ABSTRACT
Distillation is the second most common method used for the recovery of citrus oils. Distillation may be de ned as the separation of the components of a mixture of two or more liquids by virtue of the difference in their vapor pressure (Miall in Guenther, 1948). It takes advantage of two characteristics that make the recovery of the oil more feasible:
1. The volatility of most of the components of the citrus oils 2. The immiscibility of the oils with the water-based emulsions resulting in the processing of
citrus fruits
Dalton’s law states that “the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component of the mixture.” Thus, the boiling temperature for any two-phase liquid will be lower than either of the boiling points of the components in such a blend. The water-based citrus oil emulsions boil at temperatures below 100°C at atmospheric pressure, well below the boiling points of the citrus oils’ components in the range of 150°C to 280°C. This method, however, produces some changes in the composition of the oil:
The nonvolatile part of the oil, composed of coumarins, psoralens, pigments, and waxes, • is not present in the distilled oil. Consequently, the latter is relatively unstable because it lacks the antioxidants present in the nonvolatile part of cold-pressed oils. Some distilled oils obtained from a juice-oil mixture contain volatile components of the • juice not present in cold-pressed oils (Shaw, 1977). The presence of such compounds generally imparts to the distilled oils a desirable juicy note. They also lack a heavy avor note that contributes to the characteristic avor of the cor-• responding cold-pressed oil (Shaw, 1977).
