GSH-POD and GR activities of raspberry fruits stored for 8 days
were varied among treatments and storage durations as shown in
Fig. 3. After 8 days of storage, raspberry fruit from 50% Aloe vera gel
treatment had the highest activities. Raspberry fruits from the
control and 25% Aloe vera gel treatment had lower activities
compared with those from 25% to 75% Aloe vera gel treatment. After 8 days' storage, samples from the control treatment had the lowest
GSH-POD and GR activities. In this study, both GR and GSH-POD
activities reduced in raspberry fruits stored for 8 days. GR
enzyme activity first increased during the storage period, and then
reduced after 8 days of storage. 50% Aloe vera gel had the highest GR
activity. GR is a ubiquitous NADPH dependent enzyme. It adds
hydrogen ion to the oxidized glutathione to regenerate reduced
glutathione. In contrast, GSH-POD activity reduced during the
storage period. This enzyme utilizes reduced glutathione to eliminate
hydrogen peroxide and convert it to harmless water. The activity
of GSH-POD is dependent on the availability of the reduced
ascorbate and GSH that are maintained by enzymes, such as GR
using NADPH as an electron donor (Roxas, Lodhi, Garrett, Mohan, &
Allen, 2000).
3.7.2. Superoxide dismutase