Iris Publishers
Authored by Alawode Rahmatallah Adenike
Abstract
This study investigated the
physico-chemical properties, functional properties, and chemical compositions
of Ziziphus mauritiana (Jujube) seed oil using standard analytical methods. The
results indicated that Jujube seed oil exhibited swelling capacity of 6.10±0.23
%, water absorption capacity of 20.22±0.45, oil absorption capacity of
18.53±0.43%, bulk density of 0.583±0.01%, gelatinization temperature of
72.34±1.67%, foaming stability of 56.36±0.12%, foaming capacity of 8.29±0.02%,
emulsion ability of 30.21±0.13 and emulsion stability of 27.62±0.89. the oil
also shows specific gravity of 0.913±0.08 Kg/L, acid value of 2.27±0.17
mgKOH/g, saponification value of 192.40±9.98 mgKOH/g, peroxide value of
2.22±0.12 mmol/Kg, free fatty acid of 1.14±0.09 % and iodine value of
66.74±4.29 g/100g. a total of 19 chemical compound were identified from Z.
mauritiana seed oil using GC-MS. The most abundant compound N-[3-[N-Aziridyl]
propylidene] hexyl amine with retention time (RT) and peak area (PA) of 5.523 s
and 38.32 respectively, followed by Benzeneethanamine,
4-methoxy-2-Butyne-1,4-diol with RT and PA of 9.833% and 7.29 respectively
while terebic acid, n-Capric acid and oxalic acid were among the least abundant
compounds identified. In conclusion, the seed oil of Ziziphus mauritiana
(Jujube) exhibited a desirable characteristic for nutritional and industrial
application.
Keywords:
Physio-chemical; Functional properties; Chemical compositions; Ziziphus
mauritiana; Seed oil
Introduction
The United Nations projected that
by 2050, the world population will reach 9.6 billion [1]. In order to meet up
the increase demand due to population growth, oil crops production has to
increase by 133 million tones to reach 282 million tonnes [2]. The major oil
crops; soybean, sunflower, rape and oil palm, rape, and sunflower account for
83% of the global production [3], with temperate region; Europe and America
accounting for about 60% of the global oil seed production while tropical
regions such as Africa, Malaysia, and Indonesia account for less than 5% of the
global oil seed production [4]. Majority of production from these tropical
regions are cotton, coconut, oil palm, groundnut oil [2]. However, a pectoral
of traditional oil seeds in tropical Africa remain underexploited and
underutilized owing to the inadequate knowledge of the functional and
nutritional properties as well as the economic values of the seed oil. One of
such traditional oil seed is the Jujube seed (Ziziphus mauritiana) a member of
Rhamnaceae family.
Ziziphus mauritiana Lam (Z.
mauritiana) is a tropical fruit tree with oil producing seed, it is commonly
known as Jujube or magarya (Northern part of Nigeria) and grows in arid and
semiarid part of the tropics [5]. Ziziphus mauritiana leaves, fruit and seed
commonly used by Nigerian traditional herbalist for treatment of various
ailment including; sexual deficiency, diabetes, obesity, fever, cough,
convulsion, epilepsy, diarrhea, ulcers, digestive and urinary discomfort, sleep
disorders, burning sensations skin rashes and ulcers [6]. Various parts of
Ziziphus mauritiana have also received scientific validation of its
immunomodulatory [7], free radical antagonist [8], anticancer [9],
anti-diarrhoeal [10] hypoglycemic [11], antiulcer [12], antimicrobial [13],
antimycobacterial and antiplasmodial [14] activities.
However, despite the medicinal
properties of Ziziphus mauritiana, its seed is less explored, underutilized and
are often discarded as a waste. However, recent studies have indicated that the
less underutilized seed could serve as a rich source of nutrient thus
contribute to solving the problems of malnutrition. Our previous study shows
that Ziziphus mauritiana (Jujube) seed as a protein source in the diet promote
growth performance and stabilized hematology, lipid profile and serum chemistry
profile of Rattus norvergicus [13]. To our knowledge, there are limited
scientific reports on the physicochemical, functional and chemical composition
of the oil produced from the seeds of Ziziphus mauritiana. This study was
therefore carried out to determine the physicochemical, functional and chemical
composition oil extracted from Ziziphus mauritiana seeds.
Materials and Methods
Sample collections
Matured fruits of Ziziphus
mauritiana fruits were picked directly from the trees in March 2017 from
Barnawa area of Kaduna, Kaduna State. The sample was identified and
authenticated at the herbarium unit of Department of Biological Sciences Ahmadu
Bello University where existing voucher number of the specimen (No. 7072) was
given.
Sample preparation
The fruits were macerated in
water to remove the pulp and the seeds were rinsed in clean water. Thereafter
the seeds were spread out, sun dried. The dried seeds were grounded and sieved
through a mesh to obtain a fine powder which was stored in airtight container.
Analysis of physicochemical
properties
Ziziphus mauritiana seed oil was
analysed for physicochemical properties using standard procedures [15].
Specific gravity was evaluated using Specific Gravity Hydrometers (Fisher
Scientific, Pittsburgh, PA). The saponification values were determined
according to the American Oil Chemists Society method [15]. The peroxide value,
acid value and iodine value were calculated following the AOCS standard method
(Cd 8b-90), (Cd, 3d-63) and (Cd, 1c-85) respectively. Free fatty acid composition
was analysed using Gas Chromatograph (QP5050, Shimadzu, Japan) following the
AOCS (Ce 2-66) standard.
Analysis of functional properties
The standard analytical
procedures for food analysis as described below were used.
Bulk density: Firstly, a dried and
empty 10 cm3 measuring cylinder was weighed. The sample was filled gently into
the weighed 10 cm3 measuring cylinder and then gently tapped at the bottom on a
laboratory bench several times until there was no further diminution of the
sample level after filling to the 10 cm3 mark. After this, the filled measuring
cylinder was weighed and recorded [15]:
The bulk density (g/cm3) = Weight
of sample (g)/Volume of sample (cm3)
Water/oil absorption capacity:
From the ground sample, 1.00g was weighed into a conical graduated centrifuge
tube and 10 cm3 of water or oil was added to the weighed sample. A warring
whirl mixer was used to mix the sample for 30 s. The sample was allowed to
stand at room temperature for 30 min and then centrifuged at 5000 rpm for 30 min.
After then the mixed sample was transferred from the graduated centrifuge tube
into a 10 cm3 measuring cylinder to know the volume of the free water or oil.
The absorption capacity was expressed as grams of oil or water absorbed per
gram of sample. Calculation; water/oil absorption capacity of the sample was
calculated as:
(Total oil/water absorbed - free
oil/water) × Density of oil/ water [15].
Foam capacity and stability: From
the powdered sample, 2.00 g were weighed, blended with 100 cm3 of distilled
water using warring blender (Binatone BLG- 555) and the suspension was whipped
at 1600 rpm for 5 min. The mixture was then poured into a 100 cm3 measuring
cylinder and its volume was recorded after 30s. Foam capacity was expressed as
percent increase in volume using the formula of AOAC [15].
The foam stability of the sample
was recorded at 15, 30, 60 and 120 s after whipping to determine the foam
stability (FS).
Gelatinization temperature: In
triplicates, 5% sample was suspended in test tubes, heated in a boiling water
bath with continuous stirring and 30 s after gelatinization was visually
noticed, the temperature of the samples was taken as the gelatinization temperature
[16].
Emulsification capacity (EC):
From the sample, 2.00 g of sample were blended with 25 cm3 of distilled water
at room temperature for 30 s in a warring blender at 1600 rpm. After complete
dispersion, 25 cm3 of vegetable oil was gradually added and the blending
continued for another 30s. Then the mixture was transferred into a centrifuge
tube and centrifuged at 1600 rpm for 5 min. The volume of oil separated from
the sample was read directly from the tube after centrifuging. Calculation: The
emulsion capacity was expressed as the amount of oil emulsified and held per
gram of sample:
X Emulsion capacity = X/Y × 100
Where X = height of emulsified
layer and Y = height of the whole solution in the centrifuge tube [15].
Gas Chromatography mass spectrometry
(GC/MS) analysis
The GC/MS analysis of Ziziphus
mauritiana seed oil was perform using GC-MS clarus 500 per kin Elmer system
comprising an AOC- 20i auto sampler. “The instrument is equipped with a VF 5 ms
fused silica capillary column of 30 m length, 0.25 mm diameter and 0.25 μm film
thickness.” The temperatures employed were; column oven temperature 80°C,
injection Temp 250 °C at a pressure of 108.0 kPa, with total flow and column
flow of 6.20 ml/min and 1.58 ml/min, respectively. The linear velocity was 46.3
cm/s and a purge flow of 3.0 ml/min. The GC program ion source and interface
temperature were 200.00 °C and 250.00 °C, respectively, with solvent cut time
of 2.50 min. The MS program starting time was 3.00 min which ended at 30.00 min
with event time of 0.50 s, scan speed of 1666 μl/s, scan range 40-800 u, and an
injection volume of 1 μl of the propolis extract (split ratio 10:1). The total
running time of GC-MS was 30 min. The relative percentage of the extract was
expressed as percentage with peak area normalization as previously reported by
Lawal et al. (2015).
Identification of the Components:
Interpretation on the mass spectrum was conducted using the database of
National Institute Standard and Technology (NIST) having more than 62,000 patterns.
The fragmentation pattern spectra of the unknown components were compared with
those of known components stored in the NIST library. The relative percentage
amount of each bio-component was calculated by comparing its average peak area
to the total area.
Results
Physicochemical Properties of Z.
mauritiana seed
The physicochemical properties of
Z. mauritiana seed are presented in Table 1; Z. mauritiana seed showed specific
gravity of 0.913±0.08 Kg/L, acid value of 2.27±0.17 mgKOH/g, saponification value
of 192.40±9.98 mgKOH/g, peroxide value of 2.22±0.12 mmol/ Kg, free fatty acid
of 1.14±0.09 % and iodine value of 66.74±4.29 g/100g.
Functional Properties of Z.
mauritiana seed
The functional Properties of Z.
mauritiana seed are presented in Table 2; the Z. mauritiana seed showed
swelling capacity of 6.10±0.23 %, water absorption capacity of 20.22±0.45, oil
absorption capacity of 18.53±0.43%, bulk density of 0.583±0.01%, gelatinization
temperature of 72.34±1.67%, foaming stability of 56.36±0.12%, foaming capacity
of 8.29±0.02%, emulsion ability of 30.21±0.13 and emulsion stability of
27.62±0.89.
Gas chromatography and mass
spectroscopy (GC-MS)
The compound names, retention
time and peak area of chemical compositions of Z. mauritiana seed oil using
GC-MS are shown in Table 3: Z. mauritiana seed oil contains N-[3-[N-Aziridyl]
propylidene] hexyl amine, Benzeneethanamine, 4-methoxy-2- Butyne-1,4-diol,
Terebic acid, Pentanoic acid, 4-methyl-, methylester, Hexadecanoic acid, methyl
ester, 10-Undecynoic acid, 3-Dodecanol, Cyclopropane, Pentanoic acid,
2,6-Octadiene, Butane, 1,3,4-Thiadiazole, 2-amino-5-(heptylthio), 9-Oxononanoic
acid, D-Galactose, Isoxazolidine, 5-ethyl-2,4-dimethyl, 2-Phenyl-1,2-
propanediol, n-Capric acid, 1,3-Bis-t-butylperoxy-phthalan and oxalic acid.
Discussion
Food functional properties are
very important for the appropriateness of the diet, behavior of nutrients
during food processing, storage and preparation because they affect the general
quality of foods as well as their acceptability [17]. Bulk density which is a
function of particle size was 0.583±0.01 which is an indication that the
particle size was high. This value is similar to the bulk density of 0.67±0.02
reported for date palm fruit [16]. Increase in bulk density is desirable
because it offers greater packaging advantage, as a greater quantity may be
packed within a constant volume [18]. The water absorption capacity of
20.22±0.45 recorded in this study is also similar to the 2.50±0.05 reported for
date palm fruit [16]. This water absorption capacity of Z. mauritiana seed is
an indication of its heaviness and suitability as a drug binder and
disintegrate in pharmaceuticals industrials [19]. The present study also
indicated that had very higher gelatinization temperature of 72.34±1.67% °C
which affects the time required for the cooking of food substances.
The fat absorption capacity (FAC)
which is critical in determining the flavour retention in food materials was
found to be 18.53±0.43%. Emulsion stability (ES) was found to be 27.62±0.89%
and is higher than 13.19±1.0% reported for Jack beans [20]. Emulsion stability
is important for stabilization of additives in production of foods like soup
and cakes. The higher value of foaming capacity (FC) and foaming stability (FS)
of Z. mauritiana seed suggests its use as a whipping or aerating agent in food
system [20].
A high saponification value
(192.40±9.98 mgKOH/g) recorded in this study is similar to the saponification
value of 197.80 recorded for Z. oenoplia seed oil [21], this high value could
be attributed to high content of medium chain fatty acids (i.e., C16 and C18)
in the seed oil. Furthermore, this high saponification value is a desirable
property for production and manufacturing of shoe polish, alkyd resin, shampoo
and liquid soaps [21]. The value recorded in this study is also similar to
saponification values of soybean (189–195) and groundnut (187–196) as reported
by Gunstone [22]. The acidity is an important parameter in determining the
quality of the seed oil. The low levels of free fatty acids (1.14±0.09 %) and
acid value (2.27±0.17 mgKOH/g) of Z. mauritiana seed oil reported in this study
is an indication of low hydrolysis of triglyceride and thus would enhance the
shelf life and storage stability of the oil. The value recorded in this study
is lower than the free fatty acids and the acid value of 0.39% and 0.64 mg of
KOH/g respectively reported for L. kerstingii seed oil [2].
The iodine value of Z. mauritiana
seed oil (66.74±4.29 g/100g) is similar to 60.72 g of /100 g reported for L.
kerstingii seed oil [2], 65.90 g of /100 g reported for that of Moringa
oleifera Lam. oil but lower than iodine values of cotton, olive oil, groundnut,
and sunflower oils, which ranged from 86 to 145 g of /100 g of oil [23]. The
relatively low iodine value implies low nutritional value, thus implying that
Z. mauritiana seed oil is more nutritional than the cotton, olive oil,
groundnut, and sunflower oils. Furthermore, the iodine value reported in this
study suggests that the Z. mauritiana seed oil is relatively stable upon
thermal degradation when used for frying or upon storage with respect to
oxidation. The peroxide value of 2.22±0.12 mmol/Kg recorded in this study is
below the 10 meq. O2/kg of oil allowed for crude oils by Codex Alimentarius
Committee [24,25].
Conclusion
The research work indicated that
Z. mauritiana seed oil exhibited a desirable characteristic for nutritional and
industrial application. The seed oil has great potential for the use of Z.
mauritiana seed oil for both domestic and industrial uses instead of depending
solely on palm oil and peanut oil that are scarce and costly.
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