INTRODUCTION
Jakjak is one of the valuable plant species that grows naturally in Sudan,
its scientific name is Azanza garckeana. It is largely spread in arid
area such as sand and near mountain, specially in Savanna plantation area at
the Southern Darfur and Jabl Mara mountain area. It is the indigenous fruit
trees although undomesticated play many important roles in people living in
rural areas of Darfur states (Sudan). Indigenous fruit trees are important traditional
sources of nuts, fruits, spices, leafy vegetables, edible oil and beverages
(Taylor and Kwerepe, 1995). Like vegetables, indigenous
fruit trees provide vitamins and minerals essential for the proper maintenance
of human health (Saka and Msonthi, 1994).
The indigenous food and medicinal plants play an important role for many African
people. These products constitute alternative source of nutrition and the rural
people communities in many African countries use some of them in medical treatment
(Arnold and Perez, 2001; Ladio and
Lozada, 2004; Scherrer et al., 2005).
The fruits of Azanza garckeana are eaten in many African countries before
ripe while slightly green or when ripe, however, sometimes they are being dried
to be utilized after reconstitution (Mojeremane and Tshwenyane,
2004).
The indigenous fruit bearing tree species have many benefits and uses (FAO,
1982; Maghembe et al., 1994), they tree are
rich in many macronutrients such as sugars, vegetable oil and proteins and/or
micronutrients such as vitamins and minerals, beside providing shade and medicine
to rural communities as well as production of fruits and fodders.
In Darfur States (Sudan), the jakjak fruit trees yield a crop in poor rainfall
years, especially during droughts. The fruits of jakjak fruit have been reported
in many in number of African markets (Kwesiga and Muanza,
1995; Taylor and Kwerepe, 1995). This is indication
that the species is not a simple and occasionally exploited tree of the wild
vegetation but has a role in economic systems of farmers. It is increasingly
becoming popular as an alternative source of food and nutritional security.
The jakjak plant is used in traditional medication, treatment and food in Darfur
States (Sudan). Jakjak fruit may be eaten ripe (chewing), fresh or is kept for
later usage, because it consists of great proportion of sugars, vitamins and
minerals. Also it is used as a sauce before ripe, porridge (madeda), juice preparation
and for school boys chewing. All these benefits and traditional uses of jakjak
guided to investigate this beneficial plant fruit as attempt to promote the
food security and poverty alleviation in rural communities and to encourage
its utilization of basis of scientific findings. Therefore, the objectives of
this work were to determine the chemical composition and microbiological characteristics
of jakjak fruits, utilize jakjak in juice production and assessment of its quality.
MATERIALS AND METHODS
Materials: Jakjak fruits were collected from local market (Nayala) Southern Darfur State, (Sudan) during the harvesting period October (2010). The fruits were transported to the laboratory in jar at room temperature in order to carry out pending the different analyses and preparation of jakjak juice.
Physical analysis: Physical analysis was carried out in triplicate for jakjak fruits samples before juice extraction. The analyses included: measurement of fruit length, fruit width, fruit weight, fruit color and fruit volume, using a vernier caliper, digital balance, visually, volumeter, respectively.
Chemical analysis of jakjak fruit: Proximate analysis was carried out
for samples of jakjak fruits to determine moisture, protein, fiber, fat and
ash content according to AOAC (2000) method while the
carbohydrate content was determined by difference.
Minerals determination: The contents of sodium, potassium and calcium
were determined in jakjak fruit samples according to AOAC
(1970) method using flame photometer (coring 400).
Production of jakjak fruits juice: Three types of jakjak fruit juice were prepared including; Soaked Jakjak Juice (SJJ), Mixed Jakjak Juice (MJJ) and Boiled Jakjak Juice (BJJ).
For preparation of soaked jakjak fruit juice, 25 g of jakjak fruits were soaked in 200 mL distilled water in water bath for four hours, then the juice was extracted, concentrated for about 30 min.
For preparation of mixed juice, 100 g of clean jakjak fruits were pulped in 900 mL distilled water, blended, filtered then a clear juice was obtained which was then concentrated for about 30 min.
For preparation of boiled juice, 100 g of clean jakjak fruits were boiled in 900 mL distilled water at about 80°C for one hour, the contents were filtered and concentrated for about 30 min.
Evaluation of juice quality: The quality of jakjak fruits juice samples were determined using physicochemical, microbiological analyses as well as sensory evaluation.
Determination of total soluble solids and pH: The total soluble solids
content of jakjak fruit juice was measured using hand refractometer at room
temperature. The pH value was measured by using a digital pH meter, according
to AOAC (1990).
Determination of ascorbic acid: Thirteen gram of sample were blended with reasonable amount of 0.4% oxalic acid for one minute, aliquot was transferred to 500 mL volumetric flask, made up to volume with 0.4 oxalic acid and was filtered through No. 4 Whatman filter paper 20 aliquot were pipetted and titrated against the dye solution to faint pink end point:
Jakjak fruits juices sugar determination: The sugar profile of jakjak fruit was determined by Thin Layer Chromatography (TLC). Standard sugars (mannose, fructose, glucose and ribose) were spotted on silica dry plate.
Total viable count bacteria count: The total viable count per mL of
Jakjak juice was determined following the method of APHA (1967).
Incubation was accomplished at 30°C for 48 h. Plates containing between
30-300 colonies (CFU mL-1) per mL of sample were used for calculation.
Yeast and mould count of jakjak juices: The yeast and mould strains
were enumerated by culturing them on Potato Dextrose Agar (PDA) medium and incubating
for 48 h at 25°C (APHA, 1967).
Sensory evaluation: Sensory evaluation was carried out to judge the
quality of jakjak juice using 15 panelists according to Larmond
(1967). The panelists were asked to express their degree of liking or disliking.
RESULTS AND DISCUSSION
Physical characteristics of jakjak fruits: The physical characteristics of jakjak fruits are presented in Table 1. The weight, length, width and volume values were 15.6±1.5 g, 2.7±0.5, 2.5±0.09 cm and 10.6±1.5 cm3, respectively. The visual color of jakjak fruits, however, was brown. The weight of jakjak fruits seeds and pulp were 4.27±0.6 and 11.33±1.7 g, respectively. The seeds weight represented were 27.35±1.9% while the pulp weight represented about 72.65±2.1% of the total fruit weight.
Chemical composition of jakjak fruits: The chemical composition of jakjak
fruits are indicated in Table 2. The moisture, ash and protein
contents were 13.542±2.5, 7.3±0.5 and 10.05±1.8%, respectively.
| Table 1: |
Physical characteristics of jakjak fruits |
|
| Values are Mean±SD, n = 3 |
The protein content determined in the present study was lower than that reported
by Saka and Msonthi (1994) who reported a value of 12%
and within the range of legumes protein content (15-25%). The fat content of
jakjak fruits was 1.04±0.01%, this value was lower than that of (Saka
and Msonthi, 1994) which was 1.1%. The crude fiber content of jakjak fruit
was 45.52±1.4, this result was higher than 45.3% which was found by Saka
and Msonthi (1994). The total carbohydrate content was 22.444±3.7%
which was lower than that reported by Saka and Msonthi (1994)
who reported a value of 35.2% in jakjak fruit.
The minerals content of jakjak fruits is also presented in Table
2. The iron and potassium contents were 6.0 and 1360 mg/100 g, respectively.
However, the calcium and sodium contents were 56 and 60 mg/100 g, respectively.
These values were higher than those reported by Saka and
Msonthi (1994), which were 9.5 and 20.2 mg/100 g, respectively. Presence
of minerals in jakjak fruit was in agreement with (Mojeremane
and Tshwenyane, 2004) who reported that the species is an important source
of essential minerals particularly P, Ca, Mg and Na. Presence of these minerals
in jakjak fruits indicates that it is a good supplement for the consumers of
these fruits. Iron is essential in small amounts for both plant and animal life.
Biologically iron is the most important transitional element. The human body
contains about 4 g of iron. About 70% of this is foundation as hemoglobin. The
function of hemoglobin is to pick up dioxygen at the lungs. Hemoglobin is also
important biologically in myoglobin which is used to store oxygen in muscles
(Lee, 1996). Calcium is important in bones and teeth as
appetite Ca3(PO4)2 and the enamel on teeth.
Ca2+ ions are important in blood to maintain the regular beating
of the heart and daily intake 1000-1200 mg are recommended (Lee,
1996).
Sodium ions are more actively expelled from cell, than potassium ions. These
ions transport is sometimes called a sodium pump and it involves both the active
expulsion of sodium and the active take-up of potassium ions. In animal cells
the concentration of potassium is about 0.15 M the concentration of sodium is
about 0.01 M. In body fluid (lymph and blood) the concentration of potassium
and sodium are about 0.003 and 0.15 M, respectively (Lee,
1996). The different ratios of sodium to potassium inside and outside the
cells produces an electrical potential across the cell membrane which is essential
for the functioning of nerve and muscle cells and daily intake of sodium and
potassium were 2400,3500 mg, respectively (Lee, 1996).
The energy value of jakjak fruits was 2313.081 kcal/100 g. The high energy value of jakjak fruit could be attributed to its high content of carbohydrates.
Characteristics of jakjak fruits juice: As presented in Table
3, the pH values of soaked juice, boiled juice and mixed juice, were 5.47±0.01,
5.47±0.01 and 5.48±0.01, respectively. These values were closely
related to pH values of guava nectar, mango nectar and orange nectar which were
4.6±0.41, 4.4±0.1 and 4.1±0.1, respectively as reported
by Kakum (2009) the lower pH value determined in this
study was within pH of most fruit juices.
The Total Soluble Solids (TSS) of jakjak fruits juices (soaked juice, boiled
juice and mixed juice were 4.0±0.5, 4.5±0.5 and 4.5±0.5%,
respectively. These results were lower than those of guava nectar, mango nectar
and orange nectar which were 17, 28.2 and 20.9, respectively, as reported by
Kakum (2009).
The ascorbic acid content of mixed, boiled and soaked juices which were 21.1344
mg/100 g, 21.1144 mg/100 g, 21.1344 mg/100 g, respectively. These results were
slightly lower than 21.5 mg/100 g as reported by Saka and
Msonthi (1994) and lower than those of guava nectar, orange nectar and mango
nectar were 199±0.22, 44.1±0.2 and 28.9±0.06 mg/100 g,
respectively, as reported by Kakum (2009).
Ascorbic acid (vitamin C) contributes to the nutritional value of fruits juices
and it is an essential water soluble vitamin. It also aids in the formation
of liver bile which helps to detoxify alcohol and other substances. It had been
reported that ascorbic acid reduces the activity of the enzyme, aldose reductase
which helps to protect people from diabetes. It may also protect the body against
accumulation or retention of the toxic mineral lead (Raff
et al., 2004).
Microbiological analysis: Table 4 showed the microbiological
characteristics of jakjak fruits juice samples. All samples were found to be
free from moulds and yeast.
| Table 3: |
pH, total soluble solid and vitamin C values of jakjak juice |
|
| Values are Mean±SD, n = 3, Brix0: % measurement
of TSS |
| Table 4: |
Total viable count of yeast, mould and total bacteria in
jakjak juice |
|
| nd: Not detected |
| Table 5: |
Sensory evaluation of jakjak fruit |
|
| The similarity of letters within column means there is no
significant difference between the samples or brands |
These values were in agreement to those of Kakum (2009)
who found that: the orange, guava and mango nectars were free from yeast and
moulds. Absence of yeast and moulds indicates that the juice samples were produced
under hygienic conditions. In contrast, all juice samples contained appreciable
numbers of total bacterial counts, however, the mixed, boiled and soaked juices
contained 1.20x107, 1.72x106 and 1.08x107 CFU
mL-1, respectively. These high counts of bacteria might reached the
juice samples after production due to improper handling.
Sensory evaluation: The sensory evaluation of jakjak fruits juice sample was presented in Table 5. Notable differences were found in most of the sensory characteristics of the three juice types. There was significant difference in appearance, textures and color between the mixed and soaked juices while there was no significant difference in flavor and overall acceptance. The panelists gave highest scores for overall acceptance to the mixed juice (7.91), followed by the boiled juice (7.33) and finally the soaked juice (7.00). Generally, the panelists accepted jakjak fruit juice, this is an indication for potentiality of utilizing jakjak fruit in production of juice.
CONCLUSION
The outcome of this study is considered very important from nutritional point of view. The nutritional value of jakjak fruits was accomplished through determination of chemical, physical, physicochemical, microbial and sensory evaluation. Jakjak fruit contained appreciable amounts of various minerals, calcium, sodium, potassium and iron. In addition, the content of ascorbic acid was relatively high. The most profile sugar identified was fructose. In addition, the other components were found to be as follow, total carbohydrates 22.444±3.7%, fat 1.04±0.01%, protein 10.05±1.8%, crude fiber 45.624±1.4%, moisture 13.542±2.5%, ash 7.3±0.5% and the energy value 2313.081 kcal/100 g. As for microbial analysis, jakjak fruits juice was free for mould and yeast but high number of total bacteria count was found. The sensory evaluation revealed that the overall acceptance was notable for Jakjak fruits juice. People in Darfur also use jakjak fruits especially schoolboys whose chew it, porridges (madeda) preparation and use to sauce preparation before ripe.
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