Hello everyone!
We have a highly viscous homogenate. It looks like a juice containing pulp, but we need to cold(!)-sterilize it. Of course, any "pulp" must be eliminated and only the "juice" will be used.
Of course, it instantly blocks any conventional 0.2 μl filter.
Because of the viscosity, we can't clarify it by centrifugation before filtration (maybe it's possible, but it will take 10 repetitive cycles or more)
I found hollow fiber filtration modules in google, but they seem to be designed for industrial filtration of hundreds of liters of juice.
Can anyone suggest a relatively cheap disposable unit for this type of sterilization?
Thank you
One simple suggestion is to use low-boiling -point inert solvent to reduce the viscosity, do the filtration and evaporate the added solvent. Too simple but working for some polymermric solution.
Geed Luck
good idea, thank you, but no, no, no ... nothing can be added to this "juice".
I even hesitate to use a filter paper to pre-filter it, because I have never seen filter paper without endotoxin (we have to avoid all possible source of endotoxin contamination, and no question to any solvent)
Another alternative is to use "Dialysis sacks". It might take a bit long, but may work for your sample
What are the viscosity and undissolved solids content? What quantity do you want to process - just laboratory amounts, or more? Do you want to sterilize, or just pasteurize?
A wide diameter (at least 3 mm) hollow fiber may work (for example, https://www.kochmembrane.com/Products/Hollow-Fiber-Membranes/ROMICON®-SERIES). If you need to sterilize rather than just pasteurize, ask the supplier if their product will do that. Some manufacturers offer autoclavable modules. Understand that membrane products such as these will remove the pulp as well as microorganisms.
Tubular membranes are designed for higher viscosity and solids levels (for example, https://www.kochmembrane.com/Products/Tubular-Membranes/SUPER-COR-and-SUPER-G-Modules). Again ask the supplier if their product will sterilize if that is needed. Remember that pulp will also be removed.
You might also consider pulsed electric fields (https://www.newfoodmagazine.com/article/1594/pulsed-electric-field-processing-of-foods), high pressure (https://www.avure-hpp-foods.com/?gclid=EAIaIQobChMIv_iXu6Db3AIVBrbACh2SpA-REAAYASAAEgLm_PD_BwE), or supercritical carbon dioxide (https://pdfs.semanticscholar.org/e101/6564c826b33c57eb1d9da8a94aa6221dd341.pdf. These are promoted primarily for pasteurization rather than sterilization, but ask the equipment suppliers if you really need the latter.
Hope this helps,
Alan
Thank you for your reply.
I can only approximate the viscosity and I can compare it to the egg white, for example.
The solid content is high. I think 15% of the volume is taken by the solids.
We must proceed to 0.5 - 1 L in one shot. But maybe several times. For me, it's at the laboratory scale.
The filtrate should be sterile (0.2 um pore size). Thank you for the recommendation of hollow fiber of large diameter. I will try to find something like ROMICON (they do not offer a pore size of 0.2 um)
Their 500K module might work for you, but it may not be autoclavable.
Ultrafiltration membranes may serve the purpose. There are small modules for laboratory scale experiments. And the pore size can be selected.
Thank you Lian
But I'm looking for a micro (0.2 um) and not an ultrafiltration. And, unfortunately, any membrane in the dead-end filtration system will immediately be blocked. I think that only a recommended above cross-flow or similar approach could be used
Lëonid Volkov :
You're right. We tried a anti-fouling membrane for protein separation by immobilized enzyme. It can improve the flux, but the enzyme acts with the protein too. And the modified membrane cannot last very long. As your sample is so sticky, it is difficult to deal with.