Influence of Pretreatments and Drying Methods on Water Activity, Dehydration and Rehydration Ratio of Dried Tomato

The study was carried out to investigate the effect of different chemical pretreatments (2% ethyl oleate + 1% potassium carbonate, 1% ascorbic acid+1% citric acid and 2% sodium metabisulfite, 1% calcium chloride + 0.25% sodium chloride and 1% sodium chloride at different drying methods (sun drying, solar tunnel drying and cabinet drying at 45oC, 55oC and 65oC) on Water activity, Dehydration and Rehydration ratio of dried tomato slices. The effects of drying methods and pretreatments and their interactions were found statistically significant (p<0.05). Maximum water activity 0.64 was recorded in open sun dried samples in variety Shalimar I (T0) while as minimum water activity 0.38 was recorded in samples which were cabinet dried at 65oC using T4 as pre-treatment solution in Punjab Chuhra. Minimum Dehydration and Rehydration ratio 20.00 and 1.33 was recorded in open sun dried samples in variety Punjab Chuhra (T0) respectively while as maximum Dehydration ratio 33.33 was recorded in samples which were cabinet dried at 55oC (T2) in Shalimar I and maximum Rehydration ratio 2.98 was recorded in samples which were cabinet dried at 55oC (T2) in Punjab Chuhra.