Dragon Fruit Assessment Manual
This protocol seeks to provide a standard methodology for the experimentation and assessment of Dragon fruit (Hylocereus undatus (Haw.)) in the collaborative project funded by the New Zealand ADAF project (Vietnam Quarantine Barriers Assignment). This will aid in the exchange of information between New Zealand and Viet Nam, and also within Viet Nam (e.g., between SOFRI, PPD and SIAEP). It also provides a means of standardizing assessment in future research, and may be further revised in order to capture our increasing understanding of Dragon fruit behaviour and quality postharvest.
The manual focuses on the postharvest assessment of the main cultivar currently grown in Viet Nam, ‘Binh Thuan’. This is a white-fleshed fruit, which has small black seeds interspersed throughout the flesh, and a bright red skin when mature at harvest. The fruit is also known by its Vietnamese name, ‘Thanh Long’. This translates as ‘Green Dragon’ – the colour of the flesh when the fruit is immature, coupled with the ‘dragon-like’ appearance of the bracts or scales on its surface – and is the name used locally when purchased in the market. ‘Binh Thuan’ is the principal cultivar/clone grown in Viet Nam and was introduced by the French in the late 1800s. Binh Thuan is also the name of the province in Viet Nam in which the greatest amount of Dragon fruit is produced.
Red-fleshed cultivars (known as Thanh Long ‘Ruot Do’ or red flesh) are also beginning to be grown commercially using planting material imported from countries such as Thailand and Taiwan (see Yen et. al., 2002, and Hoa & Hien, 2002). Limited amounts are available for export and fetch a high price in Asian markets. The assessments in this manual refer specifically to the white-fleshed cultivar, and in most instances, they will be readily transferable to other cultivars. Obviously, difficulties will arise when trying to assess the impact of heat treatments on internal flesh quality, where the intense colouration of the flesh will mask effects such as translucency