Quality Assessment of Industrially Processed Fruit Juices Available in Dhaka City, Bangladesh

Abstract

This study was performed to evaluate the nutritional and microbiological quality of industrially processed packed fruit juices of mango (Mangifera indica) and orange (Citrus sinensis) from nine different manufacturing companies in Dhaka City. The highest quantity of total sugar (17.62%) and reducing sugar (9.99%) was recorded in mango juices while the lowest in orange juices (10.41% and 2.24% respectively) of different companies. In this study, protein contents were comparatively higher in mango juices than in orange juices. The pH of all samples varied from 3.50±0.10 to 4.70±0.05. Vitamin C content was comparatively higher in mango juices. The levels of metals tested namely, arsenic, lead, copper and zinc in the juices were within the limits of Bangladesh Standard and Testing Institute (BSTI) for fruit juices. The microbiological qualities of all the products were within the limits of the Gulf standards (the recommended Microbiological Standards for any fruit juice sold in the Gulf Region). Based on the above results, it is suggested that processed juices be prepared under hygienic conditions.

Full text

Quality Assessment of Industrially Processed Fruit Juices Available in Dhaka City, Bangladesh 431
Mal J Nutr 16(3): 431 - 438, 2010
Quality Assessment of Industrially Processed Fruit Juices
Available in Dhaka City, Bangladesh
Tasnim F*, Anwar Hossain M, Nusrath S, Kamal Hossain M, Lopa D
& Formuzul Haque KM
Institute of Food Science and Technology, Bangladesh Council of Scientific and Industrial Research
Dhanmondi, Dhaka-1205, Bangladesh
ABSTRACT
This study was performed to evaluate the nutritional and microbiological quality
of industrially processed packed fruit juices of mango (Mangifera indica) and
orange (Citrus sinensis) from nine different manufacturing companies in Dhaka
City. The highest quantity of total sugar (17.62%) and reducing sugar (9.99%)
was recorded in mango juices while the lowest in orange juices (10.41% and
2.24% respectively) of different companies. In this study, protein contents were
comparatively higher in mango juices than in orange juices. The pH of all samples
varied from 3.50±0.10 to 4.70±0.05. Vitamin C content was comparatively higher
in mango juices. The levels of metals tested namely, arsenic, lead, copper and
zinc in the juices were within the limits of Bangladesh Standard and Testing
Institute (BSTI) for fruit juices. The microbiological qualities of all the products
were within the limits of the Gulf standards (the recommended Microbiological
Standards for any fruit juice sold in the Gulf Region). Based on the above results,
it is suggested that processed juices be prepared under hygienic conditions.
Keywords: Dhaka City, processed fruit juices, quality assessment
*Correspondence author: Tasnim Farzana; Email: triptiot@yahoo.com
INTRODUCTION
Fruit juices are becoming an important part
of the modern diet in many communities.
They are nutritious beverages and can play
a significant part in a healthy diet because
they offer good taste and a variety of nutrients
found naturally in fruits. Juices are available
in their natural concentrations or in
processed forms.
Juice is prepared by mechanically
squeezing fresh fruits or is extracted by
water. Juices are fat-free, nutrient-dense
beverages rich in vitamins, minerals and
naturally occurring phytonutrients that
contribute to good health. For example,
orange juice is rich in vitamin C, an excellent
source of bio-available antioxidant
phytochemicals (Franke et al., 2005) and
significantly improves blood lipid profiles
in people affected by hyper-cholesterolemia
(Kurowska et al., 2000). Fruit juices promote
detoxification in the human body (Deanna
& Jeffrey, 2007).
The constituents of processed juices are
mainly water, sugar, preservatives, colour,
and fruit pulp. The most commonly used
preservatives are benzoic acid, sorbic acid
or sulphur dioxide. Natural colours such as
anthocynins and betanin are used. Acid is

Tasnim F, Anwar Hossain M, Nusrath S, Kamal Hossain M, Lopa D & Formuzul Haque KM
432
an essential universal constituent of juice
and the most commonly used acid is citric
acid.
Most fruit juices contain sufficient
nutrients that could support microbial
growth. Several factors encourage, prevent
or limit the growth of microorganisms in
juices; the most important are pH, hygienic
practice and storage temperature and
concentration of the preservative. Storage of
products at refrigerator temperature or below
is not always best for the maintenance of
desirable quality of some fruits. Water used
for juice preparation can be a major source
of microbial contaminants such as total
coliforms, faecal coliforms, faecal
streptococci, etc. Environmental formites
may also make the fruits unsafe and these
may have a role in the spread of Salmonella,
Shigella, Vibrio, Escherichia coli and other and
caause diseases as well fruit spoilage (Doyle,
Beuchat & Montville, 2001). Spoilage yeasts
such as Saccharomyces cerevisiae, Candida
lipolytica and Zygosaccharomyces spp. can
tolerate acidic environments. It should also
be noted that changes in pH could transform
a food into one which can support the growth
of pathogens (FDA, 2001).
The quality of fruit juices is strictly
maintained in developed countries under
several laws and regulations but in many
developing and underdeveloped countries,
the manufacturer is not concerned about the
microbiological safety and hygiene of fruit
juices because of lack of enforcement of the
law. Thus the transmission of certain human
diseases through juice and other drinks in
recent years is a serious problem.
Fruit juices are available in essentially
the same form almost anywhere in the
world. From polar bases to the tropics and
from the largest developed countries, fruit
juices are available in bottles, cans,
laminated paper packs, pouches, cups and
almost every other form of packaging
known. In recent years these juices have been
included significantly in the diet of most
people, irrespective of age. Therefore,
maintaining the quality of processed fruit
juices is an important concern. In order to
develop awareness among the people about
fruit juices, this study attempts to measure
nutritional and microbiological quality of
industrially processed locally available fruit
juices.
MATERIALS AND METHODS
Seven types of mango juices and two types
of orange juices were collected from different
manufactures in Dhaka City for nutritional
and microbiological analysis. At least 5
samples of each category were analysed to
overcome sampling bias. These samples
were designated as A (orange), B (mango), C
(mango), D (mango), E (mango), F (orange),G
(mango), H (mango) and I (mango).
Estimation of nutrient composition of fruit
juices
Moisture and ash contents of fruit juices
were determined using standard AOAC
methods (Horwitz, 2003). Crude protein
content of the samples was determined using
the Kjeldahl method (Horwitz, 2003). The
method consists of three basic steps: (i)
digestion of the sample in sulfuric acid with
a catalyst, which results in conversion of
nitrogen to ammonia; (ii) distillation of the
ammonia into a trapping solution; and (iii)
quantification of the ammonia by titration
with a standard solution. According to this
method, % crude protein content of a sample
= % nitrogen × 6.25.
Ascorbic acid was estimated by 2, 6-
Dichlorophenolindophenol visual titration
method according to AOAC. The reagents
used for the estimation of vitamin C were as
follows: (i) metaphosphoric acid (6%; (ii)
standard ascorbic acid solution; and (iii) 2,
6-Dichlorophenolindophenol dye. For
estimation of vitamin-C, the following steps
were followed: standardisation of dye
solution, preparation of solution and
titration (AOAC, 2004). The official Lane-
Eynon method described in AOAC was used

Quality Assessment of Industrially Processed Fruit Juices Available in Dhaka City, Bangladesh 433
to measure total sugar and reducing sugar
contents in fruit juices (James, 2004).
Total Soluble Solid (TSS) is one of the
more important quality factors for most fruit
juices. TSS content of fruit juices was
determined using an Abbe refractrometer
whereby a drop of pulp solution was placed
on its prism. The percentage of TSS was
obtained from direct reading of the
refractrometer.
Acidity was determined by dissolving a
known weight of sample in distilled water
and then titrated against 0.01 N NaOH using
phenolphthalein as indicator (Srivastava &
Sanjeev, 2003); pH was determined using
digital pH meter (Inolab digital pH meter).
Metals in fruit juices were measured using a
graphite furnace of Atomic Absorption
Spectrophotometer (GBC scientific
equipment XAA1175, Australia) equipped
with D2 background correction devices.
Bacterial analysis of collected juice
samples
For the quantitative determination of total
count of mesophilic bacteria, total coliform,
faecal coliform, the standard procedure was
followed (FDA, 2001). Aerobic plate count
(APC) was performed by pour plate method
using plate count agar (PCA), which was
incubated at 35±10C for 48±2h. Lauryl
tryptose broth was used for isolation of
Escherichia coli. Gassing tube was selected
for E.coli enumeration using most probable
number (MPN) method. Enumeration of
fungi was performed on Potato Dextrose
Agar medium. For the isolation of Salmonella
species, pre-enrichment was done by lactose
broth followed by selective enrichment and
finally confirmed using the standard
method (FDA, 2001).
Statistical analyses
Data analyses were performed using
Statistical Package for the Social Sciences
(SPSS version 12.0). Values were expressed
as percentage and mean±SD. Appropriate
test statistics (ANOVA) and t-test were done
to determine the effect of nutrition content in
fruit juices.
RESULTS AND DISCUSSION
In spite of the potential benefits offered by
fruit juices, concerns over their safety and
quality have been raised. An estimate of the
gross nutrient composition of the juices is
shown in Table 1 and there appear to be
some differences between the juices.
Most of the common fruits are low in
protein. A considerable proportion of the
protein content of fruits is insoluble and
consequently remains in the pomace;
therefore most fruit juices are very low in
protein (Table 1). In this study, protein
content in mango juices was comparatively
higher than in orange juices (P<0.001).
It is estimated that reducing sugar and
total sugar content are increased with the
advanced ripening of fruits. Mango juices
contained the highest (P<0.001) quantity of
reducing sugar and total sugar while orange
juices contained the lowest quantity at all
times of observation (Table 1). The combined
effect of stages of maturity and ripening
conditions significantly affected the reducing
sugar and total sugar content of the fruit
juices. The highest quantity of total sugar
(17.62%) and reducing sugar (9.99%) was
recorded in mango juices while these were
lowest in orange juices (10.41% and 2.24%
respectively) of different companies.
The total acidity of fruit juices is due to
the presence of a mixture of organic acids,
whose composition varies depending on
fruit nature and maturity. The main acids
encountered in fruits are tartaric, malic, citric,
succinic, lactic and acetic acids. Organic
acids take the lead in importance for
characteristics and nutritive value of fruit
juices and confer individual originality
among natural beverages. Total titrable
acidity varied significantly (P<0.001) in
different types of fruit juices (Table 1).
Maximum content of total titrable acidity

Tasnim F, Anwar Hossain M, Nusrath S, Kamal Hossain M, Lopa D & Formuzul Haque KM
434
(0.74%) was recorded in H (mango) juice
while it was minimum (0.45%) in G (mango)
juice.
Total soluble solids (TSS) contents are
related directly to both the sugars and fruit
acids as these are the main contributors.
Pectins, glycosidic materials and the salts of
metals (sodium, potassium, calcium etc.),
when present, will also register a small but
insignificant influence on the solids figure.
The TSS content is significantly influenced
by the combined effect of stages of maturity
and ripening conditions. The TSS content of
mango juices in this study was higher
(P<0.001) than that of orange juices (Table
1).
Fruit juices have a low pH because they
are comparatively rich in organic acid. The
overall range of pH is 2 to 5 for common
fruits with the most frequent figures being
Products Moisture Ash Protein Total Reducing TSS Acidity
(Scientific (%) (%) (%) sugar sugar (%) (%)
name) (%) (%)
A(orange)
(Citrus 89.98±0.08 0.06±0.01 0.08±0.001 10.98±0.01 4.96±0.02 9.00±0.02 0.50±0.01
sinensis)
B(mango)
(Mangifera 89.22±0.04 0.05±0.02 0.17±0.01 11.00±0.20 9.99±0.31 11.00±0.23 0.50±0.02
indica)
C(mango)
(Mangifera 87.00±0.17 0.03±0.00 0.38±0.01 13.37±0.22 5.10±0.25 12.00±0.08 0.56±0.00
indica)
D(mango)
(Mangifera 86.78±0.04 0.06±0.00 0.66±0.03 10.84±0.02 4.00±0.04 12.00±0.07 0.65±0.04
indica)
E(mango)
(Mangifera 85.75±0.33 0.07±0.01 0.58±0.02 17.62±0.05 3.37±0.21 13.00±0.09 0.61±0.07
indica)
F(orange)
(Citrus 89.19±0.61 0.05±0.01 0.001±0.00 10.41±0.04 2.24±0.06 10.50±0.01 0.59±0.011
sinensis)
G(mango)
(Mangifera 89.16±0.01 0.01±0.02 0.001±0.00 12.96±0.08 7.00±0.01 13.50±0.02 0.45±0.05
indica)
H(mango)
(Mangifera 86.42±0.78 0.08±0.01 0.08±0.01 12.44±0.12 4.25±0.00 13.00±0.11 0.74±0.02
indica)
I(mango)
(Mangifera 85.80±0.02 0.05±0.02 0.001±0.00 14.49±0.50 5.29±0.08 13.50±0.25 0.66±0.01
indica)
P-value <0 .001* <0 .001* <0 .001** <0 .001** <0.001** <0 .001** <0 .001*
Table 1. Potential nutritional value of samples of fruit juices purchased from a local market in
Dhaka city
Results are expressed as means ± SD for five observations. P-value was calculated using *One-Way
ANOVA F-test among juices and **independent sample t-test between two types of juices.

Quality Assessment of Industrially Processed Fruit Juices Available in Dhaka City, Bangladesh 435
between 3 and 4. In this study, the pH of the
fruit juices varied from 3.50±0.10 to
4.70±0.05. The highest pH was shown by I
(mango) juice (4.70±0.05), followed by H
(mango) juice (4.60±0.06), F (orange) juice
(4.50±0.08), A (orange) juice (4.40±0.02), C
(mango) juice (4.30±0.05), E (mango) juice
(4.20±0.00), G (mango) juice (4.00±0.04), B
(mango) juice (3.60±0.02) and D (mango)
juice (3.50±0.10).
Ascorbic acid not only restores
nutritional value lost during processing, but
also contributes to the product appearance
and palatability. Ascorbic acid (vitamin C)
content of different fruit juices is shown in
Table 2. The ascorbic acid content of
commercial fruit juices is lost with respect to
time and temperature during processing and
storage (Biljana & Marija, 2009). Many
processors add ascorbic acid to their
products to make up for processing losses
(Takeda U.S.A., Inc.). This could be the cause
for higher content of ascorbic acid in mango
juices in this study.
Table 3 presents the concentration of
heavy metals. Analysis of variance (P<0.001)
showed a significant variability in the
concentration of the studied metals. The
level of arsenic found in this study was low
compared to any other metal examined. The
concentration of lead in these fruit juices was
highest in A (orange) juice (0.200 mg/kg)
and was nil in C (mango) juice. The major
source of lead in canned fruit juices is the
leaching of lead from the canning. Lead
toxicity causes many signs and symptoms
such as abdominal pains, anemia, brain
damage, anoxia, convulsion and inability
to concentrate etc. (Chukwujindu et al., 2008).
The level of zinc in this study was highest in
D (mango) juice (1.640 mg/kg) and absent
in A (orange) juice. Copper is an essential
element for growth, although emetic in large
doses. However, when present in some
beverages such as fruit juices, it tends to
impair shelf life and keeping quality of
juices, so it is expected that fruit juice should
contain low levels of copper. The level of
copper found in this study was higher in G
(mango) juice (1.50 mg/kg) and was lower
in B (mango) juice (0.120 mg/kg). The levels
of all of these metals were within the limits
of BSTI standard for fruit juice (BSTI. 2002).
Standard plate count of different types
of fruit juices varied from 2×103 - 4×103 cfu/
ml. No coliform, fungus or Salmonella were
detected in these juices (Table 4). The
microbiological quality of all the products
was within the limits of the Gulf standards
for fruit juices (Gulf Standards, 2000).
Products (Scientific name) Ascorbic acid (mg/100)
A(orange)(Citrus sinensis) 5.64±0.08
B(mango)(Mangifera indica) 2.25±0.11
C(mango)(Mangifera indica) 1.27±0.15
D(mango)(Mangifera indica) 7.95±0.05
E(mango)(Mangifera indica) 8.80±0.02
F(orange)(Citrus sinensis) 4.50±0.04
G(mango)(Mangifera indica) 4.50±0.06
H(mango)(Mangifera indica) 2.48±0.09
I(mango)(Mangifera indica) 4.70±0.07
P-value <0.05
Table 2. Vitamin C (ascorbic acid) content of different fruit juices.
Results are expressed as means ± SD for five observations. P-value was calculated
using independent sample t-test between two types of juices.

Tasnim F, Anwar Hossain M, Nusrath S, Kamal Hossain M, Lopa D & Formuzul Haque KM
436
Products Arsenic mg/kg Lead Zinc Copper
(Scientific name) mg/kg mg/kg mg/kg
A(orange) 0.010±0.001 0.200±0.01 0.000±0.00 1.000±0.09
(Citrus sinensis)
B(mango) 0.003±0.000 0.043±0.00 0.570±0.09 0.120±0.02
(Mangifera indica)
C(mango) 0.010±0.001 0.000±0.00 0.420±0.04 0.190±0.06
(Mangifera indica)
D(mango) 0.005±0.000 0.020±0.00 1.640±0.11 0.200±0.01
(Mangifera indica)
E(mango) 0.002±0.000 0.042±0.01 0.230±0.02 0.260±0.03
(Mangifera indica)
F(orange) 0.005±0.000 0.045±0.02 0.427±0.05 0.513±0.04
(Citrus sinensis)
G(mango) 0.010±0.002 0.012±0.01 0.250±0.04 0.130±0.02
(Mangifera indica)
H(mango) 0.002±0.000 0.013±0.00 0.150±0.01 1.500±0.08
(Mangifera indica)
I(mango) 0.002±0.000 0.027±0.01 0.154±0.02 0.700±0.07
(Mangifera indica)
P-value <0.001 <0.001 <0.001 <0.001
Table 3. Values of arsenic, lead, zinc and copper content of different fruit juices
Results are expressed as means ± SD for five observations. P-value was calculated using One-Way ANOVA
F-test among juices.
Products Standard plate Total coliform Total Salmonella
(Scientific name) count MPN/g fungus g/ml
Cfu/ml Cfu/g
A(orange) 4 × 103ND ND ND
(Citrus sinensis)
B(mango) 3 × 103ND ND ND
(Mangifera indica)
C(mango) 3× 103ND ND ND
(Mangifera indica)
D(mango) 4× 103ND ND ND
(Mangifera indica)
E(mango) 2× 103ND ND ND
(Mangifera indica)
F(orange) 3 × 103ND ND ND
(Citrus sinensis)
G(mango) 4 × 103ND ND ND
(Mangifera indica)
H(mango) 3 × 103ND ND ND
(Mangifera indica)
I(mango) 4 × 103ND ND ND
(Mangifera indica)
Table 4. Microbiological analysis of different fruit juices.
ND= None Detected

Quality Assessment of Industrially Processed Fruit Juices Available in Dhaka City, Bangladesh 437
Because of the poor monitoring system in
developing countries like Bangladesh, it is
very difficult to evaluate how the consumer
can be affected by taking fruit juices. The
better alternative is to monitor the proper
management of raw materials and
production of the plant to prevent or
minimise microbial contamination of juices
(Doyle, Beuchat & Montville, 2001).
CONCLUSION
This work has shown that the locally
available fruit juices contain safe levels of
nutritional and microbial elements for
human consumption. Each juice provides a
different range of nutritional components
that are desirable in a diet. The levels of all
metals were within the limit of the BSTI
standard for fruit juice. On the basis of
standard plate count, about 100% of the
samples recorded an acceptable range based
on the Gulf standards for fruit juices. It was
also found that the presence of pathogenic
organisms such as total coliform, salmonella
and fungus were within the acceptable range
and considered safe for consumption. The
Government-authorised institute such as
Bangladesh Council of Scientific and
Industrial Research (BCSIR) and BSTI
should undertake pre-emptive investiga-
tions to check the microbial and chemical
quality of the fruit juices as well as initiate
increased public awareness programmes on
contaminated and adulterated juices.
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