Probing the distribution of gliadin proteins in dough and baked bread samples using conjugated quantum dots as a labeling tool

Ansari, Shadi

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https://hdl.handle.net/2142/46838 Copy

Description

Title

Probing the distribution of gliadin proteins in dough and baked bread samples using conjugated quantum dots as a labeling tool

Author(s)

Ansari, Shadi

Issue Date

2014-01-16T18:17:55Z

Director of Research (if dissertation) or Advisor (if thesis)

Kokini, Jozef L.

Department of Study

Food Science & Human Nutrition

Discipline

Food Science & Human Nutrition

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Gliadin
• Quantum Dots (QDs)
• Antibody Conjugation and Confocal Laser Scanning Microscopy (CLSM)

Abstract

Quantum dots (QDs) technology is commonly used in medical application as a probe for diagnostic procedures via imaging macroscopic and microscopic structures in life sciences. Also they can be used for designing of biosensors. However, the application of this technology is very new in food science . In this study, a novel application of QDs in food science was investigated. QDs were conjugated to gliadin antibody and used as a fluorescent probe to track gliadin protein in dough and baked bread samples. The type and quantity of gluten proteins and their subfractions, gliadins and glutenins, are critical for baked product functionality. Gliadin proteins are also able to activate coeliac disease which causes severe damages to the digestive system. Therefore, it is important to understand how gliadins are distributed in dough and the effect of baking conditions on distribution of gliadin in baked bread. QDs conjugated gliadin antibody was specifically bound to gliadin to determine its distribution in three different samples prepared at various heating times. Dough, bread baked at 5 minutes and at 9 minutes were evaluated. Three different layers (i.e. top, center and bottom) were investigated. Top layer in baked breads means the layer which is far from the direct heat then center layer and closet layer to heat is bottom layer of baked breads. The conjugation process was through covalent linkage in presence of SMCC (Succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylat) cross linker. Confocal laser scanning microscopy (CLSM) was used to image QDs conjugated with gliadin antibodies. The mean intensity of gliadin attached to quantum dots for each sample was calculated and plotted. CLSM images showed significant changes in the distribution of gliadin with baking time compared wheat flour dough. Bread baked at 9 minutes shows the highest amount of fluorescent intensity from gliadin bound quantum dots in the top layer which is not in contact with the direct heat. Similar observation was made for bread baked at 5 minutes and both contained more gliadin than dough sample. However, the amount of gliadin in dough is more than that of bottom layers which receive more heat in both baked bread samples. Analysis of variance (ANOVA) was conducted to compare the mean fluorescence intensity of QDs bound to gliadin in different samples and sections. The ANOVA analysis of the overall data with probability of 99% (α=0.01) and 95% (α=0.05) indicated that the mean intensity value of gliadin changes was statistically significant.

Graduation Semester

2013-12

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http://hdl.handle.net/2142/46838

Copyright and License Information

Copyright 2013 Shadi Ansari

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