a cla ssification step, air velocity of 4.4 or 5.6 m s-1, resulted in the re moval of 86-93% of the hulls whereas cotyledon recovery was still as h igh as 94-98%. At a higher air velocity (6.7 m s-1) the yield was sign ificantly lowered. Dehulling of the beans significantly improved the n utritional value. Removal of the hulls decreased the condensed tannin content from 0.57 to 0.06% and the crude fibre content from 8.0 to 1.3 %. Furthermore dehulling increased the crude protein content from 29.2 to 33.2% and the N-free extract content from 56.7 to 59.4%. As a resu lt the in vitro digestibility of crude protein for pigs increased from 92 to 96% and of organic matter from 86 to 99%.