Pasting properties of different wheat flour-hydrocolloid systems

The effect of several hydrocolloids on the pasting properties and gelling b ehaviour of wheat flour was investigated. The influence of the selected hyd rocolloids (guar gum, pectin, alginate, kappa-carrageenan, xanthan and hydr oxypropylmethylcellulose (HPMC)) on wheat flour was tested by using two dif ferent techniques: amylograph and differential scanning calorimetry (DSC). In order to have a general overview of their effect, hydrocolloids were cho sen from different sources implying a broad diversity of chemical structure s. Differences among hydrocolloid-wheat flour suspensions were more evident from amylographic analysis than from DSC examination. The hydrocolloid add ition largely modified the amylograph parameters of wheat flour-even at the low levels tested [0.5 and 1% (w/w), hour 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% arginate was ad ded, which produced a decrease of ca 3 degrees C. This reduction is really important since it implies an earlier beginning of starch gelatinization an d, in turn, an increase in the availability of starch as enzyme substrate d uring baking period. Xanthan and pectin increased the cooking stability whi le kappa-carrageenan and alginate did not modify it. Setback was augmented by guar gum and HPMC but alginate, xanthan and kappa-carrageenan showed the opposite effect. The bump area related to the formation of amylose-lipid c omplex, was favoured by kappa-carrageenan, alginate and pectin, and slightl y affected by xanthan and HPMC. In summary, each tested hydrocolloid affect ed in a different way the pasting properties of wheat flour. The results ob tained are important for the appropriate use of these hydrocolloids as ingr edients in the bread making process. (C) 1998 Elsevier Science Ltd. All rig hts reserved.