Taro Crop for Better Utilization through Osmotic Dehydration Process

摘要

Taro is one of the important vegetable crops in the tropics and is underutilized in the processed forms. Osmotic dehydration is attempted in taro for better utilization. The cut slices of fresh Colocasia tubers were immersed in the salt solution of sodium chloride (1.5%), tartaric acid (1.5%), citric acid (1.25%) and calcium chloride (1.25%) at 5.5% in combination at a temperature of 50°C for a time of 1, 2,3,4, 5 and 6 h in a constant temperature water bam without agitation. A control was maintained in distilled water without the addition of salts. The tubers were sliced to various thicknesses of 2, 4 and 6 mm with 3 cm 0. Osmotic pressure exerted by the above chemicals was 648.5 pa with a water activity of 0.1066. The volume of solvent used is 200 ml of water/100 g of peeled and sliced tubers. The optimised sample was of 2 mm thickness and the one soaked for a period of 6 h coupled with oven drying of 4 h at 50°C. Moisture content at the time of packaging was 30-35% from the original fresh tuber moisture of 78% at ambient condition. The types of packaging used at ambient and low temperature are air packaging and vacuum packaging. Packaging material used is HDPE of thickness 2.8 μ of size 15 x 21 cm. No appreciable changes in starch and sugar values were noted. Protein decreased from 11.81 to 9.0% on dry weight basis. The calcium oxalate, a main cause of acridity, decreased from the original value of 0.5 to 0.06%, an added advantage to this technique. Viscosity values were found reduced in the osmotically dehydrated samples. Microbial safety was checked by visual observation at weekly intervals for 3 months time period both at ambient temperature (25°C) and low temperature (5°C). Retention of freshness is more at low temperature in vacuum packaging when compared to ambient condition.