Original Article
Antioxidant capacity of underutilized Malaysian Canarium odontophyllum (dabai) Miq. fruit

https://doi.org/10.1016/j.jfca.2010.04.008Get rights and content

Abstract

This study aimed to evaluate the antioxidant capacities of various parts of the dabai (Canarium odontophyllum Miq.) fruit. The antioxidant capacities of C. odontophyllum were evaluated using a β-carotene bleaching assay, ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. Total phenolic content of the dabai fruit was estimated using the Folin–Ciocalteu method. The antioxidant capacities ranked in the following order: skin > flesh + skin > flesh > kernel. Our findings show that a high correlation exists between total phenolic content and total antioxidant activity. This indicates that phenolic compounds could be the major contributors to the antioxidant capacity of C. odontophyllum fruit. Therefore, dabai fruit, especially the skin, can be recommended as a major source of natural antioxidants.

Introduction

Extensive studies have recently been performed on natural antioxidants in fruits, vegetables, seeds, cereals, aromatic plants, teas and wines worldwide (Hsu et al., 2006, Kusznierewicz et al., 2008, Li et al., 2008). In vitro and in vivo experiments have revealed that antioxidants have substantial effects on the prevention of atherogenesis and cellular damage, with the capacity to act as anti-tumor, anti-inflammatory and anti-allergy agents (Crozier et al., 2009). Thus, it is important to discover additional natural sources of antioxidant activities in fruits and vegetables because synthetic antioxidants such as butylated hydroxyanisole (BHA) and buthylated hydroxytoluene (BHT) are suspected to be carcinogenic (Christian et al., 1998).

Southeast Asia possesses a wealth and variety of commercial tropical fruits such as durian, rambutan, mangosteen, mango and banana. Although a wide selection of indigenous fruits is available, some are still growing in the wild or in a semi-cultivated state. These fruits are classified as underutilized or under-exploited fruits due to the lack of promotion, minimal planting area and having an economic potential which has not been fully explored (Chai et al., 2008, Hainida et al., 2009). Canarium odontophyllum Miq. is one of the Malaysia's underutilized fruits. This fruit may serve as a potential source of antioxidant compounds. To our knowledge, the nutritional composition of the fruit has only been reported by Voon and Kueh (1999). Thus, this is the first paper reporting on the antioxidant capacity and phenolic content of C. odontophyllum Miq.

C. odontophyllum Miq. is commonly called ‘dabai’ by the people of Sarawak, Malaysia, and is highly nutritious relative to other indigenous fruits (Voon and Kueh, 1999). The fruit of C. odontophyllum are oblong in shape measuring 3.75 ± 0.1 cm in length, 2.4 ± 0.19 cm in diameter and weighing 11.1 ± 1.5 g. The skin of the fruit is light green in color when it is unripe and turns dark purple/black when ripe. The flesh is bright yellow in color with a single three-angled seed. The pulp contributes the bulk of the fruit's weight, comprising 46.3%, while the skin and kernel contribute 9 and 44.5%, respectively. The fruits are highly seasonal and available only during the months of October–December. This fruit is very hard to eat if consumed without soaking it in warm water. Usually, after a few minutes of soaking, the fruit becomes softer and the taste is very creamy when eaten. However, the local people in Sarawak eat the fruit with a little bit of salt or sugar to make it more delicious. Alternatively, the fruit can be processed into a pickle product. The fruit is poor in ascorbic acid but rich in minerals such as potassium (352 mg/100 g), phosphorus (65 mg/100 g), calcium (200 mg/100 g) and magnesium (106 mg/100 g) (Voon and Kueh, 1999). The fruit also contains high levels of protein (3.8%), carbohydrates (22.1%) and fat (26.2%) (Voon and Kueh, 1999). The fat content in this fruit is higher than that of avocados (25%) (Hierro et al., 1992) and olives (23%) (Salvador et al., 2001); cf. also our recent study on dabai fatty acid compared with olive and palm oils, Azlan et al., 2010.

Previous works on other Canarium species have revealed that Canarium has high antimicrobial activity (Obame et al., 2007), analgesic effects (Koudou et al., 2005) and is rich in oleic and linoleic acids (He and Xia, 2007). At present, the antioxidant properties of C. odontophyllum fruit have not been reported elsewhere. Different parts of C. odontophyllum, namely skin, skin and flesh, and flesh and kernel, were chosen in an attempt to make systematic comparisons among their antioxidant capacities and to identify the fraction with high antioxidant activity for further studies. In addition, correlations between total phenol content and antioxidant capacity were also evaluated.

Section snippets

Fruit sample

Fresh C. odontophyllum Miq. (dabai) fruits were obtained from the Agriculture Research Centre, Semongok, Sarawak, Malaysia during the month of November, 2008. The herbarium voucher specimens (S 64872) were identified and deposited in the Agriculture Research Centre, Sarawak, Malaysia. The fruits were packed in an ice box and transported on the same day to Peninsular Malaysia by flight and delivered to Universiti Putra Malaysia. Upon their arrival, and fruits without any physical damage were

Total phenolic content

The phenolic compounds found in fruits and vegetables have received substantial interest because of their potential antioxidant benefits. Phenolic compounds undergo a complex redox reaction with the phosphotungstic and phosphomolybdic acids present in the Folin–Ciocalteu reagent. However, it should be noted that some chemical groups of amino acids, proteins, organic acids, sugars and aromatic amines could also react with this reagent (Huang et al., 2005, Prior et al., 2005). The total phenolic

Conclusions

In the present study, three methods have been used to determine the antioxidant capacity of various parts of the dabai fruit (C. odontophyllum Miq.). A similar observation was found indicating that antioxidant activity exists in the order of skin > skin and flesh > flesh > kernel. Similarly, the same trend was also observed for the order of total phenolic content. Skin exhibited the strongest antioxidant capacity with the highest total phenolic content. In addition, phenolic compounds are often the

Acknowledgements

The financial support of Research University Grant Scheme (RUGS) from Universiti Putra Malaysia (Vote No. 91059) is gratefully acknowledged. The authors also acknowledge the assistance of laboratory staffs from the Department of Nutrition and Dietetics, UPM throughout the research project. They also extend their thanks to Universiti Putra Malaysia for the use of laboratory facilities.

References (39)

Cited by (0)

View full text