Effect of Drum Drying on Physico-chemical Characteristics of Dragon Fruit Peel (Hylocereus polyrhizus)

Abstract

Dragon fruit (Hylocereus polyrhizus) peel is high in antioxidants and fiber; however, it is discarded during processing. In this study, changes in physico-chemical properties of dragon fruit peel after drum drying were determined. Ground dragon fruit peel was drum dried at 1 rpm with 2 bar steam pressure, then analyzed for physical, chemical and functional properties. The betacyanin content was twofold higher in drum-dried powder (41.55 mg/g dm) than in a fresh sample (80.21 mg/g dm), yet up to 98.62% of the total phenolic content was retained with a 3.328 mg trolox/g dm reduction in the radical scavenging activity. The density of the powder was 0.1315 g/mL with 51.44% soluble in water. The functional properties determined included water holding capacity (2.523 g water/g sample), oil holding capacity (3.565 g oil/g sample) and swelling capacity (6.233 mL/g). The results of this study indicate that drum-dried dragon fruit peel can be considered to contain potentially functional ingredients.

Dietary Fibers from Fruits and Vegetables and Their Health Benefits via Modulation of Gut Microbiota

“…The WHC of IDF from grapefruit was higher than that from orange, lemon, gonggan, and ponkan (Wang et al, 2015a). DF from pineapple by-product showed a higher WHC (14.6 g/g) than that from mango, guava, and passion-fruit by-products, while DF from mango had the lowest WHC (6.4 g/g) (Martínez et al, 2012). WHC is one of the most important physicochemical properties of DFs and influences food processing and their physiological characteristics in vivo.…”

“…The OHC of IDF from citrus fruit peel was 3.6 to 8.2 g/g (Table 1), and the IDF from grapefruit peel exhibited the highest OHC among gonggan, grapefruit, lemon, orange, and ponkan (Wang et al, 2015a). The OHC of DFs from mango, guava, pineapple, and passion-fruit by-products was 0.7 to 1.6 g/g (Martínez et al, 2012), while that of purple potato was 16.8 g/g (Xie et al, 2017a). Thus, DF from purple potato has a higher OHC than that from citrus-fruit peel and exotic fruit by-product.…”

“…The IDF content of citrus fruit peels (orange, grapefruit, lemon, gonggan, and ponkan) is 48.5% to 50.3%, while that of SDF is 12.9% to 14.1% (Wang et al, 2015a). The IDF and SDF contents (Table 1) of tropical exotic fruits (mango, passion fruit, pineapple, and guava) by-products vary markedly (Martínez et al, 2012). In general, the IDF and SDF contents of different fruits/vegetables vary depending on the source and part.…”

Physicochemical properties of dragon fruit peel pectin and citrus peel pectin: a comparison

“…In this study, OHC of dragon fruit peel (2.18) is higher compared to citrus peel pectin (2.083), signified higher pectin content (Rubio-Senent et al, 2015). The possible explanation for this dissimilarity is due to the difference in their chemical and physical structure and polysaccharides (Chia and Chong, 2015). Pectin with higher OHC is widely used as an emulsion in beverages (Dona, 2019) and in soups, baked goods and as an extender in meat (Izalin et al, 2016).…”

“…Such waste is also abundant, according to literatures, with beneficial compounds like flavonoids and pectin (Hashim, 2018) (Ismail et al, 2012;Muhammad et al, 2014). Dragon fruit peel consists mainly of pectin (10.79%), betacyanin pigments (150.46/ 100g db) and a total dietary fibre of up to 69.3% (Chia and Chong, 2015). Commercial pectin has been most prevalently derived from apple pomace and citrus peel and the use of dragon fruit waste to produce value-added ingredients such as pectin has a huge potential.…”