Frying of rice flour dough strands containing gum Arabic: texture, sensory attributes and microstructure of products.

The effects of rice flour (50-56%, w/w) and gum Arabic (0-5%, w/w) on the physical, sensory and structural features of the fried dough strands were investigated. Up to 25.8% reduction in oil was possible by the incorporation of gum Arabic. The wide variations in failure force (13.8-25.3 N) and failure strain (11.0-28.6%) indicated the formation of snacks varying in texture from a soft-to-bite brittle product to a hard-to-eat less brittle sample. The snacks possessed a porous microstructure with air cells, pores and vacuoles; the cell walls were more than 100 µm in thickness. The textural parameters like failure force, failure energy and failure stress behaved in a similar manner in the principal component analysis biplot. High moisture content in the dough decreased the sensory acceptance of the fried snacks. The high desirability index of 0.9 could be achieved with a high level of rice flour (56%, w/w) while gum Arabic content was between 3.50 and 3.75% (w/w).

Characterisation of time-independent and time-dependent rheological behaviour simultaneously by multiple loop experimentation.

Flowable food materials express complex flow behaviour and are conventionally subjected to individual time-independent and time-dependent experiments. The present study proposes a single experiment to determine both these characteristics simultaneously in addition to determining the 'isoviscosity' to quantify and compare these properties by using a model food system like chickpea flour dispersion. The method employed here consists of the generation of five loops having increasing and decreasing shear-rates along with yield stress measurement in between them. The conventional rheological model like Herschel-Bulkley equation has been employed to determine the rheological properties that are affected as the number of loop increases. Though used in a model food system, the method is also expected to find applications in non-food non-Newtonian liquid systems for convenience.

Frying of the Dispersion Droplets with Varying Contents of Chickpea Flour and Gum Arabic: Product Characterization and Modeling.

Dispersions having chickpea (37%, 40%, and 43%, w/w) and gum arabic (0%, 1%, 2%, 3%, 4%, and 5%, w/w) solids were prepared. These dispersion droplets were fried, and the physical, sensory, and microstructural characteristics of the fried products were determined. The oil content in the fried snack decreased up to 20.3% when the level of chickpea and/or gum in the dispersions was increased. The compression curve for fried snack showed 5 major zones and exhibited the failure phenomenon. Failure force (6.5 to 11.4 N) increased with chickpea flour in the dispersions. Fracture strain (12.0% to 19.5%) indicated that all the fried samples were soft-crisp products. An increase in chickpea flour concentration offered an ovoid/oblong shape of dispersion droplets while falling to oil, and changed the spherical shape of the fried snack. The near-spherical product could be obtained by using 37% chickpea flour containing 0 to 2% of gum arabic, or with the 40% and 0 to 1% combinations. The hue or dominant wavelength increased from 578.5 nm (flour) to 581.0 to 582.7 nm (product) indicating a shift toward red coloration. A porous microstructure with scattered small cavities and large vacuoles of the fried snack were observed; big vacuoles were located in the inner portion of the fried product. The cells were divided into closed and open cells and were characterized by image analysis. The air cells usually had an elliptical shape with varying sizes; the cell wall thickness was between 12 and 80 µm. An artificial neural network (ANN) structure of 2-9-2 was developed for the prediction of sensory overall acceptability and oil content of the fried snack. PRACTICAL APPLICATION: Chickpea flour is used in several food preparations. The addition of gum arabic affects the textural and structural characteristics, and the sensory acceptance; the fried dispersion droplets have a lower fat content when gum arabic is used compared to samples fried without the addition of gum arabic. The fried dispersion droplets change their shape with the level of the ingredients used in the dispersion.

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.