AP projects 2015
Posts in category News
The 3D printer modification
As said in a previous post we are using the custom made 3d printer available at the applied labs for the printing of the chicken breast. This printer was used to print PLA and therefore made several modifications. First of all the original printing head was removed and we placed our custom made, 3D printed, head in place of it.
The motor makes the gears turn. The Gears make sure that with the little power of the motor the material can be printed. The last gear (the biggest one) pulls the transitional belt. Because the transitional belt becomes shorter on the side of the syringe, the syringe is pulled down. This is done fluently with the use of the belt holder with a bearing inside.
Next to this the software used for the printing is modified for this food extruder.
Now the first organic chicken breast will be 3D printed. To do this we use the 3d model we obtained from the 3d scan and we use the lupine/Alginate recipe with 30% less alginate than set. The first print will be made with three outer layers filled with an infill with a linear cross infill of 98%. After each layer manually the saltwater concentration (double as prescribed in the recipe) was added using a plant sprayer.
At the beginning the print did not work out correctly. We changed the layer height, the printing speed and the extrusion rate settings to make the printing more accurate. This worked out. In total the printing time was about 50 minutes for the chicken breast with a size of 50*105*15 mm. At the end the extruder was not printing straight lines anymore and clogs arose in the print. Probably this was due to the incorrect height of the extruder in comparison with the printing bed. The real line thickness was not the same as the expected one. Possibly as well the resistance grew inside the nozzle which caused a delayed print. As a result we got the following:
The good things about this print are that the layers are not visible from the outside. Further the side has quite a smooth surface. The biggest downside is that the top was not printed correctly.
More important the inside had a really fibrous structure as can be seen below.
A small part of the ‘chicken breast’ is tasted by one of the team members and as he responded: “You could really feel the fibers in your mouth. Further it was completely solid.” So luckily there were no parts where the mixture could be squeezed out. The food had no good taste yet. It was neutral and a little bit salt, but not too much.
For the second print we mainly changed the infill pattern. Now we used a concentric infill. The bottom part was really nice and fibrous. But in next layers strings melted together and bobbles appeared. Therefore we stopped the print.
Now we used again the concentric infill pattern. Now we changed the infill density from 98% to 90%. In this way we hoped the lines would clog less likely. Unfortunately this did not work out the way we hoped it would be and again clogs appeared. Probably the concentric pattern is not efficient for the printing of the organic meat.
This time we tried to print the chicken breast again with the cross linked infill, which we used for the first print. Now we used again the 90% infill density (same as print 3). The start went fine but the needle constipated after a while. First it was letting through much less material which caused material concentration at certain places and later on no material at all was extruded and the printer jammed. In this print we saw that the layers did stick to each other. This could be due to an overflow of saltwater added. Otherwise we must think of using a binder for the different layers.
In the incoming days we will go on experimenting with 3d printing. The modification will be during making the mixture. We will blend the mixture longer than in previous trials. This way we hope to get rid of lumps which cause the needle to clog.
We will as well try to add some flavour to the food. We will try to do this with mixing some ‘chicken flavour’ species with the salt water solution.
As we want to create an organic chicken breast, it is important to know the shape of it. The chicken breast will be 3d scanned in order to make it a 3d CAD model. Several 3D scanning methods are tested.
It does work but there is no fluent surface. A lot of repairing will be required in order to use this file for printing.
This is a device which makes a 3D photo. For acquiring a full 3D image several photo’s must be combined. The 3D photos made were not very accurate. Details were not visible. And the 3 dimensional forms were not correct some times. Besides there was no clear subscription of how to make the full 3D model with the programme.
Autodesk 123D Catch
This programme works the best for the chicken breast. After making a wide series of photos of the chicken breast the programme made a fluent 3D model of it.
In order to see the 3D model of the chicken please click the link below.
To find the best possible recipe for the 3D printing we decided to conduct more experiments, changing the different variables to see what works best. We closely documented these experiments for more understanding and reference.
- Create a fibrous lupine-based product with 30% less Alginate.
This might create a product that has a higher fluidity, making it better suitable to extrude from a syringe or even a needle.
- Instead of adding CaCl2 try adding CaSO4.
The instructions mentioned that both salts might work, we want to try to see if it is as effective.
- Experiment with different salt concentrations.
The salt solution is a key factor in solidifying the fibrous lupine-based product, perhaps using a higher concentration solution could create a sample with more structure and, or strength.
- Less Alginate
Instead of mixing 20g lupine with 10g Alginate, we used 7gr. The rest of the preparation were standard procedure, so the only difference was the Alginate. This resulted in a mixture that, as expected, had a higher fluidity and was less of a gelatin fluid. It also was a lot smoother and had fewer chunks.
We even managed to extrude it through a 0.5mm needle, creating the possibility to extrude very accurately. An extra benefit is that the salt solution can reach deeper into the product, creating an extruded line that is almost 100% solid, as can be seen below.
In the rest of the experiments we continued to use the solution with 7 gr Alginate, partly to reduce waste, and partly for convenience.
- CaSO4 instead of CaCl2
As can be seen in the picture down-right, the calcium-sulphate solution looks milky white, instead of the clear look we got with the calcium-chloride solution. To get an equivalent molar amount of CaSO4, we dissolved (111/136*5,4) = 4,4 grams in 135 mL of water. We tested this solution on a couple of extruded lines of the product mentioned in experiment 1, by dripping it on the product with a syringe. For comparison, we did the same with the calcium-chloride solution, on a different extruded line. Immediately it became apparent that the calcium-sulphate solution was a lot less effective than the calcium-chloride solution. The strands of Lupine product were still very fluid, and hardly had any bonding, in comparison to the strands we exposed to the calcium-chloride, which were bonded nicely, and had a certain strength.
- Different salt concentrations
To indefinitely rule out the use of the CaSO4 solution, we tried creating a highe
r concentrated solution. For this, we added another 5 grams of CaSO4 to the solution we already had, making it a solution with a concentration of approximately 9.4 gr / 135 mL. Apparently doing this
crossed the maximum solubility boundary, as a lot of the salt could not dissolve. We tried the solution on a new strand of the product, and the effectiveness hardly improved.
After ruling out the CaSO4 solution, it was time to experiment with different concentrations of the CaCl2 solution. We did this by adding, consecutively, a factor 0.5, 1, 2, 3 and 4 of the original 5.4 grams, to (5 times) 135 mL of water. After creating the different solutions, we created 5 different strands of the product. These strands where then used to drip the solutions on, giving us 5 different strands to test and compare. To test the strands, we used the criterion Strength. We measured the strength of the 5 strands using a digital force meter. Because the strands had a varying thickness, we tested the each of the 5 strengths in three different thicknesses (as they all showed a thick, medium thick, and a thin part).
Remark: Because the strands had a slightly different thickness, the measurements might be slightly inaccurate.
A table showing the strength’s for each thickness of the 5 different strands:
|Concentration [gr/135 mL]||2,7||5,4||10,8||16,2||21,6|
|Strength Thick [N]||0,5||1,6||2||2||2|
|Strength Medium [N]||0,9||0,6||1,2||1,8||1,7|
The following graph represents the data noted in the table above:
Less Alginate seems to be a good choice for further use, as it has a more fluid and less gelatin structure, it is more suitable to be extruded out of a smaller hole.
CaSO4 can be ruled out as a solution to solidify the product with, because it has been proven to be a lot less effective than CaCl2.
A higher concentration definitely seems to be a good choice for solidifying the product. The chart shows that there is a certain inaccuracy because of the varying strand thickness. Nevertheless, a trend can be deducted showing that a higher concentration results in a higher strength of the strands. What can also be concluded from the chart is that it is very likely that there is a maximum concentration that has an optimal result. Judging from the three categories (thick, medium and thin) it might be best to use a factor 3, or a concentration of 16,2 gr/135 mL in the solution.
The demand for meat replacers is growing, because more and more people get acquaintance with the negative sides of the meat production. For example the meat industry is more polluting than all cars together, meat is very inefficient to produce because of the huge amount of food needed to grow an animal and the wellbeing of animals is most times low in the meat industry. But currently meat replacers do not have the fiber structure which can be found in meat, which is found favourable. Therefore we will research for methods to 3d print organic meat replacers focused on the structure. In the future 3D food printers could be used at the home of the customer. Our specific focus in this project is to recreate a chicken breast shape and structure using organic materials.
In the first week of the project we mostly learned about the previous researches and findings. Together with the expert, George A. Krintiras, we started by testing two of the plant based ‘meat’ recipes to see the structure of the material and comparing the recipes.
First, we made the recipe that George was familiar with as he used it for his previous research, ‘Extrusion of plant-based meat using a modified Couette Cell’, namely: a mixture of Soy Protein Concentrate (SPC) and vital wheat Gluten. We followed the recipe precisely except for one major change. Instead of letting the mixture rest for 30 minutes to make the fiber structure even more pronounced in the final result, we only let it rest for a couple of minutes. The final result was that the structure of the mixture had dough-like properties and showed small scale fiber structures.
Next we decided to try another recipe: the lupine-based recipe, which was as well new for the expert. This process is described below.
- The lupine and SPI were mixed.
- H2O with a temperature of 50˚C was added to the Lupine/SPI mixture using a blender. This formed a honey-, vla-, cake batter- type mixture that still has lumps in it.
- After mixing it a second time, the mixture became stiffer.
- A can of CaCL2 water was being prepared at a temperature of 50 ˚C.
- The CaCL2 water was mixed with the SPI/Lupine with water mixture. It did not mix, but it made the powder mixture doughier. After mixing for a longer time the parts mixed but the structures/strings inside the material broke.
- We concluded that this was a result of not following the mixing times correctly. So we did the recipe again and made a new batch.
- We did everything as before, except for the times which were followed more accurately accordingly to the recipe.
- We tried mixing with a whisk instead of a mixer, to avoid lumps. This wasn’t an improvement however. There seemed to be more lumps in it than before. So we need to still find a solution for the lumps.
Different approaches are considered to the way the organic meat could be 3D printed. Finally we have three possible methods:
- Dual Syringe with a Static Mixer (one syringe with the powder made material and one with the salt water)
- Post Layer spray (making one layer of the powder material and next spraying the salt water over it.
- Casting based method (Using a malt to get the shape and printing the texture)
The method with the two syringes is tried. One syringe was filled with the water mix and another with the powder mixture. First we sprayed the powder mix and next we sprinkled some water on it. The salt water mixture created immediately a solid outer layer on the powder mixture.
We were impressed with the entire recipe and thrilled that one of our methods worked. Also when we started dissecting the final result, we clearly saw similar fiber structure to that of meat.
There are much more recipe possibilities. Next week new recipes will be tested. Next week we are also planning to look more to the 3D printing possibilities. As well an analysis of the chicken breast will be conducted to see what the fiber structure looks like in both a cooked and raw pieces.