Module 2: Role of ingredients in baked products manufacture- i) wheat flour, flour improvers and water.

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1 Paper No. 09 Paper Title: Bakery and Confectionery Products Module 2: Role of ingredients in baked products manufacture- i) wheat flour, flour improvers and water. The different baking ingredients can be categorized as major, minor and micro ingredients depending on the level of usage in formulations as follows: Major Ingredients: Ingredients constituting % or more of the formula weight comes under major ingredients. Wheat flour is the major ingredient. Minor ingredients: Those ingredients which are used in the level of 5-10 % of the formula weight are categorized as minor ingredients. Leavening agents, dairy products, starches and egg are the minor ingredients of baked products. Micro ingredients: These ingredients are used in micro level that is in parts per million (ppm) usually ranging from 0.1 % or less to 5%. Being difficult to measure these ingredients are added as parts of other ingredient systems. Besides these above mentioned ingredients there are some which are used for their attractive attributes and are called as characterizing ingredients. Fruits, dry fruits, resins etc. come under this category. 1.0 Wheat flour Wheat flour is the major structure forming ingredient in baked products which is obtained from the milling of wheat, one of the most important cereal crops in world. This crop belongs to the genus Triticum of the grass family Gramineae. The wheat kernel is composed of three parts: The outer bran layer forming the hard outer coating of the kernel (13-17%) The smaller germ portion that includes the embryo and scutellum (2-3%) The starchy endosperm that act as a reservoir of food for the germinating embryo (80-85%). Wheat contains % protein, % fat, 1.5 % ash and 2 % fibre. The different wheat protein fractions are as follows: Wheat protein Solubility % of total protein

2 Albumin Water soluble 5% Globulin Salt (0.5 N NaCl) 5% soluble Glutenin Dilute acid and alkali % soluble Gliadin 70% ethanol soluble % Besides these fraction proteoses also account for 2.5 % of wheat protein. The protein content of wheat grains varies from about 7% to 17% depending upon wheat variety, soil, climate and weather. Commercial wheat flour is obtained from two types of wheat hard wheat and soft wheat. Hard wheat: Wheat with a high protein content is called hard wheat. The yield of flour is also good. The dough formed has high water absorption capacity, strong gluten network, elasticity and excellent gas holding capacity. Due to these reasons hard wheat is desirable for bread production. Soft wheat: The protein content of soft wheat is low. The dough formed has poor water absorption capacity and poor tolerance to mixing and fermentation. Although soft wheat flour is undesirable for bread but for cakes, pastries and cookies etc. where a tender product is desirable soft wheat flour is required. Role of gluten: When wheat flour is kneaded with water to form dough, glutenin and gliadin fraction of wheat protein interact with each other and form gluten which has the characteristics of both- stretchability and elasticity. For proper gluten development glutenin and gliadin should be in a ratio of 1:1 of in the flour. This is the reason why only wheat flour is suitable for almost all bakery products. When the dough is allowed to rise the leavening gases are formed and expanded which are trapped by the gluten network. The gluten will continue to stretch as the gases expand during heating until the heat of the oven coagulates the gluten. This process results into a spongy texture of baked products. 1.1 Commercial grades of wheat flour Commercial grades of white flour are defined by how much pure endosperm is there. Highendosperm flours are whiter in colour because they are relatively low in bran and germ considered undesirable in baked products. Although these are considered as high-quality flours due to the high baking quality, they are lowest in nutritional quality. The traditional way for manufacturers to confirm the grade of flour is to measure its ash content which is

3 highest in bran hence indicating the amount of bran in flour and, therefore, of the flour s commercial grade. The following are the commercial grades of flour: Patent flour: Patent flour is the highest quality of all commercial grades of white flour as it consists of the innermost part of the endosperm and is essentially free of bran and germ. This makes patent flour lowest in ash and whitest in colour. It is often used by bakers for manufacturing bread, pastry cake etc. Patent flour is made by combining the first few streams of flour from the milling process. Patent flours are also graded depending on which streams of flour from the milling process are blended. The highest-quality patent flour is called extra short or fancy patent. Clear flour: Clear flour is the lowest quality of all commercial grades of flour as it consists of the outer part of the endosperm and contains germ and bran. The flour streams that remain after patent flour are the clear flour. All clear flours are relatively high in bran, high in protein and ash, and slightly gray in colour. While it is higher in total protein than patent flour, the gluten formed from clear flour is typically of lesser quality than that from patent flour. Clear flour is less expensive than patent flour. Straight flour Straight flour is milled from the entire endosperm. It is made by combining all usable streams of flour from the milling process and contains bran and germ particles that are not easily separated from the endosperm. 1.2 Types of patent wheat flour Most flours purchased by the baker are patent flours, milled from the heart of the endosperm. The differences among the various patent wheat flours are due to the type of wheat used in producing the flour and because of differences in milling practices or additives. Bread flour: The flour used for bread making is generally obtained from hard wheat. It is high in protein typically percent, that forms good-quality gluten and maximum 0.4 percent ash. This flour should form gluten of necessary strength, stability, extensibility and gas retaining property. It should also have sufficient damaged starch which will act as yeast food during fermentation or proofing of the loaves. Sometimes it contains added malted barley flour to provide for better yeast fermentation, dough handling, and shelf life. Bread flour is typically used for pan breads, rolls, croissants, and sweet yeast doughs. Pastry flour: Pastry flour is ideal for cookies and many pastries that do not need rising and hence weak, extensible gluten development in the flour is required. Pastry flour is milled from soft wheat, generally from soft red winter wheat and is low in protein, typically percent. For this purpose, soft wheat flour with lower protein content and is used.

4 Cake flour: Cake flour is milled from soft wheat. It has a high starch content and a very low amount of protein (7-9%) hence not suitable in bread making. It is short or fancy patent flour, meaning that it comes from the absolute heart of the endosperm. This gives cake flour a finer granulation, whiter colour. This flour should have good water absorption capacity. It is typically bleached with both chlorine and benzoyl peroxide, yielding a stark white colour and a distinctly changed flavor. All purpose flour: All-purpose flour is often made from a blend of hard and soft wheat and contains percent protein. This flour comes bleached or unbleached, and may contain added malted barley flour. It is mostly used in the foodservice industry like hotel and restaurants. 1.3 Other flours There are different other types of flour being used in baking industry. These can be categorized as white flour, brown flour, whole meal flour, germ enriched flour, multigrain flour, organic flour, bread making flour, biscuit flour, self rising flour, cake flour and composite flour depending on the component of wheat present in the flour. Whole wheat flour: When the flour contains all the three components of wheat kernel- bran, germ and endosperm then it is called as whole meal flour. The nutritional composition of this flour is exactly the same as that of the wheat from which it is milled. Since the germ has a high fat content and fat can go rancid, whole wheat flours are much more likely to spoil. Brown flour: The nutritional value of white flour can be increased by addition of selected coproduct stream to it. Such flour is termed as brown flour. Germ enriched flour: White flour can be enriched with cooked germ to improve its flavour and enhance its nutritional value. The germ enriched flour should contain minimum 10% (calculated on dry basis) cooked germ. Composite flour: Composite flour is prepared by blending wheat flour with other flours (cereal, legumes etc.) to lower the use of wheat by partial substitution for economic reasons. Composite flour has enhanced nutritional properties as compared to wheat flour. The increasing health concern and a growing consumer demand towards health food have led to the increased utilization of other nutritional cereals in the bakery products resulting into products based on multigrain flour. Multigrain biscuit, bread etc. are some of the examples. These are made by incorporating other cereal flours such as maize, millets, barley, rye, oat etc. in the formulation in addition to the wheat flour. Although these flour formulations reduce the performance of baked products but several research works have been extensively done to improve the quality attributes of multigrain bakery products.

5 Gluten free flour: In gluten free flour a complete substitution of wheat flour is done with other non-gluten containing flours. The gluten free flour can be obtained from rice, millets, sorghum, cassava etc. Plain or self rising flour: This flour has also become popular in recent years and is made from fairly soft wheat containing 8.5 to 10.5 per cent protein in which sodium bicarbonate is added in the form of baking powder at the mill itself. Hence there is no need of addition of baking powder in home preparations. To summarize, the major functions of flour in baking are as follows: Structure building of the baked products To absorb liquids: Starches, proteins, and gums are the three main components in flour that absorb moisture (water) and oil, helping to bind ingredients together. The absorbed water also helps preventing staling of some baked products like bread. To contribute flavour: Wheat flours have a relatively mild, slightly nutty flavor that is generally considered desirable To impart colour: Flours vary in colour, whole wheat being nut-brown in colour, whole white wheat flour - golden colour, durum - pale yellow colour, unbleached white flour a creamy colour, and cake flour a stark white colour. These colours carry over to the colour of baked goods. Add nutritional value: Wheat flour and flour based products contain complex carbohydrates (starch), vitamins, minerals, and protein. Whole wheat flour is more nutritious than white flour. 2.0 Flour improver There are some functional ingredients termed as flour improver which are combined with flour to improve processing and baking quality. These are also called as dough conditioners, dough improver and bread improver. To increase the speed of dough rising, to improve the strength and workability of the dough etc. are some of the functions achieved by these functional ingredients. There are wide ranges of these functional agents used in bakery processing, which can be grouped as: bleaching agents, maturing agents, oxidizing agents, reducing agents, enzymes and emulsifiers. These are often sold as mixtures in a soy flour base, as only small amounts are required. The major flour improvers used in baking industry are as follows: 2.1 Bleaching agents Freshly milled flour is yellowish in colour due to the presence of the xanthophyll pigment. However in some baked products like white bread white colour flour is desired. Bleaching of the freshly milled flour can be achieved naturally by oxidation when the flour is exposed to air but it is not feasible for the flour under bulk storage. Hence to accelerate bleaching the flour is treated with some bleaching agents. The most common bleaching agent used in bread

6 and all purpose flour is benzoyl peroxide which brings out the change within two days. This is used in the form of dry powder. It does not have any adverse effect on baking quality of wheat flour. In case of cake flour chlorine is used as bleaching agent, however it is detrimental to bread flour. 2.2 Maturing agents Exposing flour to air for longer period, as in natural ageing causes whitening of the flour and strengthening of the gluten that forms from flour. Oxygen, the active ingredient in air performs two major functions: Oxidizing the carotenoid pigments in flour, changing their chemical structure and whitening them and Oxidizing the gluten-forming proteins, allowing them to form stronger gluten. However natural aging has few disadvantages also- Longer time requirement, often several weeks or months which may cause storage problem Due to longer time mold growth or infestation with insects or rodents Inconsistent and lesser effective method of flour ageing Hence a number of oxidising agents are used as maturing agents to accelerate ageing of freshly milled flour. These agents primarily affect sulfur-containing amino acids, ultimately helping to form disulfide bridges between the gluten molecules. This helps in increasing gluten strength resulting into a larger, more-uniform finished product. These may or may not act as bleaching agents. The common oxidizing agents are: Various flour bleaching agents Azodicarbonamide Carbamide Potassium bromate Ascorbic acid Phosphates Malted barley Potassium iodate 2.3 Reducing agents Reducing agents weaken the flour by breaking the protein network which helps in handling a strong dough. The advantages of using reducing agents are increased extensibility, reduced

7 dough elasticity, improved machinability and shortened mixing and proofing time. The common reducing agents used in baking industry are as follows: L-cysteine Fumaric acid Sodium bisulphate Non-leavening yeast Ascorbic acid 2.4 Enzymes Enzymes act as natural catalysts to speed up reactions in dough or make reactions take place that otherwise would not. They include concentrated microbial enzymes in liquid, powder or tablet form, and enzymes present in flour or malt syrup form. The following enzymes are used in improving flour quality: Amylases break down the starch in flours into simple sugars, which further is used as yeast food, browning of product, softening and slowing staling of the product. Malt is a natural source of amylase. Proteases improve extensibility of the dough by degrading some of the gluten. Lipoxygenases oxidize the flour. 2.5 Emulsifiers (surfactants) Emulsifiers include natural lecithin and a variety of amphiphilic chemicals that are soluble at low concentrations in both oils and water. Some of these strengthen the dough and improve finished product volume by interacting with gluten while others soften the crumb and improve shelf life by complexing with the amylose starch in flour to keep it from firming after baking. Emulsifiers can be used individually or in combination to achieve both strengthening and softening effects. 3.0 Water Water is an essential ingredient for bakery products. It can be added in the formulation either in its pure form or in form of liquids like milk etc. For baking purpose hardness and ph of water are important considerations and hence should have compliance as follows- Medium hardness ( ppm) Neutral or slightly acidic ph

8 Hardness greatly affects the dough quality as too soft water results into a sticky dough and too hard water toughens the gluten and retards the fermentation that adversely affect the final baked product. The major functions of water are as follows: Gluten formation- Gluten is formed during dough making only when the glutenin and gliadin protein interact with each other in the presence of water. To assist in control of dough temperature. Hydration and swelling of starch for proper gelatinization during baking. Hydration and uniform distribution of salts and non-flour ingredients. Act as medium for enzyme activity. To contribute moistness to the baked products and improve their mouthfeel. Natural leavening -water and liquids present in dough turns to steam during baking, which causes the product to expand and hence contribute to the volume and tenderness of the baked product.