Thesis Abstract

                ABSTRACT

This work was carried out in the eastern part of Nigeria to investigate the presence of residual potassium bromate in bread. 25 different brands of bread were sampled from Enugu metropolis. The samples were analyzed using a previously reported method (David 1976). A freshly prepared 1% potassium iodide in 0.1N hydrochloric acid was used to develop the colour. The result revealed that all 25 bread samples contained residual potassium bromate. Sample A, C, R, S, T, W and X did not show any visible colour change when treated with potassium iodide. Sample C and X; 26mg/kg has the lowest concentration of residual potassium bromate. Sample B; 146mg/kg has the highest quantity. Sample N and Y; 108mg/kg also recorded quantities above 100mg/kg. Potassium bromate usually used as a bread improver is a carcinogen. All bread samples are therefore considered unsafe for human consumption.

Thesis Overview

1.0     INTRODUCTION

Bread is an important source of food prepared by cooking dough of flour and water, and possibly more ingredients. Dough is usually baked but in some cuisines, breads are steamed, fried or baked on an unoiled skillet. It may be leavened or unleavened salt, fat and leavening agents such as yeast and baking soda are common ingredients. Though bread usually contains several ingredients that would help improve the quality of the bread. Some of the basic identified ingredients apart from flour include: table salt, sugars, flavours and at least a floor improver such as potassium bromate (Vicki, 1997). Other ingredients may also include milk, egg, spice, fruit (such as raisins), vegetables (such as onions), nuts (such as walnuts) or seeds (such as poppy-seeds). The ever-growing popularity of bread may be connected with its convenience, high acceptability, high energy content and low level of blood cholesterol associated with its consumption (Gaman and Sherington, 1981). Water and flour are the major component in a bread recipe. They affect the bread texture and crumb properties.

      The major challenge in both flour milling industries and bakeries is the baking quality of flour, which is determined by the capacity of the dough prepared from it to retain gas. As a result of wide variation in the composition of flour, various treatments and supplements conditioning agents (flour/bread improver) are added for strength during mixing, extensibility for molding and also to increase loaf volume and texture.

Over the years, several improvers have been used but studies have shown some to be deleterious to health, thereby necessitating their ban. The use of potassium bromate has been a common choice among flour miller and bakers throughout the world because it is cheap and probably the most efficient oxidizing agent. It acts as a slow oxidizing agent throughout the fermentation proofing and baking process affecting the structure and the rheological properties of the dough. As a result, many bakeries use potassium bromate as an additive to assist in the raising process and to produce a texture in the finished product that is appealing to the public (Sherington, 1981).

1.2 POTASSIUM BROMATE

Potassium bromate is a flour improver that acts as a maturing agent. It acts principally in the late dough stage giving strength to the dough during the late proofing and early baking (Kurokawo et al., 1990). Potassium bromate takes the form of white crystals or powder. Potassium bromate has been used as a dough conditional for the past 60 years. According to USDA, it improves dough processing properties, internal crumb quality and low volume in concentration from a few to 75ppm, the highest concentration permitted by law. The mechanism by which bromate acts in dough is complex and not well understood (Destefanis, 1992).

      In early 1990’s, the World Health Organization (WHO) discovered that potassium bromate if consumed has the capacity to cause such diseases as cancer, kidney failure and several other related diseases. The adverse effect of potassium bromate on health and its health effects are divided into two categories. The first category deals with effects related to non-cancer effect. This includes its effect on the nutritional quality of bread. It degrades vitamin A2, B1, B2 and niacin which are the main vitamins available in bread (IARC, 1999).

Studies (IARC, 1999) have shown significant difference in essential fatty acid content of flour treated with bromate or in bread made from flour containing bromate.

      In humans, potassium bromate can cause cough and sore throat when inhaled (Atkins, 1993). Abdominal pain, diarrhea, nausea, vomiting, kidney, are some of the other non-cancer health problems associated with ingestion of potassium bromate (Atkins, 1993). In the secondary category, numerous studies have revealed the potential of potassium bromate to cause cancer in experimental animals and in humans (CSPI, 1999); Watson, 2000). Using bromate as bread improver has been banned (Ekop et al., 2008). Also, in Nigeria, the bromate use in bread making was banned in 1993 (Obot et al., 2008). However, some bread makers have continued to include potassium bromate in their bread.

      Furthermore, a preliminary survey revealed that some other materials employed in bread making (e.g. water) and the environments where these bakeries are located are not free from contamination by heavy metals such as lead.

1.3 JUSTIFICATION

      Bread is one of the oldest, stable and most reliable source of food. Its consumption is very high in the eastern part of Nigeria where most of the bread makers has resorted to using potassium bromate as a maturing agent for flour and as a dough conditioner in order to improve the quality of the dough and allowing higher rising. Potassium bromate has been considered a category 2B (possibly carcinogenic to humans) carcinogenic by the International Agency for Research on cancer (IARC). In addition, it has negative effect on the nutritional quality of bread. It degrades vitamins A2, B1, B2, E and niacin in bread (IARC 1999).

      This study confirms the presence of residual amount of potassium bromate in different brands of bread samples in Enugu metropolis.

1.4 AIMS AND OBJECTIVES

To determine the presence of potassium bromate in different brands of bread sampled