DEHYDRATION OF LOW-GRADE ASPARAGUS

Dehydration by a forced convection process is one potential method to add value to low-grade asparagus for marketing purposes, The objectives of this study were to determine the optimum drying temperature, air velocity, and predrying blanching treatment and study the effects of those parameters on the drying curves for low-grade asparagus and the efficiency of the drying process. The ranges of investigation were 60 to 93-degrees-C and 0.14 to 0.44 m/s for drying temperature and air velocity, respectively. Drying at 51-degrees-C and 0.30 m/s yielded product with an optimum quality, and drying at 79-degrees-C and 0.18 m/s yielded the optimum process efficiency of 17.9%. Drying temperature, air velocity, and predrying blanching treatment all affected the rate of drying in the constant-rate drying period and the length of the constant-rate drying period. In the falling-rate period, all of the process parameters studied had some effect on the shape of the drying curve.