Semi-sweet biscuit making potential of soft wheat flour patent, middle-cut and clear mill streams made with native and reconstituted flours

Abstract

The influence of patent, middle-cut and clear flour grades as native or reconstituted flour blends on both the rheological properties of the dough and the quality of semi-sweet biscuit (flour/sugar/fat/water ratio of 100/30/8/36) was studied. Moving from the central portion (patent) to the peripheral portion (clear) of the grain endosperm increased the dough hardness from 3.77 to 4.84 N, consistency from 19.3 to 25.5 N s, elongational viscosity from 4.13×10 −5 to 5.54×10 −5 Pa s, half-relaxation time from 0.45 to 0.59 s, but decreased the rate of relaxation from 4.51 to 3.09 s −1 of the biscuit's dough produced with the native flours due to the wide variation in the physico-chemical properties of these fractions. Quantitatively, the fractionation/reconstitution procedure reduced moderately these rheological parameters, and the flour functionality could not be restored completely. Biscuits produced with the patent flour showed the largest length and lowest thickness, whilst the clear fraction led to production of denser biscuits with greater cohesion (mean tearing force) of the biscuit inner structure and also contain more grains or group of grains per unit of penetration (number of spatial ruptures). The biscuits made with the reconstituted flour fractions had almost equivalent dimensional characteristics, and excellent surface appearance, but were also darker in colour than their native flour counterparts. The half-relaxation time (Tla) and the rate of relaxation ( k) obtained from the biscuit's dough relaxation curves were excellent predictors of the biscuit's quality (length, density, structural cohesion and resistance to solicitation). Dough hardness was correlated positively with elongational viscosity, half-relaxation time and consistency and negatively with the rate of relaxation, whilst some of the biscuit's characteristics such as density correlated positively with structural cohesion and resistance to solicitation.