Chromosorb 101 and Porapak Q columns at 135° and 175° C, respectively, are suitable for quantitative gas chromatographic analysis of volatile emanations such as methanol, acetaldehyde, and ethanol from intact ‘Valencia’ oranges. Separations were completed in 16 min and were superior to those obtained on Carbowax 20M. Chromosorb 101 was superior to Porapak Q for the separation and quantitative measurement of methanol and acetaldehyde. The terpenes were not eluted from either Chromosorb 101 or Porapak Q at these temperatures. Carbowax 20M was suitable for separation of the terpenes with temperature programming, requiring at least 35 min to complete the separations. Chromatograms of volatiles from headspace over orange juice and emanations from ‘Valencia’ oranges are presented.
Ethylene is known to accelerate the respiration and to hasten the loss of chlorophyll from lemons (3). In addition, ethylene-treated lemons, are more subject to decay than untreated fruit and, as a consequence, show a shortened storage life (1). Fruits exhibiting a respiratory climacteric typically show a concomitant increase in volatile production, including ethvlene (4). The present paper reports the effect of added ethylene on volatile production by lemons, a non-climacteric fruit (2). Although sound lemons have little or no odor, no previous study has been made of the volatile production of lemons.