ESTIMATING SKIN RESISTANCE TO GAS-DIFFUSION IN APPLES AND POTATOES

Two types of analysis of the rate of efflux of pre-loaded ethane from apples and potatoes into a container of known volume were compared as methods for estimating skin resistance to gas diffusion (R). An ''exponential model'' was fitted to transformed data obtained over a 24 h period whereas a ''linear model'' was fitted to raw data obtained over a 100 s period. R values for individual apples obtained using the two methods were in close agreement. R was higher in Golden Delicious than in Discovery apples but values for individual fruit within each variety were quite variable. The exponential analysis was unsuitable for estimating R in potatoes but the linear analysis yielded reproducible R estimates. A computer simulation of ethane efflux from an ''ideal'' organ showed that varying the size of container used in either analysis in the range of 250-9000 cm3 would have no detrimental effects on estimates of R.