6:00 The day starts early with Anton waking up for a quick run before breakfast. Also downstairs in the lobby we find several of the technicians, Maurice, Martin and Jarno, fully awake and prepping for the busy schedule that lies ahead. It is also the first night in strange beds and not everyone had a perfect sleep. Martin for instance woke up already at five.
7:51 We move quickly one to the bus, after a quick breakfast in the hostel with little breads, a table full of different breakfast cereals, drinks made from apple syrup, and tasty little sweet cakes. This day has a though time schedule and Maurice already "ordered" everybody to be in the bus before quarter to eight (even though it was scheduled at eight). Victor A came in last into the bus. He was ‘checking out to see if Mauricio wasn’t locked into the bathroom’.
8:05 Luckily our bus driver Adri, about who some stories tell that he is named like that because he needs three times to reach the destination, got us quickly and in one time to our first destination: one of the three sites of the ‘campus south’ of the Karlsruhe Institute of Technology (KIT). This is located just right next door the Karlsruhe castle that we visited with an evening walk through the park the day before. After a climb of 96 steps to the fourth floor we see coffee and pretzels awaiting us.
8:25 We are welcomed by Azad Emin who also acts as our guide for the morning program at KIT. He tells about a link with Wageningen by mentioning a long list of members in the group that studied or did their Phd’s in Wageningen.
Volker Gaukel, the thermo physical processes group leader, provides us with an overview of the institute. The section ‘Lebensmitteln verfahrungs Technik’ (LVT) is part of the ‘institute of process engineering in life sciences’ which is part of the faculty of ‘chemical & process engineering’. The KIT has 25 000 students and almost 10 000 staff members. The LVT section has three groups with a focus on thermo physical processes, emulsification technologies and extrusion. During the next hour we see presentations from these different groups.
Presentations groups at LVT
Volker provides us with three examples that are studied in the group thermo physical processes group. First, in spray drying they research methods to reduce the flux of air or air/liquid ratio. By means of experiments and modelling they got to a solution in which the air passes through the nozzle as an annular flow, rather than bubble or slug flow. The annular flow creates a spray that breaks up into small droplets.The work in this topic continuous on optimizing this annular flow and currently a good operation is achieved with an air inlet that is close at the exit point to the spray drying tower. Second, the combined use of microwave and freeze drying is studied. Good results are achieved by an initial freeze drying step which reduces crust formation and improves rehydration capacity (freshness) of the dried food product. Third and last, anti-freeze proteins are studied to improve the quality of frozen products. K-carrageenan is found to have similar properties as, the less consumer accepted, fish proteins. The Crystal growth is controlled by adding proteins that attach to the sides of the crystals allowing them only to grow in a single direction. After a question from Remko on this point we learn that the variable influence of different types of cations, which was mentioned to be indicating an effect of the gelling properties of the carrageenan on the crystal growth, may be more specifically an effect of the proteins attaching to the surface (and this effect, in its turn, is effected by the gelling properties which influences the amount of freely available proteins).
Ulrike Schmidt, who is a fresh post doc at the emulsification technologies group, provides us with four examples from her research. First, Ulrike tells us about the research on w/o/w emulsions which are useful in fat reduction of yoghurt and drug delivery. In one direction they work on the stability of the particles and in another direction they work on finding different materials to create the particles. The use of pectin from lemon, as a replacer of gum arabic, can be a good sustainable solution. The second example wows us with Navier Stokes computer simulations and high speed, 50 000 fps, imaging. It is used for the optimization of droplet breakup during homogenization, as applied for instance with milk. With their studies they have learned that elongated droplets leave the nozzle in a laminar flow that turns into a laminar flow, in which the elongated droplets deform and break up into droplets. They found that an optimization of this process can be made by placing a second orifice, further in the stream, to create a back pressure, which prevents cavitation and improves droplet brakeup. Another improvement is introducing a part of the whey stream behind the orifice, in a static mixer, to induce the turbulence. As a positive side effect this method is also energy saving because a smaller part of the product is pushed through the energy consuming homogenizer. The third example is the use of emulsions as nano-reactors and the fourth example is melt emulsification. The latter is used to reduce the amount of emulsifier needed and to create a wide variation of structures.
Azad tells us about the extrusion group. From questions asked later the day I learned that the group is still quite young. Azad started in 2008 as a Phd student and was the second Phd student at LVT on this topic. After his graduation he got the chance to set up his own group. So in 2013 an extra person joined, in 2014 another and now in 2016 in total three more people are working in the group. In Germany this possibility exists to proof that you can setup your own group and work on a ‘habilitation’. Azad tells "extrusion is a group".
Back to the contents of the presentation in the morning… Extrusion can be used for sustainable processing and examples include, cacao processing in a single process rather than multiple batch processes, creating breakfast cereals from apple peel, protein structuring and functionalization, and utilization of plant proteins to create meat-like structures. The problem with extrusion is that it is complicated to study, many things happen at the same time. Azad sketches a triangle of processing conditions, structure, and food properties which influence each other recursively (food properties depending on conditions but also influencing the conditioins) making the analysis difficult. One way that this problem is tackled is using CFD simulations although these are currently only available for the completely filled section at the end of the system. Another way was explained by Valerie Pietsch during the lab tour later on the day. She studies extrusion of plant proteins to meat analogues and studies two sections separately, the screw section and the die section, in order to gain more insight into the inner workings of the extrusion process. Azad mentions in his talk that "we can not use extruder to get reaction conditions inside the extruder". One technique that the group at KIT has available, to study more in depth the workings inside the extruder and high pressure and shear treatment of proteins, is a closed cavity rheometer, which Birgit was very jealous about.
In a questions and answer round related to the extrusion Remko mentioned a link between the research in Wageningen and Karlsruhe "this complexity we share with you". There are some paths to simplify the system to gain better understanding, but one thing to keep in mind is that it is often actually the couplings occurring in the complexity that create interesting results and new processes. We do not want to lose these.
10:10 Before we start on the lab tour we take quickly some bretzels and coffee after which we have a 10 minute walk through a very nice park before we reach the labs. Victor Qi mentions that "the weather is really good, I thought it was going to be colder".
In the labs we see presentations by post docs and Phd students. Remarkable is the large quantity of posters scattered around. These posters, all written in German, stem from a yearly conference directed to the local public and are permanently displayed next to the experiment stations. A nice way to be able to quickly instruct visitors.
In the drying lab we encounter a set of three drying machines, which Tim explains are orphans from industry. Tim is a Phd student at KIT who also works on getting these machines operational. The freeze dryer and convective air dryer are already working now. Getting the microwave heating working is still in the running. In between these machines we see a slightly smaller machine, yet still large, which is the combined freeze-drying and microwave heating instrument that Volker mentioned in his presentation. Anton asks why they don’t use a machine at a smaller lab scale at this early stage of development. Tim answers with a counter question "what is pilot scale?". The microwave freeze drying combination looks big but is working with, relatively small, samples of 250 gram. Further in the drying lab Phd student Mark shows us the spray drying setup and we get a closer look on the special nozzles that are used to create the annular flow that Volker told about in his presentation. With the spraydrying tower Mark works on getting more agglomeration, which is currently not occurring, and creating a higher feed flux (or lower gas/feed ratio).
In another lab Ulrike shows us a wide scala of homogenizers. An interesting highlight is the setup where high speed imaging is used to study the homogenization process. This setup is explained by Katharina. She tells about the main difficulty with pressure proofing and creating the slit and glas plate inside the homogenizer for the microscope that can sustain 100 bars. 1000 bars is used in the real process but this is something that is currently not obtainable. The setup allows to determine the velocity field in two dimensions and is used to study droplet formation.
We go back again to the building where we started, and pass by the offices. The coffee room is big and smells of a lot of drip coffee. The people at KIT seem to like coffee as much as Dutch people (although the taste of the brews is a bit weak). In the labs that we enter it is a little bit more difficult to see the worked compared to the pilot plant that we visited earlier. We see the setup of Serghei who studies the crystallization process in emulsions and he shows a screen where continuously droplets in the emulsion are imaged, analysed and the size distribution is determined. The crystallization process is determined as well by cross-polarization. In a question round we learn that the particle sizes range from 800-900 nm to 2 mm and that the crystallization depends on the droplet size. Basically two types of crystallization take place. On the one hand the particles retain their spherical shape if the crystallization takes place from surface to core. On the other hand the particles deform if the crystallization occurs more homogeneously. Further one we see the setups of Susanne Neumann who studies w/o/w emulsions and works on improving the stabilization of these particles. And we see the setup of Valerie Pietsch who works on plant protein extrusion to create meat analogues.
11:30 We start our own presentations and Remko kicks off this session with his talk about Wageningen University and the Food Process Engineering group. Volker asks a question about the funding of the large growth of students, ‘are we payed per student’. Remko explains that graduation is what pays the university which is a bit of a problem if there is a strong growth since it takes a while before these numbers are accommodated. However, for the group it is less of a problem since the University pre-pays the group ahead in time.
11:40 Eline tells us about single droplet drying. This study is relevant to spray drying, reducing its high energy use and improving the safety. It is currently a black box what happens during this process. In Wageningen we have a very nice setup where we place single droplets in front of a camera and dry them with hot dry air. Eline’s presentation features a very nice graphical overview of pictures of different droplets in an array with Temperature on one axis and the ratio of whey protein isolate to maltodextrin on the other. Before this slide we saw also a video of the drying process on which we see the formation of a skin on the surface, after 50 seconds. These two slides tell us that two different ways by which the droplets can dry. Droplets high in whey protein isolate concentration or dried at low temperature have a growing vacuole inside and become hollow. These particles are very brittle and can brake which is not what we want. Particles high in maltodextrin concentration or dried at high temperature create have no creation of a vacuole and the shrink during which the skin at the surface wrinkles. The slide, which already looked very nice, gets even more flashy by an overlay of pictures from X-ray tomography. These images tell us that in all the particles, also the wrinkled ones, vacuoles are present. The number of vacuoles increasing from the low maltodextrin and low temperature towards the high maltodextrin and high temperature. In the rounds of questions the people from KIT fire a range of questions on Eline asking mainly about the dimensions and the parameters of droplets and setup. Especially Mark who works on the spray drying at KIT has a strong interest into the topic.
12:05 In the presentation of Pina the sustainability, which is an important issue for our food process engineering group, is positioned extremely well. The presentation is styled with a very pleasant green font and on one of the first slides Pina explains sustainability by the 3R rule: Reduce, Replace and Recycle. Pina focusses on the first two with her research on chromatography. The problem with this is the large quantities of solvents that are used, which is not so good for the environment and costly. An example of the use of chromatography in food industry fructose separation and Pina uses it on the extraction of eicosapentanoic acid from algae. A nice slide in the presentation was the one where Pina explains the different ways of applying responsive polymers. The walls of chromatography columns can be switched between hydrophilic and hydrophobic by having proteins on the surface that can fold or bend depending on an electric field, magnetic field or temperature change. In the question round Volker asks what point of these different methods is studied. Pina answers that she first focusses on electric field triggering because it is expected to be better due to the faster response. Azad asks if there are preliminary results. There are currently good results with separating proteins of different pI and a pilot scale setup is created for the case of switching by temperature.
12:20 Birgit starts presenting her work with the creation of meat analogues from soy protein. The presentation starts nice and relaxed with videos and images of the process. The work is done with special conical shear cells.
This topic relates very well to our visits of this day. The KIT works on extrusion. Remko explained earlier in the day that In Wageningen the work on plant proteins extrusion was switched to these shear cells to study behaviour in a simpler situation and it was discovered that it created a whole new scala of aspect that are interesting on their own and now it is a large topic in the group of Wageningen. Later in the day during the visit to Thermo Scientific, where extrusion is an important case, Birgit was not presenting but during the coffee break she took out her laptop to show the people over there her work. The setup created in house in Wageningen, is powered by the drive for a Thermo Fischer rheometry setup.
Back to Birgit’s presentation, soy protein isolate alone is not working well and it seems that a two phase system with two polymers is needed. Birgit uses pectin and observed the formation of elongated droplets that create a morphology in the non-dispersed phase that looks and feels like fibres. Currently an important question is why the fibres are only formed at temperature at least 140 C, and if this can be changed. The ‘fibres’ were an important part of the questions round. "can we talk about fibres?" asks Azad. The answer is that the fibres result from the breaking of the structure in a multiphase flow. A question from Volker was confirmed by Birgit, ‘yes, the structures have been tasted’. The product that comes out of the cells is still somehhwat dry but Remko says "it’s not so bad if you bite into it". With a setup in Delft production volume is currently 7kg and there you really get big pieces that have more a feel of meat. The multiphase hypothesis to fibre formation got support from Valerie who observed in her extruder at the KIT the formation of droplets in the die.
12:35 Juliana, who was beautifully dressed that day, gave the final presentation. Juliana studies the extraction of oil bodies. These organelles present in plant cells are extracted intact in their original form. Important aspects for this research are safety environment energy health and efficiency. No solvents are used, just water, and this is possible because the oil bodies have a layer of emulsifiers and proteins around them. With the lunchtime getting near the question round is kept short. Volker asks about the size of the oil bodies. They are .3 to .6 micrometer in diameter.
12:50 The round of presentations is finished. After being overwhelmed by presents from Holland, Azad invites us to join them in the evening for a drink in Karlsruhe. He is going to help us get to a bar with nice beers.
For the lunch no special place was arranged and we have the little breads decorated with cheese and ham in the corridors of the office space. Anton found this a very nice feature of the lunch. He said later that "It’s like a party in somebody’s kitchen". Another nice feature during the lunch was a mega-pretzel that lied on the tables for the buffet and, being cut in to little breads, could cater for several tens of people.
13:25 After lunch we left for the next destination. The amount of raindrops started to increase a bit and we all waited for the bus under a walking bridge that connects the two buildings 50.31 and 50.32 at the Gotthard Franz strasse.
VISIT THERMO SCIENTIFIC
14:00 After the short travel by bus we arrive at Thermo Scientific which is located in Karlsruhe as well. While we sign in on the presence list and get id-cards our busdriver Adri is looking for a place for the bus. We are welcomed by Dirk Leister that provides us with health and safety rules and introduces the site that we visit. Karlsruhe is one of the four centers of Thermo Scientific in Germany. The site is also a training and application center, which explains the lecture type of look of the room in which we are seated. In the following hour we see presentations on three labs of Thermo Scientific in Karlsruhe.
Presentations Thermo Scientific
14:10 Fritz Soergel is an application specialist and teaches us rheology. The presentation provides us with a nice practical angle on rheology. We learn that the term rheology stems from ancient Greek and combines flow (rhei) and science (logos). A remarkable part the presentation is Fritz’s slimmy potty, which is used to explain time scales in rheology. At a low frequency, stretching the potty slowly, the slimmy potty flows like a liquid and stretches. At a medium frequency, 100 Hz, the slimmy potty is eleastic, which is demonstrated by forming it into a ball and bouncing it on the table. At high frequencies, the slimmy potty behaves solid like, which is demonstrated by pulling a strand of slimmy potty very abrupt creating a sharp break line.
The take of Fritz on the topic is very pragmatic. Reaching the topic of sinusoidal oscillatory excitation we start to deal with complex numbers. Fritz tells "we need a bit of mathematics… but don’t bother about that". This is a refreshing contrast to the presentation of Robbert Femmer the day before, which was packed with graphs on phase shifts occurring in electrical oscillations of a bipolar polyelectrolyte interface.
Tom Geilen, of the product line process & pharma, takes us on a virtual tour along all the machines that are produced at Thermo Scientific. We see machines from the smallest extruder in the world to large online rheometers. The presentation is filled with different names, TSE24-MC, Eurolab, Process 11. The reason for this is historic. In another aspect the machines are al the same. Later during the lab tour we learn that the machines for extrusion, at all sizes, have the same aspect ratios making the application of scaling laws simple.
Dirk explains us the hot melt extrusion process with videos. An example is shown of co-extrusion which can create tubes that can be used for controlled release of hormones in medical applications. Another interesting video is shown of a continuous fluid bed dryer. By placing a carrousel inside the dryer, particles move/rotate inside the fluidized bed from inlet to outlet. The resulting particle sizes are more uniform. This is important for medical applications like controlled are moving through the dryer. The advantage is a granulation process with a more uniform particle size.
15:15 Before we move on to our own presentations we have a short coffee brake that also features nice little cookies. The coffee is slightly stronger than at KIT but has also a bit of burnt notes.
15:30 Remko repeats his talk again, however this time some change occurred in the presentation and the picture of Anja Janssen ended up by accident between the emulsifiers of a graphic on a different spot on the slide. Also, Remko mentions the connection between Wageningen by saying "we use a lot of your machines".
15:50 Marlies starts her presentation on mild fractionation, aother of the many other sustainability related topic this day. Marlies starts with the casus of the current reality in food industry. First we destroy all structures created by nature, and then we blend it again to build new structures. Her solution is to use a milder treatment, just milling suspending and settling, resulting in fractions that may be less pure, however with same or better functionality. It is functionality that should count rather than chemical purity. This indeed doesn’t sound very logical but the inefficient way is how it currently works in the industry. In the question round Dirk asks about this, "how did they start in first place with…". Marlies answers that a reason might be that in the food industry there is a separation between different companies, ingredients and products, with different interests that might cause this. Remko adds that quality used to be characterized chemically and now we look more at the function. But what about dealing with geographical effects then, these natural origin materials are, after all, not easy to work with? A strong answer follows this question. Remko tells that, before people did not have the computational power to deal with the natural variability.
16:00 Dimitri provides us with a presentation that has lots of slides that are presented very smoothly, albeit a bit long because of the wide variety of aspects. His presentation is on sunflower press cake. It involves proteins and phenols, nutrition, good properties, emulsifying, especially foaming, traditionally 140 C and 50 kg/m^2, denaturation, 70 C desired, light oxidation, by-product to side-product, 14.7% fat but we decide to keep it, interactions of phenols and globular proteins, separation of protein rich fraction in electric field, and the search for phenols in these elecitrc field generated fraction.
16:25 Izabella speaks about microgells, "what is happening with a suspension of permeable and deformable particles when water is being extracted from the system?". We will see that the particles either deform or concentrate and depending on this you obtain different results. It is the end of the afternoon when coffee is not working anymore and your reporter does not remember much more about this presentation except for a PI related to Phi to the power nine point four.
16:40 For the tour around the labs we split into three groups. In the rheology lab we see again that Fritz is the practical and traditional guy. He starts with showing us traditional and simple machines. The falling ball viscometer, the company Haake, one of the origins of Thermo Scientific and established in 1882, is considered the inventor of this method. We also see a handheld viscometer, which is of course not very useful for us scientists. On the other side of the room we see the contrast with a latest version of an extension rheometer that is about to be finished before sale. Filaments are stretched while measuring the force with a piezzo element. This procent is very fast and difficult to track. Thermo Scientific adds a laser array to measure, with high speed, the width of the filament during the stretching and breaking. A high speed camera is used to determine the regularity of the filaments while stretching. In another room, that smells of heated plastics, we see work on hot melt extrusion. Fritz takes of with a historic example again and shows us an old polarization light microscope. Nowadays… we have instruments like fourier transform infrared, Raman or dielectric analysis spectroscopy attached to the rheology measurements setups. This gives us two parameters at the same time, not only how the material behaves but also what happens inside the material.
In the pharma lab we see a mini-extruder. Pharma-mini-haake, I don’t know what that means anymore, but is in my notes for this lab trip report. We see also many other extruders at various scales. A nice aspect of all of these is that they scale nicely because the extrudes have similar aspect ratios in their geometry.
Before going to the last lab, the third, we wait in the corridor. This is next to the table with cookies that was there from the previous break, which is not so unpleasant and also the burnt note in the coffee has decreased. The time schedule is getting more tight. Maurice is saying "we lopen uit".
In the process lab we see the final presentation given by Dirk Hauch. He is like a living encyclopaedia and overwhelms us with information on the different units. We start with the extruders MinigelPro, MiniCTH, and Process 11 and see a variation of mixing units and feed inlets. Then we hear "around the corner we have the bigger units", the TSE 24MC and the Rheomex OS. We are running out of time and someone enters the room telling Dirk, "bischen abkortzen". But Dirk is like a heavy oil tanker continuing his interesting load of information. At this point we are standing in front of 10 jars filled with materials that come out of the extrusion process. From crispy to brittle, we get the stories about all of these materials. Only one bottle is not opened, it is a extruded chicken liver product, dog food.
18:00 We are going back to the hotel, but of course not before thanking our kind hosts from Thermo Scientific and giving them the presents from the Netherlands. Dirk recognizes the ‘stroopwafels’, he had worked 10 months in Rotterdam, and while we are leaving the people at the institute continue on this (coincidently rheologically very interesting) product.