Effect of processing methods on the chemical composition and rheological properties of cassava from four new varieties

Abstract

Cassava (Manihot esculenta) features prominently in the diets of most West Africans. Traditionally, cassava roots are processed by a variety of methods into many different food products. One of the more recent uses of cassava is to produce flour for baking. There is therefore the need to study the effects of varying processing methods on the chemical composition of cassava have been reported. there is still the need for more studies on cassava flour production. This study investigated the effects of different flour processing methods on the chemical composition and rheological properties of cassava varieties in order to determine their suitability for various food uses. Three processing methods (grating, slicing and reconstitution of the starch and fiber) were used to obtain the cassava flours from four cassava varieties. The Flour samples were analyzed for proximate composition, starch, reducing and non-reducing sugars. free cyanide as HCN, non-glucosidic cyanogcns and total cyanogens. Pasting characteristics of the flours were determined using the Brabender viscoamylograph, Both the variety and the method of flour production significantly affected flour chemical composition. The protein. ash, sugar and fibre contents were lowest in reconstituted flours (RCF) though the starch content of RCF was highest. Cyanogen levels in the flours were also significantly affected by processing methods. Reconstituted flours had lowest cyanogenic potential. The total cyanogens ranged from 0.083 for RCF to 1.838 mg CN equiv/Kg. for flours produced by slicing. Slicing produced flours with the lowest peak paste viscosities (298BU to 456BU) whilst that for RCF were highest (714BU to 9.14BU). All other rheological indices were also lowest for flours from the method of slicing. The reconstitution method significantly reduced the total cyanogens of the flours but resulted in flours with higher viscosities. The viscosities of grated cassava flours were however more suitable for baking