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Bread of Heaven

6/28/2013 | Words: Lucie Maluck | Pictures: Robert Hack

Combined heat and power plan, bakery

Bread and butter, maybe a slice of cooked meat or cheese, and there is your meal. Bread is a staple food – a standard, you might say. Though not for Ulrike Detmers and her family. For them, bread is a lifestyle. From their large-scale bakery they sell wholemeal bread in artistically designed tins and pumpernickel in packs with a kissing couple on the wrapper. The energy for the bakery is generated by a modular CHP plant supplied by MTU Onsite Energy. Professor Dr Ulrike Detmers is not only a passionate bread lover. Along with her husband and her brother-in-law, she is also a partner in the Mestemacher bakery and a member of the management board.


"What good does the money do us sitting in the bank – it isn't earning us any interest these days in any case. So we decided to invest it in an eco-friendly modular heat and power plant," explained Ulrike Detmers. This is a family that thinks pragmatically. And one that loves bread. That is something you notice when you take a walk through the production area with Ulrike Detmers and her nephew Maik Detmers. In the white coat and hairnet that everybody has to wear in the bakery for hygiene reasons, she does not particularly stand out on the shop floor.

So far everything is running smoothly and we expect the investment to pay for itself in just under ten years.Ulrike Detmers

But without them, she would be impossible not to notice. With her elegant suit and perfectly coi"ured blond hair, she comes across strongly as someone to be reckoned with. But when the smell of bread was her way, her eyes sparkle like those of a small child. "It smells so good, like home," she enthused, adding that baking it with the aid of ecologically generated energy from a heat and power plant is just the icing on the cake. "We are bakers, and so we normally invest in improving the baking processes," explained Ulrike Detmers but observed nevertheless that the CHP module must not remain a oneo".

Perfect energy utilization

As works manager, her nephew Maik Detmers makes sure that the energy from the CHP plant is perfectly utilized. The module generates 849 kW of electricity per hour. 40% of it is needed for baking and the rest is fed into the public power grid. Mestemacher also has an absorption chiller and a steam generator with a downstream steam accumulator. That means they can utilize the thermal energy from the CHP module at virtually every stage of the baking process. An exhaust heat exchanger heats thermal fluid and a heat recovery boiler produces steam that is then stored in a separate container. The low-temperature heat from the engine cooling system in the CHP module is utilized to produce hot water. That is used to heat the building among other things. The hot water also drives the absorption chiller for chilling water. The bakery uses the chilled water for cooling the dough and keeping the room temperature low in the summer. "This concept enables us to utilize the energy from the CHP plant in the most efficient way," said Maik Detmers.

The modular CHP plant is part of Mestemacher's power generation concept. It is connected to an absorption chiller and a steam generator with a downstream steam accumulator.?
The modular CHP plant is part of Mestemacher's
power generation concept. It is connected to an absorption
chiller and a steam generator with a downstream
steam accumulator.

Chilling stops maceration

The thermal energy from the CHP cogeneration module is first put to use as part of the rye maceration process. After the rye has been ground in the in-house mill, it is left to soak for several hours in water warmed by the recovered heat from the engine. You cannot see it, however, because it takes place in steeping vats on the first floor of the bakery. After several hours, it is transferred to what are known as holding tuns. They are double-walled cylinders. The space between the two walls is filled with chilled water from the absorption chiller. The low temperature inside the holding tuns stops the maceration process so that the steeped rye can be kept in them until it is used in the dough. Seeds and flakes for special bread The steeped rye is pumped together with the sourdough into the large kneading machine one floor below. This is the first point at which a baker is involved. He pours the manually added ingredients into the kneader by the sackful: various types of seed, oat flakes, salt, yeast, etc. "The basic ingredients of every type of bread are the same: rye and sourdough. The bakers add the extra ingredients that give the various breads their distinctive tastes," explained Maik Detmers.

Although the bread is kneaded
completely automatically, a baker
oversees the process.

Then comes the kneading. That too takes pace almost invisibly – and fully automatically in the kneading machine. Fully automatic but highly skilled Ten minutes later, the dough is put into the baking tins, which are then carried by conveyor belts to the oven for baking. Everything is done automatically but there is always a baker keeping an eye on the proceedings. "All the ingredients are natural products. However, the quality of the rye always varies, so we have to respond to those variations in the baking process," said Maik Detmers. If the baker sees that the bread is not rising enough or not turning the right color as it bakes, then he intervenes. However, the bread we can see through the small oven window looks seductively good – golden-brown with a rich, freshly-baked smell. It has been in the oven for 30 minutes and so has another hour to go. The oven is heated to a temperature of 270°C by thermal fluid. The fluid is first heated in a boiler using the thermal energy from the modular CHP plant.

Bread has to be A1

After 90 minutes' baking, the divine-smelling long loaves come out of the oven. A baker takes them out one by one and places them on a trolley. They ?stay there for a day to cool down before being taken up to the next floor. There they are sliced. "We get thirteen 500 g loaves from each tin," recounted Maik Detmers. Quality is a top priority for Maik and Ulrike. "I saw one of our loaves on sale in America once, so I bought it straightaway. It tasted superb. Though I would have been surprised if it hadn't, because customers are used to our high quality standards all over the world," he continued. And you can tell that this is someone who is passionate about bread.

Six-month stay-fresh guarantee

The quality has to be right not only at the moment the bread comes out of the oven. It has to taste just the same six months later. To make that possible, the bread is not only packed in an airtight wrapper, it is also pasteurized. The loaves are steam-heated in special pasteurization ovens. The steam required for pasteurization is produced by a heat recovery boiler using the hot exhaust from the CHP module at a temperature of 450°C. The ovens heat the loaves through evenly so that all microorganisms are killed. Young couple on pumpernickel pack But that is still not the end of the journey for the bread. After pasteurization, the packed loaves are labeled. For that they are taken to a di"erent department, 'the most dangerous room in the building' as Maik Detmers jokingly calls it. That is because standing on the roof of the department is the modular heat and power plant weighing around 100 tonnes including peripheral systems. "But we can trust the structural engineers, they did a good job," he grinned. This is where a bit of color comes into the picture for the first time, with shelves full of labels of all kinds – a di"erent design for each type of Mestemacher bread, and each of those in several di"erent languages. Maik Detmers is especially proud of one particular label sporting Hebrew script. "When we make this bread, a rabbi has to come in specially to make sure it is really done according to the kosher rules," he revealed.

But whether for the Russian, Chinese or home market in Germany, one thing stands out about every label – they all have people on them. That is something Ulrike Detmers is particularly proud of. She completely changed the image in 2000. One of her students gave her the idea. In answer to  the question whether she ate pumpernickel, she had said it was only for old people. Ulrike Detmers took a look at the packaging and had to admit her student had a point. "We were not appealing to young people," was her realization. So she revolutionized the pumpernickel packaging and replaced the picture of an old country cottage with one of a young couple – and from then on the product became a top-seller. "At first everyone thought I had a screw loose, but then they let me do what I wanted," she recalled. And the success proved her right. Pumpernickel is now Mestemacher's biggest selling bread. And Ulrike Detmers is now even more convinced that bread is much, much more than a staple. For her, bread is a lifestyle and a passion.

The content of the stories reflects the status as of the respective date of publication. They are not updated. Further developments are therefore not taken into account.

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