3.4 Volatile compounds of Qingjinju seed oils
The volatile compounds of the Qingjinju seed oils are described in Table
4. The primary volatile compound classes in the Qingjinju seed oils were
esters, aldehydes, hydrocarbons,
acids, and alcohols, which agrees with results reported by Kalua el
al48. The identity and
relative concentrations of volatile compounds were significantly
different between oils produced by the different extraction techniques,
similar to results reported by Moreno et
al.21 A total of 43
volatile compounds were
identified
in SPO, 42 in SO, and 44 in SCO.
The greatest number of compounds in both SPO and SCO were aldehydes,
containing 16 and 13, respectively.
In SO, the largest number of compounds in SO
were hydrocarbons (18). Regardless
of the extraction method, seven volatile compounds were observed:
2-methylaminobenzoic acid methyl ester, 2-methylaminobenzoic acid ethyl
ester, (E )-2-heptenal, (E ,E )-2,4-heptadienal,
(E ,E )-2,4-decadienal,
2,4-decadienal, and n -hexadecanoic acid.
These compounds accounted for
40.52%, 46.19%, and 54.76% of the total volatile compounds in SPO,
SO, and SCO, respectively. These
appear to be the primarily volatile compounds of the Qingjinju seed
oils.
The relative contents of volatile compounds in SPO were esters
(30.28%), aldehydes (22.61%), and hydrocarbons (26.32%). The volatile
compounds in SO were primarily comprised of hydrocarbons (43.74%),
esters (25.79%), and aldehydes (19.91%). The volatile compounds in SCO
were primarily composed of esters (32.55%), aldehydes (30.95%), and
alcohols (12.91%). The relative content of
limonene was 13.4 times higher in
SPO (24.49%) than SCO, while no
limonene was detected in SO. The relative content of limonene could
therefore be used as a
characteristic indicator to
determine the extraction method. The relative contents of octane and
2,2,4,6,6-pentamethylheptane were 9.73% and 9.75% in SO, but were
absent from SPO and SCO. These two volatile compounds may be exogenously
supplied by the solvent used during the extraction process. Whether
these two volatile compounds are indicative of the solvent extraction
technique requires further evaluation.