Current Research Journal of Biological Sciences 3(5): 443-447, 2011
ISSN: 2041-0778
© Maxwell Scientific Organization, 2011
Submitted: March 14, 2011
Accepted: July 02, 2011
Published: September 10, 2011
Production and Microbiology of Pawpaw (Carica papaya L) Wine
S. Awe
Department of Biosciences, Salem University, Lokoja, Kogi State Nigeria
Abstract: The aim of the present study was to establish the possibilities of using the locally available fruit for
wines production. Pawpaw wine was produced by fermenting pawpaw pulp supplemented with 30% sucrose
using Saccharomyces cerevisae purchased from E. C Kraus USA. Aerobic fermentation was carried out for six
days while anaerobic fermentation was for six weeks at 29±2ºC. During aerobic and anaerobic fermentations,
changes in pH, Titratable Acidity (TTA), sugar content, alcohol content, specific gravity, total yeast counts and
total heterotrophic counts were monitored. During the aerobic fermentation, the pH dropped from 4.4 to 3.1,
titratable acidity increased from 0.2 to 0.4, specific gravity dropped from 1060 to 996 sp.gr. Alcohol content
increased from 0 to 8.0%, Sugar content dropped from 15 to 1%, total yeast counts increased from 0 to 4.75
X106 cells/ml while total heterotrophic bacterial count ranged from 5 to 50 cfu/mL. Two bacterial species:
Lactobacillus plantarum and Pediococus pentosaceus were encountered. During anaerobic fermentation pH
ranged increased from 3.2 to 3.6, TTA decreased from 0.4 to 0.19, specific gravity dropped from 995 to 992
sp.gr. Yeast population droped to 2.5×104 cells/mL by week 3, sugar was not detected and the final percentage
alcohol was 9.8%. Pediococus pentosaceus resist during anaerobic fermentation. Sensory evaluation shows
70% acceptance compared to imported red wine (90%).
Key words: Microbial quality, pawpaw, sensory evaluation, wine
different names in different countries, such as Mamao
(Brazil), Cechoso (Venezuela), Frutabomba (Cuba),
papaya in Malaysia and Thailand (Morton, 2006; Papaya,
2008). Pawpaw is grown mostly for fresh consumption or
for production of latex. Pawpaw fruit is a good source of
carbohydrate, vitamins (Vc and Va) and minerals (copper
and magnesium) (Wall, 2006). The skin is smooth and
thin, shady from deep orange or yellow when ripe to
green. The flesh varies from 2.5 to 5.0 cm in thickness, it
is a very wholesome fruit and relished for the attractive
colour, flavour, succulence and characteristic aroma
(Desai and Wagh, 1995). Fresh pawpaw fruits are very
perishable, thereby making their export problematic.
Large quantities of pawpaw are disposed off yearly due to
lack of or poor storage facilities. This result in loss of the
vital nutrients (vitamins) contained in the pawpaw fruits
and revenues obtainable from their sale. However, these
losses can be reduced and pawpaw can be made available
all year round, by utilizing the fruits for other purposes
such as wine production.
The objective of this study is to access the suitability
of using pawpaw for wine production and the
microbiological quality.
INTRODUCTION
Wine has been known for thousand of years, covering
the period of ancient civilization to modern times. It has
been produced and enjoyed by many people from
peasants to kings (Michael, 2000). It is produced by
fermentation of juice of ripe grapes using Saccharomyces
cerevisae. Other fruits such as apples, berries and
blackcurrants are sometimes also fermented. These
however are referred to as fruits or country wine
(Michael, 2000). In contrast to most foodss and beverages
that spoil quickly or that can spread diseases, wine does
not spoil if stored properly. The alcohol in wine, ethanol
is present in sufficient concentration to kill pathogenic
microorganism, which makes to be considered to be safer
to drink than water or milk (Bisson and Butzkc, 2007).
In spite of several prohibitional laws on alcohol
consumption in some human communities, a number and
varieties of alcoholic beverages have been developed,
refined and extolled in extensive and rich literatures
(Macrae et al., 1993). Virtually all alcoholic beverages are
produced using different species of Saccharomyces.
Saccharomyces spp. are generally used because they are
comparatively efficient in alcohol production and can
tolerate higher levels of ethanol than other fungi. They
also produce compounds that are believed to influence the
final flavour of the fermented liquid (Reed and
Nogodawahames, 1991).
Pawpaw (Carica papaya) belongs to the family
Caricaceae, a native of tropical America, but now spread
all over the tropical regions of the world. It is know by
MATERIALS AND METHODS
Production of pawpaw wine: The experiments were
performed during 2009 to 2010 in the Microbiology
laboratories of University of Ilorin and Ajayi Crowther
University, Oyo Nigeria. Ten Kilogram (10 kg) of ripe,
fresh and healthy peeled pawpaw fruits was , blended
443
Curr. Res. J. Biol. Sci., 3(5): 443-447, 2011
TTA
pH
0.5
5
4.5
0.45
4
0.4
3.5
0.35
pH
3
Fermentation process: Standardized amount of yeast
was added to must in a fermenting jar by sprinkling it
over the surface of the juice. The inoculated must was
covered with muslin cloth and incubated at room
temperature (29±2ºC). The fermenting must was aerated
daily by stirring twice to encourage yeast multiplication
(Berry, 2000). Aerobic fermentation was terminated after
6 days and the must was sieved to remove the shaft and
debris of the crushed fruits.
The filtrate obtained after sieving the must was
transferred into anaerobic fermentation jar and incubated
at room temperature. An air trap was fixed to the
fermenting jar to indicate the end of fermentation.
Campdentablet was added to the filtrate to supply sulfur
dioxide gas. Fermentation was terminated after 6 weeks.
The produced wine was then stored at room temperature
to allow the yeast to flocculate. The wine was racked
monthly for three months to clear the wine and then aged.
After aging for 6 months, the wine was filtered using
pressurized filtering kit, decanted into sterile bottles and
corked.
Titratable Acidity
with sterilized blender to give the fruit pulp and mixed
with warm water (45ºC) in the ratio (1:2) to give the
‘must’ needed for wine production. The must was
sterilized with sodium metabisulphate solution to remove
microbial contaminants. Standardized campdentablet,
30% sucrose and yeast nutrient were added to the must
and allowed to stay for 24 h, after which yeast was added
(Berry, 2000).
0.3
2.5
0.25
2
0.2
1.5
0.15
1
0.1
0.5
0.05
0
0
4
3
2
Period of fermentation (days)
1
0
5
Fig. 1: Variation in pH and titratable acidity of wine during
aerobic fermentation
TTA
pH
0.45
3.7
0.35
3.5
0.3
0.25
3.3
0.2
pH
3.4
Titratable Acidity
0.4
3.6
0.15
3.2
0.1
3.1
0.05
0
0
0
Microbial analysis:
Yeast monitoring: The population progress of the yeast
in the fermenting must during aerobic and anaerobic
phases were monitored by adding 0.1 mL of the wine
sample into the grid of the haemocytometer and the cells
counted under the microscope at x10 objective lenses
(Fawole and Oso, 2004).
1
4
3
2
Period of fermentation (days)
5
Fig. 2: Variation in pH and titratable acidity of wine during
anaerobic fermentation
Yeast count
Chemical analysis: Determination of alcohol content,
pH, titrabable acidity, percentage total sugar and specific
gravity: The alcohol content of the must was determined
using Triple Scale Hydrometer for beer and wine (Model
HY110). The pH was measured with a Philips PW 9418
pH m. The titrabable acidity was determined using wine
maker’s acid kit (Kraus, 2005). Total percentages of sugar
10
450
9
400
8
350
7
300
6
250
5
200
%Alcohol
Yeast countsX106ce
Enumeration of total heterotrophic bacterial counts in
the wine: The bacterial populations were determined by
preparing ten fold serial dilution of wine sample and then
plating 1ml of desired dilution on nutrient agar using pour
plate count method (Awe et al., 2009). Isolated organisms
were characterized and identified using a series of
biochemical test and identification keys by Barnettetal
(2000).
%Alcohol
500
4
150
100
3
50
2
0
1
0
1
4
3
2
Period of fermentation (days)
5
Fig. 3: Variation of yeast population and percentage alcohol in
wine during anaerobic fermentation
444
Curr. Res. J. Biol. Sci., 3(5): 443-447, 2011
Table 1: Variations in specific gravity and % sugar content during
anaerobic fermentation
Fermentation
Period (Week)
Specific gravity
(sp.gr.)
% sugar
content
0
995
0.0
1
994
0.0
2
994
0.0
3
994
0.0
4
994
0.0
5
992
0.0
were estimated using the method of Berry (2000). The
specific gravity was determined using wine hydrometer
and the SG value taken from calibration on the stem
(Berry, 2000).
Sensory evaluation: This was determined by Evaluation
Point System described by Fessler (1988) and compared
with red wine (Carlo Rossi).
RESULTS
Total heterotrophic bacterial coun cfu/ml
60
Variations in the pH and titratbable acidity of the
fermenting pawpaw must during aerobic fermentation are
shown in Fig. 1. Generally, there was a decline in the pH
from 4.4 to 3.1; there was a general increase in titratbable
acidity from initial volume of 0.2 to 0.4. During anaerobic
fermentation the changes in pH and titratable acidity are
shown in Fig. 2. The pH increased from 3.2 to 3.6 while
the titratable acidity deceased from 0.4 to 0.19.
Yeast count
%Alcohol
8
10
40
30
20
10
0
0
9.8
7
1
4
3
2
Period of fermentation (days)
5
9.6
6
Fig. 6: Total heterotrophic bacterial count during aerobic
fermentation
9.4
5
9.2
4
9
3
%Alcohol
100
90
8.8
2
89.6
1
8.4
0
8.2
5
4
3
2
Period of fermentation (days)
1
0
80
% acceptability
Yeast countsX106ce
50
6
70
60
50
40
30
20
10
Fig. 4: Variation of yeast population in wine during anaerobic
fermentation
0
Pawpaw wine
SG sp.gr
Red wine
Wine samples
SUG%
16
1080
Fig. 7: Percentage acceptability of wine produced compared to
red wine
14
1060
Yeast counts and percentage alcohol produced during
aerobic and anaerobic fermentations are shown in Fig. 3
and 4 respectively. The yeast counts increased from 0 to
4.75×106 cells/mL, alcohol content increased from 0 to
8% during aerobic fermentation while during anaerobic
there was a dropped in yeast counts from 7.5×104 cells/mL
to 0×104 cells/mL , alcohol content increased from 8.8 to
9.8%. Changes in sugar content and SG of the must
during aerobic fermentation are shown in Fig. 5. The
sugar content in the wine dropped from initial value of 15
to 1%, while the SG dropped from 1060 sp gr to 996
sp.gr. Table 1 shows the SG and Sugar content during
10
8
1020
6
SUG%
Specific Gravity sp.gr
12
1040
1000
4
980
2
0
960
0
1
2
3
4
Period of fermentation (days)
5
6
Fig. 5: Variation in specific gravity and percentage sugar of
wine during aerobic fermentation
445
Curr. Res. J. Biol. Sci., 3(5): 443-447, 2011
aftertaste and overall impression, astringency by twenty
five member panel rated the wine acceptable with 70%
acceptability as compared to Carlo Rossi (control) 90%.
In conclusion, this study has demonstrated that it is
possible to produce wines from locally available fruits
with good microbiological standard and high
acceptability.
anaerobic fermentation. SG dropped from 995 to 992
sp.gr and no sugar detected .
The total heterotrophic bacterial counts are shown in
Fig. 6. It ranged from 5 to 50 cfu/mL. There is a general
decrease in number of heterotrophic bacterial count. Two
bacterial species are isolated from the wine during aerobic
fermentation and are identified to be Lactobacillus
plantarum and Pediococus pentosaceus. Figure 7 shows
the acceptability of the pawpaw wine produced as
assessed by human volunteers with 70% acceptance.
ACKNOWLEDGMENT
I wish to express my gratitude to Mr Olabisi
Oladotun and Mr. and Mrs Adeniyi in USA for their
contributions in purchasing and forwarding some of the
materials used in this study.
DISCUSSION
The drop in pH and corresponding increase in
titratable acidity of must during the aerobic and anaerobic
fermentation stages are attributable to yeast metabolism.
These also show acidification of the medium during the
fermentation stages, which is crucial to wine production.
Acidity plays a vital role in determining wine quality by
aiding the fermentation process and enhancing the overall
characteristics and balance of the wine. Lack of acidity
will mean a poor fermentation (Berry, 2000). The pH
obtained for the final products fall within the acidity level
of sweet and dry wines. Usually, acidity of wines lies
between pH 3 and 7 for dry wine and 3.5 to 4.5 for a
sweet wine. Higher acidities are sometime encountered
with fortified and sparkling wines (Bisson and Butzkc,
2007).
The increase in the total yeast count during aerobic
fermentation can be attributed to the presence of utilizable
sugar (sucrose) and yeast nutrient. The daily aeration of
the fermenting must will also have aided rapid
multiplication of the yeast cells (Berry, 2000). During the
anaerobic fermentation stage, yeast was noted only in the
first week. This is likely because during this stage alcohol
levels had increased in the fermenting medium. During
anaerobic growth the yeast utilizes intermediate products
like acetaldehydes as hydrogen acceptors and alcohol
production (Okafor, 1987; Prescott et al., 2008).
S. cerevisae is a facultative anaerobe which produces
alcohol efficiently and tolerates higher levels of ethanol
than other fungi. The two bacterial species were
identified: Lactobacillus plantarum and Pediococcus
pentosaceus. Only Pediococcus pentosaceus persist
during anaerobic phase. This organisms are non
pathogenic bacteria and therefore do not constitute any
health threat. They are associated with fruits and locally
fermented drink (Okafor, 1987).
The final specific gravity obtained falls within the
1000 and 990 sp.gr range for wine (Jack, 2007). The final
alcohol content of the wine (9.8%) ranks it among good
table wines. According to Michael (2000) a good table
wine must have alcohol content between 8 and 14%.
Sensory evaluation of the pawpaw wine produced in
regards to flavor, colour, appearance, clarity, aroma, taste,
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