# Nutritional Analysis of Red-Purple and White-Fleshed Pitaya (_Hylocereus_) Species
## 1 Introduction  
Pitaya, known as dragon fruit, belongs to the genus _Hylocereus_ of the _Cactaceae_ family. The species is native to southern Mexico, the Pacific side of Guatem and Costa Rica, and El Salvador. There are three species in the genus _Hylocereus_. These are _Hylocereus guatemalensis (Hg)_, _Hylocereus polyrhizus (Hp)_ and _Hylocereus undatus (Hu)_. These species and their hybrids are grown commercially worldwide [1, 2]. There are distinct morphological differences in stem, flower and fruit characters in the genus _Hylocereus_ spp. [3]. The fruit is white, crimson, or dark red, or pale yellow, depending on the variety, andthe flesh is interspersed with small black seeds [4]. \(Hp\) is the common red-fleshed species and known to be a super fruit with high antioxidant capacity due to its dark red flesh. The fruit is highly decorative, with a bright red skin adorned with green scales. \(Hu\) is a vine-like cactus commonly grown as a nocturnal ornamental and fruit crop. The fruit is highly decorative, with a bright red skin adorned with green scales. The flesh is white, juicy and delicious [3; 5]. Pitaya fruits are consumed fresh or processed into juice, jellies, marmalades, jams, wine and beverages [6; 7; 8]. Fifteen years ago, pitaya was practically unknown but today is popular in the European market and in the global market, including Vietnam, Colombia, Mexico, Costa Rica, the USA (Florida and California) and Nicaragua [9]. Pitaya is considered a new and promising fruit. Australia, India, Thailand, Taiwan, Malaysia, the Philippines, Indonesia, Israel, and Turkey have begun to grow it [10; 11; 12] and it has been commercialized and consumed in many parts of the world [13; 14; 15]. Pitaya has great potential as a new crop for Mediterranean growers: it consumes little water, and it adapts well to the high temperatures present in the greenhouse. Moreover, the market shows increasing demand for new, healthy exotic fruits, and the fruit of these crops are worldwide appreciated as a super fruit. Fruit quality is a term that denotes a degree of excellence, a high standard or value, for both the producer and the consumer. These distinctive quality features are contributed to by color, appearance, taste-aroma (flavor) and nutritional values. There are a few studies on this subject in pitaya fruit. Volatile compounds and primary metabolites are important indicators of fruit quality and flavor that play an important role in determining product acceptability by consumers. Consumers determine their preferences according to these features [12; 16; 17]. Increasing awareness of the benefits of plant products to ensure adequate intake of macronutrients, dietary fiber, vitamins, micronutrients and phytochemicals that are very important to human health is increasingly widespread among the population. It has been reported that pitaya, which is very rich in bioactive substances such as betacyanins, phenolic compounds, polysaccharides and terpenoids, can be consumed as a preventive agent against cancer, obesity, type 2 diabetes and other metabolic disorders [18; 19; 20]. Recently, the identification and content of these phytochemicals in different plant products are of great importance due to their various positive effects on human health. Last decade, with the increasing death rate resulting from cancer, cardiovascular and heart diseases, more epidemiological studies have suggested that the healthy food and fruits may decrease the risk of these diseases. Since pitaya does not contain cholesterol, saturated fat or trans-fat, it helps in regulating blood pressure and keeping cholesterol under control when consumed regularly. In addition, due to the high fiber content, it is easier to remove toxic substances from the body and the blood sugar level is kept in balance [21; 22; 23; 24]. In recent years, there has been great interest in using natural antioxidants, including fruits, in preventive medicine and in the food industry [12; 17].