Abstract
1. The relationship between organic acid and potassium concentration in apple juice was studied.
2. Malic acid content in juice from Golden Delicious and Rall′s apples was approximately 88% of total acids, and other organic acids such as acetic, formic and citric acids etc. were relatively small. Potassium was the dominant cation in apple juice, comprising 92% of total cations, while the rate of magnesium and calcium was 5.8% and 2.2% respectively.
3. pH-titration curve of apple (Golden Delicious) juice paralleled those obtained by titration of malic acid.
4. High correlation was obtained between percentage of cation-bound acid and pH level in the juice, even when any correlation was not observed between free acid and potassium content.
5. The correlation coefficient of free-acid and potassium concentrations in fruit juice of Golden Delicious apple collected from 190 orchards was 0.51, and some what wide variation of pH level in collected juices might have lowered the correlation coefficient.
