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Microstructure plays a key role in oil absorption during frying. The aim of this work was to improve our understanding of the relationship between microstructure and oil absorption, through the use of glass micromodels to obtain evidence of transport phenomena in three porous networks. Micromodels were saturated with water and partially immersed in oil at 190°C. Moisture and oil profiles were imaged to get water and oil saturation maps. Image and fractal analyses were performed to describe the morphology of the evaporation and oil fronts. Results showed that higher porosity facilitated the moisture removal and promoted greater oil absorption during cooling. The fractal dimension showed that microstructures with a relatively high number of fine capillaries were less stable and propitiated fingering during the advance of the evaporation front. In all matrices, the disruption of the surface oil film due to air penetration was a critical factor to stop oil imbibition. © 2015 American Institute of Chemical Engineers AIChE J, 62: 629-638, 2016 [ABSTRACT FROM AUTHOR]

The optimal physical, chemical and nutritional properties of natural lipids depend on the structure and composition of triacylglycerols. However, they are not always mutually compatible. Lipid modification is a good way to give them specific functionalities, increase their oxidative stability, or improve their nutritional value. As such, chemical and enzymatic interesterification may be used to modify them and produce structured lipids. In accordance, the aim of this study is to compare chemical and enzymatic interesterification of binary blends of fully hydrogenated soybean oil and walnut oil, using sodium methoxide or Lipozyme TL IM, respectively, to produce a fat base with adequate nutritional and physical characteristics. Three different mass ratios of fully hydrogenated soybean oil and walnut oil blends (20:80, 40:60 and 60:40) were interesterified and evaluated. Total interesterification was determined by the stabilization of the solid fat content. Chemical reaction of the 20:80 blend was completed in 10 min and of the 40:60 and 60:40 blends in 15 min. Enzymatically interesterified blends were stabilized in 120 min at all of the mass ratios. Complete interesterification significantly reduced the solid fat content of the blends at any composition. Chemical and enzymatically interesterified fully hydrogenated blend of soybean and walnut oil at mass ratio of 40:60 showed the plastic curve of an all-purpose- -type shortening rich in polyunsaturated fatt y acids, with a high linolenic acid (C18:3n3) content and with zero trans-fatt y acids. [ABSTRACT FROM AUTHOR]

One of the most important quality parameters of flied food is the amount of fat absorbed during the process, which undermines recent consumer trends toward healthier food and low-fat products. In order to obtain a product with a low fat content, it is essential to understand the mechanisms involved during the frying process, so that oil migration into the structure can be minimized. To get such an understanding, this chapter briefly describes the frying process from technological and scientific perspectives. First, it gives a general overview of the frying process and describes the most important quality attributes of fried food. Thereafter, it centers on key nutritional aspects, particularly on the effect of excessive oil consumption on human health, oil degradation, and toxic compounds generation in fried food. Finally this chapter discusses the most important factors affecting oil absorption, oil absorption kinetics, and different strategies that may be adopted to decrease oil content. [ABSTRACT FROM AUTHOR]