Structural changes in batter coating systems during deep-fat frying

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Most foods are coated with batter before frying. Batter coatings provide opportunities to design fried products with unique sensory and textural attributes. They significantly modify heat and mass transfer characteristics during frying. The increasing emphasis on quality of fried foods have continued to present new challenges that will require fundamental science and engineering knowledge to address adequately. Progress in the past years indicate that batter formulation (flour, ingredients, etc.), its transformation (protein denaturation, gelatinization, etc.) as well as its structure (density, porosity, pore size distribution, microstructure, etc) may be among the key elements in understanding batter coating functionalities. The objectives of the proposed research program include investigating the influence of flour types and ingredients on fat absorption and texture of fried batter systems; and studying the development of starch granule gelatinization, protein network formation and porous structure in fried batters and batter coated products. Textural characteristics will be measured using the Universal Instron Testing Machine and fractal analysis. The Confocal Scanning Laser Microscopy (CSLM) technique coupled with image analysis will be used to examine fat distributions as well as water, starch and protein changes in the fried products. Structure of battered products will be studied from 3 fronts namely porosimetry, CSLM and x-ray micro-computed tomographic (MCT) methods. Protocol for obtaining quantitative data on pores and pore size distributions, previously developed in our laboratory, will be extended for batters. Appropriate protocols will be developed for the CSLM and x-ray tomography studies with combined image analysis. The x-ray MCT is a particularly novel method for reconstructing 3-D visualization of pores in the fried products. The 3 techniques will be combined to obtain a comprehensive analysis of porous structure development in the fried products. A 3-D pore network model will be developed and used to interpret texture and fat absorption characteristics. The project will actively engage graduate students and a research associate. It will provide excellent opportunities for training food engineering personnel.