UNDERSTANDING THE MIXING DYNAMICS AND STRUCTURAL FUNCTIONALITY OF GLUTEN SUBUNITS TAGGED WITH QUANTUM DOTS IN WHEAT DOUGH AND ANALYZED BY QUANTITATIVE IMAGING TECHNIQUES
thesisposted on 06.03.2020 by Jose Carlos Bonilla Oliva
In order to distinguish essays and pre-prints from academic theses, we have a separate category. These are often much longer text based documents than a paper.
Gluten is a group of wheat proteins with viscoelastic properties not seen in any other material on earth, these properties are given by its subunits, gliadins (more viscous) and glutenins (more elastic). The differences in these viscoelastic properties in gluten from different types of wheat flours make a wide variety of wheat products available worldwide, placing wheat products among the most consumed staple foods in the human diet. The objective of this research is to gain new insights about the structural functionality of the gluten subunits, low molecular weight (LMW) glutenins, high molecular weight (HMW) glutenins, and gliadins in wheat dough. To this end, a new staining procedure using antibodies conjugated with fluorescent quantum dots has been developed in order to visualize each gluten subunits individually; a new microscopy procedure with Confocal Laser Scanning Microscopy has also been developed. The fluorescent images have been processed with a protein network analysis software and with a co-localization technique. The use of these two quantitative imaging techniques has helped us move from a qualitative description of the images to quantitative and comparable data collected from the confocal microscopy images. These two techniques provide information about the structural integrity of the network from each gluten subunit, and information about the interactions of the different gluten subunits. It was shown how the three gluten protein subunits interact closely together at the time of dough maximum strength during mixing. As mixing continues, LMW glutenins separate from three-gluten subunits network first, being responsible for the initial decay in dough strength; HMW glutenins agglomerates later in the mixing, being more responsible for the long-term decay in dough strength. It was also shown that the HMW glutenins do not re-distribute themselves when the dough shows high resistance to mixing, and that the three gluten subunits disrupt similarly when the dough has low resistance to mixing. Lastly, the important role of LMW glutenins in keeping the structural integrity of semolina doughs was proven by a direct correlation of the elastic rheological component of the dough and protein network parameters of LMW glutenins. This was proven further when it was shown that gliadins and HMW glutenins stick together during different rheological deformations of the dough. The applications of the fundamental knowledge from this work can be applied by wheat breeders and food product developers to increase the variety of products made for wheat and/or improve the quality of current wheat products.