An application for the Marcus oxidized grades 3300,3400 & 3500 emulsion (essentially anionic formulations with highly volatile amines) is predominantly to citrus fruit (oranges, lemons, grapefruit etc.).

The fruit is harvested in the green (unripe) state and is washed to remove insecticide and fungicide residues. In this process the natural waxes in the skin are removed. It is imperative that these natural protectants are replaced, otherwise the fruit can lose upto 50% of it’s weight within a few weeks. At the same time, due to the loss of water, there is an interference with the chemical reactions which are responsible for the development of a full flavored juice.

The polyethelene emulsion is used in combination with an alkali soluble resin solution and variable ratios are formulated to maintain the optimum benefits for the requirements of the many different species.

Application is by dipping, brushing or spraying and the dosage rate is about one litre (of a 15-20% solids coating) per ton of fruit.

The key characteristic of the oxidized polyethylenes used in this application are related to the density of the wax, which in turn has a significant influence upon the barrier properties (permeable to gases thereby allowing the fruit to ripen under the coating and impermeable to water vapour transmission). The higher the density the better these features are. The MARCUS 3400 & 3500 with densities of 0.96 have an unsurpassed efficiency in this application, the prime advantages being:

  • Excellent barrier properties.
  • Reduced shrinkage.
  • Provision of high gloss to the coating.
  • Hard, high melting and non tacky.