A new alternative extracting technique that has attracted the
attention of many researchers is superheated water extraction
(SWE) [1]. SWE is a powerful technique based on use of water
as a solvent instead of organic solvents [2]. Superheated water
is liquid water at temperatures ranging from100 to 374 ◦C and
enough pressure to maintain its liquid state [3]. Water is an unrivaled
solvent because of its high dielectric constant, high polarity
and its highly hydrogen-bonded structure that lead to excessively
high boiling point at ambient conditions. If the water temperature
rises, its properties change dramatically [4]. Under standard
conditions, 25 ◦C and 101 kPa, water is a polar solvent with dielectric
constant () of about 80, but when temperature is increased
to around 200 to 350 ◦C, the dielectric constant fall to about 20
to 30, which is similar to the dielectric constants of solvents like
methanol, ethanol and acetone at ambient temperature [5]. The
effect of increasing temperature means that superheated water
can have a permittivity very similar to organic solvents and it can
dissolve a wide range of medium including low polarity components
[1]. Also, viscosity and surface tension of water decreases
with increasing temperature [6]. F