TSUNO Phytic acid Food

Phytic
Phytic acid | FOOD
PHYTIC ACID
Organic Acid Extracted from Rice Bran
Phytic acid (known as inositol hexakisphosphate, IP6, or phytate when in salt form) is an organic acid
extracted from rice bran. Phytic acid is used as an acidulant for pH adjustment. Phytic acid binds to
metals strongly because of strong chelating effect. Moreover, phytic acid shows antioxidant action and
prevention of color degradation. Phytic acid produced by Tsuno has been approved as GRAS by FDA
in the U.S.
O-PO3H2
PO3H2-O
O-PO3H2
PO3H2-O
O-PO3H2
O-PO3H2
Figure 1: Structure of phytic acid.
The most outstanding feature of phytic acid is its strong metal chelate function, allowing metal ions
such as ferrum (Fe) which often adversely affect the production or storage of food in various forms to
be removed or deactivated.
Physiological properties of phytic acid
1. Acidulant and pH adjustment
Figure 2 shows a relationship between pH (Y-axis) and concentrations of several organic acids (X-axis).
As can be seen, phytic acid is the best acidulant because it lowers pH level the most at the same
concentration.
Figure 2: The pH balance action of phytic acid and several organic acids. (In-house data)
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Phytic acid | FOOD
The pH values of 50% phytic acid and various organic acids at different concentrations are shown in
Table 1. Compare to various organic acids, phytic acid showed a lower pH at each concentration. In
addition in Figure 3, at the concentration of each organic acid at pH 2.35, phytic acid showed the lowest
concentration among 50% lactic acid, citric acid and malic acid. For the acidity degree of phytic acid
(Table 2), several organic acids were compared with 0.25 % citric acid and the acidity degree of 50%
phytic acid was 62.5. In conclusion, phytic acid has a mild, not a strong or sharp acid taste relatively.
Phytic acid does not affect the original taste of food or beverage and only low concentration of it is
required to achieve the desired pH level.
Table 1: The relation between pH and the concentration of each organic acid. (In-house data)
0.01%
0.05%
0.10%
1.00%
5.00%
50% Gluconic acid
4.12
3.66
3.48
2.94
2.57
Malic acid
3.49
3.20
3.00
2.50
2.15
50% Lactic acid
3.28
3.23
3.11
2.51
2.13
Tartaric acid
3.37
2.95
2.83
2.28
1.92
Citric acid
3.44
2.81
2.53
2.19
1.81
85% Phosphoric acid
3.26
2.75
2.52
1.83
1.34
50% Phytic acid
3.38
2.73
2.41
1.58
1.03
Figure 3: The concentration of each organic acid at pH 2.35. (In-house data)
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Phytic
Phytic acid | FOOD
Table 2: Acidity degree of phytic acid
(Acidity degree of 0.25% citric acid was defined as 100 as the standard solution).
(Analyzed by Japan confectionery research center)
Organic acid
Acidity degree
50% Gluconic acid
31.25
Malic acid
119.0
Lactic acid
108.7
Potassium Bitartrate
119.0
85% Phosphoric acid
178.6
50% Phytic acid
62.5
2. Prevention of color degradation
The prevention of anthocyanin degradation by phytic acid is presented in Figure 4. Anthocyanin
solutions at 0.1% were prepared then ascorbic acid, phytic acid and ferulic acid was added to the
anthocyanin solution, individually, at pH around 3 and left for 11 days. Each of the pigment residual
ratio (%) of the anthocyanin solution was then measured.
It is concluded from the results that phytic acid and ferulic acid have potential to prevent color
degradation in food or beverage including anthocyanin.
1
Beginning (0 day)
2
3
4
1
11 days
2
3
4
Figure 4: The prevention of anthocyanin degradation by phytic acid after 11 days. 1) Control: 0.1%
anthocyanin solution (no acid addition), 2) 0.05% of ascorbic acid, 3) 0.005% of 50% phytic
acid, 4) 0.05% of ferulic acid. (In-house data)
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Phytic acid | FOOD
3. Chelating action of phytic acid
Phytic acid is the most potent natural iron chelator and has strong bacteriostatic and antioxidant action
[1, 2]. Phytic acid is found to have similar iron-chelating properties as desferrioxamine, a drug
commonly used to kill germs, tumor cells or to remove undesirable minerals from the body [3].
Table 3 shows a chelate stability constant of phytic acid against several minerals. The larger value, the
more stable. The chelating stability constants of magnesium ion and calcium ion of phytic acid are
compared favorably with that of EDTA.
Table 3: Chelate stability constant of phytic acid (log K). (Original data from [4])
pH
Mg2+
Ca2+
Cu2+
Fe3+
Zn2+
1
8.5
8.6
9.2
16.5
15.5
2
10.3
8.2
9.8
16.3
15.5
3
9.6
9.7
10.4
16.8
15.5
4
10.7
10.0
10.9
17.4
15.0
5
10.8
10.0
10.9
17.4
15.0
6
10.6
10.9
10.9
17.6
15.7
EDTA
8.7
10.6
-
25.1
16.5
In fruits and vegetables, phytic acid helps to prevent oxidative browning by inhibiting polyphenol
oxidase. Phytic acid may be used as a safe preservative and antioxidant in food products [2].
Browning Prevention of cut lotus root by phytic acid was investigated by immersing cut lotus root in
0.5% phytic acid, 1.0% phytic acid, and distilled water with no additives (control) then removed after 1
hour. In figure 5 the cut lotus root with phytic acid show significantly browning prevention.
RT (25°C)
No additive
5°C
No additive
0.5% Phytic acid
1.0% Phytic acid
Figure 5: Browning Prevention of cut lotus root by phytic acid. (In-house data)
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Phytic
Phytic acid | FOOD
The chelate action of phytic acid compared to synthetic chelating agent, sodium metaphosphate is
shown in Figure 6. Sodium metaphosphate, an effective metal ions chelator has the greatest saltforming activity among phosphates, particularly with calcium salts. Phytic acid solution and sodium
metaphosphate solution were titrated to detect the color change from red color to pale pink by the
potentiometric titrimetric analyzer against the solution containing 20 mL of buffer solution at each pH
and sulfosalicylic acid as the indicator of Fe3+, and 50 mL of the standard solution (ferric sulfate)
containing 1000 ppm of Fe. Iron chelate ability of phytic acid was superior to sodium metaphosphate at
pH 5.0. Phytic acid sequesters metal ions promoted oxidation, discoloration and loss of flavor.
Iron may cause discoloration in wine or fruit juice. Hence, phytic acid can be added to chelate
polyvalent iron cations to prevent or treat these problems and make a wine more stable and
commercially acceptable.
Figure 6: The chelate action of phytic acid. (In-house data)
4. Antioxidant action of phytic acid
Phytic acid is a natural antioxidant. Phytic acid forms a chelate with iron, thereby preventing the radical
formation and oxidative damage. It blocks the formation of hydroxyl radicals and suppresses lipid
peroxidation. In fruits and vegetables, phytic acid helps to prevent oxidative browning by inhibiting
polyphenol oxidase. Phytic acid may be used as a safe preservative and antioxidant in food products
[2].
Graf et al., [2] reported the effects of added phytate upon iron-mediated OH production and
arachidonic acid peroxidation. As shown in Figure 7A, substantial amount of OH is produced by a
superoxide-generating system in the presence of iron alone. Even greater amounts of 'OH are evolved
if adenosine diphosphate (ADP) is added to chelate the iron. Generation of this oxyradical, however, is
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Phytic acid | FOOD
completely blocked by the addition of micromolar amounts of phytic acid [5]. It is important to note that
the inhibition of OH generation is found over a wide range of phytate:iron ratios from 1:4 to 20:1 [5].
The effect is due to occupation of all iron coordination sites by phytate, all ironphytate chelates
prepared were completely soluble.
Similarly, phytate prevents the peroxidation of arachidonic acid driven by ascorbic acid and iron.
Substantial amount of malondialdehyde arises from arachidonic acid in the presence of free iron or of
an iron-ADP chelate (Figure 7B). However, the addition of phytate prevents this iron-dependent
generation of malondialdehyde. The magnitude of the effect of chelating agents on OH formation does
not directly correspond to that on lipid peroxidation, suggesting that different reactions may be involved
in the two processes and that, during lipid peroxidation, iron may catalyze several steps, e.g. OHdependent hydrogen abstraction, OH-independent formation of lipid peroxides, and catalysis of the
formation of the final aldehydic cleavage products.
Figure 7: Effect of ADP and phytate on iron-mediated 'OH formation (A) and lipid peroxidation (B).
3+
Generation of hydroxyl radical ( OH) during 30 min in 50 µM Fe , 500 µM chelating agent, 50 mM
Tris, pH 7.4, 50 mM dimethyl sulfoxide, 300 µM hypoxanthine, and 18 milliunits of xanthine oxidase
at 37°C was determined [5]. Lipid peroxidation was measured by incubating 160 µM arachidonic acid,
3+
150 µM Fe , 1.0 mM ascorbate, 240 µM chelating agent, and 100 mM NaHCO3, pH 7.4, at 30°C for
60 min and determining malondialdehyde (MDA) with thiobarbituric acid spectrophotometrically.
(Original data from [2]).
5. Anticancer action
Phytic acid is an antioxidant and chelating agent. It suppresses oxidative reactions catalyzed by iron. In
plant seeds phytic acid helps to reduce the oxidation of its components but when ingested by humans it
may reduce the risk of colon cancer and some other inflammatory bowel diseases. The addition of
phytic acids to foods improves shelf life. It is also used as an antioxidant in many industrial applications
[1].
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Phytic
Phytic acid | FOOD
Number of cancer （pieces／rat）
Vucenik et al., [6] reported the effect of treatment on 7, 12-Dimethylbenz (a)anthracene (DMBA)induced mammary carcinogen, which is illustrated in Figure 7. Rats were administered with 0.6% phytic
acid in drinking water one week before a 16-week intragastric instillation of DMBA. The rate of cancer
cells palpated in rats administered with phytic acid was slower than that in the group not administering
phytic acid (Figure 8).
5
DMBA
IP6
4
3
2
1
0
0
4
8
Raising
days
Time (Day)
12
16
Figure 8: Effect of dietary phytic aicd on the initiation of rat mammary tumors by DMBA. DMBA ( ),
DMBA + Phytic acid ( ). The rats were started on this treatment one week before
intragastric instillation of DMBA and maintained on the diet throughout the length of the
experiment. (Original data from [6])
Toxicity ・Mutagen
(Japan Food Additives Association ： Surveillance study on safety evaluation of existing natural food
additives, 85, (1998))
•
Single-dose test
Acute oral LD50 is 0.9 g/kg mouse and is 0.41 g/kg in the case of rat.
•
Repeat-dose studies for 12 weeks
A nontoxic amount is 300 mg/kg/day in the case of rat.
•
Reverse mutation test, chromosome aberration examination test, micronucleus test: All are
negative.
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Phytic
Phytic acid | FOOD
Applications
Preservation of oils and fats
Chelate action
Tofu・Deep-fried tofu
Miso・Soy sauce ・Pickle ・Animal industry
product・Canned food・Browning prevention
of fruit juice
Chelate action
Buffer action
Soft drink
Sterilization ・Bacteriostatic action
Boiling noodle
Deodorant action
Mutton meat
Growth promotion action of lactic acid
bacterium
Acidulant
Other
Fermented food
Soft drink ・Pickled plum
Struvite production prevention of Canned
food・Return prevention of bleaching・
Brightness improvement of bean jam
Food type
Dosage (%)
Soft drink
0.02 ~ 0.1
Can ・Agriculture and Fishery canned food
0.02 ~ 0.2
Pickle
0.02 ~ 0.1
Bean jams
0.02 ~ 0.1
Boiling noodle
0.5 ~ 0.7
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Phytic
Phytic acid | FOOD
Properties
Product
Phytic acid (50% Solution)
Appearance
Slight yellowish or brownish viscous liquid
Specific Gravity
1.396 (50% phytic acid solution)
Solubility
Freely soluble in water, 95% ethanol, acetone
Slightly soluble in absolute ethanol
Non-soluble in oil
Stability
RT
20-30°C
Refrigerator
1-10°C
Phytic acid that were stored at room temperature (left photo)
turned pale brown in only two months, while samples stored
in refrigerator (right photo) took six months to turn pale
yellow. This suggested that the discoloration of phytic acid is
suppressed at low temperature.
Note: All Tsuno's products are extracted from rice bran and are GMO free, BSE/TSE free and non-allergy. We obtained bulk
GMP in Japan and Halal and Kosher certified products are also available.
References
[1]
[2]
[3]
[4]
[5]
[6]
Graf, E., and Eaton, J.W. (1990). Antioxidant functions of phytic acid. Free Radical Biol. Med. 8(1), 61–69.
Graf, E., Empson, K.L., and Eaton, J.W. (1987). Phytic acid. A natural antioxidant. J. Biol. Chem., 262,
11647-11650.
Hawkins, P.T., Poyner, D.R., Jackson, T.R., Letcher, A.J., Lander, D.A., and Irvine, R.F. (1993). Inhibition
of iron-catalysed hydroxyl radical formation by inositol polyphosphates: a possible physiological function for
myo-inositol hexakisphosphate. Biochem. J., 294, 929-934.
Sato, M. (1986). Monthly Food Chemical, April, 4, 48. (in Japanese)
Graf, E., Mahoney, J.R., Bryant, R.G., and Eaton, J.W. (1984) Iron-catalyzed hydroxyl radical formation:
Stringent requirement for free iron coordination site. J. Biol. Chem., 259, 3620-3624.
Vucenik, I., Sakamoto, K., Bansal, M., and Shamsuddin, A.M. (1993) Inhibition of rat mammary
carcinogenesis by inositol hexaphosphate (phytic acid). A pilot study. Cancer Lett., 75(2), 95-102.
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