A Comparison of the Aerobic and Anaerobic Respiration of Apples

Abstract

The loss of carbohydrate, acid, and cell-wall material, and the production of carbon dioxide and alcohol, have been studied in apples under aerobic and anaerobic conditions. The changes in all these metabolites, except the cell-wall material, proceed in a regular manner. The presence of oxygen has a conserving effect on the loss of carbohydrate. The presence or absence of oxygen is without effect on the rate of loss of acid. The rate of loss of acid is proportional to the logarithm of its concentration and is constant for a given variety of apple. The loss of carbohydrate plus acid accounts quantitatively for the production of carbon dioxide and alcohol, both in air or in nitrogen. The anaerobic respiration of carbohydrate by apples is identical, so far as the nature and quantity of the end products are concerned, with the alcohol fermentation of yeast. The carbon dioxide which is produced in nitrogen, over and above that produced in fermentation, is equivalent to that which would be produced by oxidation of the acid.