Andrea Lin, Germany, June 13, 2012

Sausage Making at the TiHo

We went to the food science department on TiHo’s campus with Dr. Carsten Krischek to learn how to make sausages.  There the butcher, Dietmar Küke, demonstrated the different equipment used to make raw bratwurst.  A meat grinder with several cutting blades was used to grind the pork and beef into mincemeat.  Since this was a relatively small batch, the butcher mixed the nutmeg, pepper, and salt into the mincemeat by hand.  The bratwurst filling was then put into a sausage-filling machine.  Bratwurst casing is made from intestine that has been turned inside-out with the mucosa removed.  For raw bratwurst the casing used was sheep intestine.  The package of casing is opened and placed into a bucket of water to help separate it.  The machine extrudes the filling out of the pipe into the casing – a process that was harder than it looked.  Once the casing is filled, the end is tied off and the bratwurst is twisted into individual sausages.


The boiled bratwurst was made of beef, pork, buccal fat, back fat, nutmeg, pepper, and salt.  Here the meat is a much finer grind so a rotating bowl with a spinning blade is used instead.  First the beef and pork are added and finely minced.  The blade spins at 3600 rpm so ice is added to prevent the meat from getting too hot.  Next the fat was added in and then the spices. Another bag of ice was added to the mix before the last of the meat.  Küke said he added a portion of the meat at the end to have a variation in the texture of the meat.  The finished filling had a much finer texture than that of the raw bratwurst.  We brought the mix back to the filling machine where we got to all try stuffing our own bratwurst.  The casing used this time was pork intestine, which is stronger than the sheep intestine.  This is necessary to prevent the bratwurst from bursting when it is first boiled.  It was also helpful to keep us from accidentally breaking the casing as we tried our hand at stuffing the sausage.  This was then boiled for 40 minutes before it was ready to be grilled.

Dr. Krischek then taught us about the sausage production in Germany and the food safety measures.  Sausage production is very important in German culture and is referred to as “wurst culture”.  There are 3 types of sausage: raw/dry fermented sausage, boiled sausage, raw sausage, along with raw mincemeat.  Many people in Germany eat minced meat raw and there are many guidelines for production.  Minced meat is defined as de-boned meat minced into fragments with less than 1% of salt and must comply with requirements for fresh meat.  It may not have undergone any preserving process other than chilling or freezing.  Storage and shipping temperatures of meat is <7ºC for pork and beef, <4ºC for poultry, and <3ºC for offal.  Mincemeat should be kept <2ºC or frozen as it is very sensitive to spoilage.  One major concern with food safety in this process is the meat grinder.  Residual amounts of raw material can get stuck to the grinder and it requires intensive cleaning to prevent contamination.

There is the raw/dry fermented type of sausage which is usually cured, stored unchilled (>10ºC), and consumed raw.  It is either in a spread form like “Teewurst” or a sliced form like salami.  Discerning selection of meat is important for food safety.  The meat can be stored up to 3 days, have low bacterial contamination, good color, a pH of 5.4-5.8, and be chilled or frozen prior to processing.  The back fat used needs to be fresh, firm, and white in color.  Chilling or freezing the fat prior to making the sausage makes it easier for the machine to slice.  Flavorings include salt, pepper, garlic, ascorbic acid “curing help”, a starter culture and <2% carbohydrates for the culture.  The starter culture is used for taste, lactic acid production, and competition against unwanted bacteria.  The ascorbic acid reduces NO2 to NO and Met-Mb to Mb (myoglobin).  This helps the formation of NO-Mb which gives the sausage its red coloring.  Thus the curing process affects the color, pH, water activity, and flavor.

When filling the raw fermented sausage it is important to keep it at 3ºC as it is eaten raw.  The equipment used to grind and fill sausages is important for all types of sausage.  Industrial filling machines use vacuum to avoid creating air bubbles in the casing, which are detrimental to the appearance.  Casing types are either natural or artificial.  Natural casings are cattle oesophagus, pig jejunum and caecum, or sheep jejunum.  The use of cattle caecum and colon is banned in the EU due to BSE.  Artificial casings can be made of cellulose, collagen or plastic.  Cured sausages need to be dried so the casing type must be water-permeable.


The most common type of sausage is the boiled sausage which use fine or coarse ground meat and can be cured or uncured.  “Fleischwurst” for example is a fine-ground sausage and “Weisswurst” is an uncured sausage.  The meat requirements are not as strict as in raw sausages.  Dark firm dry meat which has a higher pH is allowed.  Other ingredients include fat, salt, spices, phosphate for its binding properties and ice.  If the filling is too cold it can be difficult to fill so the final temperature should be 12-16ºC.  The sausage is then boiled or heat treated to create a stable product that can be sold.  These sausages need to be heated again before they are consumed.


Then there are the cooked sausages which are made of cooked or cured meat and cooked fat.  Depending on the type of sausage it can also include raw or cooked liver, the gelatin layer under the skin of a pig, blood, vegetables, or aspic/gelatin.  The gelatin, liver, or blood serves to bind all the ingredients together.  These sausages are filled at a temperature of 40 to 45ºC and cooked again after filling.  Blood sausages contain 10-30% blood, which is added cold with citrate for an anticoagulant.  The aspic sausages look like jelly with meat pieces suspended in them.  Liverwurst naturally contains liver and usually is a soft, spreadable sausage.


Lunch was much anticipated as we were eager to try the sausages we made earlier. We sat at picnic tables set up outside the building close to the large animal clinic.  There were bowls of “Krautsalat”, potato salad, and baguettes to go along with the sausages.  Hot off the grill the sausages smelled wonderful and were fantastic.  Two types of mustard and curried ketchup were passed around the table.  The raw bratwurst was very good and the texture of the boiled bratwurst was wonderful.  After lunch we thanked the doctors for the wonderful lunch and headed off to the TiHo teaching farm.


Visit of Ruthe, the TiHo-owned farm

We met with Dr. Christian Sürie who teaches all the TiHo veterinary students during their time at the farm.  Ruthe Farm was opened in 1961 and houses beef and dairy cattle, pigs, laying hens, broiler chickens, turkeys, and peking duck.  They used to have Muscovy duck but due to welfare issues and laws in Germany they no longer raise them.  There are also sheep and chickens used for human medical treatment research on the premises.  The farm also grows barley, wheat, corn, and sugar beets for producing silage to feed their animals.  TiHo veterinary students live in the farmhouse and take care of the animals during their 6 week study on animal husbandry.  The education goals of the farm also extend to teaching farmers proper animal husbandry techniques and teaching the local youth about where their food comes from.  Once a year, Ruthe Farm holds an open house where the public can visit their facilities.

The dairy cattle at Ruthe Farm are housed on two different kinds of bedding – either straw or slurry (manure) with rubber mat stalls.  Dr. Sürie spoke of the dilemma between public perception of animal welfare versus what may actually be better for the animals.  For example he told us that the public loves to see farm animals on straw bedding.  Yet straw bedding provides a great environment for bacteria and easily gets soaked through.  The manure is taken to be used as fertilizer for the fields.  The rubber matting was made of a similar material as used on all-weather running tracks.  While the rubber matting does not look as good visually, it provides comfort and a higher level of hygiene.  As Dr. Sürie puts it, everyone in Germany is intent on animal welfare but few understand the science behind it.

The average dairy cow in Germany spends 28 months in milk, which seems very short as it takes 24 months for a cow to grow up.  Yet by the end of 28 months the health of the cow is usually fairly poor.  Dr. Sürie explains that this may be due to genetics – when breeding, people often look only at milk production without taking other health factors into consideration.  At Ruthe Farm the dairy is largely a hands-off operation.  They have a 12 year old milking robot which is run by a computer system.  The cows wear a belt with a chip that the robot reads providing access to each animal’s history.  This ensures that cows don’t get milked too often and also tracks the milk quantity and quality.  When a cow first enters, the robot uses 28ºC water to wash the teats.  To improve milk quality and safety, the teat milk which is highest in bacteria is stripped and discarded.  Then the robot attaches each milk cup using laser positioning to find each teat.  The cups drop off as each quarter empties.  The amount and quality of the milk from each quarter is measured separately.  The milk is only sent off to the bulk tank if it is ok.  The robot then rinses each teat and opens the gate to allow the cow to leave.  Cows are taught to use the milking robot and they get milked when they choose.  Each cow is milked about 3 times a day depending on how much milk the cow is producing.  Milking is limited because it is stressful and each time it opens the teats up to possible infection.

Occasionally a cow will return too early simply to eat the sweet feed provided by the machine.  In this case the robot will open both front and rear gates to allow another cow to push the first one out.  This ensures that the cows never have a negative experience associated with the milking robot.

Next we went to see the laying hens which were all housed in a barn with access to an outdoor mesh-enclosed area.  Dr. Sürie told us that in 2010 confinement cages for chickens were banned in Germany.  They developed furnished cages, which provide a 90 square cm per hen area to walk, 2 levels of perches, and a 90 square cm per hen scratching area.  By 2025 such furnished cages will be banned as well.  Ruthe Farm houses chickens in different settings to determine the best ways for their health to manage them.  With barn or pasture type housing they saw an increase in aggression.  Chickens start by feather-picking which then leads to cannibalism.  Since cutting off the top of the beak is also banned, farms lose a lot of chickens to cannibalism.  Farm workers need to be very attentive and react quickly to train the chickens to stop their aggressive behaviors.


The hens are housed together with the rooster so the eggs are fertilized.  Hens are brought to a laying farm at 16-18 weeks of age and stay for 12 months.  After a year the eggs produced will have very thin shells.  Rebuilding calcium stores will take 8 weeks of good nutrition and no egg production.  Since this is expensive the laying hens are usually not kept for more than that production year.  60% of the cost of an egg is in the feed.  Yet as welfare standards remove more intensive housing types the costs go up.  One egg costs 5 cents with cage housing, 7 cents with enriched cages, 8.5 cents in a barn, and 10-11 cents free range.  With a barn, the building is more expensive as there is electricity needs for ventilation, heating, and cooling.  Yet free range has food safety concerns because there is less control over what the chickens are eating.  If they are exposed to an environmental toxin, it will be passed on to the eggs.  Thus Dr. Sürie sees the barn as the best compromise of hygiene, food safety, and welfare.

Every egg produced and sold in Germany is printed with the farm and specific building it was produced in.  The stamp lists country, region, smaller region, and the building on the farm.  In this way, traceback of egg-related outbreaks can be very quick and precise.

Next we went to see their pigs and the new housing methods they were developing.  Due to welfare issues, they have banned tail-docking, will stop castrating piglets in 2016, and ban crates in 2018.  At Ruthe Farm they developed a housing method that consists of a cage with a nest for each sow which the sow can leave freely.  The sow can go outside of the nest to eat but will return to the nest as the water source is located there.  She will also naturally return to the nest when the piglets call.  After 2 weeks most of the piglets will be old enough to get out of the cage.  This will allow for interaction where the piglets can learn social behavior in a group.  Yet without gestation crates there is an increased loss of piglets by 5%.  This is a sort of survival-of-the-fittest reason where weaker piglets may not make it.  As with most things there are pros and cons to increasing welfare.

We went to see their poultry houses where they keep the broiler chickens, turkeys, and the Peking duck.  They have designed second story walkway for students and visitors to view these houses without panicking the birds.  Ventilation in the buildings is very important for the health of the birds.  It is designed to bring air across the birds’ living space (without directly hitting the bird) and is vented out chimneys on the roof by pressure.  The broiler chickens were divided into 2 groups of same-aged chickens.  All variables are kept the same between the two groups except for what they are testing, such as bedding material or feed.  The turkey house was divided into 4 different research groups – half with uncut beaks and half with cut beaks.  One of the groups within each beak type was then fed conventional feed and the other with supplemented animal protein.  The theory is that animal protein will help prevent cannibalism, thus making it safe to house turkeys together without trimmed beaks.  The Peking ducks were separated into two groups.  They were taught to know that visitors would look from the overhead walkway.  Without that training they would panic.  They are relatively easy to raise and cannibalism is never seen with the ducks.  The only health risk they have is salmonella.  According to the EU standards, they must have swimming water provided.  The ducks had two large swimming pools for water, which was filled twice a day.  Within hours of filling all the water in the pools will be gone.  The bedding in the house is straw, which needs to be changed out completely on a daily basis.  After visiting the poultry houses we bade farewell to Dr. Sürie and Ruthe Farm.

Visit of Marienburg Castle

We stopped at the Marienburg Castle in Hannover for dinner.  This castle was built from 1857 to 1867 in the Gothic Revival architectural style.  In the evening the museum is closed while the restaurant stays open.  We had the courtyard almost all to ourselves.  Dinner was enjoyed and many pictures were taken in the lingering summer sunlight.  It was a wonderful end to an extraordinary day.