Effect of fermentation on the chemical composition of mango (Mangifera indica R) peels

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African Journal of Biotechnology Vol. 6 (16), pp. 1979-1981, 20 August 2007
Available online at http://www.academicjournals.org/AJB
ISSN 1684–5315 © 2007 Academic Journals

Short Communication
Effect of fermentation on the chemical composition of
mango (Mangifera indica R) peels

A.O. Ojokoh

Department of Microbiology, Federal University of Technology, P.M.B. 704, Akure Nigeria. E-mail:
[email protected]

Accepted 23 April, 2007

Ripe mango peels (Mangifera indica R) was naturally fermented for 96 h at room temperature (30oC).
The quality of the fermented mango peels were accessed by determing the microbiological quality,
proximate composition as well as the anti-nutritional content. Mixed flora of fungi and bacteria were
isolated from the fermenting mango peels. Three species of fungi (Saccharomyces cerevisiae, Asper-
gillus flavus and Rhizopus oryzae) and five bacteria (Aerobacter clocae, Leuconostoc Micrococcus
luteus, Streptococcus mutans and staphylococcus aureus) were identified. The result of the proximate
analysis revealed that there was an increase in the protein content of the ripe mango peels fermented.
There was no considerable difference in the fat and carbohydrate content while there was a decrease in
fibre content. Antinutrients such as tannin and phytate decreased in the fermented sample. A decrease
in pH was also recorded.

Key words: Mango, Magnifera indica, antinutrient, fermentation.


The mango tree is erect roughly 10 – 30 m high, with a
protein and fibre digestibility. The negative effects include
broad rounded canopy which may with age attain 30 – 38
spoilage of food products and contamination by patho-
m in width or a more upright, oval, relatively slender
genic microorganisms. Therefore this paper seeks to
crown. In deep soil, the taproot descends to a depth of 6
evaluate the effect of fermentation on the chemical comp-
inches, the profuse wide-spreading feeder root system
osition of ripe mango peels.
also sends down many anchor roots which penetrate for

several metres. The tree is long-lived, some specimen

being known to be 300 years old and stil fruiting (Henry,
1988). Ripe mango flesh contains carbohydrate and fiber.

Carotene, thiamine, riboflavin, niacin, ascorbic acid,
Fresh ripe mango fruits were obtained from Oja – Oba market
tryptophan, lysine and minerals are also present in the
Akure, Nigeria. The fruits were washed in sterile distil ed water. A
300 g of the peels were placed into a clean bowl containing 2 litres
fruit (Goldsmith, 1976). Mango peel fibre is a good source
of distil ed water and then al owed to ferment for 3 days at room
of dietary fibre and its chemical composition may be
temperature 30 ± 2oC.
compared to that of citrus fibre. The peel fibre also shows

higher values of antioxidant activity, glucose retardation

and its aroma and flavour are pleasant (Reyes and Vega,
Microbial analysis

The method of Sumbo and Adedeji (1992) was used based on plate
There are a number of roles that microorganisms can
dilution technique. Oxoid nutrient agar (NA) and Potato Dextrose
play in food processing, either positive or negative. The
agar (PDA) used for the isolation of bacteria and fungi were
positive effects are general y regarded as part of the
prepared according to the manufacturer’s instructions. Aliquots of
fermentation processing namely product preservation,
the samples and nutrient were mixed and poured aseptical y into
flavour development and reduction of antinutrient.
sterile Petri dishes for incubation at 37oC for 24 h for bacteria while
Furthermore, fermentation enhances the nutrient, vita-
those for fungi were incubated at 30oC for 48 h. The number of
colonies growing in each plate was counted. Isolates were streaked
mins, essential amino acids and protein, by improving
on fresh nutrient media and subcultured until pure colonies were

1980 Afr. J. Biotechnol.

obtained. After isolation of pure colonies, al bacteria and fungal
Table 1. Changes in pH during fermentation of mango
cultures were maintained on slants (in screw cap Mac cartney
bottles) and stored in the refrigerator at 4oC. Characterization and

identification was based essential y on cultural morphological and
Fermentation time (h)
biochemical reactions (Cowan and Steel, 1993; Buchanan and
Gibbons, 1994). The changes in pH of the fermenting mango peels
were determined.


Compositional analysis

The nutritional composition (ash, fat, crude fibre, and carbohydrate)

of the fermented peels were evaluated using the standard AOAC

(1990) method. The protein was determined using the microkjeldahl
Table 2. Proximate composition of fermented and
method (N X 6.25). The antinutrient contents of both the fermented
unfermented mango peels.
and unfermented peels were estimated. Phytate was determined by

the method of Wheeler and Ferrel (1971). The tannin content was
determined using the Makkar et al. (1993) method.

Moisture (%)

Protein (%)
Statistical analysis

Fat (%)
The data were analyzed using mean ± S.D and analysis of
Carbohydrate (%)
variance (Zar, 1984).
Ash (%)

Crude fibre (%)

A total of eight microorganisms were identified from the
Table 3. Levels of some antinutrients of fermented and
fermenting peels. The bacteria isolates were Aerobacter
unfermented mango peels.

clocae, Leuconostoc sp., Micrococcus luteus, Streptoco-
cus mutans and Staphylococcus pyogene. The fungi iso-
lates were Saccharomyces cerevisiae, Aspergil us flavus
Tannin (%)
and Rhizopus oryzae. The changes in pH in fermenting
Phytate (mg/100g)
mango peels are shown in Table 1. There was decrease

in pH throughout the fermentation. Raimbault and Tewe

(2001) indicated that the pH of a culture may change in
fermenting microorganisms thereby reducing the fibre
response to metabolic activities. The most obvious rea-
content of such food (Raimbault and Tewe, 2001).
son being the secretion of organic acids as citric, acetic
The levels of tannin and phytate which the plant proba-
or lactic this causes pH to decrease. The proximate
bly uses for defense (Aletor, 1993) were also determined
composition of the fermented and unfermented mango
in the samples (Table 3). Tannin affects the nutritive
peels in Table 2 reveals that fermentation of the peels
value of food products by forming complex with protein
increases the protein content of the fermented sample
(both substrate and enzyme) thereby inhibiting digestion
(8.64 ± 0.91%) compared to the unfermented sample
and absorption (Osuntogun et al., 1987). They also bind
(6.15 ± 0.08%). The increase in protein of the fermented
Fe making it unavailable (Aletor and Adeogun, 1995) and
mango peels sample may be due to the fact that the
other evidence suggests that condensed tannins may
microorganisms identified which degrades the sample
cleave DNA in the presence of copper ions (Shirata et al.,
readily may have secreted extracel ular enzymes in the
1998). There was a reduction of the tannin content of the
peels which subsequently increases the protein content
fermented mango peels (0.05%) compared to the unfer-
of the fermented sample as wel as microbial biomass
mented sample (0.08%). The decrease in tannin may be
(Odetokun, 2000). There was no considerable difference
as a result of the processing that the sample was sub-
in the fat, while there was a decrease in fibre content of
jected to coupled with the activities of microbial enzymes
the fermented sample. This affected the carbohydrate
involved in the fermentation. Phytate (which is capable of
content (calculated by difference) in which there was no
chelating divalent cationic mineral like Ca, Fe, Mg and
considerable difference. Aykroyd and Doughy (1982),
Zn, thereby reducing dietary deficiency) content of the
Bough and Azam-Ali (1992) and Odetokun (2000)
fermented mango peels were lower 2425.67 mg/100 g
reported that increase in carbohydrate content during
than those of the unfermented sample 2442.59 mg/100 g.
fermentation may be due to a reduction in the fibre
The decrease in phytate content could be attributed to
content and increase in both reducing sugars and total
possible secretion of the hydrolytic enzyme (phytase) by
soluble sugars. This may also be attributed to the fact
microorganisms. This enzyme is capable of hydrolyzing
that during fermentation carbohydrate including cel ulose,
phytate content in the fermented mango peels (Ojokoh et
pectin, lignocel ulose and starch are broken down by
al., 2005). The present study, therefore, reveals that fer-

Ojokoh 1981

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