Baking with Improved Ovens

Overview / Background

Baking refers to a process “to cook by dry heat“ and is therefore next to cooking another essential way of preparing food from raw staple crops. Usually, it takes place in an oven or on a hotplate, but also in hot ashes or on hot stones. Baking is primarily applied to the process of preparing bread, and is also applied for firing and hardening pottery, earthenware or bricks by heat.

During baking, the heating process is done by a combination of three forms of heat: by infra-red energy that is radiated from oven walls, by circulating hot air; and by conduction through the baking pan or tray. That means the efficiency of the baking process depends on the optimal use of three different parts of the device: the walls, the tray and the ventilation system.

Burning biomass within the device produces the desired heat. Subsequently, the goods are placed inside and are baked for a certain amount of time. In the simplest way, a fire is lighted in a pit on the ground and after being burned down, the covered food is started to be baked (earth oven).

The chemical changes during the baking process allow for two improvements:

1.) The dough is transformed into an eatable food (nutritional improvement).

2.) At the same time, microorganisms causing spoilage are destroyed prolonging keeping time of the product (food preservation).

Unlike other cooking methods, baking does not alter the nutritional value of the food item, e.g. the fat and calorie content of the food.

Baked staple food

Many different varieties of bread and pastry have emerged from regional traditions around the world: like various sorts of bread, rolls, biscuits, pastries, cakes, buns and rusks, crêpes, injera, pancakes, etc. Corn tortillas form the staple food in most of Mexico, while in Peru the diversion of bread includes ingredients like potatoes or pumpkin. In Ethiopia and in east North Africa, the wide, flat, circular bread, which is called injera, is made from a grain called teff. Divers types of unleavened flat breads, which are usually made from whole-wheat flour and baked on a hot iron griddle called tava are the staple bread in South Asia and the Middle East.

Bread doughs produced from wheat flour have a unique viscoelasticity due to the wheat protein gluten, and therefore provide a better nutrition for humans. The world production of wheat in 2010 was 651 million tons, toped only by the cereals maize and rice. At the beginning of this century, more than 45 per cent of the world’s wheat was produced in developing countries.

Bread is a convenience food in Africa for both urban and rural communities. The major challenge with bread consumption in Africa is that most countries can't produce sufficient quantities of wheat to supply the bread market. Therefore, other starchy materials such as corn, potato, banana, yam, rice, sorghum, or cassava substitute wheat.

Bakeries worldwide

Baking is also a lucrative business. In many regions the industry as well as small and micro enterprises, are often facing unfavourable conditions. It is therefore important to guarantee and improve (Dagoon 2005):

• abundant supply of wheat flour
• efficient baking technologies
• capital at low interest rate
• quality control of the products
• continuous demand for bakery products
• access to good transportation and communication
• effective promotion

 

In order to be successful, bakeries regularly require:

• Ingredient inspection
• Quality assurance of bakery products
• Process control in a bakery involves accurate weighting of ingredients, control over baking temperatures and times and correct handling procedures for products. This includes also an optimal usage and handling of the chosen technology and energy fuel.
• Cleaning routine to ensure hygienic standards.

Bakeries exist worldwide in all sizes in both the formal and the informal sector: Small bakers operating from home, retail bakers who operate in-store bakeries, independent bakers who operate stand-alone bakeries, and large wholesale bakers who operate industrial (plant) bakeries.

In India, there are around 60,000 bakeries, mostly concentrated in the informal sector. The bakery industry is among the few processed food segments whose production has been increasing consistently in the country over the last few years.  Baking constitute the largest segment of consumer foods with an annual production of around 4 million tonnes.

In South Africa, approximately 3000 bakeries were registered in 1990 and approximately 80% of the bread production was in the hands of 6 large baking groups. After abolishment of the controlled bread prices in the early 1990's, the number of bakeries increased considerably. In 2005, out of the total of 7900 bakeries, 85 were wholesale bakeries, 600 were in-store corporate bakeries, 3700  were independent bakers, and 3500 were franchise bakers. It is estimated that 53,200 informal bakers operate in non-licensed premises.

They offer their baking products to different markets such as domestic, food service establishments, institutions, and wholesale.

In small-scale bakeries, dough is rolled by hand in order to form the required shape, thickness and size, which is time-consuming and can also produce variable thickness in pieces if staff is not properly trained. At a larger scale of operation, machines are used to process the dough before baking.

Baking requires very high temperature (around 250°C) and thus needs a larger amount of thermal energy input, e.g. wood, than cooking. Efficient baking technology reduces the firewood consumption, guaranteeing not only an efficient and shorter baking process, but also reduced operating costs.

Ovens

The most important fixture in a bakery is the oven. Before obtaining an oven, a baker should consider oven prices, fuel costs, possible assistance, supply and quality of the materials, etc.
Since many projects of GIZ focus on biomass for cooking and baking, the presented ovens are fuelled with biomass. If you have information on ovens with other fuels, please feel free to contribute.

Traditional ovens

The simplest way is to bake within a so-called earth oven: after a lighted fire in a pit on the ground is burned down, the food is put inside the pit and covered: the baking process starts.
Other traditional baking ovens consist of a baking chamber made of fireproof brick, concrete, stone, clay, or cob. Traditionally they are wood-fired, but coal-fired ovens are also common. It is known as a “black oven” because the smoke from the burned wood sometimes collects soot on the roof of the oven. They often lack insulation and proper ventilation.
Traditional ovens tend to consume more than 0.5-1 kg of wood per kg of baked wheat flour.