Stability of dehydrofrozen tomatoes pretreated with alternative osmotic solutes

Quality of frozen tomato can significantly be improved by means of osmotic dehydration as a prefreezing treatment. The objective of this work was to study the effect of osmotic pretreatment with alternative osmotic solutes-glucose, a high DE maltodextrin (HDEM), oligofructose and trehalose-on the quality and functional properties of frozen tomato tissue. Colour, vitamin C content and texture characteristics of pretreated and conventionally frozen samples were comparatively measured at 3, 6, and 12 months, during storage at two temperatures, -12 and -20 degrees C. Sensory evaluation was also conducted. The results indicate that osmodehydrofrozen compared to conventionally frozen sliced tomatoes show improved quality and functional characteristics for prolonged storage period. For tomato samples pretreated with glucose, HDEM, oligofructose and oligofructose/trehalose and stored at -20 degrees C during 12 months, the retention of initial vitamin C content was 81%, 66%, 77% and 88%, while for frozen, untreated and blanched, products it was lower (44% and 58%), respectively. Sensory evaluation showed good organoleptic quality in osmodehydrofrozen tomato slices. (c) 2005 Elsevier Ltd. All rights reserved.