Red Pitaya Peel Research Articles

Purification and characterisation of a novel amylase enzyme from red pitaya (Hylocereus polyrhizus) peel

An amylase enzyme from pitaya peel was purified 234.2-folds with 72.1% recovery using ammonium sulphate precipitation, gel filtration and ion exchange chromatography. Gel filtration chromatography and SDS–PAGE revealed that the enzyme is monomeric with a molecular weight of 42.1kDa. The apparent Km and Vmax of the amylase were 2.7mg/ml and 34.30u/min/mg of protein, respectively. The enzyme was highly active and stable over a wide pH range from pH 3 to pH 11.0, with optimum activity being observed at pH 5.0. The enzyme was highly selective for soluble starch, amylopectin, glycogen and pulullan. The purified amylase did not require calcium and displayed extreme stability with regard to surfactants and oxidising agents. EDTA, a powerful chelating agent, did not have any significant effect on the stability of the enzyme. Such characteristics have not been previously reported for this type of enzyme from fruit peel. This enzyme, which possesses unique properties, could be widely used in different types of industries, especially in food and biotechnological applications.

A novel aqueous two phase system composed of a thermo-separating polymer and an organic solvent for purification of thermo-acidic amylase enzyme from red pitaya (Hylocereus polyrhizus) peel.

The purification of thermo-acidic amylase enzyme from red pitaya (Hylocereus polyrhizus) peel for the first time was investigated using a novel aqueous two-phase system (ATPS) consisting of a thermo-separating copolymer and an organic solvent. The effectiveness of different parameters such as molecular weight of the thermo-separating ethylene oxide-propylene oxide (EOPO) copolymer and type and concentration of organic solvent on the partitioning behavior of amylase was investigated. In addition, the effects of phase components, volume ratio (VR), pH and crude load of purification factor and yield of amylase were evaluated to achieve the optimum partition conditions of the enzyme. In the novel ATPS method, the enzyme was satisfactorily partitioned into the polymer-rich top phase in the system composed of 30% (w/w) EOPO 2500 and 15% (w/w) 2-propanol, at a volume ratio of 1.94 and with a crude load scale of 25% (w/w) at pH 5.0. Recovery and recycling of components was also measured in each successive step of the ATPS process. The enzyme was successfully recovered by the method with a high purification factor of 14.3 and yield of 96.6% and copolymer was also recovered and recycled at a rate above 97%, making the method was more economical than the traditional ATPS method.

Optimization of Extraction of Novel Pectinase Enzyme Discovered in Red Pitaya (Hylocereus polyrhizus) Peel

Plant peels could be a potential source of novel pectinases for use in various industrial applications due to their broad substrate specificity with high stability under extreme conditions. Therefore, the extraction conditions of a novel pectinase enzyme from pitaya peel was optimized in this study. The effect of extraction variables, namely buffer to sample ratio (2:1 to 8:1, X1), extraction temperature (−15 to +25 °C, X2) and buffer pH (4.0 to 12.0, X3) on specific activity, temperature stability, storage stability and surfactant agent stability of pectinase from pitaya peel was investigated. The study demonstrated that the optimum conditions for the extraction of pectinase from pitaya sources could improve the enzymatic characteristics of the enzyme and protect its activity and stability during the extraction procedure. The optimum extraction conditions cause the pectinase to achieve high specific activity (15.31 U/mg), temperature stability (78%), storage stability (88%) and surfactant agent stability (83%). The most desirable conditions to achieve the highest activity and stability of pectinase enzyme from pitaya peel were the use of 5:1 buffer to sample ratio at 5 °C and pH 8.0.

Características físico-químicas e atividade antioxidante total de pitaias vermelha e branca

This study aimed at evaluating the physicochemical characteristics and the total antioxidant activity (TAA) of the red and white pytaias peel and pulp. Centesimal composition, vitamin C, total phenolics and TAA were determined in pitayas pulp and peel samples. TAA was determined by using two methodologies: β-carotene/linoleic acid system and free DPPH radical for scavenging activity. Both the pitayas peels and pulps showed high moisture content and low protein and lipid contents. The total food fiber and ashes contents were significantly higher in pitayas peels, and the highest glucide contents and of energy were found in the pulps. The average contents of vitamin C ranged from 17.73 to 20.69 (mg.100 g-1) in pulps and from 22.21 to 24.05 (mg.100 g-1) in peel samples. The red pitaya peel showed the lowest total phenolics contents (77.22 mg EAG.100g-1). The pitayas samples demonstrated a high TAA in beta-carotene/linoleic acid system methodology and low TAA by DPPH. The red pitaya showed the highest TAA values, especially in pulp samples. The antioxidant and the chemical characteristics of the red and white pitayas may contribute to a beneficial diet for human health.

Comparative Antioxidant and Antiproliferative Activities of Red and White Pitayas and Their Correlation with Flavonoid and Polyphenol Content

Pitaya, commonly known as dragon fruit, has generated considerable consumer interest because of its attractive color and micronutrient content. The present study investigated the total polyphenol and flavonoid content, antioxidant activity against various free radicals, and antiproliferative effect on several cancer cell lines of extracts of flesh and peel of white and red pitayas, collected from Jeju Island, Korea. The total polyphenol and flavonoid contents of 80% methanol extracts of red pitaya peel (RPP) and white pitaya peel (WPP) were approximately 3- and 5-fold higher than those of red pitaya flesh (RPF) and white pitaya flesh (WPF), respectively. Overall, the total flavonoid and polyphenol contents of these extracts were RPP>WPP>RPF>WPF and WPP>RPP>RPF>WPF, respectively. In addition, a study involving nontargeted high-performance liquid chromatography coupled with a photodiode array and electrospray ionization mass spectrometry (HPLC-PDA-ESI-MS) of different pitaya extracts indicated the presence of phenolic, hydroxycinnamic acid derivatives, flavonol glycosides, betacyanin, and its derivatives with a few unknown compounds. Separately, peel extracts of both red and white pitayas showed higher 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, and alkyl radical-scavenging activity than did the corresponding flesh extracts. Both peel extracts also showed stronger antiproliferative activity against AGS and MCF-7 cancer cells than either flesh extract. There was a direct correlation between the phenolic content and antioxidant effect, but no correlation observed between antioxidant activity and antiproliferative activity. These results suggest that the peel of white and red pitaya may be a valuable ingredient in foods and may also be useful in cosmetic, nutraceutical, and pharmaceutical applications.

Antioxidant and antiproliferative activities of red pitaya

The red pitaya, rich in micronutrients, has recently generated a great deal of consumer interest, therefore, this paper was designed to study the total phenolic content, antioxidant activity and antiproliferative activity of red pitaya on melanoma cells and to determine if it is a valuable source of antioxidants and an anticancer agent. The total phenolic contents of flesh (42.4 ± 0.04 mg of gallic acid equivalents (GAE)/100 g of flesh fresh weight) and peel (39.7 ± 5.39 mg of GAE/100 g of peel fresh weight) were similar. The flavonoid contents of flesh and peel did not vary much (7.21 ± 0.02 mg vs. 8.33 ± 0.11 mg of catechin equivalents/100 g of flesh and peel matters). The concentrations of betacyanins expressed as betanin equivalents per 100 g of fresh flesh and peel were 10.3 ± 0.22 and 13.8 ± 0.85 mg, respectively. The antioxidant activity, measured by the DPPH method at EC 50, was 22.4 ± 0.29 and 118 ± 4.12 μmol vitamin C equivalents/g of flesh and peel dried extract; the values of EC 50, determined by the ABTS + approach, were 28.3 ± 0.83 and 175 ± 15.7 μmol of trolox equivalents antioxidant capacity (TEAC)/g of flesh and peel dried extract, respectively. The antiproliferative study on B16F10 melanoma cells revealed that the peel (EC 50 25.0 μg of peel matter) component was a stronger inhibitor of the growth of B16F10 melanoma cancer cells than the flesh. The results indicated that the flesh and peel were both rich in polyphenols and were good sources of antioxidants. The red pitaya peel fulfilled its promise to inhibit the growth of melanoma cells.