https://orcid.org/0000-0002-9404-2783
ABSTRACT
Wild fruits, directly or in combination with other foodstuff, are used by many people living in the rural regions of tropical countries to address food and income insecurity. The composition of wild fruits needs to be analyzed and compared with the composition of other traditional fruits. In the present study, we investigated the nutritional status of fruits of two wild species (eight populations) of Ziziphus mauritiana (ZM) and Z. nummularia (ZN) from the different locations of Northwest India, which were denoted as ZM-1, ZM-3, ZM-11, ZN-4, ZN-5, ZN-10, ZN-13, and ZN-14 depending on species and location. ZM-3 emerged the highest moisture content while ZM-11 showed the highest ash content. ZN-14 presented the highest crude fiber and vitamin C contents. ZN-13 exhibited the highest crude fiber content. The concentration of potassium (2456.250 ± 36.044 mg/100 g), sodium (139.257 ± 2.575 mg/100 g), copper (6.733 ± 0.097 mg/100 g), and zinc (2.223 ± 0.085 mg/100 g) was found to be highest in Z. mauritiana, and the amount of calcium (428.350 ± 2.037 mg/100 g), magnesium (110.947 ± 1.086 mg/100 g), iron (9.657 ± 0.244 mg/100 g), manganese (2.623 ± 0.067 mg/100 g), and zinc (2.223 ± 0.085 mg/100 g) was highest in Z. nummularia. Results provide an indication of the nutritional value of the wild edible fruits of Ziziphus mauritiana and Z. nummularia from different populations and can be used to promote these wild fruits for domestication.
Introduction
Ziziphus Mill. is a highly economic genus of the family Rhamnaceae Juss. (buckthorn family), distributed all over the world with about 100 species (Abalaka et al., Citation2010), of which 17 are native to India (Singh et al., Citation2000). The genus is characterized by distinct triplinerved leaves and spinous stipules (Shu, Citation2007). In Northwest India, three species are reported, of which two species, Z. mauritiana Lam. and Z. nummularia (Burm) Wight & Arn, are studied presently. Z. mauritiana, commonly called ber, has some unique characters like, glabrous leaves that are pubescent beneath. Z. nummularia, commonly called wild jujube, is characterized by densely velvety leaves which are tomentose beneath (Shu, Citation2007). The fruits of Z. mauritiana are highly nutritious and are a rich source of carbohydrates, minerals, vitamins, etc., and soluble sugars, like fructose, glucose, rhamnose, sorbitol, and sucrose were reported (Li et al., Citation2007). Z. mauritania contains a high amount of sodium, zinc, iron, and copper and a good amount of vitamin C, riboflavin, and thiamine (Pareek, Citation2013). Economically, the leaves of Z. mauritiana are eaten by cattle, camels, goats, etc. from which they obtain minerals useful for their health (Morton, Citation1987). The fruits, leaves, seeds and bark of the Z. mauritania have been commonly used as a source of traditional medicine (Abdel-Zaher et al., Citation2005; Belford, Citation1994; Croueour et al., Citation2002; Li et al., Citation2005). The fruits of Z. nummularia are used as an astringent, appetizer and also against stomachache, mucous, and increase biliousness effect (Oudhia, Citation2003). The recent studies showed that the fruit of Z. Jujuba Mill. has multiple bioactivities, such as anticancer (Plastina et al., Citation2012), anti-inflammatory (Yu et al., Citation2012), and antioxidant (Cheng et al., Citation2012).
Rural people in many tropical countries use a wide range of wild fruits as a food supplement or meet their food shortage and even for income security (Kebu and Fassil, Citation2006). But the information of major or minor elements of these wild fruits is negligible or very rare, if known in a few species. Thus, the present study explores the nutritional status of wild edible fruits of Z. mauritiana and Z. nummularia from Northwest India.
Materials and Methods
Collections of the Plant Specimen
Wild fruit samples of Z. mauritania and Z. nummularia were collected on a population basis from different parts of Northwest India, covering localities of Punjab, Haryana, Himachal Pradesh and Rajasthan ().
Table 1. The codes, location, and date of collection, geographical co-ordinates, and altitudes of wild fruit samples of Ziziphus mauritiana (ZM) and Z. nummularia (ZN) from Northwest India
Processing of Collecting Samples
The fruits were washed with tap water and shade dried for 15 days, depulped samples were made into powder using grinding machine (micro-pulverizer-hammer mill) to make a fine powder. The powder of all the samples were weighted in the polyethylene bags and stored at 4°C until analysis. All analyzes were done in triplicate.
Analysis of Samples
The homogenized fruit samples were analyzed for moisture content, ash content, and crude fat (lipid) by standard methods (AOAC, Citation2005). For moisture content, 5 g of the sample were cooked on air circulating oven at 105°C (Gallenhamp oven Model No. OV-165) for about 3 hours (ASAE, Citation1982). For determination of Ash content, 2 g of sample (oven-dried fruit powder) was ignited in a muffle furnace at 500°C for 6 hours (Method no. 930.05 (A.O.A.C, Citation2005)). Crude fat was determined by boiling 5 g of sample in petroleum ether 40 to 60ºC in Soxhlet extractor (Method No. 930.10, A.O.A.C, Citation2005). The crude fiber was determined by digesting 2 g of sample in 1.25% sulfuric acid and 1.25% sodium hydroxide (Method no. 962.09, AOAC Citation2005).
Vitamin C was estimated by redox titration with potassium iodate in the presence of potassium iodide (Suntornsuk et al., Citation2002). For this, 20 ml of sample solution was taken in 250 ml flask and 150 ml of distilled water, 5 ml of 0.6 mol L−1 potassium iodide, 5 ml of 1 mol L hydrochloric acid, and 1 ml of starch indicator solution were added. The sample was treated with 0.002 mol L−1 potassium iodate solution. The end product of titration is the first permanent trace of a dark blue- black color due to the starch – iodine complex (Method No. 967. 21, A.O.A.C, Citation2005). The levels of calcium, magnesium, iron, manganese, zinc, and copper were estimated by using Atomic Absorption Spectrophotometer (AAS) (GBC Australian makes model no 932-AA). Sodium and potassium were determined using Flame Photometer Instrument (Elcon) following the standard protocol Alpha 23rd edition 3500 Na for sodium and Alpha 23rd edition 3500 K for potassium (Method No. 984.27, A.O.A.C, Citation2005).
Results and Discussions
Proximate and Vitamin C Composition
The proximate and vitamin C compositions of Z. mauritiana and Z. nummularia wild fruits were analyzed (). The results revealed that moisture content was highest (16.273 ± 0.910) in the ZM-3 fruit population and ash content was highest in the ZM-11 fruit population. Crude fat (2.497 ± 0.171) and vitamin C (25.613 ± 0.281) contents were highest in ZN-14 fruit population, while crude fiber was highest (9.840 ± 0.275) in ZN-13 fruit population. Previously, Li et al. (Citation2007) reported moisture contents ranging from 17.38% to 22.52%, carbohydrate contents ranging from 80.86% to 85.63%, protein contents ranging from 4.75% to 6.86%, lipid contents ranging from 0.37% to 1.02%, ash contents ranging from 2.26% to 3.01%, insoluble fiber contents ranging from 5.24% to 7.18%, and vitamin C contents ranging from 192 to 359 mg/100 g in five cultivars of Chinese jujube (Z. jujuba Mill.). Similarly, Pareek (Citation2013) reported moisture contents ranging from 81.6 to 83.0 g, ash contents ranging from 0.3 to 0.59 g, a fat content of 0.07 g, and vitamin C contents ranging from 65.8 to 76.0 g per 100 g of fresh Indian jujube fruit (Z. mauritiana).
Table 2. The proximate composition and vitamin C in wild fruits of Ziziphus mauritiana and Z. nummularia from Northwest India
The literature reveals that the fruits of Z. mauritiana are highly nutritive and contains moisture content (81–83%), carbohydrates (17%) and proteins (0.8%), and also elements like calcium, phosphorus, carotene pigments, and vitamins like thiamine, riboflavin, niacin, and ascorbic acid (Pareek, Citation2013). The results of the analysis of the mineral content of wild fruits of Ziziphus species are summarized in . Macroelements (K, Ca, Na, and Mg) and microelements (Fe, Cu, Mn, and Zn) have been analyzed. Nutrient content in the fruits can be influenced by weather conditions and local environment (Feyssa et al., Citation2011).
Table 3. The amount of different elements in wild fruits of Ziziphus mauritiana and Z. nummularia from Northwest India
In the present study, the sodium content ranged between (36.747 ± 0.569 to 139.257 ± 2.575 mg/100 g), which is comparatively higher than five cultivars of Chinese Jujube (3.22 to 7.61 mg/100 g, Li et al., Citation2007). Despite its importance in cellular homeostasis and physiology, excess sodium can lead to high blood pressure which can adversely affect the target organ (Farquhar et al., Citation2015). The content of potassium (701.827 ± 10.447 to 2661.283 ± 28.123 mg/100 g) was found in much higher levels than known values of fruits such as guava (417 mg/100 g), orange (200 mg/100 g), apple (90 mg/100 g), and banana (358 mg/100 g, Mahapatra et al., Citation2012). Even in the five cultivars of Chinese jujube, the calcium content was reported with a range of 79.2 to 458 mg/100 g (Li et al., Citation2007). Similarly, calcium content also varied in both species as reported to be maximum in ZN-13 (428.350 ± 2.037 mg/100 g) and minimum in ZN-4 (149.447 ± 1.904 mg/100 g) population, which is higher than Chinese jujube (45.6 to 118 mg/100 g). The calcium contents (150 to 426 mg/100 g) were found many times higher than found in other fruits, such as guava (18 mg/100 g), orange (11 mg/100 g), pear (4 mg/100 g), and strawberry (22 mg/100 g) as reported by Mahapatra et al. (Citation2012). Calcium is essential for humans as helping in building strong bones and teeth, muscle contraction, oocyte activation, blood clotting, regulating heartbeat, and fluid balance within cells (Pravina et al., Citation2013). Further, a few important micronutrients like iron, copper, and manganese were also observed from the fruit samples of Z. mauritiana and Z. nummularia. The iron content was found to be highest in ZN-10 (9.657 ± 0.244) and least in ZN-4 (2.627 ± 0.035). Copper and manganese contents were found in a range of 0.263 ± 0.025–6.733 ± 0.097 mg/100 g and 0.037 ± 0.006–2.623 ± 0.067 mg/100 g, respectively. Zinc content was found to be maximum in ZM-3 (2.223 ± 0.085 mg/100 g) and minimum in ZN-4 (0.493 ± 0.076 mg/100 g). These microelements (Fe, Cu, Mn, & Zn) range between 4.8 − 7.90, 0.19–0.42, 24.6–42.1, and 0.35–0.63, respectively. Copper is important for lysyl oxidase involved in collagen biosynthesis (Pereira et al., Citation2002) and it participates in numerous enzyme-catalyzed oxidation-reduction reactions and processes of the mitochondrial electron transport (Takahashi et al., Citation2002). Magnesium is required by many enzymes, especially the sugar and protein kinases that catalyze ATP-dependent phosphorylation reactions (Deutscher and Saier, Citation1983). Zinc is nutritionally essential for all organisms as for its role in the immune system, insulin secretion (Chausmer, Citation1998), key enzymes, such as superoxide dismutase (Boron et al., Citation1998; Hwang et al., Citation2002) and also essential for the release of vitamin A from liver stores (Hwang et al., Citation2002).
The present study revealed that the wild edible fruits of Z. mauritiana and Z. nummularia collected from regions of Punjab, Haryana, Rajasthan, and Himachal Pradesh were rich in vitamin C and important macronutrients and micronutrients. Therefore, due to their good nutritional value, these fruits demonstrated the potential for use as a food alternative in the human diet. Further, increased use and potential domestication of these fruits may address food insecurity issues experienced by rural/tribal people, who suffer from food shortages and malnutrition.
Acknowledgments
The authors are grateful to the Department of Biotechnology for providing financial assistance under IPLS-DBT (Reference number: BT/PR 4548/INF/22/146/2012) scheme. The authors are also highly thankful to the Head, Department of Botany, Punjabi University, Patiala for providing necessary lab facilities during the work.
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