Microstructural approach to understand oil absorption during vacuum and atmospheric frying

Crust microstructure plays a critical role in oil uptake of atmospheric fried food and seems to play an important role in vacuum fried products. The objective of this study was to understand the relationship between key microstructural parameters and oil absorption, after atmospheric and vacuum frying of different vegetable tissues. The effect of drainage and centrifugation in oil-uptake reduction was also analyzed. Key microstructural parameters were determined using gas adsorption at cryogenic temperatures, while oil location and surface roughness were studied using confocal laser scanning microscopy and area-scale fractal analysis, respectively. Overall, we found a linear relationship between porosity and final oil content in vacuum and atmospheric fried chips. However, this relationship could not be extended when analyzing the whole set of data, since oil absorption was significantly higher in atmospheric fried chips. Centrifugation allowed reducing oil-uptake up to 73% in atmospheric fried chips and up to 64% in vacuum fried ones.