Assess impact of ingredients, processing strategies on tortilla cellularity.

Both a product's texture and cellularity, including the quality and condition of cells, play an important role in determining its palatability. These two components can be manipulated to improve how well consumers like a product. Researchers at the University of Illinois and elsewhere used non-destructive x-ray microtomography to understand what effects ingredient and processing strategies would have on the cellularity of tortillas. This information can yield useful knowledge to the baking industry.

In experiments, xanthan gum, carboxymethylcellulose (CMC), glycerol and propylene glycol were added individually and in combination to the tortillas. To understand the effect of processing conditions on tortilla cellularity, the scientists prepared the tortillas using different combinations of dough resting times (10 minutes and 20 minutes), different baking temperatures (350 F and 450 F), and different cooling times after baking (2 minutes, 5 minutes and 10 minutes.)

The investigators used a high-resolution, less than 5 [mu]m, commercial microtomograph to structurally characterize the tortilla samples. Images were recorded from a variety of angles and angular projections to generate two-dimensional (2-D) cross-sectional images. Software reconstructed a 3-D object from multiple 2-D images. Using image analysis software, the scientists obtained a set of 2-D images of all tortilla samples. They analyzed these to quantify cell size distribution, average cell wall thickness, and the area, perimeter, shape and diameter of each cell.

A higher baking temperature of 450 F led to the formation of larger air cells and greater air cell density. However, the thickness of the cell walls of the tortillas decreased. Cell density increased with higher tortilla cooling time, but cell size remained unchanged. As expected, more cooling time allowed moisture to escape from the samples, which caused air cell walls to shrink. More dough resting time led to smaller air cells, less cell density and higher cell thickness. Adding both gums and polyols reduced the size of the air cells, but cell thickness remained the same. Air cell density was greater when gums and polyols were added.

Further information. Jozef L. Kokini, Associate Dean for Research, College of Agricultural, Consumer and Environmental Sciences, Department of Food Science and Human Nutrition, 211B Mumford Hall, University of Illinois, Urbana, IL 61801; phone: [phone]; email: [e-mail].