Osmo-Microwave drying of garlic
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Date
2012
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MPUAT, Udaipur
Abstract
Garlic (Allium sativum) is among the most important and valued spice in India. The bulb is the most commonly used part of the garlic plant.
India is one of the prime producers of garlic with share of 13.2 per cent of world’s production. The major garlic producing states in India are Madhya Pradesh, Manipur, Gujarat, Orissa, Rajasthan, Karnataka, Tamil Nadu, Maharashtra, Uttar Pradesh and Bihar. In Rajasthan, area under garlic crop was 18.16 thousand hectares with a production of 96.88 thousand tonnes in year 2010-11.
The present study is carried out to standardize the pretreatment of garlic cloves and study drying characteristics during microwave drying. After cleaning, sorting and grading with garlic cloves were osmosed with salt solution and then dried in microwave dryer.
The effect of process parameters during osmotic dehydration such as duration of osmosis, concentration and temperature of solution on mass reduction, water loss and salt gain were studied. It was found that the mass reduction, water loss and salt gain increased with increase of solution concentration and temperature. The water loss and salt gain during osmosis at 20, 25 and 30 ºBrix was varied in the range of 12.70 to 14.10 per cent, and 5.43 to 6.7 per cent at 30, 40 and 50 ºC temperatures respectively.
The moisture diffusivity varied in the range of 8.3×10-12 to 2.21×10-11 m²/s during microwave drying of osmosed garlic samples. The power level and pretreatment as osmotic dehydration had a significant effect on the rehydration ratio, colour and water activity. The drying times of osmosed garlic cloves by microwave drying at 0.5, 1.00, 1.50 and 2.5 kW level were 4.33, 3.16, 2.25 and 1.75 hrs respectively. Quality of dried product in respect to colour, water activity and rehydration was superior. The osmo-microwave dehydrated samples were found more acceptable microwave dried ones. The garlic dried at 25 OBrix solution concentration, 40 OC osmosis temperatures and 1.50 kW microwave power level was more acceptable on the basis of colour and rehydration. The storage study suggested that ground dehydrated garlic can be stored safely in Metallized polyester polyethene (MPPE) packaging material at room temperature for one year without any adverse changes.
Description
Osmo-Microwave drying of garlic
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Citation
Waghmode and Champawat, 2012