43-11 |
Topographic and force measurements of food matrices using Atomic Force Microscopy |
C. P. PANCHAPAKESAN, C. I. Moraru, and J. L. Kokini. Dept. of Food Science, Rutgers, The State Univ. of New Jersey, 65 Dudley Rd., New Brunswick, NJ 08901-8520 A clear understanding of conformational features and internal forces (i.e. adhesion forces) characteristic to food matrices helps in gaining an insight into understanding food structure and functionality at nanoscopic level. Atomic Force Microscopy (AFM) is a powerful, revolutionary technique that enables such measurements to be taken. Using AFM, it is possible to analyze surface features upto a nano-level and also make local force measurements on surfaces. The objective of this work is to explore the possible application of this nano-tool in food biopolymer systems, primarily involving carbohydrates. Using an Atomic Force Microscope (TM Microscopes, Sunnyvale, CA) in contact mode and silicon coated, mounted Ultralever tips, we have analyzed the three-dimensional surface topography and made local force measurements on a cereal-based food matrix. The Atomic Force Microscope was used in the contact mode, at a scan rate of 1Hz and set force threshold of 10.4nN. Sample topography was measured and pores in the biopolymer matrix were observed. Typical scan sizes ranged between 5-20 mm. Structural details in the matrix were visible at scan sizes of 10 mm, and their size varied from 0.25-4 mm in width. A line analysis was done to yield the mean height of the surface features, which was around 1.5- 3 mm. The effect of plasticizer concentration (water) on sample surface adhesiveness was also studied, by measuring samples with different levels of moisture. This allowed us to characterize, for the first time, the dependence of the nano-forces responsible for surface adhesiveness, on the moisture content of a food biopolymer matrix
Session 43, Food Engineering: Rheology and texture
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