2.7. Free fatty acid content
Free fatty acid (FFA) content was determined by the
method described by Lowry and Tinsley (1976). Extracted
lipid samples (20–30 mg) were evaporated to
dryness and redissolved in 5 ml isooctane, added with
1 ml of cupric acetate–pyridine reagent, and mixed vigorously
for 90 s using a vortex mixer. The upper phase
was collected and absorbance was read at 715 nm using
a spectrophotometer (Cary model, Japan). FFA was calculated
from the standard curve of palmitic acid and expressed
as mg palmitic acid/g lipid.