Dept. of Science Laboratory,
Rufus Giwa Polytechnic,
P.M.B. 1019,
Owo, Ondo State,
Nigeria.
8th February, 2010
The Executive Editor
PJSIR,
Scientific Information Centre,
PCSIR Lab. Campus,
Pakistan.
Dear Sir,
LETTER OF UNDERTAKING
I would like to submit the attached manuscripts for possible evaluation and publication in
your Journal.
Title: Effects of Storage and Packaging Material on Some Physico-Chemical
Properties, Sensory and Microbiogical Qualities of Pineapple Juice (Anana
comosus).
Name and Address of Corresponding Author: Arawande Jacob Olalekan.
Department of Science Laboratory Technology Rufus Giwa Polytechnic, P.M.B.
1019 Owo, Ondo State, Nigeria
E-Mail:joawande1@yahoo.com; Mobile Phone Number: 234-8034391608
I affirm that the manuscript has been prepared in accordance with the given instruction
for authors and that the content of this manuscript has not been published and not under
consideration elsewhere.
I also wish the editor should send the manuscript to any potential referees of their choice.
Thanks
Yours faithfully
Signed,
Arawande, J.O.
EFFECTS OF STORAGE AND PACKAGING MATERIALS ON SOME
PHYSICO-CHEMICAL PROPERTIES, SENSORY & MICROBIOLOGICAL
QUALITIES OF PINEAPPLE JUICE (Ananas comosus)
1SHAKPO,
ITUNNU OLUBUNMI
Department of Food Science and Technology
Rufus Giwa Polytechnic, P.M.B. 1019, Owo, Ondo State, Nigeria.
E-mail: isskpo4ever@yahoo.com
Mobile Number: +2348036267170
1
2*ARAWANDE,
JACOB OLALEKAN
Department of Science Laboratory Technology,
Rufus Giwa Polytechnic, P.M.B. 1019, Owo Ondo State, Nigeria.
*
Corresponding Author: E-mail:joawande1@yahoo.com
Mobile Number: +2348034391608
2*
ABSTRACT
Concentrated pineapple juice was prepared in the laboratory and stored in Tin Cans and
Glass bottles of equal capacity at ambient temperature and observed over a period of ten
weeks. The stored juice was analyzed at a regular interval of two weeks for pH, Brix,
Total solid, Titratable acidity, Vitamin C, Specific gravity, microbiological and sensory
qualities (Taste, Colour and Aroma). There was a slight increase in the pH values from
4.2 to 4.7 and 4.8 in canned and bottled pineapple juice respectively. The titratable
acidity decreased from 8.1 to 5.1 and 4.6 in canned and bottled pineapple concentrates
respectively. The total solids (g/100ml Citric acid) of pineapple concentrates decreased
from 76.23 to 65.47 and 60.38 for canned and bottled pineapple concentrates
respectively. The Vitamin C contents of the concentrates decreased appreciably, over
90% loss of Vitamin C was observed. The bottled samples retained more Vitamin C than
the canned samples. The microbial contents of pineapple concentrate ranged from 2.0 x
103 to 2.4 x 104 sfu/ml and 0 x103 to 6 x 103 cfu/ml for fungi and total mesophilic
bacteria respectively. Sensory analysis revealed that the freshly prepared single strength
juices from pineapple were more preferred in terms of taste and colour. While the
reconstituted juice from the bottled concentrate competed favourably well with the fresh
sample in terms of colour. The canned samples lost their colours within the 10 weeks of
storage. The glass bottled samples has characteristic desirable aroma. It was established
that concentrated juice in glass bottles stored at room temperature enhanced the keeping
quality of the juice and competed more favourably with the fresh juice than the canned
concentrated juice.
2
INTRODUCTION
Fruits are developed from matured ovary and are common food materials
which contribute micronutrients (Vitamins and Minerals) and natural soluble
sugars for energy to support human nutrition (Ihekoronye and Ngoddy, 1985).
Juice is obtained from fruits among which are orange, pineapples, cashew etc.
Juice concentrates can be obtained by partial evaporation of moisture from the
fruit juice and this is likely to have a longer shelf life than the juice due to lower
moisture content (Takahashi, et al., 2000)
Pineapples (Ananas comosus) are one of the most common non-citrus
tropical and sub-tropical fruits. They have attractive flavour, reducing sugar, a
very rich source of Vitamin C and organic acids. Pineapples contain high level of
sugars and other carbohydrates and are therefore major sources of dietary fibre
and enzymes which can serve as digestion aid (Takahashi, et al., 2000). Pineapple
is a non-citrus fruit. It is a member of the Bromiliaceae family, Ananas genus and
Sativa species (Garcia and Medina, 2005).Pineapple is the second harvest of
importance after bananas, contributing to over 20% of the World production of
tropical fruits (Coveca, 2002). Nearly 70% of the pineapple is consumed as fresh
fruit in producing countries. Its origin has been traced to Brazil and Paraguay in
the Amazonic basin where the fruit was domesticated (Garcia and Medina,
2005).Thailand, Philippines, Brazil and China are the main pineapple producers in
the World supplying 50% of the total output (FAO, 2004). Other important
producers include India, Nigeria, Kenya, Indonesia, Mexico and Costa Rica and
these countries provide most of the remaining fruit available (50%).
Pineapple as a plant serves a number of uses. The leaves can be used in
three forms; fresh dried and in silage (Geo coppens, 2001). One of the best known
properties is as a diuretic. This helps to eliminated toxins through the urine,
helping patients with ailments of kidneys bladder and prostate. Due to the fibre
content of the pulp, pineapple prevents constipation and regularizes the intestinal
flora (FAO, 2004). Furthermore, there is evidence of appetite reducer, heat
protection and aid for fever, sore throat and mouth aches and inflammation
(Gastron0mia, 2004). Lightly boiled ground pineapple can be used to clean
3
infected wounds because it eliminates dead tissues, not affecting live tissue, acts
as disinfectant and accelerates cicatrisation (Mundogar, 2004).
Unfortunately, this fruit is seasonal, highly perishable and prone to high
post-harvest losses. Extracting and concentrating the juice will reduce the losses
by enhancing the keeping qualities thereby making it available all the year round.
Post-harvest losses occur in fruits during transportation, storage and while waiting
to be processed. Pineapples, after harvesting are still physiologically active.
Deterioration of fruit can result from physical factors such as bruises, action of
their own enzymes (proteolytic enzyme), microbial action, or combination of
these agents (Adetuyi, 2007).
Losses in pineapple during air transport are minimal if careful handling is
employed. Mechanical damage include bruising or puncturing caused by poor
handling, dropping or abrasion which results in localized area of softening and
development of secondary microbial infection (Food market exchange, 2004).
Pineapple handlers can minimize fruit damage by taking protective measure
throughout all handling stages. Other agents of spoilage are yeast, bacteria and
fungi. Microorganisms isolated from pineapple juices include Bacillus species,
Lactobacillus species, Pseudomonas species and Mucor species, (Aderibigbe et
al., 2001).
Canning is a method of food preservation which involves subjection of the
food materials in cans to an elevated temperature for the purpose of eliminating
both pathogenic and spoilage organisms and hermetically sealing the cans to
avoid external influence from the environment. Bottling is also a method of
preservation which employs the use of sterile glass bottles with lids in food
packaging.
The chemical and microbial compositions of a food are the most important
parameters in determining the overall quality of that food. The changes in these
parameters which occur during its preparation and storage after preparation are
indices of the suitability or otherwise of the product for consumption and its
suitability. Although, food preservation is necessary, the maintenance of the
nutrients in the food is also of utmost importance. Pineapples have been known as
4
the best source of vitamin C, greater amount of which was lost during storage at
room temperature (Aderibigbe et al., 2001).
Previous works on pineapple showed that it contains 81.2 to 86.2%
moisture and 13-19% total solids of which sucrose, glucose and fructose are the
main components. Carbohydrates are up to 85% of the total solids whereas fibre
makes up to 2-3%. Of the organic acid, citric acid is the most abundant. The pulp
has very low ash content, nitrogen compounds and lipid (0.1%). From 25-30% of
nitrogenous compound are true proteins. Out of this proportion 80% has
proteolytic activity due to a protease known as Bromelin (Dull, 1971). Utilization
of by-products from pineapple culture, canning and juice extraction has been
encouraged for feed production (Geo coppens, 2001).
There is limited information on the effect of juice concentration, canning
and bottling on pineapples. Therefore the objectives of this research work are to
extract, concentrate pineapple juice in form of thick slurry in tin cans and glass
bottles and to examine the effects of storage containers on the physico-chemical
properties, sensory and microbiological qualities of the juice stored over a period
of ten weeks.
MATERIALS AND METHOD
Pineapple fruits used for this research work were purchased from a
renowned market called “Oja Koko” in Owo Local Government area, Ondo State,
Nigeria. The fruits were extracted for juice following the procedure described by
Ihekoronye and Ngoddy (1985) (Figure 1). The juice was concentrated to 71%
brix using water bath. The concentrate was divided into two; one part was canned
in tin cans while the other was bottled in glass bottles of equal capacity. The
physico-chemical properties, sensory qualities and microbial content of pineapple
juice and concentrate were fort-nightly determined for a period of ten weeks.
5
RAW MATERIALS (PINEAPPLE FRUITS)
SORTING AND WASHING
WEIGHING
PEELING
CUTTING/CORING
CRUSHING/EXTRACTION
FILTRATION
EVAPORATION/CONCENTRATION
STERILIZATION OF CANS & BOTTLES
FILLING
BOTTLING
LIDDING/CLINCHING
EXHAUSTING/VACUUMING
SEALING
COOLING
JUICE CONCENTRATES
FIG. 1: FLOW CHART FOR THE PRODUCTION OF PINEAPPLE JUICE CONCENTRATE
6
Determination of the Physico-chemical Properties of Pineapple Juice
The physico-chemical properties determined were pH, brix, total solids,
specific gravity, total titratable acidity, and vitamin C. The pH of fresh pineapple
juice as well as the concentrated juice was determined using pH meter. While the
brix levels were determined using Abbe refractometer. The total solids, specific
gravity, total titratable acidity and vitamin C were determined using standard
methods (AOAC, 2005).
Sensory Evaluation of Pineapple Juice Concentrate
Sensory evaluation based on Taste, Colour and Aroma was carried out as
described by Larmoud (1982) using a team of 10 taste panelists for each set of
samples. Each panelist’s score was reflected on a nine point Hedonic scale
ranging from nine (9) (like extremely) to one (1) (dislike extremely). The result
obtained was subjected to Statistical analysis of variance and means were
calculated using Duncan’s Post Hoc. Test.
Microbiological Analyses of Pineapple Juice Concentrate
The media used in carrying out the microbial count of the
samples were MacConkey agar (MA) and Potato Dextrose Agar (PDA) for total
mesophilic bacteria and fungi tests respectively.
The media were prepared
according to the method described by Franzetti and Galli (1999).
RESULTS AND DISCUSSION
From the result of the various analyses after the ten weeks of storage,
several data trends were observed. The results tabulated below are a combination
of trends seen in the experiments (on canned and bottled pineapple concentrates).
The means and standard deviation are based on triplicate analysis from both fresh
and concentrated juice container per condition.
Table 1 shows some physico-chemical properties of pineapple juice and
concentrate stored in tin cans and glass bottle for a period of ten weeks. The fresh
pineapple juice contains pH 3.70 ± 0.10, Brix 12.20±0.427%, and Total titratable
acidity of 1.38 ± 0.03g/100ml citric acid, Vitamin C 153.3±0.4mg/100ml, Total
solid 10.11±0.11% and Specific gravity of 1.21±0.033. This is consistent with the
7
findings of Kristin (2005) who obtained 12.8% Brix, and 0.724g/100ml total
acidity. The concentrated juice has pH 4.20 ± 0.10, Brix 71.01±0.115%, Total
titratable
acidity
of
8.17
±
0.148g/100ml
citric
acid,
Vitamin
C
781.94±0.051mg/100ml Total solid 76.23±0.252% and Specific gravity
1.25±0.104. It was observed that these parameters except pH decreased as the
storage period increased in both the canned and bottled concentrates. The pH,
Brix and Vitamin C of bottled concentrate were relatively higher than that of the
bottled concentrate while the reverse trend was noticed for titratable acidity and
total solid over the ten weeks storage period. However, the parameters of the fresh
juice were much lower than that of the concentrated juice (Canned and Bottled
concentrates). This can be traced to the fact that the concentrated juice contains
reduced moisture content (Fagbemi and Adigun, 1998).
Over the period of storage, the range values of pH, Brix, Total titratable
acidity, Vitamin C and Total solid of canned concentrate were 4.20 – 4.70, 71.30
– 62.50, 8.17 – 5.11, 780.91 – 7.02 and 76.23 – 65.47 respectively while that of
bottled concentrate were 4.20 – 4.80, 70.92 – 66.33, 8.17 – 4.61, 781.94 – 13.02
and 76.23 – 60.38 accordingly.
8
TABLE1: SOME PYSICO-CHEMICAL PROPERTIES OF PINEAPPLE JUICE AND
CONCENTRATE STORED IN TIN CANS AND GLASS BOTTLES FOR A PEROD OF TEN
WEEKS
TIME
(WEEKS)
0
2
4
6
8
10
*PINEAPPLE JUICE
SAMPLES
*pH
*BRIX
(%)
*TITRATABLE
ACIDITY
(g/100ml citric acid)
*VITAMIN C
(mg/100ml)
*TOTAL
SOLID (%)
*SPECIFIC
GRAVITY
1.38 ± 0.03
153.3 ± 0.40
10.11 ± 0.11
1.21 ± 0.033
Fresh Juice
3.70 ± 0.10
12.20 ± 0.427
Concentrated Juice
4.20 ± 0.10
71.01 ± 0.115
8.17 ±0.148
781.94 ± 0.051
76.23 ± 0.252
1.25 ± 0.104
Canned concentrate
4.20 ± 0.09
71.30 ± 0.609
8.17 ± 0.020
780.91 ± 0.415
76.23 ± 0.330
1.31 ± 0.01
Bottled concentrate
4.20 ± 0.07
70.92 ± 0.382
8.17 ± 0.023
781.94 ± 0.05
76.23 ± 0.436
1.31 ± 0.01
Canned concentrate
4.40 ± 0.10
63.42 ± 0.289
7.64 ± 0.04
141.03 ± 0.147
74.42 ± 0.42
1.34 ± 0.142
Bottled concentrate
4.50 ± 0.10
66.30 ± 0.482
7.62 ± 0.02
177.66 ± 0.602
70.37 ± 0.07
1.33 ± 0.033
Canned concentrate
4.53 ± 0.153
63.29 ± 0.189
7.04 ± 0.02
72.99 ± 0.431
71.41 ± 0.01
1.32 ± 0.01
Bottled concentrate
4.60 ± 0.10
67.33 ± 0.147
6.94 ± 0.055
80.29 ± 0.101
66.39 ± 0.09
1.33 ± 0.01
Canned concentrate
4.57 ± 0.06
62.92 ± 0.520
6.90 ± 0.02
34.16 ± 0.183
68.39 ± 0.09
1.30 ± 0.052
Bottled concentrate
4.60 ± 0.20
66.87 ± 0.108
6.58 ± 0.026
41.13 ± 0.539
63.44 ± 0.481
1.30 ± 0.038
Canned concentrate
4.63 ± 0.06
63.07 ± 0.066
6.37 ± 0.03
12.06 ± 0.053
66.14 ± 0.087
1.31 ± 0.043
Bottled concentrate
4.70 ± 0.48
66.25 ± 0.250
6.22 ± 0.026
16.03 ± 0.095
61.82 ± 0.261
1.28 ± 0.018
Canned concentrate
4.70 ± 0.10
62.5 ± 0.33
5.11 ± 0.11
7.02 ± 0.046
65.47 ± 0.07
1.31 ± 0.01
Bottled concentrate
4.80 ± 0.06
66.33 ± 0.144
4.61 ± 0.03
13.02 ± 0.03
60.38 ± 0.07
1.29 ± 0.09
*MEAN VALUE ± STANDARD DEVIATION OF TRIPLICATE DETERMINATIONS
9
There was a sharp decrease in the brix content of pineapple juice between the
week of production (week 0) and the second week of storage (week 2) while it was
relatively steady for the rest week of storage with slight difference. Slight increase in pH
with the corresponding slight decrease in the titratable acidity of pineapple juice in both
the storage container was observed with the storage period and this is in agreement with
the findings of Fagbemi and Agun (1998). Total solid and Vitamin C were also observed
to decrease with time. Vitamin C was remarkably decreased to the tune of more than 90%
loss, while the Total solid was slightly decreased over the storage period. Specific gravity
which is a measure of purity was observed to be stable throughout the period of storage
with negligible difference.
The colour of the juice concentrate reduced with storage period. The juice
concentrates being acidic reacted with the cans and resulted to darkening of the colour.
Despite the transparency of the glass bottles, the sample in bottle container competes
favourably with the fresh samples in terms of colour. This may be due to the fact that the
samples were not exposed to light.It was also observed that the bottled sample retained
more Vitamin C which is the major nutrient in juices than the canned samples.
Table 2 depicts the mean score of the sensory quality; it was observed that there
were significant differences in terms of taste, colour and aroma among the samples
examined. However, the fresh juices were mostly preferred to the reconstituted juices
followed by the bottled concentrate, while the canned concentrates were ranked least in
terms of colour.
Table 3 reveals the microbial contents of Pineapple fresh juice and concentrate. The
total mesophilic count, yeast and mould counts were reduced with concentration process.
However they increased with storage up to fourth and sixth week and later start
diminishing. The predominant members were mould and yeast and this is due to the fact
that the juice concentrate are acidic (Ihekoronye and Ngoddy, 1985). Bacteria
contamination may be due to poor handling during processing. In the canned sample, the
microbial load was lesser than that of the bottled samples due to the anaerobic condition
in the cans. In any case, the reconstituted juices from the concentrates are
microbiologically fit for consumption since the microbial loads were within tolerable
limit for human consumption.
10
TABLE 2: SENSORY QUALITY OF PINEAPPLE JUICE AND CONCENTRATE
SAMPLES
Time (Weeks)
Attributes
TASTE
5.8b
5.5b
5.3b
0
COLOUR
7.4a
5.8b
6.9ab
AROMA
6.3b
5.5b
5.5b
2
4
6
8
10
Fresh juice
C PC
BPC
TASTE
6.2a
4.2b
4.7b
COLOUR
6.2a
5.9a
5.7a
AROMA
7.5a
6.5a
5.8a
TASTE
7.8a
6.1b
6.1b
COLOUR
7.0b
6.8b
8.2a
AROMA
7.1b
6.4b
6.2b
TASTE
6.7a
5.1b
4.8b
COLOUR
6.6a
7.1a
6.8a
AROMA
7.9a
6.2b
5.8b
TASTE
8.0a
5.8b
5.5b
COLOUR
7.9a
6.4b
6.7b
AROMA
7.2a
5.6b
6.2b
TASTE
5.3b
4.3b
4.1b
COLOUR
7.8a
6.4b
6.4b
AROMA
4.9b
6.0ab
6.2ab
Means of sensory scores
Means with different subscript in a row for each week are significantly different (P=0.05)
CPC: Canned Pineapple Concentrate, BPC: Bottled Pineapple Concentrate
11
TABLE
3:
MICROBIAL
CONTENTS
OF
PINEAPPLE
JUICE
AND
CONCENTRATE
Time (Week) Pineapple Sample
0
2
4
6
8
10
Fungi (sfu/ml)
Total Mesophilic bacteria (cfu/ml)
Fresh Juice
2.4 x 104
5 x 103
Concentrated Juice
2.0 x 103
1 x 103
Canned concentrate
2.0 x 103
1 x 103
Bottled concentrate
2.0 x 103
1 x 103
Canned concentrate
6.0 x 103
2.0 x 103
Bottled concentrate
8.0 x 103
4.0 x 103
Canned concentrate
1.2 x 104
3.0 x 103
Bottled concentrate
2.0 x 104
6.0 x 103
Canned concentrate
8.0 x 103
2.0 x 103
Bottled concentrate
2.0 x 104
6.0 x 103
Canned concentrate
6.0 x 103
NP
Bottled concentrate
4
1.4 x 10
2.0 x 103
Canned concentrate
4.0 x 103
NP
Bottled concentrate
1.0 x 104
2.0 x 103
NP – Not Present
CONCLUSION
It was shown that the juice concentrates that are stored in glass bottles had better
physico-chemical and sensory qualities due to glass inertness; therefore it prevented
certain reactions from occurring. However, concentrated fruit juices in cans contained
lesser microbial load but with unacceptable colour. Conclusively, Pineapple juice and
concentrate stored in glass bottle retained more nutrient and is preferred to the juice
stored in cans in terms of colour, taste and Vitamin C retention.
12
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