Freeze drying was achieved under vacuum at a low temperature. Besides,
the freeze drying method, provided highly efficient extraction. The
reason for this could originate from the ice crystals in the plant
extract matrix damaged cellular structures, thereby causing intracellular
components of the cells to reach the solvent to help provide
better extraction (Asami, Hong, Barrett, & Mitchell, 2003).
Our results are in agreement with previous studies. The samples
from the FD method had more GSH loss than Cys loss, because
the cellular GSH synthesis was limited due to the availability of
Cys. In addition, GSH, a substrate for oxidative enzymes and nonenzymatic
reductant for free radicals and peroxides, is a very active
antioxidant (Kleinman & Richie, 2000; Sen & Packer, 2000).