일반적으로 EC 측정기를 사용하여 커피의 농도를 측정한다. EC 측정기의 TDS 측정값이 1,000ppm인 경우 커피 농도를 1.0%라고 사용하고 있다. 그런데 ppm은 1백만분의 1값으로 1,000ppm은 1백만분의 1,000으로 퍼센트로 환산한다면 0.1%가 된다. 그렇다면 1,000ppm은 0.1%일까 아니면 1.0% 일까? 무엇이 잘못되었을까?
E C meter electric property of ion in liquid. Conductance is ability of electric moving. If there are lots of dissolved ion in liquid, Conductivity is very easy. But amount of dissolved ion is low, it is very difficult. Mostly, EC meter measure dissolved solid in water. If we measure brewed coffee, it is work. 10% of dissolved solid in brewed coffee have electric property. And then If you measure EC meter for coffee, you can measure only 10% of dissolved solids. 1,000ppm is 0.1%. If you measure brewed coffee, you must multiply 10. When you get 1,000ppm with brewed coffee, you can get coffee strength value multiply 10. 1,000ppm of brewed coffee is 1.0%. If you measure soluble coffee(instant coffee), you must multiply 20. Because of only 5% of soluble coffee have electric property.
