Osmotic dehydration of pineapple by continuous system
1999
Chutamat Niwat
Increasing of blanching time from 0 to 2.5 5.0 7.5 and 10.0 minutes increased the mass transfer rate of water and sugar, but the blanching time longer than 5.0 minutes contributed to soft texture. Syrup flow rate at 3.0 6.0 9.0 and 12.0 ml/min gave no significantly difference in water loss and solid gain, but the flow rate at 6.0 ml/min was selected out of economy. Increasing of surup concentration from 45 to 50 and 55 Brix and pineapple to syrup ratio from 1:3 to 1:4 and 1:5 increased the mass transfer rate of water and sugar. The suitable conditions for continuous countercurrent osmotic dehydration system were; the pineapple with soluble solid content of 15 Brix in 1st tank and pineapple which passed through osmotic dehydration once in the 2nd tank, starting syrup concentration was 60 Brix, pineapple to syrup ratio was 1:2, syrup flow rate was 6.0 min/ml and operating time was 8 hrs. When the osmosis is over, the soluble solid content in 1st and 2nd tank pineapple were 46.2 and 54.5 Brix respectively. After osmotic dehydration by continuous system for 16 hrs, pineapple had soluble solid content of 55 Brix while the one by traditional system had soluble solid content of 41 Brix. After drying for 12 hrs, pineapple by continuous system had aw 0.72, moisture content 11.77 percent and puncture force 24.45 N., whereas the other had aw 0.77, moisture content 13.13 percent and puncture force 28.09 N. In addition, the continuous system caused lesser shrinkage and deshape than the traditional one.
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