Since there is a growing consumer awareness on the safety, and health issues concerning the use of food and natural health products which includes nutraceuticals, food supplements, cosmeceuticals, and among others, there is a need to establish the qualitative and quantitative values that carry an assurance of quality, efficacy, safety, and reproducibility of raw materials in the product development. Notably, literature suggests that geographical locations have considerable impact on the levels of phytochemicals, proximate nutrients, selected minerals and conversely their biological activities
2, 2-diphenyl-1-picrylhydrazyl (DPPH), 1,10-phenanthroline monohydrate, ferric chloride and ascorbic acid were obtained from Sigma-Aldrich (Germany/USA). All other chemicals were of analytical grade and supplied from other commercial sources.
An approximate of 30 kilograms of
The physicochemical characteristics of powdered peel and extract were determined as per WHO guidelines
The peel crude extract was qualitatively tested to reveal the presence of phytochemical constituents such as alkaloids, coumarins, flavonoids, phenols and triterpenoids. These were identified by characteristic color changes (chemical-based) using previously reported procedure
Analyses on proximate, heavy metal, mineral and vitamin composition of
Antioxidant radical scavenging activity was determined by DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The assay was performed as previously described
The ferric reducing capacity (FRC) assay is based on the formation of FeIII-(Phen)3 complex and its disruption in the presence of reducing agents
All analyses for antioxidant activities (DPPH and FRC assays) were carried out in triplicates and data reported are mean ± standard deviation (SD). All statistical analyses including computation of IC50 values were performed using GraphPad Prism 9.0.
Parameter |
Peel Powder |
Methanol Peel Extract |
Color |
Dark pink |
Red purple |
Appearance |
Fibrous powder |
Gummy |
Odor |
Indistinct |
Indistinct |
Taste |
Acidic |
Acidic |
pH |
5 |
4.8 |
Specific gravity |
--- |
1.1361 |
Moisture content |
67.2 mg/g |
--- |
Ash content |
147 mg/g |
--- |
Aqueous solubility |
Very slightly soluble |
Freely soluble |
The peel powder’s water solubility is a consideration in establishment of a suitable formulation strategy in product development. Peel powder was very slightly soluble (1:1000-10000) to water while the peel crude extract was freely soluble (1:1). The peel powder’s low moisture content implies its stability for a longer period and less susceptibility to microbial contamination
The presence of constituents such as alkaloids, coumarins, flavonoids, phenols, and triterpenoids in
Phytochemical |
Test |
Result |
Alkaloid |
Wagner |
+ |
Phytosterols |
Libermann-Burchard |
- |
Tannins |
Ferric Chloride |
- |
Phenols |
Lead acetate |
+ |
Flavonoids |
Alkaline reagent |
+ |
Coumarins |
10% Sodium hydroxide |
+ |
Saponins |
Froth |
- |
Quinones |
Sulphuric acid |
- |
Cardiac Glycosides |
Keller-Killani |
- |
Triterpenoids |
Salkowski |
+ |
Anthraquinones |
2% HCl |
- |
Steroids and Phytosteroids |
Chloroform + sulphuric acid |
- |
In parallel with the increasing interest in the health benefits of
On the other hand, the crude protein content of the dragon fruit peel which is 42.8 mg/g may be useful in food formulation systems
Composition |
Amount per 1 gram |
Crude Protein (Nx6.25) |
42.8 mg |
Total Fat |
5.26 mg |
Saturated Fat |
2.26 mg |
Total Carbohydrate |
738 mg |
Total Sugar |
37.3 mg |
Total Dietary Fiber |
632 mg |
Food Energy |
317 Kcal/100g |
Minerals |
Amount per 1 gram |
Calcium |
9.56 mg |
Magnesium |
3.79 mg |
Sodium |
0.83 mg |
Iron |
0.023 mg |
Potassium |
54.4 mg |
Manganese |
0.11 mg |
Vitamin C |
49 mg/kg |
As secondary antioxidant,
The
The authors gratefully acknowledge the research fund and support provided by the Commission on Higher Education of the Philippines and the Mariano Marcos State University.