What are the nutrition, functions and product development of red dragon fruit?

Dragon fruit (Britt), also known as red dragon fruit, green dragon fruit, etc., belongs to the cactus family Triangular column genus (also known as the measuring tape genus) plants, in China, Guangxi, Fujian, Hainan, Guangdong, Guizhou and other places are planted. According to the color of the fruit skin and fruit can be divided into three categories: red skin and white heart, red skin and red heart and yellow skin and white heart, among which red skin and white heart and red skin and red heart series are the best.
Red heart dragon fruit and white heart dragon fruit nutrient comparison
Dragon fruits are rich in nutrients, containing not only carbohydrates and proteins, but also a large number of polyphenols, anthocyanins, beet red pigment, dietary fiber, vitamins, etc., and the red-skinned red-centered dragon fruits are richer in nutrients than the red-skinned white-centered dragon fruits (see Table 1). Although the amino acid content of red-skinned red heart dragon fruit is slightly lower than that of red-skinned white heart dragon fruit, its essential amino acid ratio is better than that of red-skinned white heart dragon fruit.
Functional properties of red heart dragon fruit active substances
2.1 Antioxidant effect of red heart dragon fruit pulp has antioxidant capacity, and the antioxidant capacity of different components of which is ranked beet red pigment > flavonoids > phenols.
2.2 Whitening, fat-lowering and weight-loss effects Dragon fruit is rich in skin whitening vitamin C, and its vitamin C content is similar to that of bananas, peaches, jujube
The content of vitamin C is similar to that of banana, peach, date and other fruits. At the same time, dragon fruit is also rich in water-soluble dietary fiber, so it has whitening the skin, weight loss, lowering blood sugar, laxative, prevention of colorectal cancer and other physiological functions.
2.3 Antidiabetic effect of red dragon fruit beet red pigment can improve high-fat diet-induced glucose intolerance and insulin resistance, its fasting blood glucose, insulin levels, insulin resistance index (insulin resistance, HOMA-IR) than the high-fat diet group decreased significantly, the insulin secretion index (insulin sensitive index, HOMA-IS) than the high-fat diet group decreased significantly, the insulin secretion index (HOMA-IS) than the high-fat diet group. HOMA-IS) increased compared with the high-fat diet group.
2.4 Preventing vascular sclerosis, lowering blood pressure effect of full red heart dragon fruit fresh fruit or extracted beet red pigment can effectively reduce the index of atherosclerosis, reduce the thickness of the aortic mid-membrane, repair the arterial endothelial layer, play a protective role of blood vessels, the prevention and treatment of coronary heart disease has a very important significance.
Red heart dragon fruit contains anthocyanins can also effectively prevent vascular sclerosis, thus preventing heart attack and blood clot formation caused by stroke.
2.5 Detoxification, detoxification, protect the stomach lining
Red heart dragon fruit is rich in general fruits and vegetables less plant albumin, the content of which can reach 13 g / kg. This active albumin not only has a strong antioxidant effect, but also automatically with the body of heavy metal ions combined with the excretory system out of the body, so as to play a role in detoxification. In addition, albumin has a protective effect on the stomach lining.
2.6 Prevent anemia
The iron content in red dragon fruit is higher than the general fruit, its iron content can reach 4 mg/kg, while its vitamin C can also promote the body’s absorption of iron, intake of appropriate amount of red dragon fruit can help prevent anemia.
Product development of red dragon fruit
Based on the above description of the functional properties of the active substances of red dragon fruit, it can be seen that its rich nutritional value, so that it has great development value in the field of health food and medicine.
Deep processing of red dragon fruit as the main raw material can further increase the added value of its products, which is very beneficial to the promotion of social and economic development.
3.1 Fruit Juice Beverage
Luo Jin et al. optimized the enzymatic conditions of red heart dragon fruit, when the pectinase addition of 285U/g, enzymatic temperature of 46 ℃, substrate pH value of 3.7, enzymatic time of 2h, the retention rate of beet red pigment in the dragon fruit can reach 80.8%, and the juice rate can reach 64.4%.
Red hearted dragon fruit juice contains spoilage microorganisms, which is very easy to cause juice deterioration during storage, and the common heat sterilization is easy to cause loss of heat-sensitive nutrients and browning in the product, the researchers used the technology of ultrasonic co-pasteurization to effectively retain the nutrients in the juice and improve its antioxidant property.
LEE FS et al. found that the retention of beet red pigment can be improved by juice concentration and the sensory acceptability can be enhanced.
3.2 Fruit Wine
Fruit wine is a low-alcohol beverage made from fermented fruits, which retains the original nutrients and flavor of the fruits. The yeast used for fermentation can be either commercial or natural.
Li Kai et al. screened a strain of brewer’s yeast from more than 200 strains isolated from the surface of a variety of berries, and the fermentation conditions were 22°Bx for dragon fruit juice and 25°C for 7d, which could brew dragon fruit wine with an elegant aroma and a harmonious taste with an alcoholic precision of 11.75%vol.
YUAN Xingxing et al. used their isolated natural yeast strains, 20 ℃ fermentation for 6d alcohol can reach more than 10%vol.
CHOO K Y et al. studied the changes of beet red pigment during storage of dragon fruit wine, indicating that the degradation of beet red pigment is affected by temperature and time, and the lower the temperature, the better the retention, and the beet red pigment can still be retained by more than 80% for 8 weeks of storage at 4℃.

3.3 Fruit vinegar
Fruit vinegar has higher nutritional value, health care function, and flavor and taste than vinegar, and the market scale of the industry is increasing year by year.
Lu Min et al. studied the fermentation process of red heart dragon fruit as 8%vol of initial alcohol, pH4.0, 10% inoculation of acetic acid bacterial strain LB1, fermentation temperature of 30℃, 180r/min constant temperature fermentation for 7d, and used self-absorption oxygen supply to carry out the amplification test of 30L fruit vinegar fermentation tank, and the final acidity reached 6.34g/100 mL.
Yuan Shijie et al. blended the red heart dragon fruit fruit vinegar, and under the process conditions of 8% addition of original fruit vinegar, 3% addition of white granulated sugar and 1% addition of xylitol, the resulting red heart dragon fruit vinegar beverage had an organoleptic score of 86 points, the total acid content of 5.6 g/L, and the soluble solids content of 5.4%.
3.4 Others
Li Li et al. investigated the optimal formulation of curdled dragon fruit yogurt as lactic acid bacteria inoculation of 0.27%, fermentation time of 7.7h, fermentation temperature of 40℃, and sugar addition of 8.8%.
Sun Xuejiao et al. prepared dragon fruit yogurt according to the ratio of 12% dragon fruit juice, 11% white sugar, and 2% Lactobacillus plantarum inoculum fermented at 37°C for 19h. The enzyme made by fermentation of dragon fruit as raw material increased the content of organic acids and polyphenols compared with the raw material, and the antioxidant capacity and reducing power were improved.
The red dragon fruit has high nutritional value and good health care function, in addition to this it was also made into a variety of products such as red dragon fruit juice rolls and cookies.
Outlook
The anthocyanins and beet red pigments in red dragon fruit are easily affected by temperature and time, how to maximize the maintenance of flavor substances and nutrients of dragon fruit raw materials during processing is the difficulty and focus of its deep processing.
At the same time, dragon fruit skin and seeds also have high nutritional value. Research shows that the antioxidant active ingredients of dragon fruit peel, such as phenols, flavonoids, beet red pigment content is higher than the pulp, and has an inhibitory effect on the growth of melanoma cells. Dragon fruit seeds are rich in linoleic acid, linolenic acid and other unsaturated fatty acids, oleic acid content of up to 20% or more.
The skin of dragon fruit is often discarded during generation and processing, so the comprehensive development and utilization of dragon fruit can reduce environmental pollution and improve the economic value of dragon fruit.