Structural stability of white sauces prepared with different types of fats and thawed in a microwave oven

This paper describes the microstructure and dielectric properties of white sauces prepared with different fats (sunflower oil, olive oil, soy oil, and butter) and agitation speeds (350, 1100 and 3250 rpm). The structural stability of sauces during thawing using conventional oven (CO) and microwave oven (MO) are studied. The results showed that, for fresh samples (not subjected to the freeze-thaw cycle) an increase in agitation speed during elaboration from 350 to 1100 rpm caused a significant decrease (p < 0.05) in the fat globules area - regardless of the type of fat used; in the samples with sunflower and olive oils, a significant increase (p < 0.05) in the fat globules circularity and dielectric properties (dielectric constant and loss factor) was also produced. The thawing method used did not significantly (p > 0.05) affect fat globule size and shape, regardless of the agitation speed and type of fat. Sauces that were stable during the freeze-thaw cycle were obtained using speeds of 1100 and 3250 rpm. (C) 2011 Elsevier Ltd. All rights reserved.