3.3.2. Antioxidant and color release during dissolution
Guava is a good source of vitamin C and pitaya contains red purple
colored betalain compounds. Both the compounds have potential antioxidant activity. A preliminary study showed that freeze drying techniques had no significant effects on both of these compounds (data
not shown). The release of vitamin C and betalain during dissolution
was assessed by determining radical scavenging activity at 50% (IC50)
as well as by determining the red color value a* (Table 4).