Effect of ultrasound on mass transfer during vacuum impregnation of low-porous food materials on the example of potato (Solanum Tuberosum L.)

Vacuum impregnation (VI) is a process that allows modification or enrichment of porous food products with vitamins, minerals, functional ingredients, etc. There are many factors that hamper mass transfer during VI, e.g. low porosity, composition of the matrix, processing pressure and time, etc. The objective of this study was to evaluate the effect of starch on blocking mass transport during VI, and the potential of ultrasound as a factor enhancing mass transfer. The effectiveness of VI was evaluated on the basis of the ascorbic acid content (AAC), a marker compound introduced from the solution. It was found that starch can hinder the mass transfer but ultrasound intensifies the flow of the impregnating solution (16–67% increase in AAC). The quantitative effects, however, depended on the application stage. This may be explained by the different types of cavitation (stable or transient) dominant at different pressures. Importantly, the negative effects of VI on the analyzed quality parameters analyzed (e.g., color, texture, structure-forming compound content) were not stated. The results indicated that the effectiveness of VI in low-porous and starch-rich materials may be increased by applying ultrasound, but more research is required to analyze the stability of the compound introduced during preservation processes.