Centre for Grain Food Innovation Pore Structure of Bread Crumb Shuo Wang ARRC Seminar May 18, 2010 :: Perth, WA

Centre for Grain Food Innovation Introduction What is bread? Why research bread? What is bread texture? What has been done in this research? What are the results of this research?

Centre for Grain Food Innovation What is bread? Bread is a staple of life Bread is a baked product Bread is a spongy material with open- and closed- pores (Keetels et al., Journal of Cereal Science, 1996;Mills et al., Trans IChemE, 2003)

Centre for Grain Food Innovation Why research bread? The cereal market’s expanding – worldwide Breads in traditionally non-bread eating Asian markets (new markets) Unacceptable texture and/or shape of breads if made with wheat grown in WA. Significant benefits to Australian industries if WA’s wheat was used in blends for breads and healthy wheats marketed ~20% market penetration is worth $50 million p.a.

Centre for Grain Food Innovation The Conversion of Dough to Bread Bubbles must pre-exist in dough Leaveners do not create new bubbles CO 2 from leaveners migrate into bubbles Dough rises – proofing and heating Starch gelatinizes and cell walls fracture stabilizing expansion with respect to atmospheric pressure No further expansion There could be a mix of open and closed cells in breads, affecting both shape and texture

Centre for Grain Food Innovation What is bread texture? Texture is sensory perceptions attributed to a food product during handling and mastication Goal of the research is to be able to understand and control bread texture

Centre for Grain Food Innovation What is bread texture? 11.5% Protein10.15% Protein

Centre for Grain Food Innovation What is bread texture? Not processedFolded, sheeted Breads made at CGFI lab With commercial baker’s flour

Centre for Grain Food Innovation What has been done in this research? 5 different breads Commercially available popular bread from SE Asia 4 from different flours made at Polytechnic Bakery Training School in WA % protein SE Asia (US) 13.2 Hi Protein (Maximus) Baker's Supreme 11.5 Cake10.15 Hi Ratio9.47

Centre for Grain Food Innovation Experimental Methods Permeability Testing Uniaxial Force Displacement Testing Micro CT Scanning - 1cm x 1cm x 1cm Studied parameters: connectivity, material properties, and microstructure 25mm

Centre for Grain Food Innovation Mechanical tests Intact Cellular solids: Gilbert and Ashby Total collapse Buckles, tears

Centre for Grain Food Innovation Stress-Strain Curves Increasing density / increasing firmness Hi Ratio (3.1 ml/g) Cake (5.5 ml/g) Baker’s (6.2 ml/g) Hi Protein (8.0 ml/g) SE Asia (6.3 ml/g)

Centre for Grain Food Innovation Deriving Yield and Collapse Points Gradual transition between phases Second derivate gives inflection points

Centre for Grain Food Innovation Micro CT Scan Stack of 470 layered slices with maximum resolution of ~5 um, resulting in images of 1000x1000 pixels. Images recombined in Avizo® Earth 6.1 into 3-D replica and analysed for properties on iVEC’s bigVis machine

Centre for Grain Food Innovation Micro CT Scans Baker’s Cakes Hi Protein Hi Ratio SE Asia

Centre for Grain Food Innovation Bread structure and texture Baker’sCake One continuous open cell in both breads. More closed cells in the cakes flour.

Centre for Grain Food Innovation Workflow CT Scan3D ModelStatistical Analysis Volume of the largest interconnected pore space comprises ~99% of total pore space. This means that bread is one large interconnected pore

Centre for Grain Food Innovation What are the results? SE AsiaHi ProteinBaker’sCakeHi Ratio Protein Content of Flour (%) Specific Volume (cm 3 /g) Standard Deviation of Specific Volume Young's Modulus (Pa) Yield Strain Yield Stress (Pa) Collapse Strain Collapse Stress (Pa) Porosity79.75%84.00%72.48%79.00%72.87% Number of Pores Volume of Largest Pore / Total Pore Volume99.95%99.97%99.66%99.70%98.59% Average Closed Pore Volume (mm 3 * )

Centre for Grain Food Innovation Open Pore Movie

Centre for Grain Food Innovation Closed Pores Movies CakeBaker’s

Centre for Grain Food Innovation Visualization of Closed Pores SE AsiaHi ProteinBaker’s CakeHi Ratio Real Cake ~ mm 3 (blue), (red), (green), (yellow), 0.1+ (teal)

Centre for Grain Food Innovation Summary of Current Research 1.Bread crumb is a maze in 3-D; one big, inter-connected, open cell. 2.Distribution of pores is a driver for texture 3.Localized clusters of closed cells leads to crumbliness 4.Protein is not proving to be the absolute driver for texture Now what?

Centre for Grain Food Innovation Why Digital Modelling? Limited Resources – Time/Materials Control of bubble distribution Less variability in sample material Digital rock model already established (Fusseis et al., Nature, 2009)

Centre for Grain Food Innovation Digital Rock Model Greyscale images Binary images Label materials Build the 3D micro-structure

Centre for Grain Food Innovation Finite Element Modelling Digital sample has consistent parameter (porosity, permeability, anisotropy, cell wall strength) distribution just like real bread Each element has embedded parameters Successful completion means a full understanding of texture as a function of input variables and input distribution

Centre for Grain Food Innovation Ph.D. Goals Develop digital bread Validate texture through Finite Element simulations Track conversion of bubbles in dough to bubbles in bread.

Centre for Grain Food Innovation Thank you for attending! Questions?