Rheology of Rice Flour Dough with Gum Arabic: Small and Large-Deformation Studies, Sensory Assessment and Modeling.

The absence of gluten protein makes the rice flour doughs difficult to handle when flattened/sheeted products are to be prepared. The rheological, sensory and microstructural changes in rice flour doughs having gum Arabic (0% to 5%, w/w) and moisture contents (44% to 50%) were studied for improving the dough handling characteristics. Rheological parameters like storage modulus (G') and complex viscosity (η*) decreased with an increase in moisture content while loss angle (δ) increased. A power-law type equation was suitable to relate angular frequency (ω) with G', G", and η* (0.814 ≤ r ≤ 0.999, P ≤ 0.01). An increase in gum and moisture contents increased δ from 6.9° to 15.5° but decreased the energy required for compression/flattening. The 6-element spring-dashpot model was suitable (r ≥ 0.991, P ≤ 0.01) for creep curves. The sensory panel had the opinion that dough with a low to moderate hardness between 3 and 4, and stickiness of ≤ 3.5 was suitable for the purpose of flattening in relation to the preparation of sheeted/flattened products; the appropriate condition for dough formulation was with the moisture and gum contents of 47.0% to 47.9% and 1.55% to 2.25%, respectively to offer the desirability index between 0.50 and 0.52. The microstructure of the rice flour dough in the absence of gum Arabic appeared to possess loosely bound flour particles. The presence of gum provided a coating on flour particles to yield dough having good cohesive microstructure.

Shanthilal J ，Bhattacharya S 《-》

Gluten-free biscuits based on composite rice-chickpea flour and xanthan gum.

Benkadri S ，Salvador A ，Zidoune MN ，Sanz T ... -  《-》

Effects of whey and soy protein addition on bread rheological property of wheat flour.

The development of wheat-based foods that are enriched with proteins is increasingly popular due to consumer demand regarding food nutritional content and quality. This study was performed to compare the effect of whey and soy protein on the rheological properties of wheat dough and bread-making quality in a relatively wide range of protein addition (0-30%). We found that the incorporation of whey protein (WP) decreased dough stability time (MST), minimum torque (MMT), G' and G″, but increased dough peak torque (MPT), stickiness, G' and G″ in temperature sweep. With the increasing level of WP from 0 to 30%, the specific volume of bread initially decreased from 2.61 to 2.22 cm3 /g, then increased to 3.08 cm3 /g when WP was at higher concentration than gluten. However, the crumb hardness increased from 173 to 1291 g at the same time. As a contrast, the addition of soy protein (SP) increased dough MST, MMT, G' and G″, but decreased MPT, stickiness, G' and G″ in temperature sweep. With the increasing level of SP from 0 to 30%, the specific volume of bread decreased from 2.61 to 1.31 cm3 /g and the hardness first decreased from 173 to 152 g, then increased to 696 g. The results suggested that selection of the protein source and amount with appropriate functionalities played an important role in certain applications for protein fortified bakery products. Since it is known that the gluten network is responsible for viscoelastic properties in wheat dough and for dough structure strength and gas retention, most studies reported that enrichment of foreign proteins interfered with gluten development and therefore, had negative effects on bread quality. This study compared the effects of whey and soy proteins on the thermomechanical, dynamic rheological and microstructural properties of wheat dough and bread-making quality in a relatively wide range of protein addition (0-30%). The results suggested that selection of the protein source and amount with appropriate functionalities significantly affected the structure of the dough and quality of the bread. Our study is essential for product development and process control when considering the popularity of protein fortified bakery products.

Zhou J ，Liu J ，Tang X 《-》

Time-Independent and Time-Dependent Rheological Characterization of Dispersions with Varying Contents of Chickpea Flour and Gum Arabic Employing the Multiple Loop Experiments.

The chickpea (Cicer arietinum) flour dispersions as the model system with different contents of flour (37% to 43%) and gum arabic (0% to 5%) were subjected to multiple loop experiments for simultaneous determination of the time-independent and time-dependent rheological characteristics. The Herschel-Bulkley model was suitable (0.993 ≤ r ≤ 0.999) to relate the time-independent characteristics linking shear stress and shear rate data for the individual upward and downward curves. The yield stress, consistency index, and apparent viscosity increased with the increasing flour and/or gum contents while flow behavior index (n) decreased. The yield stress generally decreased with the number of loops but n increased. In the individual loop tests, the n values for the decreasing shear stress/shear rate curves were always higher than corresponding increasing curves meaning a shift toward Newtonian characteristics. The time-independent properties (yield stress, apparent viscosity, consistency index, and n), the time-dependent characteristics like the area of the loop, and liquid characteristics like pourability and the nonoral sensory attributes (viscosity, spreadability, and tackiness) were individually predicted by artificial neural networks wherein the root mean square errors were between 3.6% and 17.2%. The sensory assessment indicated that the desirable parameters for a free-flowing and easily pourable spherical chickpea batter droplets occurred when the average pourability and spreadability values were 6.9 and 5.9, respectively. The normalized indices for these 2 parameters indicated that the batter having 40% flour and 2% gum contents was most suitable exhibiting a deviation of only 10% from the ideal sensory scores; these values were 40% and 0% to 3%, and 43% and 0%, respectively exhibiting up to 20% deviation.

J S ，Bhattacharya S 《-》

Effect of inulin on rheological, textural, and structural properties of brown wheat flour dough and in vitro digestibility of developed Arabic bread.

The brown wheat flour (BWF)-based Arabic bread was fortified with chicory-derived inulin. The objective of this work was to assess the influence of the inulin concentration (1.25 to 5%) on the rheological, textural properties, and fermentation efficacy of enriched BWF dough. Farinographic measurement established that only 3.75% BWF can be substituted by inulin in a dough formulation, which resulted in lowering the water absorption capacity. The peak gelatinization temperature, Tp detected at 74.4 °C by rheometric measurement, which increased linearly with increasing the inulin concentration. The elastic modulus (G'), however, differed significantly among doughs with the addition of inulin. The dough hardness and compressibility increased as a function of inulin concentration. TPA measurement indicated that the Arabic bread fortified with 3.75% inulin was the best in texture. The addition of inulin improved the volume of CO2 generation in the yeasted dough. The distribution of starch particles on the top layer of bread surface was visualized through SEM. In-vitro digestion and steady-flow measurement of the BWF/inulin bread digesta exhibited a slow digestion and an increment in the apparent viscosity against the control bread, which further confirmed potential health benefits of the developed Arabic bread. PRACTICAL APPLICATION: Arabic bread is a staple food in many Asian countries, and an incorporation of soluble fiber, like inulin, definitely improves its health benefits. This work optimized a formulation based on BWF and inulin with technical feasibility. Rheological and textural studies demonstrated that blend bread could be made by replacing 3.75% BWF by inulin with significantly lower water content. Inulin has replaced the sugar in the yeasted dough, and carried out the bread fermentation adequately.

Ahmed J ，Thomas L ，Khashawi RA 《-》