Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Food Engineering, Turkey
Approval Date: 2014
Thesis Language: English
Student: Oğuz Kaan Öztürk
Supervisor: BEHİÇ MERT
Abstract:The main objective of this study was to investigate the potential use of microfluidization as a milling process for corn zein, and its effects on emulsifying properties of zein emulsions, and on rheological and textural properties of gluten-free bread formulations. Also, the effects of microfluidization were tried to improved with alkaline treatment. In the first part of the study, microstructural properties of zein slurries were evaluated by SEM analysis. In the second part of the study, rheological properties of zein emulsions and their stabilities were determined. Herschel-Bulkley model was found to explain the flow behaviors of zein emulsions. Also, emulsions were examined in terms of their viscoelastic properties, and the highest elastic (G') and viscous (G'') moduli values were obtained for emulsions containing 50% oil and 15% zein concentrations. The stability of the emulsions were measured, and emulsion containing 10% of zein concentration and 30% of oil concentration (10:30:60) gave the best result in terms of emulsion stability according to our study. Lastly, the rheological properties of different gluten-free dough formulations were investigated. For this purpose, the effects of microfluidized corn zein and different hydrocolloids at different pH values on the rheological properties of bread dough and the final quality parameters (texture, specific volume, color and storage) of gluten-free bread samples were measured. In dough rheology experiments, firstly, the linear viscoelastic region was determined as approximately a strain of lower than 0.3% for all formulations. Then, the viscoelastic behavior of dough in viscoelastic region was examined, and the highest moduli values were obtained from samples with hpmc, containing 80g starch content and treated by microfluidization. In the end, the effects of different formulations and storage time on staling were studied, and texture profile of the bread samples were measured. Volume of the bread samples were improved especially with the addition of hpmc and guar.