International Journal of Health & Nutrition

Int J Health Nutr 2013 4(1): 15-20

International Journal of Health & Nutrition www.academyjournals.net ISSN 1309 8071

Original Article

Determination of Potassium Bromate content in Selected Bread Samples in Gwagwalada, Abuja-Nigeria. Lukman Adewale ALLI 1*, Maxwell Madueke NWEGBU 1, Bassey I INYANG 1, Kenneth Chiwuba NWACHUKWU 1, John Onimisi OGEDENGBE 2, Olufunke ONAADEPO 2, Mustapha Abubakar JAMDA 3, Ganiyu Akintunde AKINTAN 1 , Sani Okoye IBRAHIM 1, Ernest Adebowale ONIFADE 1 1

Department of Medical Biochemistry, College of Health Sciences, University of Abuja, FCT, Nigeria 2 Human Physiology, College of Health Sciences, University of Abuja, FCT, Nigeria 3 Community Medicine, College of Health Sciences, University of Abuja, FCT, Nigeria Received: 26.11.2012

Accepted: 21.12.2012

Published: 13.02.2013

Abstract Background: Potassium bromate (KBrO3) is a nephrotoxic and carcinogenic substance used in food and cosmetics industry, and also found in drinking water as a by-product of disinfection. Despite the ban placed on the use of potassium bromate as bread-enhancer in Nigeria, it is commonly used by bakers to increase bread volume and texture. This study was aimed at determining the potassium bromate content of bread consumed in the Gwagwalada area council of Abuja, Nigeria, and evaluating the level of dietary exposure of this community to potassium bromate. The maximum concentration of potassium bromate allowed in bread by the US Food and Drug Agency (FDA) is 0.02μg/g (0.02mg/kg). Methods: Quantitative determination of the level of potassium bromate in bread samples was done using spectrophotometric method that is based on the redox reaction between bromate and promethazine hydrochloride in an acidic medium. The absorbance of the product was read at 515nm. The qualitative test was performed directly on a portion of each bread sample using 2ml of 0.01M promethazine and 0.6ml of 12M hydrochloric acid. The change in colour of each bread sample to pink indicates the presence of potassium bromate Results: The 20 bread samples analyzed contain potassium bromate. The concentration of KBrO 3 in the sampled bread is between 3.6µg/g and 9.2µg/g. The quantity of KBrO3 in each bread sample correlates with the degree of pink colour obtained in the qualitative test. Conclusion: All the sampled bread had potassium bromate, in concentration above safe level for human consumption, therefore bread consumers and bakers are at risk of exposure to potassium bromate with health implications. The need for continuous surveillance and enforcement of the ban on use of potassium bromate in baking industry in Nigeria is recommended. Keywords: Bread-enhancer, Carcinogens, Mutagen, Potassium Bromate, Spectrophotometer.

*

Corresponding author: Lukman Adewale ALLI, e-mail: [email protected] Phone: 08033664037

INTRODUCTION Bread, a baked staple food made from wheat flour, is widely consumed in all parts of Nigeria among all socioeconomic groups. Potassium bromate (KBrO3) is a colourless, odourless and tasteless white crystal/powder that is used as a food additive (Joint FAO/WHO 1992) and it is a commonly used flour enhancing agent in Nigeria (Emeje et al. 2009), because of its efficient oxidising

properties (Gandikota et al. 2005). It acts as a maturing agent and dough conditioner by oxidizing the sulfhydryl groups of the gluten protein in flour into disulphide bridges making it less extensible and more elastic, this will make the dough viscoelastic such that it can retain the carbon dioxide gas produced by the yeast. The overall effect is to make bread rise in the oven, increase loaf volume and texture (Nakamura et al. 2006).

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Int J Health Nutr 2013 4(1): 15-20 Apart from its use in bread and confectionaries, potassium bromate is also used in production of fish paste, fermented beverages and making cold wave hair lotion (Diachenko and Warner 2002). It is generated as a contaminant in drinking water due to the conversion of bromide found naturally in water to bromate by ozone which is used as water disinfectant (Ueno et al. 2000; Warner et al. 1996). The ozonation process is used for purification of the common “sachet water” sold in Nigeria. Potassium bromate has many adverse effects on the nutritional quality of bread and the health of consumers of bread made with bromate (Ginocchio et al. 1979; Fisher et al. 1979; Fujii et al. 1984). It degrades essential vitamins in bread (Ekop et al. 2008) and has been classified by the International Agency for Research on Cancer (IARC) as a possible human carcinogen based on sufficient evidence that KBrO3 is carcinogenic and mutagenic in experimental animals (IARC 1986). In the acute phase of poisoning, vomiting, diarrhoea and abdominal pain are the main symptoms. Features of chronic toxicity of KBrO3 include oliguria, anuria, deafness, vertigo, hypotension, depression of the central nervous system, and thrombocytopenia (Kurokawa et al. 1986). The lethal dose of KBrO3 in man has not been accurately established but it is estimated at about 5 to 500 mg/kg body weight (Kurokawa et al. 1990). In Nigeria, the National Agency for Food and Drug Administration and Control (NAFDAC) in 2002 announced the dangers associated with the use of potassium bromate and banned its further use in bread. The maximum concentration of potassium bromate allowed in bread by the US Food and Drug Agency (FDA) is 0.02μg/g (0.02mg/kg) (Ekop et al. 2008). Despite the ban on use of bromate in bread by NAFDAC, and the fact that there are other non-toxic, flourenhancing alternatives such as ascorbate (Ayo et al. 2002), many bakers are still using potassium bromate to enhance their bread thereby putting the life of the consuming public at risk. This study was aimed at determining the level of potassium bromate in some selected bread samples consumed in Gwagwalada area council of Abuja-Nigeria, with the view of ascertaining the level of dietary exposure of consumers of bread in Gwagwalada to the risk of Potassium bromate. It will also help to assess the safety of these breads for human consumption in view of the adverse effects of KBrO3 and also determine the level of compliance with NAFDAC directive of non-inclusion of potassium bromate in bread.

L.A. Alli et al. METHODS Twenty different brands of bread out of the twenty-two common and prevalent bread brands available in retail outlets in Gwagwalada area council of Abuja were used for this study. Quantitative determination of potassium bromate content of the bread samples were done following the spectrophotometric method described by El Harti et al. (2011). Spectrophotometer (Spectrum Lab 752S) was used in measuring the absorbance. Qualitative test was performed directly on a portion of each bread sample with 2ml of 0.01M promethazine and 0.6ml of 12M hydrochloric acid. Promethazine hydrochloride and potassium bromate (Sigma chemical, USA), analytical grade were used for preparation of standard solutions. Preparation of Standard Solution Aliquots of 100μl, 200μl, 400μl, 600μl, 800μl, and 1000μl from the primary stock solution of potassium bromate were placed in 20 ml capacity test tubes, and 1ml of 0.01M promethazine (PTZ) were added. Mixtures were then diluted with distilled water up to 10ml to obtain a final concentration of bromate in the range of 0.5μg/ml to 5μg/ml, 0.2 ml of 12M hydrochloric acid were added. Mixtures were well shaken for 1 minute and the absorbance was measured at 515nm against a blank reagent, results were used to plot the calibration curve. Preparation of Bread Samples A quantity of 10g was taken from the centre of each loaf of bread and dried in an oven for about an hour at 75 oC. The dried crust was pulverized and 1g of each powdered sample was weighed into a clean 250 cm3 beaker and 20 cm3 of distilled water was added. The mixture was stirred thoroughly using a spatula and then filtered using a Whatman no 1 filter paper. 8ml of the filtrate solution was transferred into a 20ml volumetric tube and mixed with 1ml of 0.01M promethazine. 0.2ml of 12M hydrochloric acid was added, the mixture was shaken for 1minute and absorbance of the coloured solution obtained was measured using a spectrophotometer at 515nm. The concentration was calculated from the linear regression curve obtained from the standard solutions of potassium bromate as mentioned above. A preliminary qualitative test was performed directly on a portion of each bread sample with 2ml of 0.01M promethazine and 0.6ml of 12M hydrochloric acid. The change in colour of each bread sample to pink indicates the presence of potassium bromate. Values presented are a mean of five replicate determinations. Statistical analysis was done using Graph pad prism 5.0.

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L.A. Alli et al.

RESULTS Table 1: Quantitative and qualitative determination of potassium bromate in some brands of bread sold in Gwagwalada area council of Abuja. Bread samples Quantity of KBrO3 (μg/g) Colour change (Qualitative test) A

5.0 ± 0.35

Pink colour

B

5.8 ± 0.37

Pink colour

C

6.2 ± 0.80

Pink colour

D

7.0 ± 0.63

Pink colour

E

6.8 ± 0.80

Pink colour

F

4.6 ± 0.40

Pink colour

G

6.8 ± 0.20

Pink colour

H

5.6 ± 0.25

Pink colour

I

4.8 ± 0.49

Pink colour

J

3.6 ± 0.40

Light-Pink colour

K

4.4 ± 0.40

Pink colour

L

5.4 ± 0.25

Pink colour

M

6.4 ± 0.40

Pink colour

N

8.6 ± 0.25

dark-Pink colour

O

6.6 ± 0.25

Pink colour

P

9.2 ± 0.20

dark-Pink colour

Q

4.8 ± 0.20

Pink colour

R

6.8 ± 0.20

Pink colour

S

6.0 ± 0.00

Pink colour

T

4.6 ± 0.25

Pink colour

Letter A to T represents the code for different loaves of bread sample analyzed. Values represent mean ± SEM of 5 replicate determinations.



L.A. Alli et al.

Sample A: Bread sample before treatment

Sample A: Bread sample after treatment

Sample D: Bread sample before treatment

Sample D: bread sample after treatment

Sample P: Bread sample before treatment

Sample P: Bread sample after treatment



L.A. Alli et al.

Sample J: Bread sample before treatment Sample J: Bread sample after treatment Figure 1: Some bread samples showing colour change (from cream to pink) when treated with Promethazine (PTZ) and hydrochloric acid (HCL)

All the 20 bread samples analyzed in this study contain potassium bromate. The bread with the least content of KBrO3 is sample-J, containing 3.6µg/g while sample-P has the highest concentration of KBrO3 at 9.2 µg/g (Table 1). The quantity of KBrO3 in each bread sample correlates with the degree of pink colour obtained in the qualitative test (Figure 1).

the high amount of potassium bromate found in the analyzed bread samples and coupled with the fact that bread is a staple food consumed on a daily basis by residents of Gwagwalada irrespective of their socio economic status, we can conclude that there is high dietary exposure of Gwagwalada residents to potassium bromate through bread consumption. Also the workers in the bakery where these breads are baked are also exposed to additional risk from inhaled bromate. Consequently there may be future occurrence of carcinogenicity and other symptoms associated with chronic exposure to high level of potassium bromate in this community. The presence of bromate in bread samples also implies that the compliance with NAFDAC ban on use of potassium bromate in bread is poor and the regulatory agency need to step up their surveillance and enforcement of this rule. Potassium bromate added to bread is harmful to consumers of bread because it has been associated with neuro- and nephro-toxicity (kurokawa et al. 1990), ototoxicity (Diachenko and Warner 2002), and it poses additional risk to the health of bakery workers as potassium bromide, a heat decomposition product of potassium bromate, is also toxic (Giesecke and Taillie 2000). In addition, potassium bromate reduces the nutritional quality of bread by degrading essential vitamins such as vitamin A, B and E (Joint FAO/WHO 1996). Oloyede and Sunmonu (2009) also reported adverse effects on liver and kidney functions of rats fed on diet formulated with bread containing potassium bromate. In view of the many adverse effects of KBrO3, other oxidizing agents, such as ascorbic acid, that is non toxic and equally enhances the quality and value of bread can be used in place of KBrO3. Also enzymes such as hemicellulases (volume enhancing), glutathione oxidase (protein strengthening) and exo-peptidase (improves colour and flavour) can equally be used.

DISCUSSION The amount of potassium bromate in each of the 20 bread samples analyzed is higher than 0.02µg/g, which is the permissible safe level of potassium bromate allowed in bread by the US Food and Drug Agency (FDA) (Ekop et al. 2008) and it also contravenes the NAFDAC ban on use of potassium bromate in bread. This implies that, none of the bread samples from Gwagwalada area council, analyzed in this study, is safe for human consumption as far as potassium bromate content is concerned. The sample with the least concentration of KBrO3 contains > 150 times the permissible level, while the highest concentration contains > 400 times the permissible level of KBrO3 in bread. The colour change of light-pink to dark-pink in the qualitative test correlates with the concentration of potassium bromate in the quantitative test. Potassium bromate in bread reacts with promethazine hydrochloride in the acidic medium to form a pink colour product (El Harti et al. 2011). The level of potassium bromate in bread samples obtained in this study is similar to the 3.7µg/g and 12.6µg/g for the lowest and highest level of KBrO3 found in bread samples consumed in Kaduna metropolis as reported by Ojeka et al. (2006). However it is slightly different from the values of 1.2µg/g and 10.4 µg/g, minimum and maximum quantity of potassium bromate respectively, obtained from bread samples analyzed in Eastern part of Nigeria by Emeje et al. (2009). Considering



L.A. Alli et al. Kurokawa Y, Maekawa A,Takahashi M, 1990. Toxicity and carcinogenicity of potassium bromate : a new renal carcinogen. Environ. Health Perspectives 87: 309-315 Mizushima, N, 1978. Experimental study on the ototoxicity of the bromate. Nichidaiishi, 37: 1057-1082. As cited in: Kurokawa et al. (1990). NAFDAC, 2003. Consumer Safety Bulletin Volume 2 No. ISSN: 1576-3594. Parsons, J.L. and Chipman Nakamura M, Murakami, T, Himata K, Hosoya S, and Yamada, Y 2006. Effects of reducing agents and baking conditions on potassium bromate in bread. Cereal Foods World. 51:69-75 Ojeka EO, Obidiaku ML, Enukorah C, 2006. Spectrophotometric determination of bromate in bread by oxidation of dyes. Journal of Applied Science Environmental Management. Vol 10 (3) 43-46. Oloyede OB and Sunmonu TO, 2009. Potassium bromate content of selected bread samples in Ilorin, Central Nigeria and its effect on some enzymes of rat liver and kidney. Food Chemical Toxicology 47(8):2067-70 Ueno HK, Oishi K, Sayato, Y and Nakamuno K, 2000. Oxidative cell damage in kat-sod assay of oxyhalides as inorganic disinfection by-product and their occurrence by ozonation. Archive of Environment and Contamination Toxicology 38:1-6. Warner CR, Daniels D.H, Joe FL Jr, and Diachenko, GW 1996. Measurement of bromate in bottled water by high-performance liquid chromatography with post-column flow reactor detector. Food Additives and Contaminants, 13(6):633-6

In conclusion all the twenty loaves of bread sampled, had potassium bromate in concentration above safe level for human consumption, therefore bread consumers and bakers are at risk of exposure to potassium bromate with health implications. The need for continuous surveillance and enforcement of the ban on use of potassium bromate in baking industry in Nigeria is recommended. ACKNOWLEDGMENT We wish to acknowledge the support of the staff of Department of Biochemistry, College of Health Sciences, University of Abuja, for the use of laboratory facilities. REFERENCES Ayo JA, Claride P, Ayanlere O, 2002. Ascorbic acid, an alternative to potassium bromate on the quality of bread. Nigerian Food Journal, 20: 33-35 Diachenko G.W and Warner, C.R, 2002. Potassium bromate in bakery products: food technology, toxicological concerns, and analytical methodology. in: Bioactive Compounds in Foods. ACS Symp. Ser. 816. Page 218. T.-C Lee and C.-T Ho, eds. American Chemical Society, Washington, DC. Ekop AS, Obot IB, Ikpatt EN, 2008. Anti-Nutritional Factors and Potassium Bromate Content in Bread and Flour Samples in Uyo Metropolis, Nigerian E-J Chem. 5(4): 736-741 El harti J, Rahali Y, Benmoussa A, Ansar M, Benziane H, Lamsaouri J, Idrissi MOB, Draoui M, Zahidi, A, Taoufik, J, 2011. A simple and rapid method for spectrophotometric determination of bromate in bread. Journal of Mater. Environmental Science 2 (1) 71-76 Emeje MO, Ofoefule SI, Nnaji AC, Ofoefule AU and Brown SA, 2009. Assessment of bread safety in Nigeria: Quantitative determination of potassium bromate and lead. African Journal of Food Science Vol. 4(6) pp. 394 - 397, June 2010. Fisher N, Hutchinson JB, Berry R, Hardy J, Ginocchio A.V, Waite V, 1979. Long-term toxicity and carcinogenicity studies of the bread improver potassium bromate. 1. Studies in rats. Food Cosmetics Toxicology, 17, 33–39 Fujii M, Oikawa K, Saito, H, Fukuhara, C, Onosaka S, Tanaka K, 1984. Metabolism of potassium bromate in rats; In vivo studies. Chemosphere, 13, 1207–1212 Gandikota S and MacRitchie F, 2005. Expansion capacity of doughs: methodology and applications. Journal of Cereal Science 42, 1579 Giesecke, AG and Taillie, SA, 2000. Identifying factors affecting bromate residue levels in baked products: preliminary studies. Cereal Foods World. 45 (3):111-120 Ginocchio AV, Waite V, Hardy J, Fisher N, Hutchinson JB and Berry R, 1979. Long-term toxicity and carcinogenicity studies of the bread improver potassium bromate. 2. Studies in mice. Food Cosmetics and Toxicology, 17, 41–47 International Agency for Research on Cancer (IARC) 1986. Potassium bromate. IARC Monograph Evaluating Carcinogenic Risk to Humans, 40:207–220 Joint FAO/WHO, 1992. Expert Committee on Food Additives. Evaluation of certain food additives and contaminants. Geneva, World Health Organization. 25-30 Kurokawa Y, Aoki S, Matsushima Y, 1986. Dose response studies on carcinogenicity of potassium bromate in F344 rats after long term oral administration. J. Natl. Cancer Inst. 77, 977–982
