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BIOCHEMICAL CONSTITUENTS OF
PALMWINE
Q1: Page 256, line 38: Is the year important here?
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255
Ecology of Food and Nutrition, 42:255–264
Copyright © 2003 Taylor & Francis
ISSN: 0367-0244 print / 1534-5237 online
DOI: 10.1080/03670240390226222
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Address correspondence to I. E. Ezeagu, Medical Biochemistry Department,
College of Medicine, University of Nigeria, Enugu Campus, Nigeria. E-mail:
ikezeagu@yahoo.com.uk
BIOCHEMICAL CONSTITUENTS OF
PALMWINE
I. E. EZEAGU AND M. A. FAFUNSO
Biochemistry Department, University of Ibadan, Ibadan, Nigeria
F. E. EJEZIE
Medical Biochemistry Department, College of Medicine, Univer-
sity of Nigeria, Enugu Campus, Nigeria
(Received xxx; accepted xxx)
Biochemical constituents, which includes sugars, protein, amino acid, lipid, alcohol,
mineral and trace elements of palmwine, a sap obtained from Elaeis guineensis,
Jacq (oil palm), are reported. Mean sugar contents ranged between 0.10 in maltose
and 8.74 mg/100ml in sucrose. Values of 39.03, 59.63, and 62.65 mg/100ml are
reported for protein, free amino acids, and lipids, respectively. Ethanol content was
3.40g/100ml. Magnesium, P, and Zn were the most abundant elements, while Pb,
Cd, and Co were detected at nontoxic levels. Public health implications of palmwine
consumption briefly were accessed. As palmwine is becoming an important source
of revenue for the rural poor and as consumer demand increases, it is concluded
that the nutritional and economic potential of palmwine should be further explored
and given more research attention.
Keywords: Palmwine, Elaeis guineensis, Biochemical Constituents, Heavy Metals,
Sugars, Public Health
Palm wine is the fermented palm sap obtained by tapping of palms
(family Palmea). Two sources of palmwine in Nigeria are the fer-
256 I. E. EZEAGU ET AL.
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mented sap of oil palm tree (Elaeis guineensis, Jacq) and the Raphia
palm tree (Raphia hookeri, Mann and Wendl). Raphia palms in-
habit swampy regions or areas of wet soil. E. guineensis, otherwise
known as oil palm is the specie of Elaeis genus found in Nigeria. It is
widely distributed in West and Central Africa. Methods of tapping
include tapping at the base of male flower bud (in inflorescence tap-
ping) or at the base of the terminal bud (in stem tapping) (Essiamah
1993; Tuley, 1965a, b). Intensive tapping often results in termination
of growth and death of palm trees. In other parts of the world, like
Philippians, Tunisia, Algeria, and Libya, equivalents of palmwine
are produced by palm trees (Dowson, 1953).
In Nigeria, palmwine has been associated with peasant life be-
cause it is cheaper and produced in the rural areas (Uzogara et al.,
1990). However, as the cost of brewed alcoholic beverages rises, the
trend is changing and demand for palmwine has risen even among
the urban dwellers. The palmwine industry is of considerable eco-
nomic and nutritional importance in West Africa. Palmwine is fast
becoming an important source of revenue for the rural poor, but has
received very little scientific attention.
Fresh palmwine is very sweet and refreshing because of the
presence of sucrose, but within 24 hours the concentration of su-
crose falls to less than 50% the initial amounts (Bassir, 1962). Mi-
croorganisms contaminate the palm sap and convert the sap into
palmwine by a fermentation process. Fermentation virtually ends
when the pH falls to 4.0; this the whole process lasts about 48
hours (Bassir, 1962). Seasonal variations in palmwine constitu-
ents and factors that influence the constituents (including season,
type of soil, time of tapping, and process of storage occur) (Faparusi
and Bassir, 1972a, b). In the light of the growing economic im-
portance of palmwine in Nigeria, is useful to investigate further
the composition and possible nutritional significance of palmwine
obtained within a city environment.
MATERIALS AND METHODS
Palmwine samples were collected fresh (3 to 6 hours old) and were
tapped and pooled from about 40 palm trees around the Ibadan
University campus in the month of March. Samples were collected
BIOCHEMICAL CONSTITUENTS OF PALMWINE 257
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on four different days with the help of a local palmwine tapper and
labelled S1, S2, S3, and S4.
Pretreatment of Samples
Prior to sugar estimation 100 ml aliquots of the palmwine samples
were desalted by first passing through a cation exchange resin—
Amberlite 1R 120 (H+ form)—and amino acids are eluted with 2N
NaOH using Ninihydrin test to indicate complete elution (Redfield,
1953). The residue was dissolved in water and passed through a col-
umn of anion exchange—Amberlite IRA 400 (OH- form). The de-
salted palmwine was then concentrated in vacuo from about 5:1
volume.
Estimation of Sugars
For each sample, 5µl of were spotted in triplicates along side a mix-
ture of each standard sugar solution on separate Whatman No. 1
chromatography papers. The sugars were separated by means of one-
way descending paper chromatography method as described by
McFarren et al. (1951) and Durso and Paulson (1958) using
ethylacetate-pyridine- water (12:4:4 v/v) as the separating solvent and
allowed to run for 16 hours. Ammonical silver nitrate solution was
used as the locating reagent as described by Travalyan (1950). The
Rf values were calculated and recorded. Areas containing the spots
were marked out and corresponding areas on each of the remaining
unspread duplicates were removed and eluted by direct dipping of
each sugar regions in 5 ml distilled water contained in boiling tubes
for 4 hours. The respective sugar concentrations were determined
by the phenol-sulphuric method and were read off their standard
curves by extrapolation.
Total Nitrogen, Free Amino Acid, and Protein Determination
10ml aliquots of samples were digested and total nitrogen determined
by microKjeldahl method. To determine true protein and free amino
acid contents, HgCl2 (10 mg) were added to 10 ml aliquots of samples
to precipitate proteins and was centrifuged at 3,000rpm for 10 min-
utes. Nitrogen in both the precipitate and supernatant were deter-
258 I. E. EZEAGU ET AL.
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mined by microKjeldahl method as protein and free amino acid N,
respectively.
Determination of Total Lipids
Total lipid was estimated by the method of Folch et al. (1957). Miner-
als were estimated by the wet digestion method (AOAC, 1984) using
an atomic absorption spectrophotometer (Perkin Elmer 305B). Phos-
phorus was determined colorimetrically by phospho-vanado-molyb-
date method (AOAC, 1984). Specific gravity (SG) and pH of samples
were determined using a hydrometer and a pH meter, respectively.
Alcohol content was determined by distillation of a 100 ml sample
until 90–95 ml of distillate was collected at 20oC. The SG of the
distillate was determined and the percentage of alcohol by volume
was read-off a conversion table of SG of alcohol (AOAC, 1984).
RESULTS AND DISCUSSION
Results of alcohol, pH, and SG are reported in Table 1. Alcohol
content ranged between 2.7 and 5.2 gm/100ml, similar to the 5%
ethanol level reported by Osin et al. (1991). Fresh palm sap usually
contains no alcohol but levels could rise to 4.5–5.2gm/100 ml after
72 hours and may fall slightly after the fifth day of storage due prob-
ably to oxidation of alcohol by invading microorganisms (Bassir, 1962;
Faparusi and Bassir, 1972b). A mean SG value of 1.0 shows that the
palm sap contains mainly water. The pH was between 7.2–7.4.
Faparusi and Bassir (1972b) observed that pH fell sharply after the
first two days of storage and also that acidity was due to production
of tartaric, acetic, and lactic acids.
TABLE I
Specific Gravity, pH, and Alcohol Contents of Palmwine
Samples S1 S2 S3 S4 Mean±SD
SG 0.99 0.99 1.0 0.99 0.99±0.01
pH 7.2 7.4 7.3 7.4 7.32±0.10
Alcohol 2.8 3.1 2.7 5.2 3.05±1.08
(g/100ml)
BIOCHEMICAL CONSTITUENTS OF PALMWINE 259
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Plates I and II of Table 2 shows the qualitative analysis of sugar
and the corresponding Rf values as measured from the chromato-
grams. Presence of raffinose (Rf = 0.163), sucrose (Rf = 0.326), and
glucose (Rf = 0.372) was indicated on Plate I while on Plate II the
presence of maltose, glucose (Rf = 0.419), and fructose (Rf = 0.442)
were obvious. Other reference sugars—xylose, arabinose, and lac-
tose—either were absent or present in undetectable amounts in the
samples. The quantitative estimates of sugars in the palmwine samples
are shown in Table 3. Concentration of sucrose seems very low (2.50–
2.83 mg/100 ml), and hence was not quite clear on the chromato-
gram. The low content of sucrose can be explained by the fact that
sucrose is preferentially utilized in the fermentation medium by yeasts
(Bavisotto et al., 1958). Leibowitz and Hestrin (1945) showed that a
brewery yeast strain removed sugars from wort in the following or-
der: sucrose, monosaccharides, maltose, and maltotriose. Sucrose
also can be hydrolyzed by invertase to glucose and fructose. The two
sugars are then broken down by enzymes to produce ethanol. Inver-
tase has been identified in appreciably high amounts in palm sap
and could be responsible for the absence or rapid decrease in su-
crose concentration (Visser and Bassir, 1969). Sucrose level there-
fore would be dependent on the degree of fermentation that has taken
place prior to analysis
Maltose levels were low which bears on the use of fresh samples
in this study. Maltose could only be identified in palm sap after the
TABLE II
Rf of Reference Sugars on Paper Chromatogram
Reference Sugar Plate I Plate II
Fructose 0.465 0.442
Xylose 0.512 NS
Raff inose 0.163 0.186
Maltose 0.302 0.302
Sucrose 0.326 NS
Glucose 0.372 0.419
Lactose NS 0.233
Arabinose NS 0.465
Rf = distance moved by solute from origin
distance moved by solvent from origin
NS = reference not spotted
260 I. E. EZEAGU ET AL.
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first day of storage (Faparusi and Bassir, 1972b). Mean glucose, fruc-
tose, raffinose, and maltose levels are 0.65, 0.90, 0.32, and 0.10, re-
spectively. Total sugar levels ranged between 4.36–5.26 mg/100 ml.
Faparusi (1966) also reported the presence of glucuronic acid and
noted that glucuronic usually is identified only after the first day and
concentrations remain constant on storage. However, variations in
sugar contents of palm sap usually occur depending on the period of
tapping and storage due to microbial activities. Microorganisms re-
ported in palmwine include Bacillus, Streptococcus, Saccharomy-
ces, Schizosaccharomyces, Pischia, Leuconostoc, Micrococcus,
Serratia, Aerobacter, Pseudomonas, Cornybacterium, Asppergillus,
and Candida (Bassir, 1962, Omobuwajo, et al., 1987)
Total nitrogen, protein, free amino acids, and lipid contents are
shown in Table 4. The total nitrogen and free amino acids varied
between 85.12–119.7 and 50.5–66.5 mg/100 ml, respectively. Mean
protein content was 39.03 mg/100 ml. The proteins may have been
produced by the plant and are being translocated in the palm sap.
Occurrence of high protein levels, coupled with the oil and high
sugar contents, could be of nutritional significance. The amino ac-
ids are probably of plant origin too, but microorganisms also may
TABLE III
Sugar Components of Palmwine (mg/100 ml)
SAMPLE S1 S2 S3 S4 Mean±SD
Fructose 1.05 0.80 0.80 0.95 0.9±0.12
Glucose 0.75 0.50 0.75 0.60 0.65±0.11
Sucrose 2.83 2.63 2.50 2.70 2.67±0.14
Maltose 0.13 0.09 0.09 0.10 0.10±0.02
Raff inose 0.50 0.30 0.37 0.10 0.32±0.17
Total Sugar 5.26 4.32 4.51 4.45 4.64±0.42
TABLE IV
Protein, Free Amino Acids, and Total Lipids in Palmwine (mg/ 100ml)
S1 S2 S3 S4 Mean±SD
Total N 101.1 85.12 119.7 93.1 99.76±14.81
Free Amino Acid 66.5 50.5 66.5 55.0 59.63±8.15
Protein 34.6 34.6 47.9 39.0 39.03±6.27
Lipids 83.0 55.0 54.9 57.7 62.65±11.80
BIOCHEMICAL CONSTITUENTS OF PALMWINE 261
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contribute to amino acid production (Sjoblohm, 1965). Mean lipid
content was 62.65 mg/ml. E. guineensis is a well-known economic
source of edible red palm oil, which is very rich in palmitic acid, a
precursor of vitamin A.
Macro and micro mineral element contents are shown in Table
5. Magnesium and P (32.0 and 59.75mg/L, respectively) were the
most abundant minerals. Cadmium, Pb, and Co occurred in very
low levels (<0.1 ppm), though levels may vary widely with location.
Some elements such as Pb, Cd, and Zn could act as cumulative poi-
sons if long-term, low-level exposure and possible build-up to thresh-
old levels occur (Onianwa et al., 2001; William, 1977). However such
a situation usually is averted by the homeostatic mechanism of the
body, except in disease conditions or where the exposure is too high
for the body to handle. Palmwine usually is taken occasionally, al-
though an average consumer may take up to 2.5 L at a time. Based
on a 2.5 L daily consumption of palmwine, the potential intake of
heavy metals was compared to the normal acceptable daily intake
(ADI) (Table 6). Only Co and Cu (1.2–2.5 and 6.25–12.5 mg/2.5L,
respectively) intake exceeded recommended normal ADI levels, even
though these levels were lower than the toxic levels. Such occasional
consumption of palmwine therefore is not considered hazardous.
Other constituents variously reported in palmwine include ni-
trates (18.16–91.26 mg/L), nitrite (0.00–2.81mg/L) dimethylamine
(4.06–28.36 mg/L), (Bassir and Maduagwu, 1978; Ezeagu, 1995) and
tyramine (11.27 mg/100 ml) (Uzogara et al., 1987). The public health
TABLE V
Mineral Composition of Palmwine (mg/L)
SAMPLE S1 S2 S3 S4 Mean±SD
Cadmium <0.1 0.1 0.1 0.1 0.10±0.0
Cobalt 1.0 1.0 0.5 1.0 0.88±0.25
Copper 2.5 3.8 3.8 5.0 3.78±1.02
Iron 3.0 2.0 2.5 3.0 2.63±0.48
Magnesium 28.0 40.0 30.0 30.0 32.00±5.42
Manganese 1.25 1.25 1.30 1.25 1.26±0.03
Phosphorus 60.0 59.0 60.0 60.0 59.75±0.50
Lead <0.10 0.10 0.10 0.10 0.10±0.00
Zinc 2.0 1.8 2.0 2.0 1.95±0.10
Calcium 0.10 0.4 0.8 0.6 0.48±0.30
262 I. E. EZEAGU ET AL.
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implications of these factors have been reviewed in the literature,
though their levels in palmwine are of little or no hazard (Uzogara et
al., 1987; Van Maanen et al., 1994; Walker, 1990). According to Osim
et al. (1991), fresh palmwine is not ulcerrogenic as might be thought
despite its content of 5% ethanol.
CONCLUSIONS
As palmwine is becoming an important source of revenue for the
rural poor, and as consumer demand increases, the nutritional and
economic potential should be further explored. Expanding its culti-
vation from family farms to plantation scale will ensure a sustainable
and commercial exploitation, both at local and national levels.
REFERENCES
AOAC (1984). Off icial methods of analysis, 14th ed. Washington, DC: Association
of Official Analytical Chemists.
Bassir, O. (1962). Observations on the fermentation of palmwine. West African
Journal of Biological Chemistry, 6, 20–26.
Bassir O., and E.N. Maduagwu (1978). Occurrence of nitrate, nitrite dimethylamine,
and dimethynitrosamine in some fermented Nigerian beverages. Journal of
Agricultural Food Chemistry, 26, 200–203.
Bavisotto V.S, L.A. Roch, and E.J. Petrusek (1958). Chromatographic evaluation
TABLE VI
Heavy Metal Levels in a Daily Palmwine Intake
Element Sample 2.5L/Day ADIaToxic Levels
Mean intake (mg/day) (mg/day)
(mg/L) (mg)
Cd 0.10 0.25 0.06 3.0
Co 0.88 2.20 0.0002 500
Cu 3.78 9.45 2–5 250–500
Fe 2.63 6.58 12–15 760
Mn 1.26 3.15 3–9 —
Pb 0.10 0.25 0.30–0.40 1000
Zn 1.95 4.88 10–15 509(rat)
aAverage man (70 kg body weight) (Bowen, 1966).
BIOCHEMICAL CONSTITUENTS OF PALMWINE 263
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35
40
of wort fermentation patterns with selected yeast cultures. Proceedings of the
American Society of Brewing Chemists, 10–22.
Bowen H.J.M. (1966). Trace elements in biochemistry. London: Academic Press.
Dowson V.H.W. (1953) . Palmwine in Libya. Tropical Agriculture, 34(4), 295–309.
Durso D.F and J.C. Paulson (1958). Chromatographic analysis of pulps. Utilising
direct densitometry. Analytic Chemistry, 30, 919–xxx.
Essiamah, S.K. (1993). Sapping of oil palm (E. guineensis Jacq) in rain forest region
of West Africa. Pl. Research & Development, 38, 36–48.
Ezeagu, I.E. (1995). Occurrence of nitrate and nitrite in water and some alcoholic
beverages in Nigeria. Die Nahrung, 39, 530–534.
Faparusi, S.I., and O. Bassir (1972a). Factors affecting the quality of palmwine I.
Period of tapping and palm tree. West African Journal of Biology and Applied
Chemistry, 15, 17–23.
Faparusi S.I, and O. Bassir (1972b). Factors affecting the quality of palmwine II.
Period of storage. West African Journal of Biology and Applied Chemistry, 15,
24–28.
Folch J., M. Lee, and S. Stanley (1957). Simple method for the isolation and puri-
fication of total lipids from animal tissues. Journal of Biological Chemistry, 226,
497–
McFarren E.F, K. Brand, and H.R. Rutkowski (1951). Quantitative determination
of sugars on filter paper chromatograms by direct photometer. Analitical Chem-
istry, 23, 1146–1149.
Onianwa P.C. (2001) Copper and zinc contents of Nigerian foods and estimates of
the adult dietary intakes. Food Chemistry, 72, 89–95.
Osim E.E., S.E.E. Efem, and K.M. Etta (1991). The effect of fresh palmwine on
human gastric acid secretion. East African Medical Journal, 68(12), 959–962.
Redfield R.R. (1953). Two-dimensional paper chromatographic systems with high
resolving power for amino acids. Biochemica et Biophysica Acta, 10, 244–345.
Sjoblom L. (1965) The occurrence of free amino acids in baker’s yeast. Finska
Kemistmfundets Medd, 74, 73–79.
Trevelyan W.E., D.P. Procter, and J.S. Harrison (1950). Detection of sugars on
paper chromatograms. Nature, 166, 444–445.
Tuley P. (1965a). How to tap palm. The Nigerian Field, xxx (i), 29–37.
Tuley P. (1965b). How to tap palm. The Nigerian Field, xxx (i), 120–132
Uzogara S.G., L.N. Agu, and E.O. Uzogara (1990). A review of traditional fer-
mented foods. Condiments and beverages in Nigeria: their benefits and pos-
sible problems. Ecology of Food and Nutrition, 24, 267–288.
Uzogara S.G., N.F. Ezeokoli, and E.O. Uzogara (1987). Tyramine content of some
Nigerian foods. Ecology of Food and Nutrition, 19, 257–264.
Van Maanen, J.M., A. van Dijk, K. Mulder, M.H. de Baets, and P.C. Menheere
(1994). Consumption of drinking water with high nitrate levels causes hypertro-
phy of the thyroid. Toxicology Letters, 72, 365–374.
Visser, S.A. and O. Bassir (1969). Enzymes during the fermentation of palmwine.
Journal of Food Science and Technology (India), 6(1), 23–28.
Walker, R. (1990). Nitrates, nitrites and N-nitroso compounds: A review of occur-
264 I. E. EZEAGU ET AL.
5
10
15
20
25
30
35
40
rence in food and diet and the toxicological implications. Food Additives and
Contaminates, 7, 717–68
William R.B. (1977). Trace elements and congenital abnormalities. Proceedings of
the Nutrition Society, 36(1), 25–32.