Study On Pre-treatment Conditions And Rehydration Characteristics Of Dehydrated Amaranth

Amaranth was used as material in this subject, and the effects of several blanching factors on dehydrated speed, color, pigment, vitamin C and crude protein were analyzed, then the variety rules of dehydrated amaranth under different conditions were obtained. At the same time, through some experiments on the rehydration of dehydrated amaranth, elementary conclusions for the characteristic of rehydration was obtained.The processing of dehydration first showed a short accelerated processing, then a constant processing, and finally a slowdown processing. Dry velocity of the amaranth was highly related to blanching temperature, and the temperature was higher, the velocity was faster. The influence of blanching time to dry velocity of the amaranth was not distinct. The increase of the concentrations of sugar solution induced the decline of dry velocity. The dry velocity would be the fastest when the concentration of salt solution was 1%. The pH of blanching solutions was higher, the dry velocity was faster.The blanching temperature was higher, the color of dehydrated amaranth was worse, and the content of amaranth pigment in dehydrated amaranth was lower. Extending blanching time would make the color of dehydrated amaranth become worse, and the content of amaranth pigment in dehydrated amaranth was concomitant decrease, which was less comparatively. The concentration of sugar was higher, the color was better. Sugar solution had slight bad effect on amaranth pigment. The color of product was better when the concentration of salt solution was between 0.5% and 1.0%, and the increase of the concentration of salt solution was concomitant with the decrease of the content of amaranth pigment, but the influence was tiny when the concentrations of salt exceed 1.0%. Better color of dehydrated amaranth was obtained when the pH of blanching solution was 4.0 and 9.0. Amaranth pigment was steadier between pH 4.0 to 7.0.Along with the increasing of the blanching temperature, the preserve rate of Vc and the content of crude protein were decreased. Extending blanching time, the same trend was obtained. Vc could be preserved better under acidic than alkaline, but acidic and alkaline conditions induced the loss of crude protein. Increasing the concentrations of salt could preserve Vc better, but the content of crude protein decreased at the sametime. Sucrose could heighten the preserve rate of Vc. Sucrose solutions which concentrations were lower than 1.0% induced losses of crude protein. Zn2+ and Ca2+ preserved Vc better, and Mg2+ had slightly effect on Vc , while Cu2+ induced heavy losses. Zn^ Mg2\ Ca2+ and Cu2+could induce loss of crude protein.The optimum rehydration condition that dehydrated amaranth was immersed in water was 90 "C for 60 minutes. Disposed with the mixture of dextrine-sugar-salt, which had a concentration ratio of 3:3:2, better reversion rate could be obtained, in addition, the concentration of dextrine was 15%.