Experiments were conducted to study the drying characteristics of raw cauliflower florets. A mechanical tray dryer was used in this study. The samples were dehydrated at 60, 70, 80 and 90°C air temperatures with blanching pretreatment of two minutes in 0.75 per cent potassium metabisulphite. Drying characteristics were determined with the help of mass transfer data. Moisture content of cauliflower was found to decrease rapidly during the initial 150 minutes. Cauliflower behaved like a hygroscopic non-porous food material during the drying. Drying time of 330 to 510 minutes was required to reduce the moisture content from 92.50 per cent to 5.00 - 6.00 per cent. The moisture diffusivity during drying process was determined and found in the range of 2.54 x10-12 to 3.80 x10-12 m2/s. Quality of the dehydrated samples such as carbohydrate content, ascorbic acid retention and rehydration were also evaluated. The carbohydrate and ascorbic acid content in dehydrated samples ranged from 3.25 to 3.45 g per 100 g and 39.75 - 24.10 mg / 100 g as against 5.40 g / 100 g and 55.55 mg / 100 g respectively, in fresh vegetable indicating a significant loss of nutrients during processing. Product was found to be good in terms of appearance and taste up to 60 days for all the four temperature ranges.
©2011 Walter de Gruyter GmbH & Co. KG, Berlin/Boston
