ISHS Acta Horticulturae 343: Physiological Basis of Postharvest Technologies
DETERMINATION OF THE RESPIRATION ACTIVITY OF FRUIT AND VEGETABLES IN CONTROLLED ATMOSPHERES USING AN AUTOMATIC MEASURING DEVICE |
| Authors: | H. Bohling, B. Bauer |
| Abstract:
The respiration activity is an important criterion for the postharvest behavior of fresh plant organs such as fruit and vegetables. In the majority of investigations in this field respiration was studied in normal atmospheres. At the Federal Research Center for Nutrition in Karlsruhe, Germany, respiration of various fruit and vegetable species has been measured also under CA conditions comparable to those of commercial stores since the mid-seventies. CO2 and O2 were measured in a flow system. CO2 measurement was based on infrared absorption, O2 measurement on magnetic properties. In both measuring devices, zero suppression was achieved by using a flow-through reference system. The CO2- and O2-concentrations in the reference gas corresponded to those of the gas mixtures flowing into the test containers. Control of the system, and processing of the data were transferred to an electronic data-processing system. The composition of the gas leaving the test containers was measured over a certain period of time-usually 55 min. The mean values of 40 individual values each, measured at intervals of 0.2 sec, were stored; they may be monitored simultaneously on the analogue screen. In the subsequent phase of bypass measurement which was limited to 5 minutes, the initial concentrations of CO2 and O2 were measured in the same way. Changes in concentration of CO2 and O2 caused by respiration were calculated from the stored mean values of both measuring phases and printed out when a measuring cycle was completed. Studies for many years in many fruit and vegetable species and cultivars have shown that in the majority of cases controlled atmospheres, as compared to normal air, reduce the respiratory activity considerably; this is not linked with a substantial increase of the respiration quotient. Advantages of the present system are reduction of labor and time, immediate availability of measured data and avoidance of errors due to atmospheric pressure fluctuations. | |
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