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S. KO and S. Gunasekaran. Dept. of Biological Systems Engineering, Univ. of Wisconsin, Madison, Food & Bioprocess Engineering Lab., 460 Henry Mall, Madison, WI 53706-1533 Globular proteins are commonly used as functional ingredients in foods because of their ability to gel upon heating. The important functional properties of heat-induced protein gels are strongly influenced by their microstructure. The confocal laser scanning microscopy (CLSM) can be used to study the thermally-induced microstructural morphologies of protein aggregates and gels in situ. Our objectives were to investigate the evolution of microstructure during gelation of a model globular protein, b-lactoglobulin (BLG) using CLSM, and to develop techniques to quantify and visualize the time-resolved, in situ two-dimensional (2D) and three-dimensional (3D) characteristics of the gel microstructure. Bovine BLG solutions, at various concentrations (5-15% w/v) were prepared at 0, 0.1, or 0.3 M NaCl, and pH 7.0, 5.0, or 2.0 in phosphate buffer. Each BLG solution was in a concave slide glass and stained with 0.025% Rhodamine B solution to facilitate easy visualization of the protein phase during imaging. The sample was heated at 5 oC/min from 25 to 90 oC using a Peltier thermoelectronic temperature controller. During gelation, 41 sequential 2D layer images (0.5 µ interlayer gap) of the gelling system were obtained at 5 oC increments. The images were processed and analyzed to extract 2D features of the gel matrix. Further, the processed image layers were used to reconstruct a 3D view of the gel matrix. Several 3D features of the gel mictrostructure were computed. The results would help understand the real-time evolution of gel microstructure and gelation kinetics
Session 64, Dairy Foods: Milk proteins
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