1Ph. D. Scholar, Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, 131028, Haryana, India
2Associate Professor, Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, 131028, Haryana, India
3Professor, Department of Food Engineering, National Institute of Food Technology Entrepreneurship and Management, Kundli, Sonepat, 131028, Haryana, India
*Corresponding author email address: sehrawatrachna2017@gmail.com.
Online published on 29 March, 2018.
The effect of combined low pressure superheated steam drying (LPSSD) followed by vacuum drying (VD) on quality of onion slices at different temperature (60–80°C∼10 kPa) was determined. In the first stage, the moisture content of onion slices was reduced to 50% (w.b.) from 88–90% (w.b.) using LPSSD; and then it was further reduced up to 7–8% (w.b.) by VD. It was found that among the various drying temperatures studied, retention of colour, rehydration ratio, thio-sulphinate content and antioxidant capacity of dehydrated onion was better at 60°C, followed by 70°C, whereas total phenol contents were higher at 80°C. The results of control dried sample and sample dried at 60°C had significant differences in time taken for drying, thio-sulfinate content, total phenol content and antioxidant capacity, whereas insignificant effects of drying temperature was observed on rehydration and water activity of dried onion slices.
Onion, low pressure superheated steam drying, vacuum drying, colour, thiosulfinate
