Emprego do método número de queda fúngico na determinação da atividade de alfa-amilase em farinha de trigo

Abstract

Summary The quantity of fungal alpha-amylase used in wheat flour must be controlled since an excess negatively affects the baking process. Since the classical falling number method does not quantify fungal alpha-amylase, a method must be used that does determine the amount present. The aim of this work was to study the fungal falling number method in the determination of the amylolytic activity of wheat flour, and to evaluate its influence on the functional properties of the loaves. Four wheat flour samples were characterized with respect to their moisture, crude protein and damaged starch contents, and also alveography and falling number. Concentrations of 0, 0.028, 0.056 and 0.084 g.kg –1 of fungal alpha-amylase in the treatments were evaluated, determining the falling number and carrying out baking tests. The results were analyzed by the analysis of variance and the comparison of means by Tukey’s test at the 5% level of significance. The flour characterization results showed that the values for dough deformation energy (W) correlated with the percentage of damaged starch, and there was no relationship between W and the percentage of crude protein. The amylolytic activity proportionally reduced the amount of fungal alpha-amylase added. This method is appropriate to predict the total amount of amylolitc enzymes present in wheat flour, producing better loaf volume yields and crust colours when fungal alpha-amylase concentrations of 0.056 and 0.084 g.kg – ¹ were used.