Abstract: :To investigate the effects of altitude on the performance of soymilk maker, the variation of urease activity was tested during the boiling process by three leading brands of soymilk maker. The urease activity was also determined at different water boiling points corresponding to the altitudes of 1500m, 3000m and 4500m. Finally, the feasibility of using spectrophotometer to verify the results was discussed. The results indicated that three soymilk makers met the requirement of standard at the attitude of 50m (39°53'N, 116°21'E). However, more time was essential when the attitude increases and boiling point decreases, laying basis for designing soymilk maker exclusively used in plateau. Besides, employing spectrophotometry at 420nm to measure the absorbance of samples could avoid the optical disparity among individuals, providing the foundation for promoting the amendment and perfection of relative standard.

Key words: Soybean milk maker, Urease, Boiling point, Altitude, Spectrophotometry