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Mineral and Vitamin Concentrations of Heat Processed Plukenetia conophora Seed Kernel Consumed in Nigeria



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Journal of Scientific Research & Reports
3(20): 2694-2708, 2014; Article no. JSRR.2014.20.007
ISSN: 2320–0227
SCIENCEDOMAIN international
Mineral and Vitamin Concentrations of Heat
Processed Plukenetia conophora Seed Kernel
Consumed in Nigeria
Ernest A. Anyalogbu
, Eugene N. Onyeike
and Michael O. Monanu
Department of Biotechnology, Federal University of Technology, Owerri, Nigeria.
Department of Biochemistry, Faculty of Chemical Sciences, College of Natural and Applied
Sciences, University of Port Harcourt, Port Harcourt, Nigeria.
Authors’ contributions
This work was carried out in collaboration between all authors. All authors read and
approved the final manuscript.
Article Information
DOI: 10.9734/JSRR/2014/9450
(1) Christian Scheckhuber, Goethe University, Frankfurt, Germany.
(1) Anonymous, Federal Polytechnic Ilaro, Nigeria.
(2) Anonymous, University of Calabar, Nigeria.
Peer review History:
Received 10
February 2014
Accepted 3
April 2014
Published 21
August 2014
Mineral and vitamin concentrations of heat processed Plukenetia conophora seed kernel
consumed as snacks in Nigeria were investigated. The seeds which were obtained from
Ojoto in Anambra State, Nigeria were washed in several changes of distilled water,
divided into four lots - PC
(raw sample), PC
, PC
and PC
(samples cooked for 45,
90 and 135min respectively), oven-dried and milled into flours. Concentrations of the
minerals (Ca, K, Mg, Na, Pb, Cu, Fe, I and Mn) in PC
decreased as the time of cooking
increased from 45min (PC
) to 135min (PC
while for P, Zn and Se the concentrations
increased over time of heat processing. The most abundant mineral was sodium
(27.41mg/100g) followed by calcium (21.04mg/100g) and lowest in iodine (3.0µg/100g).
Original Research Article
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
Iodine was the most heat-labile mineral followed by iron and then lead. Plukenetia
conophora seed kernel flours were found to be excellent sources of vitamins E, K, B
, B
and B
and good sources of vitamins D, B
, B
, B
and thus the plant food is
recommended for consumption sinceit could provide significant amount of the
recommended daily allowance of these micronutrients for adults.
Keywords: Micronutrient concentrations; heat processing; Plukenetia conophora seed flour.
Nutrients (in food) are needed by the body for generation of energy and for growth and
maintenance. Vitamins and minerals are classes of nutrients required by the body in minute
amount and are therefore called micronutrients. Micronutrients are essential in the
maintenance of human health [1,2]. Minerals (inorganic substances) serve a variety of
functions including the formation of bones and teeth; as essential constituents of body fluids
and tissues, components of enzyme systems, nerve function. For microminerals the amount
needed by the human body per day is less than 100mg while for macrominerals it is greater
than 100mg. Vitamins are either fat- or water- soluble and are involved in the body’s
metabolism, cell production, tissue repair, and other vital processes.
Edible wild plants and fruits are exploited to provide supplementary nutrition in developing
nations [3,4,5].
Studies have shown that many plant foods contain high amount of minerals, vitamins, fiber
and phytochemicals that make them nutritionally important [6]. One of such plant foods is
Plukenetia conophora. P. conophora (African walnut) a climbing and twining plant (Liane)
over 30m long, is indigenous to Africa, especially West Africa. It is of the family
Euphorbiaceae and is commonly known in Nigeria as “Ukpa” (Igbo), “Asala” or “Awusa”
(Yoruba), “Okhue or Okwe” (Edo) [7,8]. The fruit is a capsule, 6-10cm long by 3-11cm wide
containing sub-globular seeds 2 - 2.5cm long with a thin brown shell resembling the template
walnut (Plate 1). The seed is eaten raw, roasted or cooked mainly as indigenous snacking
nut (masticatory).
Plate 1. Photograph of P. conophora seeds
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
Heat processing has been reported to have the potential to alter the nutrient quality of foods
[9,10,11,12]. This, according to Ebirien et al. [13] depends on the degree of processing and
the nutrient in question.
Nutrients may be destroyed or lost when foods are processed because of their sensitivity to
heat, light, oxygen, pH of the solvent or combinations of these [14].
Processing may also made nutrients more available through the release from entrapment in
the plant’s matrix [15] or reduction in the concentration of antinutritional factors inherent in
the food [16,17,18]. Food processing method should therefore be such that does not
adversely affect the colour, texture, flavor, nutritional values especially the vitamins and
minerals [19]. This article is intended to evaluate the effect of heat processing on the mineral
and vitamin concentrations of P. conophora seed kernel consumed in Nigeria.
All reagents were obtained from Merch (Darmstadt, Germany) and used as such. Fresh fruit
capsules of P. conophora were purchased from a farmer at Ojoto, Idemili South Local
Government Area of Anambra State, Nigeria. The capsules were cut open with a sharp knife
and the wholesome seeds collected.
2.1 Sample Processing
Wholesome samples were washed in several changes of distilled water and divided into four
(4) lots. The first lot was used raw and therefore labeled PC
. Trial cooking using traditional
cooking method(which involved boiling at 98±0.03ºC in an aluminum cooking pot with
sufficient water) showed that accepted eaten tenderness was obtained 90min. The 2
, 3
and 4
lots were boiled in water (98±0.03
C) for 45, 90, and 135 min and labelled PC
, and PC
respectively. The shell of PC
, PC
, PC
and PC
were cracked with a
hammer and the kernels collected. The kernels were sliced thinly with a knife and dried for
48hr in an air-circulatory oven (50ºC) (Model OVE.100.130M.Gallenkamp, UK). The oven-
dried samples were groundin a mill (Model BL357. Kenwood, Birmingham UK), passed
through a 60-mess size screenand used in the analyses.
2.1.1 Mineral content analyses of the samples
The mineral content of the samples were determined by the use of Atomic absorption
spectrophotometry [20] as described by Onyeike and Acheru [21].
Three grams of the stock sample was incinerated in a muffle furnace (Model AAF 11/7,
Cabolite, Derbyshire, UK) at 550ºC until ash was obtained. The non-combustible inorganic
mineral contents of the ash were extracted with 20ml of 2.5%HCl. The extract was reduced
to 8.0ml by heating in a water-bath (98±0.03ºC) for 1hr, diluted to 50ml with deionized water
and stored in clean polyethylene sample bottle.
The mineral contents were determined using atomic absorption spectrophotometer (Model
2380, Perkin-Elmer, USA).
The instrument was calibrated with standard solution containing known amounts of the
minerals being estimated. The results were expressed in mg per 100g sample.
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
2.2 Vitamin Analysis
The modified AOAC [22] method 992.03, 992.04 and 992.26(Codex-Adopted-AOAC
Method) for vitamin analysis was used. This involved the gas chromatographic analyses of
the vitamin contents of the sample extract using HP5890 powered with HP ChemStation
Rev.A09.01 (1206) software (Hewlett-Packard, California, USA).
The sample was pressed in a mortar carefully to avoid forming lumps. A 0.1g of the sample
and 0.05g ascorbic acid (as antioxidant, to reduce oxidation reactions that could affect
vitamins during saponification and extraction) were weighed into 16x126mm test tube and
5ml of alcohol (made by mixing 90.2% ethanol, 4.9% methanol, and 4.9% isopropanol) and
0.5ml of 80% KOH(w/v) were added and the tube vortexed for 30sec. The alcohol was
needed to stabilize the saponification solution and prevent the precipitation of soap material
[23]. Then, the test tube was flushed with nitrogen gas(N
) and capped (to reduce vitamin
loss to oxidation), and incubated for 30min in a water-bath (70
C) with periodic vortexing.
The tube was then placed in an ice bath for 5min to reduce the solubility of interfering
substances [24].
Deionized water (3ml) and 5ml of hexane were added to the test tube, vortexed for 30sec,
and then centrifuged at 1000xg for 10min. The upper hexane layer was transferred to
another test tube and the residue re-extracted two more times, each with 5ml hexane. The
pooled extract was concentrated to 1ml by evapouration under N
The concentrated extract was analyzed for vitamin contents in a HP Gas chromatograph
(Model 5890, Hewlett-Packard, USA) powered with HP ChemStation Rev.A09.01 (1206)
Software. The GC was calibrated with selected standards.
The gas chromatography conditions for the analysis of vitamins were as stated below.
The injection temperature was split while split ratio was 2:1. Carrier gas was nitrogen with
inlet temperature of 250ºC in a HP5 column type of dimension 30x0.25mmx0.25µm. The
oven was programmed to give initial temperature of 50ºC, first ramping at 10ºC/min for
20min maintained for 4min and second ramping at 15ºC/min for 4min maintained for
2min.The detector used was pulsed flame-photometric detector (PFPD) at 320ºC with
hydrogen and compressed air pressures of 20psi and 30psi respectively.
From the chromatogram of the sample extract and that of the mixture of standards produced
by the GC, the vitamin contents of the sample were identified and quantified by an enhanced
integrator which gave the result as mg/100g sample.
The mineral contents of raw and cooked samples of P. conophora seed flours are presented
in Table 1.
Concentrations of Ca, K, Mg, Na, Pb, Cu, Fe, I and Mn decreased with increasing
processing time. Ebuehi [25] reported that boiling brings about losses of some minerals.
However, P, Zn and Se increased as time of heat processing increased. Adeniyan et al. [18]
reported that while the concentrations of some minerals were reduced others were increased
by boiling. Earlier, Severi et al. [9] reported that cooking resulted in losses of vitamins and
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
Table 1. Mineral concentrations
of raw and cooked P. conophora seed flour
Values are means of duplicate determinations on dry matter basis. NDL = non -detectable level
While the value for Se increased from PC
to PC
, those of P and Zn were maximum at
. The percentage differences between the mineral contents of raw and cooked samples
areshown in Table 2.
Table 2. Differences in mineral concentrations between raw and cooked
P. conophora seed flour
Differences (percentage difference)
- PC
- PC
Negative sign indicates increase in value
Na was the most abundant mineral in the raw and sample cooked for 45min followed by Ca
and then K. The abundance of Ca, P and K in plants has been reported by Canellas and
Saura-Calixto [26]. The mineral with the lowest concentration was iodine in the raw sample
(PCraw), Se in PC
and PC
and, Pb in PC
Iodine was reduced beyond detectable level at PC
, Fe at PC
, and Pb at PC
.The level
of the effect of cooking depends on the processing time and the mineral in question as
earlier reported by Ebirien et al. [13]. At 45 min of heat processing, iodine was the most
susceptible being reduced by almost 100% followed by Fe (65.93%) and then Se (55.62%),
and Zn (3.64%).
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
At 90 min, iron was the most affected (100%) followed by Se (63.60%) and then K (47.1%)
while selenium (111.66%) became the most susceptible at 135min followed by Pb (100%)
and then Na (81.76%).Osum et al. [27] and Adeniyan et al. [18] also reported reduction in
the Na content of Vitex doniana (black plum) leaf by blanching and Sesamum indicum
(beniseed) by boiling respectively. The observed range for the sample was comparable with
the value 10.4mg/100g obtained for the fruit pulp of black plum by Vunchi et al. [28]. The
recommended daily allowance (RDA) of Na for adult is 1000-13000mg [29]. It follows that
1kg of the sample could supply 27.44-17.0% of the RDA of Na for adult if not cooked for
more than 90min. Na is an essential element which in conjunction with K works for
extracellular fluid balances and normal osmotic pressure in the body, and in nerve
transmission [30,28,31,32].
Na/K ratio is of significance especially to a hypertensive patient [2]. A ratio of less than one
has been recommended for the prevention of high blood pressure [33]. The ratio obtained in
this work at all levels of processing is above 3. The consumption of the plant food is
therefore not recommendable for hypertensive patients.
K has been shown to play protective role against hypertension, stroke, cardiac dysfunctions,
renal damage, hypercalciuria, kidney stones and osteoporosis [34]. The RDA for K is
4700mg for adult. The K content of the P. conophora sample was reduced from 8.97-
3.63mg/100g by cooking. Adeniyan et al. [18] also reported that cooking progressively
reduced the K content of Sesamum inducum. The sample investigated is a poor source of
dietary K as 1kg could not supply up to 2% of the RDA for adult.
On the other hand the plant could be adjudged a good source of Mg as 1kg could supply at
least 15.69-21.97% of the 320-420mg RDA of Mg for adults[29]. Mg content of the sample
was reduced at all levels of processing given the range 5.02-7.03mg/100g. This value was
higher than the values 1.80-2.00mg/100g reported for African bread fruit by Ijeh et al. [35].
Mg is an important mineral element and is implicated in circulatory diseases [2,36]. It is
involved in the maintenance of the electrical potential of nerves and cell membranes and,
activation of many enzyme systems [37,38]. It also functions as a co-factor for many
enzymes in energy metabolism and biosynthesis of macromolecules [35].
P in the raw sample (17.0μg/100g) was made more available by heat processing. Adeniyan
et al. [18] also showed that P content of beniseed increased progressively with boiling time.
These contradicted earlier reports that boiling reduced the phosphorous content of yellow
yam [11] and red kidney bean [33]. P helps to control the acid-alkaline state of the blood
[39]. In association with Ca, P is involved in blood formation and, bone, teeth and muscle
growth and maintenance [40,4]. P is also a component of nucleotide molecules that are
structural components of the nucleic acids, DNA and RNA and of the energy transfer
molecules such as ATP, NAD, and FAD. Based on the RDA of P of 500mg for adults [11],
P. conophora is not a good source of dietary P.
Ca level was decreased by cooking. Akin-Idowu et al. [11] and Adeniyan et al. [18] earlier
reported that Ca content of yam and beniseed increased with boiling time. When cooked to
tenderness (PC90), the concentration of Ca was highest (18.83mg/100g).
The observed range of concentration of calcium 10.77-21.04mg/100g compared favourably
with the range 10.2-23.1mg/100g obtained for cashew nut [41, 39]. P. conophora could be
adjudged a good source of Casince 1kg of the sample could supply 13.46-26.3% of the
800mg RDA of Ca for adults [11,42]. Over 99% of Ca in the body is used as structural
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
components of bones and teeth [43,27]. Ca participates in many enzyme-mediated
processes [41,28] and is involved in nerve conduction, aids muscle growth and prevents
muscle clamps [38]. Intestinal Ca absorption is governed by Ca/P ratio of the diet. A ratio of
more than one indicates the diet as “good” as more Ca would be absorbed [44,28,33]. At 45
min cooking, 65.93% of the 2.26mg/100g iron in theraw sample was lost leaving 0.77g/100g
which is lost completely when cooked to eaten tenderness. The plant food is a good source
of Fe but must be eaten raw or undercooked to contribute 9.63-28.25% of the 8mg RDA [28]
per 100g sample. Fe is an essential trace element required for haemoglobin formation,
normal function of central nervous system and energy metabolism [45, 46].
P. conophora is an excellent source of dietary copper as 100g could supply 48.89-62.22% of
the 900μg RDA [28]. Cooking decreased the Cu content of the sample giving the range
440.0-560.0μg/100g. Reduction was also reported by Musa and Ogbadoyi [32] for Hibiscus
sabdariffa. Earlier Ijeh et al. [35] reported that processing made copper more available in
cashew nut giving the range as 350-400μg/100g. Like Fe, copper is a component of
haemoglobin and participate in blood function [39].
Mn was progressively decreased (17.08-30%) by cooking giving the range 1.68-
2.40mg/100g. Adeniji and Tenkuano [47] and Audu and Aremu [33] also reported reduction
on Mn contents of plantain-banana hybrid and red kidney beans respectively. The observed
values for P. conophora compared favourably with the values 1.6-1.7mg/100g obtained for
red kidney beans. The Mn content of the raw sample (2.40mg/100g) compared very well with
the value (2.20mg/100g) obtained by Ayoola et al. [48] for air-dried fresh C. conophora
sample obtained from Oyo State, Nigeria. The concentrations of other minerals in this study
were tremendously lower than the corresponding values obtained by the researchers.The
sample investigated is an excellent source of Mn as 100g could supply the 1.2-3.2mg RDA
for adult [29] at all levels of processing. Mn is an activator of many enzymes [49] and a
component of the bone which functions in reproduction and actions of the CNS [50].
Processing increased the zinc content of the sample by 3.64-11.74%. The sample is a good
source for dietary Zn as 100g could supply 30.9-34.5% of the 8-11mg RDA for Zn [29]. Zn is
important in the absorption and action of B-complex vitamins and inhibits 5-alpha reductase
from converting testosterone into dihydrotestosterone (DHT), a form of testosterone that
promotes prostate growth. Zinc increases testosterone, and sperm count. In zinc deficiency,
sex drive is reduced in order to conserve the zinc (zinc is concentrated in semen) [51]. Zn is
also involved in gene expression, regulation of cellular growth and acts as cofactor for
enzymes responsible for carbohydrate, protein and nucleic acid metabolism [52]. It plays
important role in the metabolism of cholesterol, heart disease and diabetes [53,54].
Iodine was the most heat-labile element in the sample. The 3.0μg/100g concentration in the
raw sample reduced to non-detectable level at 45min cooking. The trace element is required
by the developing foetus due to its effect on brain development and is required for the
synthesis of thyroid hormones [55,35]. The sample is not a source of dietary iodine. On the
other hand, the Se content of 4.89-10.35μg/100g could supply 23.76-51.24% of the 20.2-
26.2μg RDA for Se [56,35] and was increased by cooking.
Higgs et al. [57] reported that Se content of oat and wheat were increased by boiling but
reduced to non-detectable level when the boiling time was beyond 45min. Most of the
selenium in the body is found in proteins as seleno-analogues of sulphur amino acids. Se is
an antioxidant that protects vitamin E from degradation and is involved in the maintenance of
defense against infections and modulation of growth and development [58,59]. Two
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
selenium-containing enzymes (selenoenzymes) glutathione peroxidases and thioredoxin
reductases (Endogenous antioxidants) are involved in the protection of the body tissues
against oxidative damage by the highly reactive oxygen-containing metabolites (hydrogen
peroxide or lipid hydroperoxide) [60].
The lead content of the raw sample (10.0μg/100g) was not affected by cooking for 45min,
but decreased to non-detectable level at 135min. Audu and Aremu [33] reported 10μg/100g
for red kidney bean and that the value dropped to non-detectable level with boiling. Lead is
ubiquitous in the environment and thus present (at very low levels) in all foods. The
observed value may be site-specific relating to the extent of lead pollution of the sample area
[61]. Lead is very toxic when accumulated in the body and can lead to death [62,31]. The
daily permissible amount of lead for adult is about 232.14μg [63]. With 1kg of the sample
supplying at most 100μg of lead, the plant food is safe for consumption at all levels of
Tables 3 and 4 respectively represent the fat-soluble and water-soluble vitamin levels for raw
and cooked samples of P. conophora. The data showed that the most abundant fat-soluble
vitamin in the plant food at all levels of processing was vitamin E while the lowest
concentration was obtained in vitamin D
Table 3. Concentrations
of Fat-soluble Vitamins in raw and cooked P. conophora
seed flours
K (µg/100g)
Values are means of duplicate determinations on dry matter basis
The water-soluble vitamin with the highest concentration was niacin (Vit. B
) and Choline
) the lowest.
Heat processing (cooking) generally increased values of the fat-soluble and water-soluble
vitamins.Similar results have been reported for vitamins A and D
in raw English walnut and
soybean [64,65].
The concentration of vitamin K (Table 5) increased with increase in cooking time from PC
giving a range of 29.87 - 32.57µg/100g (i.e. 1.21 9.04%). This is higher than the
values of 0.3μg/100g and 2.7µg/100g obtained for egg and English walnut respectively [64].
One kg of the sample when processed to acceptable cooking tenderness (PC
) could
supply 15.5-7.76% of 500-100µg RDA for vit. A 15-30% of 5-10µg RDA for vit.D, 75-
107.14% of 7-10mg RDA for vit.E and, 50.03-162.6% of the RDA for Vit.K for children and
adult [42,11]. Vitamins E, K and A are essential nutrients [66]. Vitamin E, through its
antioxidant property mops up excess free radicals produced in the tissues and thus controls
the development of oxidative stress - induced diseases [67]. Vit. K functions as cofactor in
the enzyme system that forms native prothrombin involved in the haemostatic (styptic)
coagulation [68]. Vitamin A on the other hand, is required in small amount by humans for
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
normal functioning of the visual system and its deficiency leads to xerophthalmia, anaemia,
and weakened resistance to infection [27]. As reported by WHO [69], Vit. A deficiency affect
about 2.5million pre-school children in Africa. Consequently, the consumption of the kernel is
highly recommendable. Vit. A is also involved in the maintenance of growth, development
and soundness of cells, epithelial cellular integrity, immune function and reproduction [70].
Vitamin D through its regulatory effect on the transcription of a number of genes is involved
in Ca and P metabolism and, in the modulation of cell proliferation and differentiation [70].
From the comparison with the RDA, a properly processed sample of P. conophora seed
could be adjudged a moderate source for vitamins A and an excellent source for vitamins E
and K. The consumption of the seed kernel is therefore recommended for the prevention and
management of cellular diseases, haemophilia, and visual system dysfunction and, general
Table 4. Concentrations
of water-soluble vitamins in raw and cooked P. conophora
seed flours
Ascobate, C (mg/100g)
Values are means of duplicate determinations on dry matter basis
Table 5. Difference in fat-soluble vitamins contents between raw and cooked
P. conophora seed flours
Differences (percentage differences)
PCraw – PC
– PC
– PC
Negative sign indicates increase in value
The most abundant water-soluble vitamin, niacinas shown in Table 6 was progressively
increased (8.85-12.39%) by cooking given the value 1.13-1.27mg/100g. The lowest
concentrated, choline, together with folate was steadily reduced by cooking giving the values
0.82-0.87µg/100g and 74.22-94.76µg/100g respectively from PC
to PC
. Choline, though
not a vitamin by FDA definition, is a vital nutrient of B-complex vitamins needed for proper
functioning of the nervous system, muscle movement, brain function and maintenance of cell
membrane integrity [65]. It also regulates liver function and is necessary for normal fat
metabolism. Folate recorded 12.99-21.68% reduction (Table 6) to be the most sensitive
water-soluble vitamin in the sample. The observed value for folate compared closely with
77µg/100g obtained for egg [64].
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
Table 6.
Differences in water-soluble vitamins contents between rawand cooked
P. conophora seed flour
Difference (percentage difference)
– PC
– PC
– PC
Negativesign indicates increase in value
The concentrations of thiamine, riboflavin, pantothenate and pyridoxine increased when
cooked for 45min. Ayoola et al. [48] could not detect pantothenate, pyridoxine and folate in
their sample. Apart from ascorbate (4.15mg/100g) the values for vitE (0.12mg/100g),
thiamine (0.06µg/100g), riboflavin (0.02µg/100g) and niacin (0.05µg/100g) obtained by
Ayoola et al. [48] for air-dried C. conophora sample were far lower than the corresponding
values obtained in this study. The observed levels of thiamine and pyridoxine are
comparable to the values 0.341 and 0.537mg/100g obtained for English walnut [64].
Thiamine, riboflavin and pyridoxine principally function in macronutrient metabolism [27].
Ascobic acid content of the sample was reduced (6.67%) only when cooked for 135min
(Table 4). Ascobate is a dietary antioxidant acting as an electron donor for eight enzymes in
humans [71]. It prevents the formation of the potential mutagen N-nitroso compounds in the
stomach and thus reduces the risk of gastric cancer [72,73]. It is involved in protein
metabolism and collagen synthesis [28].
B-vitamins generally help the body to use energy-yielding nutrients such as carbohydrate, fat
and protein for fuel [74]. They are also involved in red blood cell formation and, cell
multiplication through their role in DNA replication.
Most nutrients in plant food are entrapped in the plant matrix and therefore not easily
accessible [15]. Some nutrients are also made unavailable to the consumer through the
formation of insoluble complex with antinutrients [75]. The observed increase in nutrient
content of the food sample due to cooking could be attributable to the fact that cooking, a
hydrothermal process may have disrupted the cell structure and membrane partitions of the
seeds and caused the release of minerals and vitamins, and also antinutrients from
entrapment in the plant matrix. The heat involved in cooking may also have caused the
destruction/inactivation of antinutrients making available the nutrients that are trapped in
complex formation [76,17,18]. The level of the antinutrients could also be reduced
(increasing nutrient availability) through leaching of soluble ones into the processing water
when the epidermal layers of the seeds are ruptured by heat processing [16]. The decreased
effect of cooking on minerals and vitamins could be attributed to leaching (extraction) of the
micronutrients into the processing water [77]. The leaching may be enhanced by the heat of
processing which increases the solubility of most of the nutrients [74]. Decreasing effect may
also be due to oxidation and thermal destruction of the micronutrients especially vitamins
Anyalogbu et al.; JSRR, Article no. JSRR.2014.20.007
It can be concluded that cooking influenced the concentrations of all the minerals and
vitamins in the food samples investigated. The effect depended on the micronutrient and
duration of cooking. The plant food (sample) is an excellent source of vitamins E, K, B
and B
but good source of vitamins D, B
, B
, and B
Authors have declared that no competing interests exist.
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... Avalanche of supporting evidences of the significant roles of EFAs in many biochemical pathways identifies the nutrients as functional foods and nutraceuticals [15]. Rohland [16] reported that the healthiest sources of essential fatty acids are found in a variety of plant foods. This study therefore evaluates the fatty acid composition of African walnut kernel and African elemi pulp; two plant foods commonly used as masticatories as well as traditional snacks in Nigeria with the aim of elucidating their potentials as functional foods and nutraceuticals relative to their EFAs contents. ...
... Fresh seeds of African walnut from Ojoto community, Idemili South Local Government Area of Anambra State, and fruits of African elemi from Ngwa Road market in Aba, Aba South Local Government Area of Abia State were washed severally in deionized water and divided into four. Each of the plant samples was processed as masticatory based on the quality achieved by following the traditional method of cooking to eating tenderness as described by Anyalogbu et al. [16], [17]. The first lots were used raw and therefore labeled AW raw and AE raw for African walnut and African elemi respectively. ...
... The other lots were given different wet-heat treatments. The 2 nd , 3 rd and 4 th lots of African walnut were boiled in water (99±1 0 C) for 45, 90, and 135 min and labeled AW 45 , AW 90 , and AW 135 respectively [16]. While the 2 nd , 3 rd and 4 th lots of African elemi were macerated in hot water (55 0 C) for 15, 30 and 45 min and labeled AE 15 , AE 30 , and AE 45 respectively [17]. ...
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Fatty acid composition of plant food (oil) is important for its economic and nutritional value. Assessment of fatty acid contents of two Nigerian masticatories cum traditional snacks: African walnut kernel (AW) and African elemi pulp (AE) were carried out. Samples were subjected to graded wet heat contact time based on their traditional methods of processing and their oil extract evaluated for fatty acid (FA) contents using chromatographic method. The processing methods had no statistically significant effect on both the oil and FA contents of the samples. Both samples contain nutritionally relevant levels of fat ranging respectively from 49.8±1.08 to 52.8±2.70g/100g sample and 41.93±6.03 to 42.8±4.61g/100g sample in AW and AE. A total of six fatty acids including two essential ones namely omega-6 (C18:2) and omega-3 (C18:3), were identified and quantified in the two plant foods. The predominant FAs in the plant foods were oleic acid (16.12±1.86-17.11±1.31g/100g fat), linoleic acid (16.88±1.66-18.80±1.52g/100g fat) and linolenic acid (55.95±5.68-57.08±6.57g/100g fat) in AW and palmitic acid (48.59±4.35-50.51±3.29g/100g fat), oleic acid (32.02±3.27-35.74±1.46g/100g fat) and linoleic acid (15.15±3.57-15.40±3.82g/100g fat) in AE. The study shows that on the average, one serving of AW could supply about 41.52% and 647.09% of the Recommended Daily Intakes (RDIs) for the essential FAs Linoleic and Linolenic acids respectively, while that of AE will supply about 29.13% of the RDI for Lineleic acid. Based on their essential FAs contents the plant foods apparently have potentials for applications as nutraceuticals.
... The effects of sunlight exposure on food products depend on the intensity of the light wavelength, how long the exposure took place, the temperature, as well as the type of material used to make the container (13). Thus, various nutrients which are contained or incorporated into the product maybe destroyed or lost because of their sensitivity to heat, light, oxygen, pH of solvents or a combination of these (14). Sunlight exposure, could have deteriorating effects on the products, thereby making the products deficient in the valuable nutrients in addition to loss of flavor and taste (12). ...
... Zinc was found to increase in both samples after ten days of sunlight exposure with greater increase in flavoured milk drink than in the yoghurt sample, but remained relatively stable at room temperature. Anyalogbu et al. (14) also found increase in zinc during the heat processing of African walnut. ...
... Sample processing: The samples were processed following the methods enunciated by Anyalogbu et al. [12], [13]. The plant samples were severally washed in deionized water and divided into four (4). ...
... The first portions were labelled AE raw and AW raw for African elemi and African walnut samples respectively and used raw. Accepted eating tenderness was obtained for African elemi by macerating in hot water (55 o C) for 30 min [12] and, for African walnut by boiling in water (99±1 o C) for 90 min [13]. The remaining portions of African elemi were labelled AE 15 , AE 30 , and AE 45 and macerated in hot water (55 o C) for 15, 30 and 45 min respectively. ...
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It has been reported that seeds and fruits, but for their content of antinutrients, could offer a cheap means of providing adequate nutrients to their consumer. The effect of processing on antinutrients contents of the pulp of African elemi, AE (Canarium schweinfurthii) and kernel of African walnut, AW (Plukenetia conophora) consumed as traditional snacks (masticatories) in Nigeria were investigated. The levels of the antinutrients in raw samples of the traditional snacks as well as their corresponding residual levels in samples subjected to graded doses of heat treatment were evaluated using standard methods. Saponins, alkaloids, cyanogenic glycosides and oxalate were obtained in both samples while AE contained tannins and flavonoids in addition. The concentrations of saponins (1.00±0.19) and flavonoids (14.98±2.91) in raw AE and saponins (1.05±0.13) in AW were increased by the processing methods. The rest of the antinutrients were decreased in both samples. The effects on saponins and oxalate became significant (p<0.05) as the processing time was increased. The plant foods, with respect to the tolerable limits of the antinutrients, could therefore be considered safe for human consumption at all levels of processing.
... The concentration of minerals (Ca, K, Mg, Na, P, Pb, Cu, Fe, I, Mn, Zn, and Se) in the stock samples were quantified using Association of Official Analytical Chemists" Atomic absorption Spectrophotometric method (2000) described by Anyalogbu et al. (2014). Each of the stock samples (3.0 g) was incinerated in a muffle furnace set at 550ºC until ash of constant weight was obtained. ...
Full-text available
The antinutrient and micronutrient (minerals and vitamins) contents of processed and raw seeds of “Nturukpa” (Pterocarpus santalinoides), a wild plant in Nigeria were analyzed using accepted methods. The various quantities (in mg/100g sample) of the antinutrients ranging from hydrogen cyanide (11.25±1.46), through alkaloids, saponins, flavonoids, oxalates, tannins, phytic acid to phynols (0.18±0.02) contained in raw “Nturukpa” (Pterocarpus santalinoides) seed powder were reduced by 4.98% (in saponins) to 63.64% (in oxalates) when processed. In mg/100g sample, the micronutrients: P (86.21±16.48), Na (16.07±1.76), Fe (0.68±0.02) and K (0.48±0.12) and, Ascobate (5.87±0.84), B3 (1.32±0.41), and B2 (0.31±0.05) were respectively the most abundant minerals and vitamins in the raw sample. Except for potassium and vitamin D that were not affected by processing, the concentrations of other micronutrients were diversely increased. The processed plant food, relative to the established physiologically tolerable limits for the antinutrients is safe for human consumption and an excellent source of the minerals: Fe, Zn, P, I, Mn, Cu and Se; the B vitamins and Ascobate (vitamin C) as 1kg could supply substantial proportion of the RDA for the nutrients.
... The concentration of minerals (Ca, K, Mg, Na, P, Pb, Cu, Fe, I, Mn, Zn, and Se) in the stock samples were quantified using Association of Official Analytical Chemists" Atomic absorption Spectrophotometric method (2000) described by Anyalogbu et al. (2014). Each of the stock samples (3.0 g) was incinerated in a muffle furnace set at 550ºC until ash of constant weight was obtained. ...
Full-text available
Mature kersting’s groundnut (Kerstingiella geocarpa) seeds were processed into raw dried, boiled, cooked, roasted and sprouted seed flours. Proximate, mineral and amino acid composition of the seed flours as affected by different processing methods employed were investigated using standard analytical techniques. The different processing methods showed varied deviation of nutrients from the raw seeds either by enhancing or reducing nutritional values. Boiling, cooking and sprouting were found to reduce crude fat whereas crude protein was found to be enhanced by boiling, cooking, roasting and sprouting with an increase of 6.6, 2.9, 27.0 and 18.2%, respectively. Processing significantly affected some minerals content of the seed flours (p≤0.05). Boiling, cooking, roasting and sprouting reduced the values of Na, K and Ca by 20.9, 61.3 and 9.7%; 63.4, 75.7 and 7.0%; 70.9, 80.0 and 4.6%; 68.7, 83.8 and 38.0%, respectively while the same processing methods increase the values of Mg by 32.4, 29.2, 36.7 and 36.1%, respectively. Generally, raw and processed kersting’s groundnut seed flours were found to be good sources of essential minerals but Cu and Cd were not detected. Amino acid profile revealed that all the different processing methods improved Arg, Thr, Ser, Glu, Gly and Cys content while Met, Ile and Leu were reduced by the same methods. However, dietary formula based on the raw and processed seeds of kersting’s groundnut will require essential amino acids supplementation such as Lys, Met + Cys (TSAA), Thr and Val for boiled seed; Ile, Leu, Lys TSAA, Thr and Val for cooked, roasted and sprouted seeds in accordance with the recommended FAO/WHO provisional pattern.
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Cashew nut samples from three geographical locations of Nigeria viz: Anambra state, Oyo state and Kogi state were obtained and analysis were carried out on the nuts and oil. The proximate composition of the cashew nuts was determined. The extracted oil was analyzed for both physical (colour, specific gravity and refractive index) and chemical (saponification value, iodine value, peroxide value and free fatty acid value) properties. The vitamin content of the samples was also determined. The protein content ranged from 23.42% – 26.39%, the moisture content ranged from 5.66% - 6.17%, ash content ranged from 3.03% - 3.18% and the crude fibre content ranged from 5.60% - 6.12%. The fat content of the cashew nut from Oyo state was the highest (42.03%) followed by the cashew nut from Kogi state (40.72%) while the cashew nut from Anambra state had the least value (40.15%). The refractive index ranged from 1.452 – 1.463nD 20ºC and specific gravity ranged from 0.848 – 0.860g/cm3. The oil from the three samples had a light yellow colour. The saponification value ranged from 233.19 – 237.00mgKOH/g oil; iodine value 83.65 – 86.93mgKI/100g oil; peroxide value 19.75 – 20.34meqO2/Kg oil and free fatty acid 0.05046 – 0.05601%. The mineral content of the samples correlated with the values from literature. Statistical analysis was carried out using the Analysis of Variance (ANOVA) at 95% confidence limit and Duncan test. There was significant difference between the Vitamin A and B12 content, Sodium, Potassium, Magnesium, Phosphorus, moisture, fat, fibre, ash, carbohydrate and free fatty acid content of the samples while there was no significant difference in the Vitamin B12 and B6, Iron, Zinc, Iodine value and Saponification value of the samples. The cashew nuts from the different locations demonstrated high potential as industrial materials.
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Five heavy metals lead (Pb), cadmium (Cd), zinc (Zn), iron (Fe) and cobalt (Co) were determined in four (4) branded Pax-herbal products - Paxherbal Health Tea®, Paxherbal Potensine®, Paxherbal Malatreat tea® and Paxherbal Black powder® using atomic absorption spectrophotometry (AAS) after acid digestion. The samples were purchased from manufacturer's (Pax-herbal) retail out-let in Yenagoa. The concentration of lead (Pb), Cd, Zn, Fe and Co in all the samples ranged from BDL to 102.200 ± 1.838 μg/g, 0.249 ± 0.010 μg/g to 2.839 ± 0.018 μg/g, BDL to 14.638 ± μg/g,), 88.557 ± 1.135 μg/g to 269.074 ± 3.433 μg/g and 0.604 ± 0.002 μg/g to 9.781± 0.032 μg/g respectively. Pb content was below detection limits (BDL) in Paxherbal Health Tea® and Paxherbal Potensine®, while the amount in Paxherbal Malatreat tea and Paxherbal Black powder was 102.200 ± 1.838 μg/g and 49.528 ± 0.583 μg/g respectively. The corresponding daily intake of heavy metals in herbal drugs were below limits stipulated by regulatory agencies such - FAO/WHO, Canadian and American National Sanitation Foundation (NSF) International, except for Paxherbal Malatreat tea where the value of 418.611 μg/day (based on recommended dosage by manufacturer) was significantly above the FAO/WHO permissible limit of 232.14 μg/day, assuming an average body weight of 65 kg for an adult human.
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Raw, boiled and roasted groundnut (Arachis hypogea) seeds were analysed for proximate, mineral and fungi properties. The results revealed that the raw, boiled and roasted seeds contained 3.76%, 5.70%, 2.90% moisture, 24.5%, 16.11%, 20.57% crude protein, 47.9%, 38.81%, 50.11% fat, 11.31%, 18.04%, 13.05% carbohydrate, 3.04%, 2.70%, 2.90% ash, 9.49%, 18.64%, 10.47% fibre and 574.3kcal/g, 493.61kcal/g, 585.19kcal/g of energy respectively. There was a significant difference (p<0.05) between the raw and heat processed samples. Boiling increased moisture, carbohydrate and fibre contents, while crude protein, fat and ash decreased with boiling when compared to the raw and roasted groundnut. Minerals increased with heat processing. Sodium, potassium and magnesium ranged from 0.9%-2.10%, 0.18%-0.23% and 0.21%-0.45% respectively with the raw sample having the least value. Whereas calcium ranged from 1.24%-1.48%, iron ranged from 0.30%-0.39% with the boiled sample having the highest value. The groundnut samples had a total of six fungi isolates with varying degree of severity, including Geotrichum candidum, Sclerotium rolfsii, Botrytis cinerea, Aspergillus niger, Rhizopus stolonifer and Penicillum italicum. Heat processing eliminated Sclerotium rolfsii and Aspergillus niger, leaving Geotrichum candidum 80% and Botrytis cinerea 20%, in the boiled seed while Rhizopus stolonifer 80% and Penicillum italicum 20% were predominant in the roasted seeds.
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The proximate and mineral composition were determined in two varieties of Calicum annum L. commonly found in the Nigerian markets. Both wet and dry samples were analysed. The varieties were bell pepper (tatase) and cherry pepper (rodo). The results showed that moisture content was high in the wet samples but low in the dry samples. Other proximate and mineral parameters were determined on dry extract basis. Crude protein and crude fibre values were higher in the wet sample than the dry sample in bell pepper while ash, crude fat and available carbohydrate values were higher in the dry sample of bell pepper. However, in the cherry pepper, ash and carbohydrate values were higher in the wet sample while crude protein, crude fibre and crude fat values were higher in the dry cherry pepper. Minerals on dry extract basis showed that Ca, Mg, Zn, Fe and Na were more concentrated in the wet sample than in the dry sample of bell pepper. Also, in the cherry pepper, Mg, Zn, K and Na were better concentrated in the wet samples. The peppers are good sources of calcium, magnesium, sodium, zinc and iron which are important components of bone and supporting tissues, body osmotic pressure, enzymes and blood formation respectively.
Nutrients are destroyed when foods are processed largely because they are sensitive to the pH of the solvent, to oxygen, light and heat, or combinations of these. Trace elements, especially copper and iron, and enzymes may catalyze these effects.
The proximate and mineral composition were determined in two varieties of Calicum annum L. commonly found in the Nigerian markets. Both wet and dry samples were analysed. The varieties were bell pepper (tatase) and cherry pepper (rodo). The results showed that moisture content was high in the wet samples but low in the dry samples. Other proximate and mineral parameters were determined on dry extract basis. Crude protein and crude fibre values were higher in the wet sample than the dry sample in bell pepper while ash, crude fat and available carbohydrate values were higher in the dry sample of bell pepper. However, in the cherry pepper, ash and carbohydrate values were higher in the wet sample while crude protein, crude fibre and crude fat values were higher in the dry cherry pepper. Minerals on dry extract basis showed that Ca, Mg, Zn, Fe and Na were more concentrated in the wet sample than in the dry sample of bell pepper. Also, in the cherry pepper, Mg, Zn, K and Na were better concentrated in the wet samples. The peppers are good sources of calcium, magnesium, sodium, zinc and iron which are important components of bone and supporting tissues, body osmotic pressure, enzymes and blood formation respectively.
Fresh tomatoes, okra and pepper were uniformly sliced to 1cm thickness and dried using cabinet and vacuum oven drying at 45oC to moisture contents of 12.5% and 11.8% for tomatoes, 13.0% and 12.0% for Okra, 11.0% and 10.5% for Pepper. Weight loss at 5 minutes interval and consequently the drying rates at every 30 minutes were observed. The dried products were also analyzed for bulk density, viscosity, pH andrehydration. The sensory evaluation of the dried samples, using preference test showed that drying with cabinet drier gave an acceptableresult for tomatoes and okra in terms of colour and texture. For pepper, better-dried products were obtained with vacuum oven drying in termsof colour. There was no significant difference in shrinkage by the two drying methods in all the samples at both 1% and 5% levels of probability.