THE EFFECTS OF LOW-MOLECULAR-WEIGHT ADDITIVES ON THE VISCOSITIES OF CASSAVA STARCH

The influence of a range of additives on the change in the viscosity o f cassava starch pastes on ageing following gelatinisation has been in vestigated. The inclusion of sulfite with pasted starch markedly decre ases the viscosity of the paste with time and this is prevented by the addition of propyl gallate. Intrinsic viscosity measurements strongly support the view that sulfite addition promotes polysaccharide degrad ation. Ascorbate has a greater degradative effect than sulfite, wherea s only limited degradation is observed with glutathione. Salts such as sodium chloride and sodium sulfate show no effect on viscosity. If th e chelating agent EDTA is added as well as sulfite, the reduction in v iscosity is smaller, although the effect is not cancelled out complete ly. Interestingly, the degradative effect of sulfite and ascorbate can be shown at 30, 60 and 80 degrees C. The results presented uphold the previous suggestion that sulfite addition promotes oxidative reductiv e depolymerisation (ORD) and largely rule out any residual enzyme acti vity as the cause. It is suggested that the strong degradative action of ascorbate on starch could be one of the explanations for its action in baked products. (C) 1997 Published by Elsevier Science Ltd. All ri ghts reserved.