High-pressure and heat pretreatment effects on rehydration and quality of sweet potato

Abstract

The effects of high-pressure and heat pretreatments, used prior to drying, on the rehydration rate and quality of sweet potato was investigated. Sweet potato was pressurized at 200 Mpa for 5 min and heat treatment was performed at 100°C for 5 min. Three different types of pretreatments were performed: heat treatment, heat treatment after high-pressure treatment and high-pressure treatment after heat treatment. There were no differences in the color parameters (L*, Cz.* and h) and gelatinization rate of rehydrated sweet potato exposed to the three different pretreatments. However, heat treatment after high-pressure treatment resulted in pronounced texture improvement compared to the other pretreatments. The relative hardness of the rehydrated sweet potato exposed to heat treatment after high-pressure treatment was higher than with the other pretreatments. Furthermore, it was found that the rehydration rate of sweet potato exposed to heat treatment after high-pressure treatment was lower than either heat treatment or high-pressure treatment after heat treatment. Heat treatment after high-pressure treatment prior to drying prevented cubes of sweet potato from collapsing during rehydration. This study shows that in sweet potato, the use of heat treatment after high-pressure treatment prior to drying could serve as an effective method for texture improvement. © 2011 Academic Journals Inc.