Abstract
Pitaya (Hylocereus undatus Britt. et Rose) is in the Cactaceae family and is native to and and semiarid regions. Pitaya fruits have 17-19° Brix and are a good source of minerals, glucose, fructose, dietary fiber and vitamins. They are normally consumed fresh or preserved in jams, syrups, or candies, and their juices can be used as a drink base with other beverages or used in flavorings and food colorings. Because pitaya can withstand prolonged drought, it is considered to be a potential economic crop for semiarid regions. Soluble solids and enzyme activities in the core part, stylar-end, and peripheral part of the fruit were determined for varieties Vietnam (white flesh) and Hsian Lung (red flesh). The predominant sugars in the fruit are glucose and fructose. The patterns of sugar distribution in various parts were closely related to invertase activity and amylase activity in the tissues. The high ratio of glucose to fructose was attributed to the hydrolysis of starch by amylase.
