The Effect of Conditions of Storage on the Respiration of Apples

Abstract

SummaryThe production of carbon dioxide and uptake of oxygen by several varieties of apples have been studied over long periods, at temperatures from 32° to 54° F. (0-12·2° C.), in air and in several mixtures of carbon dioxide, oxygen and nitrogen.It has been shown that, in sound apples, the mean rate of respiration varies directly with temperature and that the mean percentage increase, for a rise in temperature from 38° to 45° F. (3·3-7·2° C.), is 40% for CO2 output and 60% for oxygen uptake, for apples in air.In apples which are susceptible to low temperature injury, the rates of CO2 output and oxygen uptake, at temperatures below 38° F., increase with time and with onset of injury. The rates fall again when injury becomes severe. This abnormal type of respiration is less affected by concentration of oxygen than is the normal type, but it is not anaerobic.The course of respiratory activity of apples under controlled-atmosphere storage is similar for all varieties which have been tested, and yields no indication of suitability for this type of storage.Increasing the concentration of CO2 or decreasing the concentration of oxygen in the storage atmosphere reduces the rate of respiration; the effects of given concentrations of CO2 and oxygen are additive as regards rate of respiration, but not as regards prolongation of storage life.The respiratory quotient (R.Q.) is constant at any one temperature, for all concentrations of oxygen from 2% to 21%. It is lower in the presence of CO2 than in its absence, rises with falling temperature and reaches values in excess of 1–3 at 32°, 35°, and 38° F. in air.