Breadmaking Case Study

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Chapter 8 Conclusions and future work 8.1. Conclusions A detailed experimental study has been carried out on the influence of wheat bran addition on the volume and structural development during the different stages of breadmaking, by considering it as a series of aeration or foaming stages. Bread dough was considered as viscoelastic foam which increases in volume due to the growth of CO2 bubbles enclosed in it. The investigation was focused to unleash the consequences of bran addition on the bubble dynamics and temperature-induced state transitions during the foam-developmental (mixing, fermentation and proving) and foam-setting (baking) stages, respectively. 8.1.1. Bubble growth during breadmaking process The evolution in bubble…show more content…
Bran was added at 5%, 10% and 15% as replacement to the wheat flour in the bread dough formulation. Bran addition had an adverse effect on the increase in bubble size which increased with the bran concentration in bread dough. The reduced mean bubble size resulted in a consequent decrease in the volume development during the mixing, fermentation and proofing stages. This was found to be due to the retardation of coalescence-mediated bubble growth in the presence of bran particles, as evident from the hindered coarsening of bubble size distribution, reduced connectivity between bubbles and undistorted bubble shape with increase in time, until proving. Further, the bubble growth showed an inverse relationship with dough overpressure (measured by biaxial extension), elastic modulus, complex viscosity and strain hardening index (determined from oscillatory rheometry) and surface tension of dough liquor (calculated using sessile drop method using a goniometer). The above experimental observations were collated to devise a customized empirical model for the calculation of bubble coalescence frequency (Cf) in bread dough, which consider both the rheological and surface tension properties that govern bubble growth in bread dough. This is the key deliverable from this study as the coalescence…show more content…
The above was apparent from the experimental results. In addition, the finer bran particles owing to their reduced size might have penetrated the thin liquid film that exists between two bubbles, adsorb to the bubble surface and eventually promote their coalescence. This hypothesis is put forth by the present study based on the possibility that has been proven in a study on bubble column reactors which also involves the event of coalescence. The study stated that non-porous hydrophobic particles promote bubble coalescence by exhibiting attractive forces while approaching a gas-liquid interface (Omota, 2005). The same might have occurred in the bread dough system, as the finer bran particles demonstrated a lower zeta potential (highly negative surface charge) when compared to the coarser bran fractions. The negative surface charge may be attributed to the opening up of bran layers and the resultant structural modifications of particle surface during the milling operation. Zeta potential of particles below a certain negative value has been known to promote aggregation due to enhanced attractive forces (Greenwood and Kendall 1999; Hanaor et al., 2012). Thus in this study, the finer bran particles might have adsorbed to the

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