Studies on osmotic dehydration of carrot (Daucus carota L.)

Abstract

Carrot is one of the important root vegetables rich in bioactive compounds like carotenoids and dietary fibers with appreciable levels of several other functional components having significant health-promoting properties. Osmotic dehydration of carrot seems to be convenient alternative for long-term storage as compared to cold storage or canned products. Keeping this in view the present investigation was carried out on “Studies on Osmotic Dehydration of carrot (Daucus carota L.)”. Among the osmotic pre-treatments 70°B syrup for 40h resulted in maximum weight reduction (11.24%), water loss (49.29%) and solid gain (38.05%). Pretreatments with low sugar syrup concentration of 40 and 50°B at both osmotic duration 20 and 40h resulted in an overall weight gain as values for weight reduction (WR) were negative (-9.37 to -29.00%), as well as an increase in solid gain and water loss in osmotically dehydrated carrot slices. Carrot slices subjected to 70°B syrup for 40h osmosis had maximum yield (58.33%) and lowest drying ratio (1.71:1) followed (58.26%) by 60°B syrup for 20h and (57.17%) 60°B syrup for 40h. Lowest yield 7.37 per cent and maximum drying ratio 13.88 was observed in untreated control samples. In osmotically dehydrated slices of carrot slices at initial stage the values were in range of reducing sugar (52.31-58.45%), non-reducing sugar (10.22-17.36%), total sugar (67.31-70.70%), carotenoids (32.04-39.09 mg/100 g) and total titrable acidity (0.31-0.52%). There was loss in carotenoids after six months storage and values ranged from (28.52-32.15 mg/100 g). Non-enzymatic browning in osmo-dried samples were very low at initial (0.100 to 0.151) and increased during storage which was (0.168-0.306) after six months of storage. Osmotically dehydrated carrot slices made by dipping in 50°B syrup for 40h were found superior with respect to sensory characteristics at initial as well as during storage. However, all osmotic dehydrated samples were found to be acceptable after six months of storage at ambient temperature. Hence osmotic dehydration was found to be very effective in improving the quality of dehydrated carrot slices.