Evaluation of Constituents and Physicochemical Properties of Malaysian Underutilized Ziziphus mauritiana (Bidara) for Nutraceutical Potential

ABSTRACT

Ziziphus mauritiana plant also known as Bidara in Malaysia is well-known since ancient for their usage especially in Islamic traditional medicine due to health beneficial effect. However, the nutraceutical potential of this plant remains unrevealed scientifically. Therefore, the aim of the present study was to analyse the proximate composition and to read characteristic like pH, titratable acid (TA) and total soluble solids (TSS) of Z. mauritiana fruit, leaves and seed. Based on the proximate analysis, the highest percentage of ash (9.06%) and crude protein (14.59%) were found in the leaves. Moisture content (88.32%) was the highest in fruit, while the crude fiber (48.12%), fat (1.89%), carbohydrate (63.24%) and calorific value (411.61 kJ) were the highest in the seed. Physicochemical characteristic of Z. mauritiana has shown that the fruit possess the higher value of 11.70°Brix TSS and 0.32% TA than the leaves with 0.97°Brix TSS and 0.09% TA. While the pH of the leaves and fruit are 5.47 and 4.77 respectively. Interestingly, Z. mauritiana plant can be an excellent source of carbohydrate, protein and its fiber. This study suggested that leaves, fruit and seed of Z. mauritiana can find potential applications in food and pharmaceutical product as nutraceutical ingredients.

KEYWORDS:

• Ziziphus mauritiana
• proximate analysis
• physicochemical
• nutraceutical

Introduction

Ziziphus mauritiana comes from a family of Rhamnaceae and is commonly known as bidara by local people in Malaysia. This tree can be found native to warm climate region of Southeastern Asia (Orwa et al., 2009) and can withstand unfavorable condition such as salinity, drought and water-logging which making it susceptible to grow in various type of soil (Orwa et al., 2009). However, this fast-growing tree can form dense stands and have been globally classified as a weed by Global Compendium of Weed (Randall, 2007, September 13). This hardy tree has drooping branches with stipular spines and usually grew up to 15 m tall with trunk 40 cm or more in diameter (Orwa et al., 2009). Z. mauritiana leaves has tip rounded or slightly notched base. The leaves have a shiny green color above and whitish color below (Orwa et al., 2009). Meanwhile, the fruit has variable shape and sizes depending on the varieties. The local fruit variety has either round or oblong shape. Moreover, the unripe fruit has light green peel color with white crisp flesh and become yellowish peel color with soft white flesh upon ripening. During the unripe stage, the fruit has strong aromatic smell making it more preferable to be consumed compared to fruit at the ripening stage. Furthermore, the seed kernel was located in the middle of the fruit and has a brown tuberculate and irregular furrowed stone with 6 mm long (Orwa et al., 2009).

Bidara leaves, fruit, seed and other parts of the plants had been used as a traditional medicine to treat varieties of diseases and also in traditional rituals. The bidara leaves had been used in cleansing the deceased body by Malay people which had been believed to help soften the body, strengthen the skin and delay the decaying process (Muhammad Yusri et al., 2017). The bidara leaves were also used by Islamic therapeutic centers in Malaysia to treat patients that had been affected with evil spells by bathing the patients with water mixed with the leaves (Ahmad, 2012). The research of ethnomedicinal uses of wild fruit species had reported that Z. mauritiana fruit and leaves were used as a traditional medicine to treat constipation, dandruff (Khan et al., 2015) and jaundice (Kankara et al., 2015). Meanwhile, bidara fruit has a considerable amount of essential nutrients that regular intake of this fruit in the daily diet can decrease the risk of metabolic syndrome, cardiovascular disease (Esmaillzadeh et al., 2006) and chronic diseases (Rui, 2013). Z. mauritiana fruit also being consumed by people of Nigeria during drought season to replenish their nutrients and energy (Lockett et al., 2000). The Z. mauritiana tree was wildly found in the sub-system of rice fields and known to be one of the important wild food source for the poor in the rural area of Northeast Thailand (Cruz-Garcia et al., 2016). The seed extract of Z. mauritiana showed a hypoglycaemic effect on alloxan-induced diabetic mice (Bhatia and Mishra, 2010) and improve lipid composition in the serum of dietary hyperlipidemic animals (Kim, 2002). The seed also can be used to treat diarrhea, nausea and vomiting during pregnancy (Goyal et al., 2012).

However, Z. mauritiana remains as an underutilized plant in Malaysia despite having nutraceutical potential in which can be used as a natural resource in pharmaceutical products. This research will provide information on proximate composition and physicochemical characteristic of Z. mauritiana fruit, seed and leaves from Malaysia.

Materials and Methods

Sample Collection and Preparation

The leaves, fruit and seed of Z. mauritiana (Figure 1) were obtained from 3.7476° N to 101.9794° E. The collected leaves and fruit were thoroughly washed and weighed before separating the seed from the fruit by cutting the fruit. The cleaned leaves, fruit and seed were oven dried at 60°C until constant weight obtained. All the samples were ground separately into fine powders and stored until further analyses.

Figure 1. Ziziphus mauritiana (a) leaves (b) fruit and (c) seed.

Proximate Nutrient Analysis

Proximate composition of moisture, ash, fiber, protein and fat in all samples were carried out according to methods by Association of Official Analytical Chemist (AOAC, 1995). Moisture contents were determined using an oven-drying method which samples were dried at 110°C until constant mass obtained. The percentage of ash was obtained by incinerating the samples in a muffle furnace at 550°C for 5 hours. A Kjeldahl method was used to obtain total nitrogen content while crude protein values were determined using calculation by multiplying with 6.25. Crude fiber value was obtained by digesting the samples with 0.13 M H₂SO₄ and 0.313 M NaOH using Fibrebag system (Gerhardt, UK). The digested samples were then incinerated in a muffle furnace at 600°C for 4 hours and crude fibers were expressed as the percentage of weight loss during ashing. Percentage of fat in samples were analysed using Soxhlet apparatus (Gerhardt, UK) with petroleum benzene at 40°C–60°C. Carbohydrate percentage in the sample was calculated by using the difference method (AOAC, 2000). The sample calorific value (kJ) was estimated by multiplying the percentage of crude protein, crude fat and carbohydrate by the factors 16.7, 37.7 and 16.7, respectively (Aberoumand, 2011).

Physicochemical Analysis

The total soluble solids (TSS) was determined using a hand refractometer (Atago, Model PAL-1) and expressed in Brix° value. The pH value was measured using a laboratory benchtop pH meter (Mettler Toledo EL20). Titratable acidity (TA) was measured by the titrimetric method (AOAC, 1995) and expressed as % malic acid.

Statistical Analysis

All samples were analysed in triplicate and presented as ± SEM (Standard Error Mean). All the results were statistically analysed using Minitab14 software and performed a one-way analysis of variance (ANOVA) for mean differences. The value of p < .05 was considered statistically significant.

Result

The proximate composition (moisture, ash, crude protein, crude fibers, fat, carbohydrate and energy) and physicochemical characteristic (pH, TSS and TA) of Z. mauritiana leaves, fruit and seed are shown in Tables 1 and 2.

Table 1. Proximate composition of Ziziphus mauritiana leaves, fruit and seed.

	Ziziphus mauritiana
Nutritional composition (%)	Leaves	Fruit	Seed
Moisture	55.45 ± 0.50^b	88.32 ± 0.13^a	29.42 ± 1.29^c
Ash	9.06 ± 0.02^a	2.77 ± 0.13^b	0.35 ± 0.06^c
Crude protein	14.59 ± 0.52^a	6.67 ± 0.05^bc	6.64 ± 0.18^bc
Fat	1.51 ± 0.11^ab	0.45 ± 0.04^c	1.89 ± 0.22^ab
Carbohydrate	19.39 ± 0.16^b	1.97 ± 0.09^c	63.24 ± 1.53^a
Crude fibers	13.89 ± 2.52^b	4.76 ± 0.08^c	48.12 ± 0.71^a
Energy (kJ)	634.13 ± 4.86^b	161.37 ± 2.09^c	411.61 ± 6.58^a

^a-cEach value represent the ± SEM of triplicates on dry weight (DW) basis in percentage (%). The superscript letters in the table indicate the significant differences (p < 0.05) in a same row and analysed by ANOVA-Turkey post hoc test.

Table 2. Physicochemical characteristic of Ziziphus mauritiana leaves and fruit.

	Ziziphus mauritiana
Parameters	Leaves	Fruit
pH	5.47 ± 0.01^a	4.77 ± 0.01^b
Total soluble solid (°Brix)	0.97 ± 0.03^b	11.70 ± 0.15^a
Titratable acid (% malic acid)	0.09 ± 0.01^b	0.32 ± 0.01^a

^a,bEach value represent the ± SEM of triplicates. The superscript letters in the table indicate the significant differences (p < 0.05) in a same row and analysed by ANOVA-Turkey post hoc test.

Moisture content in Z. mauritiana fruit (88.32%) was significantly (P < .05) the highest followed by leaves (55.45%) and seed (29.42%). Meanwhile, Z. mauritiana leaves had the highest amount of ash (9.06%), crude protein (14.59%) and energy (634.13 kJ) as compared to fruit and seed. However, there is no significant difference in crude protein amount found in fruit (6.67%) and seed (6.64%) of Z. mauritiana. The crude fibers content in seed (48.12%) was found to be the highest while the lowest amount was observed in fruit (4.76%) of Z. mauritiana. Carbohydrate in fruit (1.97%) of Z. mauritiana was the lowest compared to the leaves (19.39%) and seed (63.24%). Based on the results in Table 1, the fat content of leaves (1.51%) and seed (1.89%) of Z. mauritiana showed no significant difference. However, the fruit (0.45%) has a lower content of fat compared to the other parts. Based on the physicochemical parameters presented in Table 2, Z. mauritiana fruit possesses significantly (P < .05) higher TSS (11.70 °Brix) and TA (0.32%) value than leaves. Meanwhile, the leaves of Z. mauritiana showed significantly (P < .05) higher pH (5.47) than fruit (4.77).

Discussion

Moisture content in Z. mauritiana fruit was found to be similar to common local fruits found in the market such as orange, watermelon, and pineapple with moisture percentage of 86.8–91.3% (Rotimi et al., 2018). The high content of moisture > 80% in fruit can replenish the water intake of a person when dehydrated. Results also demonstrated that Z. mauritiana fruit has an ascertainable amount of nutrients needed to be developed as a dietary supplement (Abubakar et al., 2017). Ash content is commonly associated with the presence of many mineral compounds which is important in determining the nutritional value. The amount of ash in leaves of Z. mauritiana from Malaysia is significantly similar to Z. mauritiana leaves as reported from Nigeria (El-Ishaq and Nangere, 2016) and also comparable with commonly eaten leafy vegetables of Brasicca oleracea var. capitata (Khan et al., 2013).

Interestingly, the protein content of Malaysian Z. mauritiana leaves is on par of protein content found in leaves of Z. mauritiana grown in Pakistan (Azim et al., 2011). In fact, Bidara leaves can become a good source of protein as it surpassed the protein content found in vegetables consumed by indigenous people in Borneo (Abdul Wahab et al., 2015) and green leafy vegetables in Pakistan (Arasaretnam et al., 2018). The fiber content in leaves of Z. mauritiana obtained is similarly reported by researchers from India and the leaves possess pharmacological properties such as anti-inflammatory, antiulcer and anti-allergic (Gupta et al., 2012). It was shown that the leaves of Z. mauritiana have higher nutritional value compared to indigenous vegetable available in Southern Thailand which contain small to moderate amount of macro-nutrients; protein 1.16–8.79%, carbohydrate 1.25–16.75% and fat 0.08–4.36% (Kongkachuichai et al., 2015). Fiber usually consists of cellulose present in plant parts which is indigestible and passed through the digestive system. In addition, an adequate amount of nutrients content found in bidara leaves can be utilized as an alternative resource for ruminants feed (Azim et al., 2011). The high content of fibre in Z. mauritiana (48.12%) seed compared favourably with level of fibre in Z. spina-christi (31.8%) which is of the same family of Ziziphus (Osman and Asif Ahmed, 2009).

Meanwhile, carbohydrate aid body metabolism by supplying the energy needed. The amount of carbohydrate in Z. mauritiana seed from Malaysia was found to be higher while the crude fat was similarly reported in Z. spina-christi and Z. jujuba seed (Amoo and Atasie, 2012; Abd-Alrahman et al., 2013). Hence, the seed can be a great source of energy and fiber needed for body function. Previous research had reported that Z. mauritiana seed oil had abundance of monounsaturated fat with minor component tocopherol sterols (Memon et al., 2012). In fact, monounsaturated fat help lower cholesterol levels and reduce the risk of heart disease. The previous study also found that the seed extract exhibit anti-diabetic and hypnotic effect which have potential to be developed as nutraceutical or pharmaceutical product (Bhatia and Mishra, 2010; Moh et al., 2013).

The pH value (4.77) of Z. mauritiana fruit was in the range as the tropical fruit found in Bangladesh (Ara et al., 2014). The TSS value of the fruit from this study is also in accordance with the range in Z. mauritiana with 12 different genotypes as reported by Koley et al. (2011). However, Z. mauritiana fruit has slightly lower TA value than the range of TA in different genotypes of Z. mauritiana found in Pakistan (Anjum et al., 2018). Generally, the leaves from the plant were expected to have a lower pH value than soil. However, the pH value which is similar to human skin pH finds an advantage to be used as topical treatments. In a recent study by Akhtar et al. (2016), leaves extract of Z. mauritiana was used in emulsion formulation which exhibits cosmeticeutical properties such as anti-ageing, skin lightening and moisturizing on human skin.

Brix° value is associated with sugar content present in sample demonstrated that the low value of TSS in leaves contain less amount of sugar which insusceptible for bacteria growth. In addition, the leaves contain many bioactive compounds and exhibit antimicrobial properties that can be useful in treatments caused by bacterial infections (Abalaka et al., 2010; Ashraf et al., 2015). Meanwhile, low acidity percentage in Z. mauritiana leaves can be seen as the plant can comprehend drought and retain more water than any other plants and also the leaves extract can form a protective layer onto mild steel to decrease corrosion caused by acidity (Shivakumar and Mohana, 2012). The leaves of Z. mauritiana have the potential to be utilized as a natural source for pharmaceutical product and as a natural corrosion inhibitor.

In conclusion, Z. mauritiana leaves accounted for a high amount of protein and minerals which can be an alternative resource for ruminants feed or health supplement. Z. mauritiana plant in Malaysia appeared to be elite plant capable of yielding fruit with high moisture, carbohydrate and energy contents, demonstrating a desirable amount of energy needed for body metabolism. Furthermore, Z. mauritiana seed’s high fat and fiber content can be further utilized as a natural resource for nutraceutical and pharmaceutical product to decrease the dependable on the artificial product. The present findings demonstrated that Z. mauritiana has performed as a high-value medicinal plant with many potentials to be discovered. Therefore, identification of phenolic compound and biological activities present in Malaysian species of Z. mauritiana are need to be further investigated.

Acknowledgments

The author would like to thank the Laboratory of FAMTech, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia and staff of Laboratory of Nutrition, Faculty of Veterinary Medicine, Universiti Putra Malaysia for their help during the research work. Special thanks to Mr Lim Chin Khee, the owner of the farm for providing the sample used for this research. Lastly, I would also give my appreciation to all the people who had contributed to this research project.

Additional information

Funding

The author would like to thank the Universiti Putra Malaysia for providing the research fund (Geran Putra – IPS 9519400) and facilities in order to carry out this research work.