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    SPRAY DRYING OF TOMATO JUICE
    (PAU Ludhiana, 2011) Wungshim Zimik; Mahesh Kumar
    A study was conducted to produce tomato powder using spray dryer (LSD-48) in the food engineering laboratory. The rheological parameters of fresh tomato juice and reconstituted juice were evaluated with the help of CVO-100 rheometer in engineering properties laboratory. A full factorial central composite rotatable design was used. The variable selected were air inlet temperature (140-160oC), feed flow rate (2.1-4.1 ml/min) and maltodextrin concentration (22.5-32.5%). The responses used in the analysis includes: recovery, lycopene content, solubility and ascorbic acid content. The air inlet temperature (145oC), feed flow rate (2.6 ml/min) and maltodextrin concentration (27.5%) were found to be optimum. Experiments were also performed to find out the total soluble solids, hue angle, chroma, titrable acidity, packed bulk density and moisture content. Results shows that with increase in air inlet temperature and feed flow rate, the moisture content, lycopene, packed bulk density, ascorbic acid, titrable acidity and solubility time decreased. Colorimetric analyses showed that the hue angle and chroma values changed with the inlet temperatures. The flow characteristics studies of the tomato juice and reconstituted juice of the optimized spray dried powder was undertaken at different processing temperatures. The flow behaviour of the samples were studied at different temperature levels from 40°C to 60°C at an interval of 5°C and shear rate range of 10 to 100 s-1 with 60.5oBrix total soluble solids. The flow behaviour of the samples was predicted by the values of consistency coefficient and flow behaviour index. The range for consistency coefficient of the fresh juice and reconstituted juice was found to be from 5.93 Pa sn to 20 Pa sn for Power law model and 1.47 Pa sn to 9.81 Pa sn for Herschel-Bulkley model. The flow behaviour index of fresh juice and reconstituted juice was found to be in the range of 0.70 to 0.89 for Power law and between 0.70 to 0.90 for Herschel-Bulkley model. Sensory evaluation and overall acceptability was also conducted for the fresh tomato juice and reconstituted juice on a 9-point hedonic scale.