Baking is the process that uses an oven or hotplate to cook a wide range of flour-based foods. The main purpose is to produce products that have characteristic flavours, aromas, shapes, sizes, colours and textures. The secondary purpose is to preserve the food by controlling the moisture content and destroying enzymes or contaminating micro-organisms to extend the shelf life. There is a huge range of bakery products as a result of combining a wide variety of ingredients and using different baking techniques and conditions to produce the different products (Figure 1).
Hard Hard wheat flour
Soft wheat flour
Bread Pizza and buns bases
Doughnuts Raising agent
Flans/ Pastries Scones Pie casings
Leavened (sour dough or yeast)
Unleavened (or chemically aerated)
Dough Ciabatta Muffin Lavash Naan Rye
Batter Crepe Dosai Injera Kisra Pancake Arepa Chapatti Matzo Paratha Tortilla Crispbreads Pitta Baladi
Figure 1: Types of baked cereal products (from Fellows and Axtell, 2004)
Practical Action, The Schumacher Centre, Bourton on Dunsmore, Rugby, Warwickshire, CV23 9QZ, UK T +44 (0)1926 634400 | F +44 (0)1926 634401 | E email@example.com | W www.practicalaction.org ______________________________________________________________________________________________ Practical Action is a registered charity and company limited by guarantee. Company Reg. No. 871954, England | Reg. Charity No.247257 | VAT No. 880 9924 76 | Patron HRH The Prince of Wales, KG, KT, GCB
Baking therefore offers the opportunity for small-scale processors to add considerable value to basic ingredients using relatively inexpensive equipment, and as a result it is a popular and potentially profitable business in nearly all countries. The quality of bakery products is the most important factor to ensure consumer acceptance and small differences in the aroma, colour, taste, texture and appearance of a product can result in success or failure. The characteristic aromas produced by baking depend on the temperature of baking and the composition of the ingredients, particularly the moisture content and the different types and amounts of fats, amino acids and sugars, which react together at high temperatures (known as ‘Maillard’ reactions). Other reactions that produce aromas are caramelisation of sugars and localised over-heating that produces burnt or smoky aromas. The golden brown colour associated with baked foods is also due to reactions between amino acids and sugars and the caramelisation of sugars. The taste (sweetness, saltiness) of bakery products is due to the amounts of sugar and salt that are added as ingredients. The characteristic textures of different bakery products is mostly due to the amount of starch gelatinisation in the flour: for example, partly gelatinised starch is found in products such as shortbread and the crumb in bread, whereas fully gelatinised starch produces the harder texture found in crackers. Raising agents (yeast or sodium bicarbonate) are also used also produce different textures in bakery products.
The baking process The
Baking is one stage (or unit operation) in the process of making the products shown in Figure 1. It is preceded by other stages, such as cleaning and sorting grains, milling flours, weighing and mixing ingredients, fermentation for some products, and forming doughs. After baking, some products may be sliced, but are otherwise ready for sale without further processing. The stages used in a bakery to produce different products are described below, followed by simple methods of quality assurance. Further information on fermentation is given in Technical Brief: Fermented Foods, and information on milling is given in further information at the end of this technical brief.
The basic equipment used in even the smallest bakery includes a range of utensils (Table 1), a mixer, an oven and/or hotplate, and a prover for leavened products (see Technical Brief: Food Fermentation). HandHand Hand-tools
Baking trays Biscuit cutters Bowls Bread tins Bread slicer Cake hoops Cake tins Cooling racks Dipping forks Dough dockers Dusting boxes Flour sieve Glaze brushes Knives Measuring jugs, scoops, spoons Oven gloves Oven peel Pastry cutters Piping tubes and bag Rolling pins
Steel trays of various sizes for bread and flour confectionery For cutting shapes from rolled out dough sheets Plastic, aluminium or stainless steel, for mixing ingredients Single tins of various sizes for different sized loaves, or ‘straps’ of 3-6 tins joined together. Special shaped tins for speciality breads For cutting bread into slices of uniform thickness A range of large tins for baking cake batter A range of sizes for small cakes, pies or tarts, fluted or plain For temporary storage of baked products before packing, or dough awaiting oven space. May be fixed or fitted with wheels For decorating cakes Spikes for puncturing the surface of dough or pastry For shaking a thin layer of flour onto tables for dough kneading Wire or nylon mesh to remove large particles from flour For brushing on milk or egg to give a glossy surface to products A set of cutting knives and a set of palette knives For measuring correct volumes of liquid or powder ingredients To protect hands when handling hot baked products A long-handled, flat shovel used to removed baked products from the oven A fluted set and a plain set to cut shapes in pastry A small set for cake decoration and a large set for depositing batter onto baking trays or filling products with cream For rolling out flat dough sheets
Sandwich tins Scales Spatulas Storage bins Thermometer Whisks
A range of larger tins for sponge cakes 0-1 kg for minor ingredients, 0-50 kg for weighing flour For stirring or beating ingredients For bulk ingredients, baskets/trays for distribution of bakery products For testing dough temperature or oven temperature. Special sugar thermometer for testing the temperature when making sugar confectionery For beating batters
Table 1: Small items of bakery equipment (Adapted from Fellows and Axtell, 2004)
Mixing is laborious and time-consuming, especially when preparing thick batters and doughs, and electric mixers are used whenever they are affordable. At household- and micro-scales of production it may be possible to use domestic mixers that are similar in operation to planetary mixers (below), but they are not designed for lengthy periods of continuous use and may need regular replacement of drive shaft pins or other components. All mixers are potentially dangerous and should be fitted with covers or grilles to prevent operators putting their hands into the mixing bowl when the mixer is operating. They should also have fail-safe devices such as an electric interlock to stop the machine operating if the cover is opened or not properly secured. Planetary mixers (Figure 2) are commonly used in small-scale bakeries. They are fitted with either gate blades for mixing thick cake batters, hooks for mixing doughs, or whisks to prepare thin batters or cake fillings such as whipped cream.
Figure 2: Planetary mixer for use in a bakery. Photo:
Forming Forming pieces
In small-scale bakeries, dough for flat breads, such as chapatti, naan, paratha and tortilla, is rolled by hand with a rolling pin to form the required shape, thickness and size. Batters for flat products such as crêpes, injera and pancakes are poured in a thin layer and both types of products are baked using a hotplate. Other types of doughs and pastries (e.g. for bread, pies, samosas etc. are also formed by hand, but this is time-consuming and can also produce variable thickness in pieces if staff are not properly trained. To overcome these problems, rolling bars may be used to roll out the dough, and dough may be cut and shaped into uniformly sized pieces using a variety of manual or powered equipment. Rolling bars are strips of metal that have the same thickness as that required in the sheet of dough: two bars are placed either side of the dough and support a rolling pin so that it reduces the dough to the same thickness every time. For example, biscuits need to be the same size and thickness so that they bake to a uniform colour and texture, and there are a large number of hand-operated biscuit cutters (Figure 3a) that produce different shapes by pressing them into a sheet of biscuit dough that is rolled to uniform thickness. Alternatively, biscuit dough may be formed into different shapes using a cookie press (Figure 3b).
Figure 3 a) Biscuit cutters, b) cookie press (The Bakers’ Kitchen at www.thebakerskitchen.net).
At a larger scale of operation, machines are used to form biscuit dough using one of four methods: 1) a die forming machine has a metal roller with shaped cavities: a sheet of dough is pressed into the cavities and the excess is scraped away to leave the shaped biscuit dough; 2) two cutting rollers cut shapes from a sheet of dough and simultaneously imprint a design on the upper surface using raised characters on the rollers; 3) a ‘wire-cut’ machine extrudes soft dough through dies, and wires cut the dough into the correct lengths; 4) a ‘rout press’ (similar to a wire-cut machine but without the cutting wires) cuts extruded dough to the required length using a reciprocating blade. These machines are considerably more expensive than the manual equipment and are suited to larger scale bakeries. Pie and tart cases are formed from sheets of shortcrust pastry using one of three methods: 1) ‘Hand-made’ pies are formed by creating a cylinder of pastry that is joined to a circular base and filled with a filling of meat, fish, vegetables etc. Then a circular pastry lid is either crimped on or sealed with egg wash; 2) Sheets of pastry dough are pressed into reusable pie moulds or single-use aluminium foil dishes to form the shape of the pie or tart. The filling is then added, and for pies, a sheet of dough is laid over the top to form the lids and crimped around the edges and/or sealed with egg-wash (tarts do not have lids). In each method, the lids may be decorated with indentations, latticework pastry strips, or small shapes (e.g. leaves, hearts etc.) cut from sheet pastry using biscuit cutters (Figure 3a); 3) Pies are formed using a manual blocking/lidding machine (Figure 4). First a weighed piece of pastry dough is placed into a pie or tart mould and the blocking head is lowered to press the pastry to a uniform thickness. The casing is then filled and covered with a circular piece of pastry, and the blocking head on the machine is replaced by a lidding head. This is lowered and simultaneously forms and decorates the lid and trims off excess pastry. A video clip of this machine is available at www.johnhuntbolton.co.uk/Gallery/Video/easy_pieF.htm. The advantages of the blocking/lidding machine are first time-saving because the casing pastry does not have to be rolled to a sheet and the lid is simultaneously sealed and decorated; and secondly it produces uniform thicknesses of both the casing and lid. With a larger investment, two machines can be used to speed up production, one fitted permanently with a blocking head and the other with a lidding head, or the manual equipment can be replaced by semi-automatic electric machines together with a depositor used to measure out uniform amounts of filling. Small pastie makers have a two-piece hinged mould that forms the shape of the final pastie (e.g. ‘Cornish’ pastie or slice pastie filled with meat, vegetables or cheese). A sheet of dough is placed over both halves of the mould, the filling is added to the lower half and the lid is lowered to crimp, seal and decorate the edges. Video clips of manual and semimechanised moulding equipment are available at www.johnhuntbolton.co.uk/English/Pages/gallery.html. To form bread dough into the required shape, a small manual dough divider (Figure 5a) is used to produce uniform sized pieces. At larger scales of operation, cut pieces of dough can be shaped using either a conical moulder (Figure 5b), where they are formed into ball shapes, or in a cylindrical moulder that shapes dough into cylinders. The cylindrical moulder has 2-4 pairs of ‘sheeting rollers’ that have successively smaller gaps, to roll the dough gently into a sheet. This is then rolled into a cylinder; the ends are sealed and it is deposited into a baking tin.
Figure 4: Manual pie forming and lidding machines (John Hunt Ltd. at www.johnhuntbolton.co.uk)
Figure 5: Forming bread dough into shapes, a) Dough divider (Pie Master at www.piemaster.com) b) Conical dough moulder There are many variations of these machines as well as other equipment that laminates sheets of dough with fat to produce Danish pastries and croissants, folding doughs to form pastries and rolls, and filling doughs to form sausage rolls and fruit bars such as ‘fig rolls’.
Making batters Making cake batters
Cake batters are complex oil in water emulsions: added fats or oils are finely dispersed in water that contains both sugar, egg, starch and flavours, and also a foam that is produced by incorporating air when the batter is mixed or by adding baking powder. The cake texture depends partly on the amount of air incorporated during batter mixing and partly on the time and temperature of baking. Where emulsifiers are used, they improve the texture, volume and uniformity of cakes by controlling the size of air bubbles in the cake batter. The ingredients in a cake mix each have particular functions: flour and egg provide strength and structure to the cake; sugar, fat and baking powder make a lighter texture; and milk and water make a heavier texture. It is therefore necessary to balance these ingredients. There are hundreds of different recipes for cakes, and each complies with three basic rules for cake-making: • The weight of fat should not exceed the weight of egg. • The weight of fat should not exceed the weight of sugar. • The weight of sugar should not exceed the total weight of liquids. The two methods of making cake batters are the ‘sugar-batter’ method and the ‘flour-batter’ method. In the sugar-batter method, fat, margarine or butter is beaten with sugar to create a cream. Any colouring or essences are added at this stage and then egg is mixed into the cream. The sieved flour and baking powder are then folded into the batter to achieve a smooth, lump-free batter but without ‘toughening’ it by too much mixing. Other ingredients (fruit, nuts etc.) are mixed into the batter and it is poured into a greased baking tin and baked. In the flour-batter method, sugar and egg are whisked together to form a batter. The flour is sieved to incorporate air, and folded into the egg/sugar mixture, causing as little disturbance as possible to its structure, until the batter is smooth and free from lumps. Any other ingredients are then blended into the batter. If the recipe uses margarine or butter this should be creamed (mixed) with an equal amount of flour before mixing with the egg/sugar. The sugar/egg mixture is added to the fat/flour mixture in about four equal portions, beating each portion together. The batter is then placed into a greased baking tin and baked.
Hotplates Hotplates and ovens
Hotplates are used to bake a wide range of flatbreads, batter-based pancakes, crêpes and scones. They are normally made from aluminium or steel and may be coated with Teflon to give non-stick properties. They are heated either by gas burners or by thermostatically controlled electric elements embedded in the plate. In Ethiopia, a ‘mitad’ made from clay and fuel fired, or an electrically heated metal version are used to prepare the flatbread, injera. A non-stick hotplate can be made from a sheet of thick steel (e.g. 1 cm) that is heated over a fire. The steel plate is made non-stick by covering it with a 1 cm thick layer of salt and heating it to a dull red heat for 20-30 minutes. At this
By Pete Fellows, Published by Practical Action on 03/29/12
Let us know which of the options below best describes you and we'll direct you to the most relevant content.
Practical Action uses technology to challenge poverty, working with poor women and men around the world.
Explore our work by Country
Explore our work by Technology
+44 (0)1926 634400 firstname.lastname@example.org
© Practical Action