AbstractA study has been made of the pectin‐demethylating enzyme system in apple tissue and the level of activity compared with that in some other fruits. The apple varieties tested show considerable differences in their pectase content. The enzyme shows a maximum activity at pH 6–6: over the pH range of the fruit the activity is much lower, but the enzyme can still produce appreciable effects. Methods for the extraction and concentration of the enzyme are described. The concentrated enzyme preparations are readily inactivated by normal pasteurizing temperatures (68–70°c.), but in juices the enzyme shows a much greater stability. The significance of these findings is discussed in relation to the production of apple juice and