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Mal J Nutr 15(2): 213 - 222, 2009
Determination of Phytate, Iron, Zinc, Calcium Contents and
Their Molar Ratios in Commonly Consumed Raw and
Prepared Food in Malaysia
Norhaizan ME* & Nor Faizadatul Ain AW
Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences
Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
ABSTRACT
The inhibitory effect of phytate on the bioavailability of iron, zinc and calcium
was determined by measuring their molar ratios. A total of 29 food samples
consisting of 12 rice and rice products, 5 wheat and wheat products, 5 grains and
cereal based products and 7 different popular varieties of cooked rice and rice
products were selected. The phytate content was analysed using anion-exchange
chromatography whereas mineral contents were analysed using atomic
absorption spectrophotometry(AAS). One-way ANOVA test was used to
statistically analyse the mean difference between the phytate and mineral contents
between the food group samples. In general, results show that cooked products
have lower content of phytate and minerals as compared to raw products. This
could be due to the influence of the cooking method on phytate and mineral
content in the food. Based on one-way ANOVA test, there were no significant
difference in phytate and zinc content between four food groups (p >0.05).
Significant differences were found only in iron and calcium content (p <0.05). Of
the 29 food samples, 25 food samples had a phytate/iron molar ratio > 1, 5 food
samples had a phytate/zinc molar ratio > 15 and 23 food samples had a phytate/
calcium molar ratio of 0.24. These results show that although many of the food
samples analysed had high mineral content, the high phytate content may
impair the bioavailability of the mineral in the body.
Keywords: Calcium, iron, molar ratios, raw and prepared food, phytate, zinc,
Correspondence author: Dr Norhaizan Mohd Esa; Email: nhaizan@medic.upm.edu.my
INTRODUCTION
Bioavailability is a general term that refers
to how well a nutrient can be absorbed and
used by the body. It can be affected by many
factors such as the presence of anti-nutrients,
for example, phytates, oxalates, tannins and
polyphenols in foods, a person’s need, fibre,
competition with other nutrients and acidity
of intestinal environment (Paul, Turner &
Ross, 2004).
Minerals, classified as micronutrients
are needed by our body in small amounts.
Deficiency in minerals, however, can have a
major impact on health such as anemia and
osteoporosis that commonly occur in both
developed and developing countries. This
study focused only on iron (Fe), zinc (Zn)
and calcium (Ca). In Malaysia, the incidence
of anemia due to deficiency of iron is nearly
one million cases (969,645), osteoporosis due
Norhaizan ME & Nor Faizadatul Ain AW214
to calcium deficiency is 2, 421, 432 cases
while data on Zn status in the Malaysian
population is unavailable. The cause of
mineral deficiency is commonly due to its
low bioavailability in the diet. One of the
factors as mentioned earlier is the presence
of phytate.
Phytate, which is also known as inositol
hexakisphosphate, is a phosphorus-
containing compound that binds with
minerals and inhibits mineral absorption.
The presence of phytate in foods has been
associated with reduced mineral absorption
due to the structure of phyate which has high
density of negatively charged phosphate
groups which form very stable complexes
with mineral ions causing non-availability
for intestinal absorption (Walter et al., 2002).
Phytates are generally found in food high in
fibre especially in wheat bran, whole grains
and legumes (Lori, Thava & James, 2001).
Due to evidence showing that fibre-rich
foods protect against diseases such as
cardiovascular disease (CVD), colon and
breast cancer, more Malaysian have now
started adopting a dietary pattern
containing high fibre foods. Also, the food
industry has introduced various food
products enriched with fibre. This has
indirectly caused increased consumption of
phytates, hence possibly reducing bio-
availability of minerals.
There have been a number of studies
determining the level of phytate content in
different foods in other countries. A few
studies show that the Asian diet contains
very high amounts of phytate compared to
western diets. For example, a study in India
showed that the phytate content in their
foods ranged from 480 to 520mg/100g
(Pushpanjali & Santosh, 1995). The phytate
content of Korean foods ranged between
191.7 to 973.3mg/100g for cereals and 508.5
to 1371.8mg/100g for legumes (Joung et al.,
2004), while a study in Indonesia showed
that phytate content ranged between 8 to
319 mg/100g for cereals and 24 to 1018 mg/
100g for legumes (Sanny et al., 2007). The
phytate intake of Malaysians is still
unknown. This is due to the lack of data on
phytate content in local food. Even though
the phytate content in other Asian foods
might be available for use, the different
cooking methods, food processing tech-
niques and the variety of food consumed by
Malaysians compared to the people of other
countries renders such data unusable for
assessing the phyate intake of Malaysians.
There are many techniques used to
determine the bioavailability of minerals in
the human body. One of the methods is by
measuring the molar ratio of phyate/
minerals in the food and diet (Morris & Ellis,
1989). The proportion of samples with ratios
above the suggested critical values has been
calculated: phytate: calcium > 0.24 (Morris
& Ellis, 1985), phytate : iron > 1 (Hallberg,
Brune & Rossander, 1989), phytate : zinc >
15 (Turnlund et al.,1984; Sandberg et al., 1987;
Morris & Ellis, 1989), phytate : calcium/zinc
> 200 (Davies, Carswell & Mills,1985;
Bindra, Gibson & Thompson, 1986).
This study aimed to estimate the
inhibitory effect of phytate on the bio-
availability of iron, zinc and calcium in
commonly consumed raw and prepared food
in Malaysia by measuring their molar ratios.
MATERIALS AND METHODS
Sample selection and collection
A total of 29 different food samples were
selected consisting of 12 rice and rice
products, 5 wheat and wheat products, 5
grains and cereal based products and 7
different popular varieties of cooked rice and
rice products by convenience sampling.
Each raw sample was purchased from three
different supermarkets and shops while the
cooked samples were purchased from three
different shops in Seri Serdang, Selangor.
Each type of sample was then homogenised
and kept at –20°C until further use.
Determination of Phytate, Iron, Zinc, Calcium Contents and Their Molar Ratios 215
Determination of phytate
Phytate was determined using anion-
exchange method following Ma et al. (2005).
Samples were accurately weighed (1.0 –
2.0g) and transferred into 100ml conical
flasks. A total of 40 – 50ml of Na2SO4 (100g/
l)-HCl (1.2%) was added. Flasks were then
capped and shaken vigorously for 2 hours
on a rotator at ambient laboratory
temperature. The supernatant was then
filtered through qualitative filter paper no 4.
A total of 10ml of filtered extract was
diluted to 30ml with distilled water after
mixing with 1ml of 0.75M NaOH and then
passed through an anion resin column
(resin AG1-X4, ~ 100 – 200mesh, Biorad
Laboratory Inc., column 0.8 x 10cm). The
column was washed before use with 0.5M
NaCl solution and deionised water. After
sample application, the column was washed
with 15ml of distilled water and 20ml of
0.05M NaCl solution in order to remove the
inorganic phosphate. Then the retained
phytic acid was eluated with 0.7M NaCl.
The post column reagent was made up as a
0.03% FeCl3 solution containing 0.3%
sulphosalicyclic acid. A total of 4ml of the
reagent was added into 5ml of collected
eluate and centrifuged at 3000rpm for 10
minutes. The absorbance of the supernatant
was measured at 500nm using a
spectrophotometer (SECOMAM CE, France).
A calibration curve for the colorimetric
method was obtained by using sodium
phytate standards (P-8810 Sigma, USA) as
shown in Figure 1.
Determination of calcium, zinc and iron
The contents of Ca, Zn and Fe in foods were
measured by atomic absorption spectro-
photometer (AAS) (Analytikjena AG,
Germany) according to the method of
Hernandez et al. (2004). A 5g sample was
placed in a previously weighed porcelain
crucible and heated. The resulting white ash
was weighed, dissolved in 3ml of
concentrated nitric acid and diluted with
distilled water in a 25ml calibrated flask.
The solution then was used to determine Ca,
Zn, and Fe. Standard stock solution of iron,
zinc and calcium was prepared from AAS
grade chemicals (Sigma, USA) by
appropriate dilution.
Determination of molar ratio of phytate/
mineral
The mole of phytate and minerals was
determined by dividing the weight of phytate
and minerals with its atomic weight
Figure 1. The concentration of sodium phytate (mg/ml) against absorbance (500nm).
Norhaizan ME & Nor Faizadatul Ain AW216
(phytate: 660g/mol; Fe: 56g/mol; Zn: 65g/
mol; Ca: 40 g/mol). The molar ratio between
phytate and mineral was obtained after
dividing the mole of phytate with the mole
of minerals.
Statistical analysis
The statistics software Statistical Package
for Social Sciences (SPSS) version 12.0 for
Windows was used to analyse the phytate,
iron, zinc and calcium content and the results
expressed as mean ± standard deviation
(SD). The comparison of the difference in
phytate and mineral content between food
groups was analysed using one-way
analysis of variance (ANOVA) analysis.
Significant difference was determined by p<
0.05. Triplicate sample solutions from each
food sample were analysed. The
measurement was repeated until the relative
standard deviation (%RSD) was within
10%.
RESULTS AND DISCUSSION
Phytate and mineral content within food
groups
All 29 food samples were analysed for
phytate and mineral content as well as their
molar ratio. Table 1 presents the phytate
and mineral content in all food samples
while the molar ratios of phytate/mineral of
all food samples are summarised and
shown in Table 2.
Rice and rice products
Rice is the main staple food in Asia
including Malaysia. Rice products such as
mee hoon is a common food choice of
Malaysians. In this study a total of 12 rice
and rice products were analysed for phytate,
iron, calcium and zinc content. Phytate
contents ranged from 15.12 + 0.07 mg/100g
for glutinous flour to 91.52 + 1.00 mg/100g
for Malaysian rice (Brand D). For iron
content, the highest value obtained was 1.98
+ 0.03 mg/100g for rice flour and the lowest
was 0.24 + 0.03 mg/100g for Malaysian rice
(Brand B). The range of zinc content in rice
and rice products was between 0.14 + 0.01
mg/100g for kueh teow to 1.70 + 0.04 mg/
100g for Malaysian rice (Brand C), while
calcium content ranged from 0.26 + 0.01 mg/
100g for kueh teow to 0.64 + 0.03 mg/100g for
Malaysian rice (Brand B).
The molar ratios of phytate/iron of all
rice and rice products were > 1.00. A similar
molar ratio for phytate/calcium of > 0.24
was obtained. These ratios predict that all
the food samples from rice and rice products
had poor bioavailability of iron and calcium.
This could be due to the high content of
phytate in this food group which affects the
mineral bioavailability of these foods.
Another possibility could be due to a loss of
nutrients during the polishing process, the
main process to produce white rice. Most of
the nutrients in rice can be found in the rice
bran. However, during the polishing
process, the rice bran is removed along with
its nutrient composition. For zinc content,
all food samples had good bioavailability
except for kueh teow, which had > 15 molar
ratios of phytate/zinc.
Wheat and wheat products
Wheat is an important ingredient in bread,
flour, cookies, noodles etc. Wheat and wheat
products are other important staple foods
that are commonly consumed in Malaysia.
An analysis of the five samples chosen,
showed that the phytate content ranged from
2.86 + 1.23 mg/100g for mee kuning and
110.07 + 2.01 for wheat kueh teow. Iron
content in wheat and wheat products ranged
between 0.87 + 0.06 mg/100g for wheat flour
and 3.07 + 0.09 mg/100g for white bread,
while zinc content ranged between 0.32 +
0.003 mg/100g for mee kuning (noodles) and
1.99 + 0.09 mg/100g for wholegrain bread.
Lastly for calcium, the range was between
0.39 + 0.02 mg/100g for mee kuning and
110.66 + 2.04 mg/100g for white bread.
A factor that decreases phytate content
is bread making. During bread making, the
phytate content decreases due to the action
Determination of Phytate, Iron, Zinc, Calcium Contents and Their Molar Ratios 217
Table 1. Phytate, iron, zinc, and calcium content of the foods analysed
Sample Phytate Iron Zinc Calcium
content content content content
(mg/100g) (mg/100g) (mg/100g) (mg/100g)
Rice and rice products
Malaysia rice (Brand A) 60.96 ± 1.29 0.70 ± 0.02 0.92 ± 0.05 0.53 ± 0.02
Malaysia rice (Brand B) 36.40 ± 0.67 0.24 ± 0.03 1.63 ± 0.02 0.64 ± 0.03
Malaysia rice (Brand C) 76.24 ± 1.07 0.32 ± 0.03 1.70 ± 0.04 0.62 ± 0.01
Malaysia rice (Brand D) 91.52 ± 1.00 0.62 ± 0.04 1.64 ± 0.02 0.52 ± 0.002
Malaysia rice (Brand E) 68.05 ± 0.98 0.39 ± 0.05 0.80 ± 0.01 0.59 ± 0.02
Malaysia rice (Brand F) 62.59 ± 0.89 0.44 ± 0.03 1.22 ± 0.03 0.38 ± 0.02
Indian rice (Brand A) 66.41 ± 1.11 0.55 ± 0.03 0.81 ± 0.01 0.46± 0.01
Glutinous rice 57.14 ± 1.33 0.53 ± 0.05 1.50 ± 0.02 0.59 ± 0.02
Glutinous flour 15.12 ± 0.07 0.57 ± 0.05 0.91 ± 0.01 1.60 ± 0.04
Mee hoon 17.84 ± 0.18 1.23 ± 0.03 0.76 ± 0.01 0.56 ± 0.01
Rice flour 75.14 ± 1.43 1.98 ± 0.03 1.21 ± 0.01 0.45 ± 0.01
Kueh teow 38.04 ± 0.52 0.47 ± 0.03 0.14 ± 0.01 0.26 ± 0.01
Wheat and wheat products
Wheat kueh teow 110.07 ± 2.01 1.18 ± 0.07 0.60 ± 0.02 5.78 ± 0.08
Wheat flour 84.96 ± 1.88 0.87 ± 0.06 0.37 ± 0.01 1.68 ± 0.03
Wholegrain bread 14.57 ± 0.09 2.78 ± 0.07 1.99 ± 0.99 51.58 ±1.22
White bread 34.22 ± 0.65 3.07 ± 0.09 0.76 ±0.02 110.66 ±2.04
Mee kuning 2.86 ± 1.23 1.33 ± 0.02 0.32 ± 0.003 0.39 ± 0.02
Raw grain and cereal
based products
Oat cereal 394.92 ± 0.99 3.57 ± 0.12 2.94 ± 0.05 2.41 ± 0.08
Chocolate chip cookie 120.98± 1.76 2.34 ± 0.06 0.42 ± 0.02 203.62 ±16.68
cereal
Honey coated cereal 27.12 ± 0.24 1.46 ± 0.02 0.42 ± 0.004 138.88 ± 5.89
Chocolate coated cereal 75.14 ± 1.69 2.49 ± 0.09 0.52 ± 0.01 70.78 ±0.40
Chocolate malt drink 74.60 ± 1.47 2.33 ± 0.11 0.85 ± 0.01 69.61 ±0.96
Cooked rice and rice products
Chicken rice 4.20 ± 0.07 0.12 ± 0.03 0.32 ± 0.01 1.05 ± 0.03
Nasi lemak 187.56 ± 3.09 0.17 ± 0.03 0.34 ± 0.004 1.15 ± 0.01
White rice 18.20 ± 0.07 0.31 ± 0.02 0.47 ± 0.01 0.67 ± 0.02
Fried rice 12.93 ± 0.13 0.28 ± 0.05 0.13 ± 0.001 1.90 ± 0.03
Nasi dagang 53.86 ± 1.15 0.60 ± 0.02 0.84 ± 0.01 5.06 ± 0.05
Nasi kerabu 24.39 ± 0.52 0.44 ± 0.03 0.32 ± 0.002 0.42 ± 0.01
Fried kueh teow 4.75 ± 0.09 0.64 ± 0.03 0.13 ± 0.002 0.53 ± 0.004
Values are expressed as mean ± standard deviation, SD (n=3).
of phytase as well as the high temperature.
Phytate is also affected by hydrolyses,
including the type and extraction rate of
flour, and fermentation techniques (Ma et al.,
2005). This explains why bread has lower
phytate content compared to wheat flour.
The iron and calcium content obtained in
the wholegrain and white bread was also
high due to addition of minerals in the
fortification process (as stated in the food
label). The addition of milk as a ingredient
in bread making is also another possible
reason for the high calcium in bread. In
terms of bioavailability, two food samples
Norhaizan ME & Nor Faizadatul Ain AW218
in this food group, wheat kueh teow and
wheat flour, might have poor bioavailability
of iron, zinc and calcium. This could be due
to the high phytate content in these foods.
However, another three food samples,
wholegrain bread, white bread and mee
kuning, were found to have good
bioavailability of these minerals.
The study reveals that the fortification
process helps in improving the bio-
availability of minerals. However, as all
wheat products require extra processing to
improve texture, loss of nutrient content in
wheat during the process is possible.
Raw grain and cereal based products
Our analysis revealed that the phytate
content in these food groups was higher
compared to other food groups. Phytate
Table 2. The molar ratio between phytate and mineral of foods analysed
Sample Phytate/Fe Phytate/Zn Phytate/Ca
Rice and rice products
Malaysia rice (Brand A) 7.08 6.57 7.08
Malaysia rice (Brand B) 13.75 2.20 3.44
Malaysia rice (Brand C) 19.33 4.46 7.25
Malaysia rice (Brand D) 12.64 5.56 10.69
Malaysia rice (Brand E) 14.71 8.58 6.87
Malaysia rice (Brand F) 11.88 5.00 9.50
Indian rice (Brand A) 10.10 8.42 8.42
Glutinous rice 9.67 3.78 5.80
Glutinous flour 2.30 1.64 0.58
Mee hoon 1.23 2.25 1.93
Rice flour 3.26 6.00 10.36
Kueh teow 7.25 29.00 8.29
Wheat and wheat products
Wheat kueh teow 7.95 18.56 1.15
Wheat flour 8.06 21.50 3.07
Wholegrain bread 0.44 0.71 0.02
White bread 0.95 4.33 0.02
Mee kuning 0.17 0.80 0.40
Raw grain and cereal
based products
Oat cereal 9.34 13.29 9.97
Chocolate chip cookie cereal 4.36 30.50 0.04
Honey coated cereal 1.58 6.83 0.01
Chocolate coated cereal 2.59 14.25 0.06
Chocolate malt drink 2.69 8.69 0.06
Cooked rice and rice products
Chicken rice 3.00 1.20 0.23
Nasi lemak 94.67 56.80 9.79
White rice 4.67 4.00 1.65
Fried rice 4.00 10.00 0.42
Nasi dagang 7.45 6.31 0.65
Nasi kerabu 4.63 7.40 3.36
Fried kueh teow 0.64 3.50 0.54
Values are expressed as mean ± standard deviation, SD (n=3).
Determination of Phytate, Iron, Zinc, Calcium Contents and Their Molar Ratios 219
content ranged from 27.12 + 1.69 mg/100g
for honey-coated cereal to 394.92 ± 0.99 mg/
100g for oat cereal. Iron content ranged from
1.46 +0.02 mg/100g to 3.57 + 0.12 mg/100g,
while calcium content ranged from 2.41 +
0.08 mg/100g to 203.62 + 16.68 mg/100g.
The high mean contents of iron and calcium
in this food group compared to other groups
could be due to the fortification of these grain
and cereal based products with iron and
calcium. For zinc content, the range was from
0.42 ± 0.02 mg/100g for chocolate chip
cookie cereal to 2.94 + 0.05 mg/100g for oat
cereal.
The molar ratios of phytate/minerals in
grain and cereal-based products were
almost similar to the other groups, although
iron was added during the fortification
process. This could be due to the high
content of phytate in this food group. From
the analysis of data, indications are that all
food samples from this food group might
have poor bioavailability of iron because the
molar ratios of phytate/iron were > 1.00.
However, all food samples had high
bioavailability of zinc and calcium except
for chocolate chip cookie cereal and oat
cereal, respectively. From these results, it is
suggested that the food industry take the
initiative of adding extra minerals or
reducing the phytate content in food in order
to improve bioavailability of minerals.
Cooked rice and rice products
There are many different ways to cook rice,
for example nasi lemak is prepared by adding
coconut milk, chicken rice is prepared by
boiling rice in chicken broth, or even by using
different types of rice. Seven popular cooked
rice and rice products consumed in Malaysia
were analysed for phytate and mineral
contents. In general, the phytate content in
this food group was lower compared to other
food groups except for nasi lemak. The phytate
content ranged from 4.20 + 0.07 mg/100g
for chicken rice to 187.56 + 3.09 mg/100g for
nasi lemak. For minerals, iron content ranged
from 0.12 + 0.03 mg/100g for chicken rice to
0.64 + 0.03 mg/100g for fried kueh teow, while
the range for zinc content was from 0.13 +
0.002 mg/100g for fried kueh teow to 0.84 +
0.01 mg/100g for nasi dagang. Meanwhile,
calcium content ranged from 0.42 + 0.01 mg/
100g for nasi kerabu to 5.06 ± 0.05 mg/100g
for nasi dagang. The mean of iron, zinc and
calcium content in cooked rice and rice
products were 0.37 + 0.20, 0.36 + 0.24, and
1.54 + 1.63 mg/100g, respectively. Most of
the food samples selected had a phytate/
iron and phytate/calcium molar ratios > 1.00
and 0.24, respectively. This shows that the
bioavailability of iron and calcium is more
likely to be affected by phytate in these kinds
of food. All the food samples had a phytate/
zinc ratio < 15 which indicates good
bioavailability of zinc except for nasi lemak.
In general, the phytate and mineral contents
in this food group were lower compared to
other groups. This could be due to the variety
of cooking methods used. For example,
Almana (2000) reported that discarding
excessive water in cooking rice may result
in phytate degradation of ~37% to 65%, while
retaining the water only results in a phytate
reduction of 12%.
The results from this study also found
that nasi lemak and nasi dagang had the highest
phytate content compared to other cooked
rice. Both of these two rice preparations had
been cooked with coconut milk. So, we
suspect that high phytate content could be
due to coconut milk that has been added
during cooking. According to Oberleas &
Harland (1986), fat content influences the
extractability of phytate from food products
and should be kept low (<5%) or reduced
before phytate determination. However, fat
content in nasi lemak, which comes from
coconut milk is only about 3.6% (Tee et al.,
1997), indicating that the method used to
analyse phytate in this study should not be
the problem. Generally high fibre foods have
high phytate content. Coconut milk as stated
in the Nutrient Composition of Malaysian
Foods (Tee et al., 1997) does not contain fibre,
an indication that the high phytate content
Norhaizan ME & Nor Faizadatul Ain AW220
does not necessarily come from high fibre
food. This is supported by the results
obtained by Chen (2004) who showed that
there was no correlation between total phytic
content with total dietary fibre in raw and
dry red kidney beans. It is suggested that
further research investigate the phytate
content of coconut milk.
Phytate and mineral content between
food groups
The comparison of phytate content between
food groups shows that raw grain and cereal
based products have the highest level of
phytate followed by wheat and wheat
products, rice and rice products and lastly
cooked rice and rice products (Table 3). For
iron content, the food group that had the
highest value is raw grain and cereal based
products while cooked rice and rice products
had the lowest. Raw grain and cereal-based
products also had the highest content of
calcium while rice and rice products had
the lowest. However, zinc, rice and rice
products had the highest level followed by
raw grain and cereal-based products. Based
on one-way ANOVA test, there were no
significant differences in phytate and zinc
content for four food groups (p >0.05).
Significant differences were found only for
iron and calcium content (p <0.05).
A study by Ma et al. (2005) in China
showed that grain food groups had the
highest phytate content (223 to 1419 mg/
100g) followed by rice and rice product
groups (14 to 183 mg/100g) and wheat and
wheat product groups (3 to 420 mg/100g).
In this study, we found that the phytate
content of the sample (4.20 to 394.92 mg/
100g) was low but still within the phytate
range found in other Asian countries. This
could be due to the influence of factors such
as soil, climate, duration of growth period
and human intervention in food processing
and cooking.
There are two major ways to improve
mineral bioavailability: (i) by reducing the
phytate content in the foods or (ii) by adding
extra minerals in the fortification process.
Effective reduction of phytate can be obtained
via the action of exogeneous phytate-
degrading enzymes (use of microbial or
fungal phytases), breeding (selection of low
phytate varieties), agronomic conditions
(optimisation of fertilisation, better
knowledge of the benefits or organic crop
growing), genetic engineering or food
processes (bread making, lactic acid
fermentation) (Walter et al., 2002). Studies
have been carried out on food processing to
reduce phytate content by soaking whole
grain, soaking pounded grains, dehulling,
Table 3. The mean of phytate and mineral content between food groups
Rice and Wheat and Raw grain Cooked rice P-value
rice products wheat products and cereal and rice
based products products
Mean phytate 55.45 + 60.19 + 138.55 + 43.70 + 0.170
content (mg/100g) 23.72 38.30 147.11 65.63
Mean iron 0.67 + 1.80 + 2.44 + 0.37 + 0.000*
content (mg/100g) 0.48 1.03 0.75 0.20
Mean zinc 1.10 + 0.78 + 1.03 + 0.36 + 0.122
content (mg/100g) 0.47 0.71 1.08 0.24
Mean calcium 0.60 + 34.01 + 97.06 + 1.54 + 0.001*
content (mg/100g) 0.33 47.84 76.66 1.63
Determination of Phytate, Iron, Zinc, Calcium Contents and Their Molar Ratios 221
malting and fermentation (Hotz & Gibson,
1995; Lestienne et al., 2005). There are also
recommendations to reduce phytate content
of bread by lowering the extraction rate of
flour, prolonging the time for yeast
fermentation or addition of phytase in the
products (Almana, 2002). Bioavailability of
minerals such as iron also can be increased
under certain conditions. For example, by
including meat, fish, poultry and vitamin C
in the diet. So by adding fruits that are rich
in vitamin C in our breakfast cereal or having
fish, eggs and chicken in our meals will help
increase the absorption of iron from our
meal.
A study by Shamsuddin (1999) has
shown that only phytate in the form of
inositol trisphosphate (IP3) can inhibit the
absorption of minerals. In our study,
however, we have looked at the total phytate
content and did not differentiate between the
different classes of phytate. It is probable
that the phytate present in the foods analysed
was not in the form of IP3 that would inhibit
the absorption of minerals. Further in vivo
and in vitro studies need to be carried out in
order to get a clearer picture of the effect of
phytate on bioavailability of minerals.
CONCLUSION
In conclusion, varying levels of phytate can
be found in food commonly consumed in
Malaysia. Variation in phytate level was
not only observed in different food groups,
but also in the same food samples but
prepared (cooked) differently. Of the 29 food
samples, 25 food samples had a phytate/
iron molar ratio > 1, 5 food samples had a
phytate/zinc molar ratio > 15 and 23 food
samples had a phytate/calcium molar ratio
of 0.24. These results show that although
the foods analysed had high mineral
content, they also had a high phytate content
which may impair the bioavailability of
minerals to the body. Therefore, optimal food
processing and cooking methods should be
chosen to minimise this effect.
ACKNOWLEDGEMENTS
We would like to thank the Government of
Malaysia for financial support (03-03-08-
44FR) and the laboratory staff of the
Department of Nutrition and Dietetics of
UPM for their technical assistance.
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