Effect of Ethylene on the Ripening of Bananas

Abstract

Bananas ripening at 65[degree] C. in an atmosphere containing 1:1000 parts of ethylene turn yellow at a rate only slightly more rapid than do controls. Such bananas also show more rapid increase of sugar and decrease in starch from day to day than do controls, but the difference is even more slight than the color. Concentrations of ethylene from 1:100 to 1:10,000 all seem equally effective in bringing about the small changes observed. At full ripeness bananas have 17-20% total sugars, 10-14% sucrose, and less than 1% starch, in both Gros Michel and Cavendish varieties. The respiratory activity of bananas treated with ethylene differs little or not at all from that of untreated ones, when 12-hr. periods are considered, regardless of the concentration of ethylene used. Rarely there is found a bunch of bananas in a quasi-dormant condition, and in this case ethylene stimulates an immediate commencement of ripening, while the controls are delayed several days in starting. The "coefficient of ripeness" is unreliable as well as insensitive. Comparable results cannot be secured by using fruit from different bunches for parallel treatments, no matter how similar the aspect of the bunches, but only by using bananas properly selected from the same bunch.