My concept is to create a bilayer protective wall for cells. CMC is anionic materia and maltodextrin is cationic material, thus negative charge of gram-positive cells will interact with maltodextrin to form first protective layer and CMC will further interact with maltodextrin to form second layer. May I know is my concept correct?

cmc is anionic but maltodextrin is neutral. The cationic modification is missing!

Shi Yiing, just a quick few queries back to you. 

• what is your control sample? are they also centrifuged? As there are often many losses with the centrifugation step.
• Additionally how do you measure the survival of your cells? 
• do you wash the cells after you have stirred them in the CMC/malto solution?

Dear Titus Sobisch, 

Can I use milk protein as cationic modication? 

Thanks. 

Dear Krishnaa Mahbubani, 

1. Non-capsulated cells will be my control sample. Yes, it was centrifuged as well. 

2. Measure survival of cells through CFU count

3. Yes, I washed the cells using PBS after stirred with CMC/malto. 

Thanks for your advice. 

as 'natural' cationic compound there is chitosan. Do not know whether this fits your need. Further you might use cationically modified starch.

You may read the following works:

- Corbo, M. R., Bevilacqua, A., Gallo, M., Speranza, B., & Sinigaglia, M. (2013). Immobilization and microencapsulation of Lactobacillus plantarum: Performances and “in vivo” applications. Innovative Food Science & Emerging Technologies, 18, 196-201.

- Gallo, M., Bevilacqua, A., Speranza, B., Sinigaglia, M., & Corbo, M. R. (2014). Alginate beads and apple pieces as carriers for Saccharomyces cerevisiae var. boulardii, as representative of yeast functional starter cultures. International Journal of Food Science & Technology.

Dear Titus Sobisch,

• Can I directly use cationic compound for microencapsulation without the presence of anionic compound and cationic modified starch? 
• Do you think the protective layer will become stronger if both cationic and anionic compound present? Cationic compound will interact with gram-positive cell wall and antionic compound will further interact with cationic compund to form bilayer of protection?

Thanks for your advice. 

Dear Shi,

I have no personal experience with microencapsulation, so this is only theoretical arguing. I do not know how viability will be influenced. Can it be that due to encapsulation viability test will always show lower values that a fresh product? I mean encapsulated material cannot work instantaneously.

Yes, I would expect layers by oppositely charged polymers would be stronger.

For CMC there are products with different degree of carboxymethylation. This maybe also an option for optimization.

I suggest you try using starch (high amylose corn starch, resistant starch or lyophilized corn starch). the theoretical concept is that since you are encapsulating microorganisms, nature made materials should work better. You can check these literature for details of the extrusion and emulsification methods of encapsulation King AH (1995). Encapsulation of Food ingredients: a review of

available technology, focusing on hydrocolloids. In

Encapsulation and controlled release of food ingredients, pp.

213-220, S.J. Risch and GA. Reineccius (Eds.). Washington DC.

American Chemical Society

Lacroix C, Paquin C, Arnaud JP (1990). Batch fermentation with

entrapped cells of Lactobacillus casei: optimization f the rheological

properties of the entrapment gel matrix. Applied Microbiology and Biotechnology. 32: 403-408

Thanks for all the suggestions. Do you think spray dry process must be perform to complete the microencapsulation? I meant, do you think the cells will be better encapsulate if perform spray drying after mix with the encapsulated agents? Thanks