Pasting properties of different wheat flour-hydrocolloid systems

The effect of several hydrocolloids on the pasting properties and gelling behaviour of wheat flour was investigated. The influence of the selected hydrocolloids (guar gum, pectin, alginate, κ-carrageenan, xanthan and hydroxypropylmethylcellulose (HPMC)) on wheat flour was tested by using two different techniques: amylograph and differential scanning calorimetry (DSC). In order to have a general overview of their effect, hydrocolloids were chosen from different sources implying a broad diversity of chemical structures. Differences among hydrocolloid-wheat flour suspensions were more evident from amylographic analysis than from DSC examination. The hydrocolloid addition largely modified the amylograph parameters of wheat flour - even at the low levels tested [0.5 and 1% (w/w), flour basis], and the extent of their effect depended upon the chemical structure of the added hydrocolloid. The greatest effect on pasting temperature was observed when 1% alginate was added, which produced a decrease of ca 3°C. This reduction is really important since it implies an earlier beginning of starch gelatinization and, in turn, an increase in the availability of starch as enzyme substrate during baking period. Xanthan and pectin increased the cooking stability while κ-carrageenan and alginate did not modify it. Setback was augmented by guar gum and HPMC but alginate, xanthan and κ-carrageenan showed the opposite effect. The bump area related to the formation of amylose-lipid complex, was favoured by κ-carrageenan, alginate and pectin, and slightly affected by xanthan and HPMC. In summary, each tested hydrocolloid affected in a different way the pasting properties of wheat flour. The results obtained are important for the appropriate use of these hydrocolloids as ingredients in the bread making process.

The authors gratefully acknowledge the financial support of the Comisión Interministerial de Ciencia y Tecnología (CICYT) and Consejo Superior de Investigaciones Científicas (CSIC). J.A.R would like to thank the predoctoral grant from Consejo Nacional de Ciencia y Tecnología (Mexico).