Vacuum impregnation: A methodology for the preparation of a ready-to-eat sweet potato enriched in polyphenols

Abstract

Vacuum impregnation (VI) is a widely used methodology to add various substances of interest to porous foods, thus acquiring enhanced nutritional and sensory properties depending on the functionality of the impregnation solution. The work reported here was thus aimed at the preparation of sweet potato containing the addition of polyphenols through vacuum impregnation and low-pressure cooking. A commercial solution of polyphenol extract (95% [v/v] proanthocyanidins) was used as an impregnation medium. In the characterization of the vacuum-impregnated samples, the physicochemical parameters of pH, moisture, color, texture, and total polyphenol content were measured, the cooking behavior was evaluated, and sensory assessments were performed (preference tests and the CATA—check-all-that-apply—questionnaire). The result was a preparation of sweet potatoes that had been vacuum-impregnated with a subsequent increase of 473 % in the concentration of phenolic compounds compared to the control sample. The parameters such as color and texture remained stable. We conclude that VI enabled the preparation of a product providing some 220.0 mg of gallic-acid equivalents of polyphenols per 100 g (GAE/100 g) per serving, a value similar to those of vegetables rich in those compounds.