Cold pressing is generally preferred in the production of
high–quality RHSO [18]. Oil extraction by cold pressing provides
significant advantages in preserving many of the bioactive compounds
such as essential fatty acids, phenolics, flavonoids and
tocopherol in the oils, but it gives a low oil yield. The oil content
of seeds at the end of separation process is between 5 and
15%wt. Cold–pressed oils are considered as healthy oils that are
important to human nutrition due to their favorable polyunsaturated
fatty acid content, notably –linolenic acid and linoleic acid
[19]. However, the high amounts of polyunsaturated fatty acids in
cold–pressed oils are prone to lipid oxidation [19]. For the solution
of these bottlenecks, extraction of the oil in rosehip seeds
with supercritical CO2 (scCO2) is an alternative separation process
for increasing the yield of the separation and protecting biologcal potentials of valuable biological molecules in the oil. High–tech
separation and purification processes using scCO2 in the form of
“green solvent” as a separation agent are among alternative processes
in the development of industrial processes with GMP used
today. In order to increase the yield of oil recovery in the separation
process, the physical specifications and transport characteristics
of scCO2 may be modified as desired by variation of the pressure
and temperature conditions of the extraction. And also the polarity
can be modified with a polar/non–polar entrainer addition [20–23].
When the pressure condition of stream leaving the extractor is
reduced to atmospheric conditions, the products obtained may be
separated in a single stage.
The extraction process of oil from seeds isolated from dried
rosehip fruit using subcritical and supercritical fluids (such as CO2
and propane) have been examined by various researchers [24–31].
Some of these studies were performed to determine the efficiency
of oil recovery from the seeds milled in different grinder systems.
Furthermore, the effects of operation conditions (such as particle
size, pressure, temperature and supercritical solvent flow rate) on
the extraction yield were investigated. In addition to the apparent
solubility of RHSO in scCO2, the effects of operation conditions
on the fatty acid compositions were also examined. However, no
detailed study on the recovery of rosehip seed oil from food industry
waste by scCO2 extraction processes was found in literature.
The aim of this study is to recover the oil in the rosehip seeds
emerging as a waste product in an organic marmalade production
process by using a process with GMP. RHSO in waste seeds
were separated by scCO2 extraction process. The effects of main
process parameters on the extraction yield were investigated. The
effects of operation conditions on the initial extraction rate and
the apparent solubility of the oil in the solvent under supercritical
conditions were also investigated. Furthermore, the compatibility
of some semi–empirical solubility models based on pressure and
temperature with experimental data were tested. The changes in
morphological structures of seeds before and after the separation
process were examined using a scanning electron microscope at
the microscopic level. Fatty acid profiles of the extracted oil were
analyzed by gas chromatography.