The Drying Characteristics and Germinability of Barley Grains (I)

Abstract

We studied the drying characteristics of barley grains to clarify the relationship between drying condition and drying rates or germinability.
The results were as follows:
1) It was found that the drying process of barley grains appeared to be falling-rate drying. The falling-rate drying theory was employed to determine the effect of air temperatures and initial moisture contents on drying character of barley grains. The drying rate was given by the following empirical formula as
-dM/dθ={0.0727e^{0.0788(T-T_W)-0.00417M₀}}
×{M+0.224(T-T_W)-12.39}
where M₀=initial moisture content % db
M_E=equilibrium moisture content % db
M=moisture content after a time % db
θ=time hr
T=drying bulb temperature of drying air °C
T_W=wet bulb temperature of drying air °C
A graphical comparison of calculated and observed moisture profiles is shown in Fig. 7.
The departure from the straight-line relationship at the early drying stage suggested that the drying rate of hull was very high at that stage.
2) The falling-rate of germinability by heated air drying was obtained as follow,
D=M₀{0.063e^{0.0788(T-T_W)-0.00417M₀}-0.085}
Where D=falling-rate of germinability %
To keep D less than 5%, when M equals to 30, 50, 70 and 90%, T-T_W, calculated was 19.2, 16.4, 15.2 and 15.0%, respectively.
3) In TTC tests, staining pattern of barley grains dried at higher temperatures or at higher initial moisture contents proved to be S type. (Fig. 9) These results suggested that the heat damage was inflicted on the scutellum in embryo.