The determination of TPC was carried out using a previously
reported procedure after some modification (Singleton & Rossi,
1965). The absorbance of the samples was determined at 760 nm
using a microplate reader spectrophotometer (Synergy HT, BiotTek
instruments, USA). The equation obtained for the calibration curve
of gallic acid (0.5–100 mg/l) was Y = 0.006X + 0.111 (r = 0.9967).
The results were expressed as milligram gallic acid per 100 g dry
weight (mg GAE/100 g DW).