Studies of the Fine Structure of the Wax Layer of Sultana Grapes

Publisher Website
Google Scholar
Abstract
The surface waxy bloom of sultana grapes has been studied using the carbon-replica technic in combination with electron microscopy. This layer consists of a series of overlapping wax platelets, each of which is about 0.1 [mu] wide. The air spaces between the wax platelets become filled with liquid when sultana berries are dipped in commercial emulsions known to accelerate their drying rate. Washing in distilled water removes this layer of dipping emulsion from the surface. The appearance of dipped and washed grapes is similar to that of untreated grapes. Rubbing the grapes with lens tissue destroys the precise arrangement of wax platelets but does not remove the wax. Dipping the grapes in chloroform (four changes of 10 sec.), a treatment known to remove most of the wax, leaves sufficient wax to enable replicas to be prepared. Treatment of the grapes with chloroform for longer periods and Soxhlet extraction removes all the waxy structures. These results are discussed, and a hypothesis is presented which may explain the mechanism of action whereby dipping emulsions increase the rate of water movement from grapes.

This publication has 1 reference indexed in Scilit: