Properties and qualities of microwave-vacuum dehydrated Russet potatoes

Microwave-vacuum drying (MVD) is dehydration method that can provide rapid heat transfer at reduced drying temperatures compared to atmospheric hot air drying. Several dryer configurations are reported; in this study, a MIVAC® configuration was used. This MVD modulates the application of microwave power based upon surface product temperature at any time during the drying processing. This research evaluated properties and quality of MVD dehydrated Russet potatoes (Solanum tuberosum) and compared these with heated air dried (HAD) and freeze-dried (FD) potatoes. Color, texture, microscopic structure, porosity, rehydration and sensory properties were analyzed in this research. MIVAC® drying behavior was also determined by evaluating the moisture distribution and the color change after drying.;Drying at a moderate (60°C) temperature at longer times produced more desirable dried potatoes compared to higher temperature drying for a shorter time due to scorching. MIVAC® was equipped with a turntable and drying using a rotating turntable produced more even microwave distribution and reduced the occurrence of scorching. The moisture distribution for potatoes on the turntable was determined by divided the turntable into three ring regions; an outer, middle, and center regions. The outer and center rings had a lower moisture distribution compared to the middle ring. Operating MIVAC® with the turntable static showed that hot spots occurred most often at the middle ring.;Texture Profile Analysis (TPA) and SEM images indicated that the dried MVD potatoes were crispy, HAD potatoes were hard and brittle due to case hardening, and FD potatoes were soft and spongy. The color retention of MVD potatoes was higher compared to FD and HAD potatoes. The rehydration properties of MVD potatoes were similar to HAD, while FD potatoes had higher rehydration properties. However, FD potatoes lost structural integrity following rehydration. Sensory analysis indicated that the panelists preferred MVD potatoes among the drying potatoes tested.