PRODUCTION AND EVALUATION OF BREAD USING BLEND OF WHEAT FLOUR AND FERMENTED PLANTAIN FLOUR
CHAPTER ONE PRODUCTION AND EVALUATION OF BREAD USING BLENDS OF WHEAT AND FERMENTED PLANTAIN FLOURs
1.0 INTRODUCTION 1.1 BREAD:
Bread is the loaf that results from the baking of dough which is obtained form a mixture of flour, salt, sugar, yeast and water. However, other ingredient like milk, sugar and egg etc may be added. Due to increasing population, urbanization and change in food habits, consumption of leavened bread has increased tremendously in developing countries in recent years (Eggleston, 2005) It is however relatively expensive being made from wheat which is as a result of climatic reasons does not grow well in the tropics and has to be imported ( Edema, Etal 2004) efforts has been made to promote the use of composite flour in which flour from locally grown crops and high protein seeds replace a portion of wheat for use in bread. Thereby decreasing the demand for imported wheat and producing protein enriches bread ( Giami, etal 2004). Although wheat flour is the indispensable ingredient in leavened bakery products flours and meals from many other grains are frequently used as ingredients for the purpose of enhancing flavour or colour and improving nutritional aspect ( Samuel, 2004). The predominance of wheat flour for baking of levened breads due to the properties of its elastic gluten protein, which helps in producing a relatively large loaf volume with a regular finely crumb structure. If the wheat flour used in bread making is to be substituted with flour produced from other crops, they must be milled to acceptable baking quality. However such products cannot compare favourably with wheat flour product and therefore can only be referred to as non- wheat bread or named after their flour sources ( Opara Etal 2005).
1.2 NUTRITIONAL VALUE OF BREAD per 100g Carbohydrates 41g Dietary fiber 7g Fat 3g Protein 13g Thiamine (Vitamin B1) 0.4mg(35%) Riboflavin ( Vitamin B2) 0.2mg(17%) Niacin (Vatamin B3) 4.7mg(31%) Sodium 472mg(31%)
1.3 TYPES OF BREAD We have two main type of bread White Bread Brown Bread - White Bread: Is made from flour containing only the central core of the grain ( endosperm). - Brown Bread: Is made with endosperm and 10% brain ( pieces of grain husk separated from flour after milling. It can also refer to white bread with added colouring often caramel colouring) to make it brown e.g. wheat bread .
1.4 INGREDIENT IN BREAD MAKING Flour Sugar Yeast Butter Preservations (e.g) calcium propionate) Salt Water.
1.5 COMPOSITION AND CHEMISTRY OF BREAD 1.6.1 FORMULATION AND COMPOSITION. The proportion of water to flour is the most important measurement in a bread recipe, as it affects texture and crumb the most. Professional baker use a system of percentage known as baker’s percentage in their recipe formulations. They measure ingredients by weight instead of by volume because measurement by weigh is much more accurate and consistent than measurement by volume, especially for the dry ingredients(Edema,2004). The amount of flour is always stated as 100% and the amounts of the rest of the ingredient are expressed as a percent of that amount by weight. Common table bread contain 75% water. In yeast bread, the higher water percentage result in more Carbon(iv)oxide bubbles and a coarse bread crumb. Calcium propionate is commonly added by commercial bakeries to retard the growth of molds and extend the shelf life of the bread.(Edema,2004) Flour is a product made from grain that has been grounded to a powdery consistency flour provides the primary structure to the final based bread. Commonly available flour are made from rye, barley, maize and other grains, but wheat flour is meat commonly used for bread. Each of these grains provides the starch and protein need to form bread. The quality of the protein contained in the flour serves as the best indicator of the quality of the bread dough and the finished bread. Wheat flour, in addition to its starch contains there water soluble protein groups ( albumin, globulin, and proteoses) and two water insoluble protein group ( qlutein and qliadin). When flour is mixed with water the water soluble protein dissolve, leaving the qluten and qliadin to form the structure of the resulting bread when relatively dry dough is worked by kneading, or wet dough is allowed to rise for a long time the qlutenin forms strands of long, thin, chainlike molecules, while the shorter qliadin forms bridges between the strands of qlutenin. The resulting networks of strands produce by this two protein are known as qluten Glutein development improves if the dough is allowed to autolyse(Giami,2004).
1.6.2 CHEMISTRY. A simple technique for leavening bread is the use of gas – producing chemicals. There are two common methods. The first is to use baking powder or a self-rising flour that includes baking powder. The second is to include an acidic ingredient such as butter milk and add baking Soda, the reaction of the acid with the soda produces gas.(Bhatty,2003)
1.6.3 YEAST Many breads are leavened by yeast. The yeast used for leavening bread is saccaromyces cerevisae, this yeast ferments carbohydrates in the flour including any sugar producing carbon dioxide. Yeast has the advantage of producing uniform, quick and reliable results, because it is obtained from a pure culture.
1.6.4 STEAM: The rapid expansion of steam produced during baking leavens the bread, which is as simple as it is unpredictable. The best known steam- leavened bread is the popover. Steam – leavening is unpredictable since the steam is not produced until the bread is baked. Steam leavening happens regardless of the rising agents ( baking soda, yeast, baking powder, sour dough, beaten egg white e.t.c). - The leaveny agent either contains air bubbles or generates carbondioxide. - The heat vaporizes the water from the inner surface of the bubble within the dough. - The steam expands and makes the bread rise and this is the main factor in the rise of bread once it has been put in the oven, Co2 generation, on its own, is too small to account for the rise. Heat kills Co2 generation.
1.6.5 BACTERIA Salt rising bread employs a form of bacterial leavening that does not require yeast. Although the leaving action is not always consistent and requires close attention to incubating condition. This bread is making a comeback due to its unique flavour and fine texture. 1.6.6 FAT OR SHORTENINGS Fat such as butter, Vegetable oils, lard affects the development of gluten in bread by coating and lubricating the individual strands of protein and also helps to hold the structure together. Also fat also serves to tenderize the bread they are used in and also help to keep bread fresh longer after baking
1.6.7 BREAD IMPROVERS: Are often used in producing commercial breads to reduce the time needed for rising and to improves texture and volume . chemical substance commonly used as bread improver include ascorbic acid, hydro chloride sodium metabisulfate etc.
1.6.8 SALT Is one of the most additives used in production. In addition to enhancing flavour and restricting yeast activities, salt affects the crumb and the overall texture by stabilizing and strengthening the qlutein.
1.6.9 BREAD CRUST: The bread crust is formed from surface dough during the baking process. It is hardened and browned through the maillard reaction using the sugars and amino acids and the intense heat at the bread surface. The nature of bread crust is different depending on the type of bread and the way it is baked. Commercial bread is baked using jets that direct steam towards the bread to help produce a desirable crust.
1.7 AIMS AND OBJECTIVES - This work is aimed at the production and evaluation of bread using blends of wheat flour and fermented plantain flour. - Determination of functional and microbiological properties of wheat – plantain composite flour. - The acceptability of bread baked from the flours with a view to increasing the level of plantain flour inclusion in wheat – plantain composite flour for bread production as this will lead to higher utilization of plantain thereby reducing post harvest losses.