2.9. Extraction and estimation of lipids and fatty acid
analysis
The total lipids from the freeze-dried mushroom samples
were extracted by the method of Folch, Lees, and
Solane-Stanely (1957), using chloroform–methanol mixture
in a ratio of 2:1 (v/v). Methyl esters were prepared
from the total lipids by the method of Craig andMurthy
(1959). Fatty acid analysis was performed by gas–liquid
chromatography, run on a Hewlett Packard 5750 chromatograph
fitted with a flame ionization detector. The
glass column (2.15 m · 0.535 cm) was packed with
15% diethylene glycol succinate on 80–100 mesh acid –
washed chromosorb – W. The carrier gas was nitrogen
at a flow rate of 32 ml min1. The column temperature
gradient was 4 C min1 from 190 to 240 C. Heptadecanoic
acid (17:0) was used as an internal standard.
Identification of the peaks was based on comparison
of retention times of samples and standards. The
amount of each fatty acid was calculated by the data –
handling and control unit of the instrument. All determinations
were done in triplicate and mean values
reported.