Certainly.

I have another question: Let's say, there are 4 parameters in my optimization experiment, one of them is duration, the other 3 are compounds (in concentration). Aims is to obtain reasonable duration and optimal concentration levels for the compounds. Is it sound logical? (The reason I ask this because many papers reported only on the optimization of concentrations of compounds at fixed time.) Thank you.

Based on the type of experiment, the duration can be consider as key parameter for optimization. If duration is your key and critical parameter or it score high in FMEA then u can consider it has key point.

Ex: Fermentation time, Protein refolding time, Enzyme digestion,incubation time etc.

Thanks Kishore. May I know what is FMEA, and how do I calculate the score?

failure mode effective analysis, based on your lab experiments with different process parameters, we can optimize the key control parameter with FMEA.

I feel you can certainly take time as your parameter and build up your experimental design. But, I have a question , as Kishore stated to check to check the score of a parameter by FEMA, but whether such score analysis is built up with the software or you do manually?

http://www.fda.gov/downloads/Drugs/.../Guidances/ucm073511.pdf

gothrough this article, you will get brief idea.

After doing some literature reviews, I find that 'time' can be taken as one of the parameters because in some batch experiments/processes, time needs to be optimized as well rather than fix it. Referring to the score check of parameter by FMEA, I am not sure how does it work? Perhaps Kishore could share with us how it is conducted... Thanks =)

I think time is one of the most important parameters to take into account at least in the bacterial species that I've been studing (Pseudomonas, Bacillus, Pantoea..). However, probably is more or less important according to your final objective. If you are looking to reach high cells density, the time is lesser important than if you are looking for metabolites production

Yes, time has its importance as a variable/parameter.

Hi! Teck Nam,

I don't know how much you have succeeded in optimizing your parameters. I wanna suggest that there are many statistical softwares that you can use for optimization of all your culture parameters including time as one of your factors, for ex-Minitab 16, Unscrambler, Systat, Statistica. You can try any of them. All the best. Thanks.

Hi Puja. I am conducting my optimization studies with the aid of a software called DesignExpert, which is very much like Minitab.

Hi! Well, all the best thn for the success of ur expt.

In my thesis I optimized product quality while satisfying safety constraints in canned food. This is a batch process and I had to consider final time one of my optimization variables. Good like with your experiments.

Certainly. Every step of the methodology have to be accounted for.

Hi Teck! Definitely. Incubation period is one of the most important parameters. If you are dealing with any sort of production, definitely incubation time has to be accounted for. In case, if you are dealing with processes such s bioconversions or biodegradation, you may ignore it in the first part and follow it up with a kinetic/time dependent study. Otherwise, a prior time dependent study may even be hndy to analyze the entire process at one time point. Hope that helps!

Good Luck!!