Prediction of the sensory texture of a thick yam paste (Amala) using instrumental and physicochemical parameters

Abstract

Amala is a traditional thick paste consumed in West Africa (Nigeria, Bénin, Togo). It is prepared from blanched dried yam flour and has a particular texture. The texture attributes of amala pastes obtained from market and prepared in laboratory were sensorily evaluated. Both compression and extrusion tests were done from which maxima force and slope were calculated. The physical (particle size), starch characteristics and functional properties (solubility, swelling power [Sp], viscosity) of yam flours were also determined to establish a predictive model for amala sensory texture attributes. The main amala sensory attributes were stickiness, firmness and smoothness. Stickiness and firmness could be assessed by uniaxial extrusion test: These attributes were highly correlated with the maximum extrusion slope (r = -0.60 and r = 0.53, respectively). Stickiness was associated with yam flour Sp, which in turn was related to gelatinization temperature and enthalpy changes. In addition, soluble matter and soluble amylose were found to be indicators of amala sensory stickiness. No clear relationships were observed between sensory firmness and yam flour physicochemical characteristics or functional properties