By Obasi, BC; Ukpoju,
L (2023).
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Greener Journal of Agricultural
Sciences ISSN: 2276-7770 Vol. 13(3), pp. 198-207, 2023 Copyright ©2023, Creative Commons
Attribution 4.0 International. |
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Evaluation of
Physiochemical, Sensory and Microbial Qualities of Mixed Fruits Juice from
Watermelon and Lime Fruits
*
Department
of Food Science and Technology, Faculty of Agriculture and Life Sciences,
Federal University Wukari.P.M.B.1020, Taraba State,
Nigeria.
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ARTICLE INFO |
ABSTRACT |
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Article No.: 092123099 Type: Research Full Text: PDF, HTML, PHP, EPUB, MP3 |
This study investigated the evaluation of physiochemical, sensory and
microbial qualities of mixed fruit juices from blends of watermelon and lime
fruits. The mixed fruit juices were extracted using juice extractor, blended
and mixed in the ratios of 90:10,85:15,80:20,50:50 and 100% respectively. The
juice samples were pasteurized at 85oC for 5 minutes. All the
analyses were carried out using standard methods for physiochemical
parameters which included pH, titratable acidity,
brix(%) crude protein, crude fiber, moisture
content, ash, fat, carbohydrate, vitamin C and some mineral elements such as
calcium, potassium, iron and magnesium. The results showed that mixed fruit
juices are rich in carbohydrates, vitamin C, magnesium and potassium.
Significant difference existed (p <0.05) in terms of color,
taste, flavor, aroma and general acceptability of
the various juice blends when compared with control sample. Sample A (100%)
had the highest acceptability in terms of taste, color
and flavor, while sample E (50:50%) had the least
acceptability. Microbial count result showed no growth because the count was
below the acceptable limit of < 10/cfu/ml for
pasteurized fruit juices, for total aerobic viable cells, coliform and fungi
counts. However, the biochemical test revealed some microbial flora such as
Bacillus spp, Escheria
coil and Salmonalla spp. Thus, from this study it
can be concluded that the development of new products where two or more kinds
of fruit juices are blended to obtain a new product that combines the
nutritional value of both fruits with the benefits of a pleasant taste, safe
and accepted by consumers could be encouraged by the food industry. |
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Accepted: 25/09/2023 Published: 28/09/2023 |
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*Corresponding Author Dr. Obasi,
Blessing Chidi E-mail: blessed200067@ yahoo.com Phone: 2347035852279; 2348140447496 |
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Keywords: |
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Fruits are highly perishable, non-staple
foods which make up about 39% of the food intake (fresh state or processed
form) of people living in developing countries of Africa (Akusu
et al., 2016). Fruits and its juices
constitute one of the most important foods for man and their regular
consumption maintains health and makes up for the losses in the human diet (Okwori et al.,
2017). Consumption of fresh juices is increasing all over the world due to
their freshness, high vitamin content, low caloric consumption and ability to
reduce risk of many diseases (Rathnayaka, 2013), such
as diabetes, heart diseases and cancer. Fruit juice contains antioxidants,
vitamins and minerals that are essential for human beings (Aneja
et al 2014).
The high
potassium and low sodium characteristic of most juices help in maintaining a
healthy blood pressure. Vitamin C is naturally present in juices which are
essential for the body to form collagen, cartilage, muscle, and blood vessels.
It also helps in the absorption of iron (International Federation of Fruit
Juice Union, 2011).
Fruit juice
is defined as a “non-fermented and non-sparkling fruit or vegetable beverage,
obtained by dilution in potable water of the juice, pulp or vegetable extract
of the fruit of origin, with or without sugar”. These are the unfermented, but
fermentable, liquids obtained from the edible part of sound, appropriately
mature and fresh fruits or fruits maintained in fresh condition by physical
means or other suitable treatments. Juices can be obtained by mechanical
extraction processes or by reconstitution of concentrated fruit juice with
clean water. Juices can be cloudy or clear and have the essential
characteristics typical of the juice of the fruit from which it comes. Diluting
and/or blending are common practices as many fruit juices are either too acidic
or too strongly flavored to be pleasant for consumption.
Watermelon (Citrullus lanatus;
family: Cucurbitaceae), also known as the sweet
desert watermelon, is believed to have
originated in North Eastern Africa over 5,000 years ago and is cultivated for
water and food (Paris, 2015). Watermelon consists of approximately 93% water,
is highly nutritional, especially the rind and seed (Erhirhie
and Ekene, 2014).
Lime (Citrus aurantifolia)
a citrus fruit is a household essential ingredient in numerous food or in
cuisine worldwide sequel to its distinctive sour taste. Its juice can be directly
squeezed into food during cooking (Cruz-Valenzuela et al., 2016). Lime
juice contains organic acid which is majorly citric acid that can serve as a
natural preservative. Good antimicrobial agents can be gotten from major citrus
family such as lime, lemon, orange and another genus in the group (Ezeigbo et al., 2015).
Mixed fruit
juices are liquid, non-alcoholic drink produced from the blends of fresh fruit
juice such as orange, tangerine, banana, watermelon, and pineapple among others
(Onwuka, 2014). In Nigeria, there is an availability
of suitable fruits which could be exploited for juice making such as passion
fruit, watermelon, pineapple, banana, and orange among others. These fruits are
highly perishable in nature (Fish and Davis 2003). Large quantities of the
fruit are traditionally and commercially processed into the different products
such as wine, fruit juice, soft drink, carbonated beverages, and alcoholic
drinks which help to prevent post-harvest loss.
Studies
conducted on pre-cut watermelon in the northern (Kano), eastern (Imo and Abia), and western (Oyo and Ogun)
parts of Nigeria revealed a high level of either pathogenic or spoilage
organisms such as Salmonella spp.,
Escherichia coli, Pseudomonas aeruginosa,
Staphylococcus aureus, Aspergillus
Niger, Rhizopus stolonifer and
Lactobacillus spp., which are a
reflection of the sanitary conditions and habits involved with handling the
fruits (Chukwu et al., 2010; Ijah et al., 2015
and Titilayo and Salome, 2014). However, little
information is available on the microbiome of the
whole watermelon.
Watermelon
consumption can be useful in maintaining acid–base balance in the body that has
a major role in normal physiology, maintaining appetite and normal digestion (Choudhary et al.,
2015). Hence, consuming contaminated juice of the fruit may give rise to
infection of digestive systems like diarrhea (Gry et al., 2016). Watermelon fruit juices
processed under hygienic conditions could an play
important role in enhancing consumer’s health through inhibition of breast
cancer, congestive heart failure (CHF) and urinary tract infection (Bello et al., 2014). The fruit supplies an
excellent medium for the growth of both pathogenic and spoilage microorganisms
thus, watermelon mixed fruit juices when pasteurized could prevent possible infection
routes of these pathogens when investigated and possible measures outlined so
as to maintain the nutritional component of mixed fruit juices.
Thus, the objective
of this work was to determine the physicochemical, sensory properties and
microbial qualities of pasteurized mixed fruit juices produced from blends of
watermelon and lime fruits.
The raw material that was used in this study
was purchased from new market in wukari, Taraba state, Nigeria. They were conveyed to Food Science
and Technology laboratory for analysis.
2.2.1 Preparation of Sample
The
method as described by Ijah et al., (2015) was used to prepare mixed fruit juice (watermelon
and lime). The fruits were washed, in clean water, sliced and extracted using
juice extractor (JEX328 UK). The fruit juices were divided into portions in ratio
of 90:10, 85:15, 80:20, and 50:50. Thereafter, the juices were dispense into
sterile plastic containers of 100mls each, and pasteurized at 85°C for 5
minutes.

Fig 1: Production of
watermelon lime juice
Source;
(Ijah et al.,
2015).
2.3.1 Physiochemical Analysis of Mixed Fruit Juices
2.3.1.1 Determination of pH
The
pH of the samples was determined using digital pH meter (JENWAY 3510) according
to the method reported in AOAC (2010). 10ml of the juice sample blends each
were used for the calibration of the pH using standard buffer solution of pH
4.0 and 7.0.
2.3.1.2. Determination of titratable
acidity (%TTA)
The
method as described by AOAC (2010) was used to determine titratable
acid value of the samples. 10 ml of the mixed fruit juice was diluted to 250 ml
using distilled water and titrated with standardized 0.1 N sodium hydroxide (NaOH) solution using 0.3 ml phenolphthalein indicator for
each 100 ml solution titrated to a pink
end point, which persisted for 30 seconds and the result were expressed in terms of NaOH/100
ml of the sample.
2.3.1.3 Determination of Sugar content (°Brix) :
Sugar
content (°Brix) was determined using a hand refractometer
(Bellingham and Stanly, Model
A85171) at 20 °C according to the method of (AOAC,2010) and the
value obtained from the reference
standard table was expressed as percentage sucrose by weight (°Brix).
2.3.2 Determination of Vitamins
2.3 .2.1 Determination of vitamin C
The
vitamin C (Ascorbic acid) was determined according to the procedures of AOAC
(2010). 20 ml of the fruit juice sample was pipette into 250 ml conical flask;
150 ml of distilled water and 1ml of starch solution indicator was added. The
sample was titrated with 0.005 M iodine solution. The endpoint of the titration
indicated a dark blue black colour. The amount of
vitamin C in the sample was calculated in mg/100 ml.
2.4.1 Determination of moisture content
The
moisture content was determined using the method described by AOAC (2010). 10mls
of juice sample was measured into a crucible and heated in the oven at 105oc
for 4 hours until constant weight was obtained. The loss in weight from the
original sample weight was calculated as the moisture content.
2.4.2 Determination of crude Fiber Content
The
crude fiber was determined according to the method of AOAC (2010). Petroleum
ether was used to defat 2g of sample. This was poured in a beaker containing
200 ml of 1.25 % H2SO4, boiled for 30 minutes, filtered
through muslin cloth on a fluted funnel and washed with boiling water until it
was free of acid. The residue was returned into 200 ml boiling NaOH and allowed to boil for 30 minutes. It was further
washed with 1 % HCl and then with boiling water to
free it of acid. The final residue was drained and transferred to silica ash
crucible (porcelain crucible) and dried in the oven to a constant weight and
cooled. The crude fiber content was calculated as:
%
Crude fiber =
x100,
Where;
W1= weight of content before ashing, W2= weight of
the crucible and ash, W3=
weight of dried material
2.4.3 Determination of crude protein:
One
gram (1g) of the sample was introduced into micro Kjeldahl
digestion flask and one tablet of Selenium catalyst was added. The mixture was
digested on an electro thermal heater until a clear solution was obtained. The
flask was allowed to cool after which the solution was diluted with distilled
water to 50ml and 5ml of this was transferred into the distillation apparatus,
5ml of 2% boric acid was added into a 100 capacity conical flask (the receiver
flask) and four drops of methyl red indicator were added. A 50% of NaOH was continually added to the digested sample until the
solution turned cloudy which indicated that the solution had become alkaline.
Distillation was carried out in the boric acid solution in the receiver flask
with the delivery tube below the acid level. As the distillation was going on,
the pink colour solution of the receiver flask turned
blue indicating the presence of ammonia. The resulting solution
was then titrated with 0.1 M HCl
and the protein content calculated (Oyelade et al; 2003 AOAC., 2005).
2.4.6 Determination of total ash:
The
ash content was determined from the loss in weight that occurred during
incineration of the evaporated sample at a temperature high enough to allow all
organic matter to be burnt off without allowing appreciable decomposition of
the ash constituents. Ashing was carried out in a
muffle furnace subjected to heat at 550°C for 6 hours (AOAC.,2005).
2.4.7 Determination of fat content
This
was carried out using the method of AOAC (2005). 5g oven dried sample was
weighed. The sample was placed in the thimble and inserted into the soxhlet apparatus and extraction under reflux was carried
out with petroleum ether for 6 h. After the barrel of the extractor has been
empty, the condenser and the thimble was removed, taken into the oven at 100°C
for 1 h and later cooled in the desiccator and weighed again to obtain the fat
content.
2.5.1 Determination
of Magnesium, Calcium, Potassium and iron.
Atomic
absorption spectrophotometer (Model Pu 91003,
England) was used to determine Mg, Ca, k, Fe contents
as described (Ibitoye, and Onwuka,
2005). 1.0g of each juice sample was weighed and first digested with 20ml of
acid mixtures (650ml Conc. HNO3, 80ml Perchloric
acid, 20mL Conc. H2SO4) to obtain clear digest, which was made up to 100ml with
distilled water. This was used for atomic absorption spectrophotometry using
individual lamps and wavelength for each element. Concentration
of element were determined using the calibration
curve by interpolation.
The samples were
assessed using a nine-point Hedonic Scale, where “9” represented extremely
liked and “1” represented extremely disliked as described by Ihekoronye
and Ngoddy (1985). A 20 - man semi-trained panelists
consisting of students from the Department of Food Science and Technology,
Federal University Wukari, Taraba
State were used. The panelists were asked to evaluate the samples for the
following attributes; flavor, color, aroma, taste, mouth feel and overall acceptability. The samples were
presented in a well packaged material. It was served simultaneously to ease
possibility of panelists evaluating the sample. Necessary precautions were taken
to prevent bias of panelists. They were given sachets of water to rinse their
mouth after each stage of sensory evaluation.
2.7.1
Media Preparation
The
enumeration of bacteria cells and fungi count from the samples of mixed fruits
juices from blends of watermelon and lime fruits was
done using Nutrient agar, Macconkey agar, and Potato
dextrose agar. .They were prepared according to the manufacturers (Titan
Biotech Ltd) instruction and sterilized by autoclaving at 121°C for 15 minutes
at 15 pounds per square inch (PSI).
2.7.2 Isolation and
Enumeration
Total
bacterial count was determined using the method as described by (Obasi et al., (2019).
The stock solution was prepared by dissolving 1ml of the sample each of the
mixed fruits juices from blends of watermelon and lime fruits in 9ml of sterile
peptone water. Serial dilution (10 fold) was carried out (1:10, 1: 100,
1:1000…10,0000). 0.1 ml of appropriate dilutions (10-2
and 10-4) was placed on various agar plates using pour plate method and
incubated at 37°C for 18-24 hr for total bacteria and
coliform count. For fungi 0.1 ml amount of appropriate dilutions (10-2 and
10-4) was also poured into the plates of potato dextrose agar and incubated at
room temperature 28±1°C for 3 to 5 days. All enumeration was expressed as
colony forming unit per milliliter (cfu/ml).
2.7.3 Purification
and Maintenance of Microbial Isolates
Bacteria
isolates were transferred into fresh agar medium of isolation and incubated at
37°C for 24hr. Pure colonies of bacteria cells were
picked, subcultured, purified and stored at 4°C until
when needed.
2.7.4 Identification and Characterisation
of the Isolates
Bacteria
isolates were identified and characterized based on their cultural,
morphological and biochemical tests as described by Cheesbrough,
(2006) and Obasi et
al., (2019). Biochemical tests included: indole,
catalase, citrate utilization , oxidase, hydrogen
sulfide production, Triple-Sugar Iron
agar (TSI) etc.
The
experimental design used was the factorial design and data obtained were subjected
to analysis of variance (ANOVA) using the statistical package for Social
Sciences Version 17.0. Duncan’s multiple range test
was used to compare the treatment mean. Statistical significance was accepted
at (p<0.05).
The
results of the physiochemical analysis of the mixed fruits juices from blends
of watermelon and lime fruits are presented in the Table 1 below, shows the
physicochemical properties of mixed fruit juice from blends of watermelon and
lime. The pH ranged from 2.70-5.40, titratable acidity
0.10-1.28, vitamin C 34.50-39.00mg/100g and the brix(%)
3.75-6.50. Based on the result from Table 4.1, it shows that the pH of mixed
fruit juice decreases significantly (p<0.05) as the concentration of lime
juice increases. This could be due to the liberation of organic acid from lime
which lowered the juice pH. The result obtained from
this study is in agreement with a previous study by (Adedeji
and Ezekiel, 2020), which showed a reduction in the pH of apple juices. There
was a corresponding significant increase in titratable
acidity (TTA) following an increase in lime juice. This aligned with the
reduction of pH consequent to the elaboration of organic acid.
There was no significant difference
(p<0.05) in the vitamin C content of the juice for every mg/100g. The result
of this study is in line with the report of Ijah, et al; (2015). There was a significant (p > 0.05) increase in
brix (obrix) following an increase in lime
juice. This could be due to the degradation of complex polysaccharides and
pectin to sugars (Sharma et al.,
2014). Adedeji and Ezekiel, (2020) also reported an
increase in brix of mango juice.
Table 1: Physiochemical analysis of mixed fruit juices
from blends of watermelon and lime fruits
|
Parameters |
A(100) |
B(90:10) |
C(85:15) |
D(80:20) |
E(50:50) |
|
pH |
5.40b±0.10 |
4.64b±0.47 |
3.30
b ±0.05 |
3.12c±0.02 |
2.70c±0.20 |
|
TTA |
0.07
c ±0.02 |
0.10c±0.01 |
0.09c±0.01 |
0.95
d ±0.05 |
1.28c±0.03 |
|
VITC
(mg/100g) |
39.00a±1.00 |
36.75a±1.75 |
37.00a±1.00 |
36.50a±0.50 |
34.50a±0.50 |
|
Brix
% |
3.75b±0.25 |
4.25
b ±0.25 |
4.75b±0.25 |
5.60b±0.20 |
6.50b±0.50 |
Results expressed in mean ± standard
deviation of duplicate determination. Values are means ± standard deviation of replicates
values within a column with the same superscript are not significantly
different at (P< 0.05).
Table
2 shows the result of mixed fruit juice from watermelon and lime fruit. The
result obtained from the various samples ranged from A-E, as follows for
calcium 0.40-0.90, iron 0.40-0.85, potassium 1.80-2.10, magnessuim 0.55-0.95 respectively. The concentration
of lime lead to decrease in all the minerals, however potassium and magnesium
had the highest mineral content. The result of this study is in line with the
report of Ijah, et
al; (2015) who also obtained a high value in potassium and magnesium in
watermelon and orange juice samples which
reported a high value in mineral composition of watermelon and orange
juice sample. Natural fruits and fruits and vegetable are good sources of
potassium. Inadequate intake of micronutrients (minerals) has been associated
with severe malnutrition, increased disease conditions and mental impairment (Dosumu et al.,
2006).
Table 2 Mineral
Composition of pasteurized mixed fruit juice from blends of Watermelon and Lime
fruits
|
Samples |
Calcium (PPM) |
Iron (PPM) |
Potassium
(PPM) |
Magnesium (PPM) |
|
A (100) |
0.90a±0.14 |
0.50b±0.14 |
2.10a±0.14 |
0.95a±0.01 |
|
B (90:10) |
0.90a±0.14 |
0.40b±1.41 |
2.00a±1.41 |
0.91ab±0.00 |
|
C (85:15) |
0.75a±0.01 |
4.00a±1.41 |
1.95a±0.01 |
0.85b±0.01 |
|
D (80:20) |
0.65ab±0.01 |
0.65b±0.01 |
1.90a±0.014 |
085b±0.01 |
|
E (50:50) |
0.40b±0.14 |
0.85b±0.01 |
1.80a±0.14 |
0.55c±0.01 |
Results
expressed in mean ± standard deviation of duplicate determination. Values are means ± standard
deviation of replicates values within a column with the same superscript are
not significantly different at (P< 0.05).
The
proximate composition of mixed fruit juice samples for sample A-E is shown in
Table 3. The result ranged from 3.80- 6.30% moisture content, Ash
0.03-2.05,Crude fiber 1.65-4.55,Fat 6.5-5.2%,1.65-4.55,Crude protein 1.65-
2.05%, and carbohydrate 39.56-54.85. The samples were rich in carbohydrates and
moisture but low in protein, fats, crude fiber and ash. Significantly
(p<0.05), there is a difference in the proximate composition. Moisture
content of the juice samples was significantly low as compare to standard
percentage. Vicente et al.
(2009) reported that the moisture content of juice falls at 90%. Ash content of
the juice ranges form 0.30-2.05%. The low ash content may be due to long-stored
fruit. Freshly harvested fruits have higher ash content. Higher ash content
implies good source of minerals. Fat content was higher in the 100% watermelon
juice and decreased as the level of lime juice increases. This is
in line with the report of Ijah et al., (2015), who had a similar result
that most citrus family such as watermelon contains more fat than any other
fruit. The low fat content observed in the juice samples is an indication that
the juice produced can keep for long periods at right temperature and moisture
without spoilage by oxidative rancidity (Adedeji et al., 2014).Crude protein contents
were not high in the samples of the mixed juices this is an indication that the
watermelon lime juice mixed had moderate protein content which implies that the
freshly made juice samples may be enough to prevent protein malnutrition. The
protein content is adequately enough to meet the FAO/WHO
recommended daily allowance of protein content of 0.59g kg-1b.wt., for
children aged 1-10 years as reported by (Anon,1995) and also it could serve as an
ideal diet for a select people with liver problems (hepatic cirrhosis,
hepatitis or hepatoma) who need little or no protein
in their menu and the obese or those watching weights (Adedeji
et al.,2014) The result obtained from
this study compared favorably with the result of (Ijah
et al., 2015) who researched on watermelon juice and watermelon orange juice
mix. After
water, carbohydrates are the most abundant constituents in fruits and
vegetables, representing 50% to 80% of the total dry weight. This is true as
the carbohydrates content of the mixed fruit juice sample obtained in this
study is significantly high.
Table 3: Proximate
Composition of pasteurized mixed fruit juices from blends of watermelon and
lime fruits
|
Parameters/sample |
A(100) |
B(90:10) |
C(85:15) |
D(80:20) |
E(50:50) |
|
Moisture content |
51.00c±0.05 |
49.70b±0.20 |
45.00b±.35 |
40.90b±0.25 |
37.30b±0.80 |
|
Ash |
0.30c±0.10 |
2.05c±0.05 |
2.00b±0.10 |
1.75c±0.25 |
1.35b±0.15 |
|
Crude fibre |
1.65d±0.15 |
1.65c±0.25 |
1.75b±0.25 |
1.75c±0.25 |
4.55b±0.05 |
|
Fat content |
6.20b±0.20 |
6.15b±0.35 |
6.10b±0.30 |
5.60b±0.20 |
0.30b±0.10 |
|
Crude protein |
1.80d±0.00 |
2.05c±0.15 |
1.80b±0.20 |
1.90c±0.10 |
1.65b±0.15 |
|
Carbohydrate |
39.56a±0.95 |
38.40a±2.20 |
43.35a±2.65 |
48.10a±1.70 |
54.85a±0.20 |
Results
expressed in mean ± standard deviation of duplicate determination. Values are means ± standard
deviation of replicates values within a column with the same superscript are
not significantly different at (P< 0.05).
The
result of the mixed fruits juices from blends of watermelon and lime are shown
in Table 4 below. The sensory evaluation test were carried out on the five
blends of juice samples in ratios of A(100), B(90:10),
C(85:15), D(80:20), and E(50:50) percent respectively. The overall
acceptability of any food product is one of the very important and basic
criteria for the acceptance or rejection of a food product (Alim-un-Nisa et al.,
2012).The results showed that a significant, difference existed. (p<0.05) among the sensory attributes of the juice. The
sensory evaluation result revealed that the control sample (100% watermelon
juice), recorded the highest score in terms of color, taste, flavor, and
general acceptability, this was followed by sample B (watermelon and lime
juice),which was more preferred in terms of color probably due to the presence
of lycopene which gives watermelon its natural color, (Erhaedt
et al.,2003). Sample E was least
preferred the in terms of all the parameters assessed. This study agrees with
the report of Ijah,
et al (2015).who obtained a similar results in a previous study on
watermelon and orange juice blends.
Table 4 Sensory evaluation
of pasteurized mixed fruit juices from blends of watermelon and lime fruits
|
Parameters/sample |
Taste |
Colour |
Aroma |
Flavour |
General
acceptability |
|
A(100) |
7.90a±0.22 |
7.80a±0.24 |
7.40a±0.28 |
7.05a±0.29 |
6.95a±0.34 |
|
B(90:10) |
5.25b±0.40 |
6.65b±0.33 |
5.45b±0.37 |
4.80b±0.48 |
5.45b±0.29 |
|
C(85:15) |
4.60b±0.46 |
6.55b±0.46 |
4.85b±0.41 |
4.55b±0.46 |
4.50b±0.51 |
|
D(80:20) |
5.05b±0.46 |
6.55b±0.39 |
5.65b±0.33 |
5.05b±0.43 |
5.00b±0.42 |
|
E(50:50) |
3.35c±0.42 |
4.35c±0.44 |
4.35c±0.56 |
4.10b±0.54 |
3.35c±0.56 |
Results
expressed in mean ± standard deviation of 20 panelist.
Values are means ±
standard deviation of replicates values within a column with the same
superscript are not significantly different at (P< 0.05).
Table
5 shows the result of the total aerobic plate count of bacterial cells. The total aerobic plate count for bacteria, coliform, and fungi
counts. Results obtained from this study is recorded as not detected or
no growth. This result is in agreement with the microbiological limits in fruit
juices and nectars according to UNBS (2009).Which states maximum of 103 cful/ml for total plate
count and 30 cful/ml for unpasteurized fruit
juices. Based on this standard limit, it can be deducted that microbial load of
the fruit juice samples analysed is not high. The
result of this study is in agreement with the work of (Ijah
et al.,2015).
Table 5: Total
aerobic plate count of bacteria cells and fungi (cfu/ml)
obtained from mixed fruit juices from blends of watermelon and lime fruits
|
Parameter (cfu/ml) |
Samples |
||||
|
A |
B |
C |
D |
E |
|
|
Total
aerobic plate count |
NG |
NG |
NG |
NG |
NG |
|
Coliform
count |
NG |
NG |
NG |
NG |
NG |
|
Fungi
count |
NG |
NG |
NG |
NG |
NG |
Key: A=Control
(100%), B=(90:10), C=(85:15), D =(80:20),
E=(50:50), NG = No growth
The result in (Fig 2) showed the microbial
flora isolated from mixed fruit juices from blends of watermelon and lime fruit.
The microbial flora identified and its prevalence include; Staphylococcus aureus (6.4%), Esherichi coli (16.1%), Bacillus (6.4%), enterobacter aerogen
(3.2%) Staphylococcus spp (16.1%),
Salmonella spp (3.2%),proteus vulgaris (9.6%) Klebsiella
pneumonia (12.9%) Pseudomonas (16.1%), Klebsiella spp (3.3%). were isolated. Esherichi coli should not be detected (Braide et al., 2012). The high magnitude of Esherichi coli and
Staphylococcus spp
in these juices could be due to high water activity of ready-to-serve juices.
Products with high water activity possess good amount of combined water
molecule that support growth and survival of microorganisms. (Asha et al., 2014).
The result of this study is similar to the report obtained from watermelon and orange juice mix by (Ijah et al., 2015).
Other
species of organisms isolated from the mixed fruit juices mix include: bacillus, staphylococcus spp
and klebsiella spp. as reported by Ayodele and Aranisola (2015). They stated that bacillus is a major
spoilage organisms in juices. The presence of staphyloccus spp in the juice
could be attributed to its wide spread in the environment. Pseudomona spp are commonly found on the fruit
surfaces which can end up in the juice during production. The result obtained
from this research is in line with the report of other reserachers
(Braid et al., 2012, Ijah et al., 2015,
Bernard et al 2021).

Fig 2: Prevalence of organisms isolated from mixed fruits
juices from blends of watermelon and lime fruits
This study
showed that freshly made juice from blends of water melon and lime fruits
contained high amount of nutrients and the combination increased the nutrient
composition based on all parameters assessed. The result of this research
revealed that mixed fruit juice blends had high amount of potassium, magnesium,
calcium, carbohydrate and moisture content but low in protein, crude fibre, fat and ash content. Combining natural fruit juices
could be of great health benefit to man. Pasteurized watermelon and lime have
great potential in the development of healthy fruit drink as shown in this
study. This could form a better alternative to the soft drinks flooding our
markets which put our health at a greater risk. The microbial count was very
low even beyond the allowable limit by Commission Regulation (EC) No. 2073, this showed that pasteurization had a positive effect
on the mixed fruit juices. Sample B (90:10) which is the best among all the juice sample analysed
should be used for pilot scale production and subsequent commercialization in
the food industry.
No conflict of interest to disclose.
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Cite this Article:
Obasi, BC; Ukpoju, L (2023). Evaluation of Physiochemical, Sensory
and Microbial Qualities of Mixed Fruits Juice from Watermelon and Lime Fruits.
Greener Journal of Agricultural
Sciences, 13(3): 198-207. |