Structural changes in batter coating systems during deep-fat frying

大多数食物在油炸前都涂上一层面糊。面糊涂层为设计具有独特感官和质地属性的油炸产品提供了机会。它们显著地改变了油炸过程中的传热和传质特性。对油炸食品质量的日益重视不断提出新的挑战，需要基础科学和工程知识来充分解决。近年来的研究进展表明，面糊的配方（面粉、配料等）、转化（蛋白质变性、糊化等）以及结构（密度、孔隙率、孔径分布、微观结构等）可能是理解面糊涂层功能的关键因素。该研究计划的目标包括调查面粉种类和成分对油炸面糊系统脂肪吸收和质地的影响；研究了油炸面糊和面糊包覆制品中淀粉颗粒糊化、蛋白质网络形成和多孔结构的发展。纹理特性将使用通用Instron试验机和分形分析来测量。将使用共聚焦扫描激光显微镜（CSLM）技术结合图像分析来检查油炸产品中的脂肪分布以及水、淀粉和蛋白质的变化。将从孔隙度法、CSLM和x射线微计算机层析成像（MCT） 3个方面研究破碎产品的结构。先前在我们实验室开发的获得孔隙和孔径分布定量数据的协议将扩展到电池。将为CSLM和结合图像分析的x射线断层扫描研究制定适当的方案。x射线MCT是一种特别新颖的方法，用于重建油炸产品中孔隙的三维可视化。这三种技术将结合起来，以获得油炸产品中多孔结构发展的全面分析。将开发三维孔隙网络模型并用于解释结构和脂肪吸收特性。该项目将积极吸引研究生和一名研究助理。这将为食品工程人才的培养提供良好的机会。

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.