What is the plan of experience that I had to choose?

[#1]

As part of a study on a cake recipe, I am trying to find out the effect of an ingredient on the water activity of the finished product (measured parameter which is fixed or belongs to an interval of values). I am not limited by constraints to set the limits of the experimental plan. I wanted to know in this case how I can make an experiment plan.
The objective is to determine the quantity of this ingredient which allows me to obtain a precise value of water activity while having the possibility of varying the other compounds which constitute the recipe.

[#2]

Hello @Syrine ,

In order to better help you, can you give more details on:
- The number of factors and their types (continuous/discrete numeric, categorical, ...)
- Possible dependencies between factors: can the ingredients be varied independently or do some of them have to have a constant total sum for example?
- What is "water activity"? How is it measured? Is this the only answer? You mention a "fixed or within a range" measured parameter, I'm not sure I understand.
- Have you already carried out preliminary experiments with these factors, which could make it possible to create a plan taking this information into account?
- Are you only interested in the effect of this ingredient on the response? Do the other ingredients in the recipe necessarily have to be varied in their levels?

Here are some questions that will help you see more clearly and help you more effectively.

[#3]

Thank you for your reply,
In fact the variables are numerical variables (amount in grams). In fact there are variables which are dependent and others independent. In reality I wanted to substitute an ingredient in the reference recipe with another element but by testing several I will vary the quantity of this substitute until I have the same effect as that in the reference recipe. This compound has an effect on the water activity (the available or free water in the food and which could cause the growth of micro-organisms). The substitute has a sweetening power is therefore by increasing its quantity, we should decrease a quantity of sugar, it is here that the dependence between the variables is presented, otherwise for the other variables, they are independent.
For the water activity response, we aim for a value but we can say that it is an interval.
The measurement is made using a measuring device
I did not do any experiments beforehand

And thank you

[#4]

Good evening @Syrine ,

It remains difficult to help you without more information on the system to be studied.

Is it possible to describe it more, even if it means anonymizing/coding the name of the ingredients? Specify how many and which are dependent on each other (eg ingredients 1, 2 and 3)?

• How many mixing variables (variables dependent on each other whose total quantity is fixed) do you have?
• How many independent variables do you have? For each, what is its type (continuous, categorical, etc.), its range of values (high and low for continuous numerical factors, or the number of levels for categorical factors)?
• Is the ingredient to be substituted part of these mixing variables or is it an additional independent variable (whose quantity can be freely chosen without impacting the quantity of other ingredients)?
• Are there several possible substitutes for this ingredient that you wish to test (alternative A, B, C, ... : categorical factor with a number of levels/alternatives?) ?
• Do you have an experimental budget (number of experiments) limit that you would like not to exceed? 

Since your plan seems to mix mixing factors with continuous factors, it seems appropriate to use the "Optimal Plans" platform, as it will give you more freedom to define and mix different types of factors and choose the model and the terms to be included, as well as some flexibility in choosing the number of experiments.

For the subject of the target response value, you will anyway have in the analysis of your plan water activity predictions, with their confidence interval. Depending on the type of plan, the variability of the response, the number of experiments, the level of confidence (95% for example), ... this interval will be more or less large, and you will thus be able to verify that the predicted optimum value (and its confidence interval) for a certain combination of values of your factors corresponds to your target and that the deviation from the confidence interval is sufficient for your needs.

Edit: If you want more information or training on Design of Experiments or if this topic is your first Design of Experiments, I highly recommend the following free JMP trainings:

- Introduction to design of experiments: Design of Experiments Intro Kit | Getting Started with JMP

- Statistical Thinking for Industrial Problem Solving (a module is dedicated to DoE): Statistical Thinking (STIPS) - Free Online Statistics Course | JMP

- Other resources or examples: Design of Experiments | JMP

This content can allow you to build your skills on experimental plans, as well as to be able to describe more precisely the plan you want to carry out.

[#5]

Hello,

There are also simulation software that use databases of hundreds of ingredients, additives, .. and which will calculate the aw.

= another search strategy.

cordially

[#6]

Thanks for your reply,
Can you please send me the link of simulation software? Maybe that could help me.

Best regards

[#7]

Hello @Francoise and @Syrine ,

Indeed, if models already exist, this approach can be complementary to the experimental design, by building an experimental design adapted to the problem, and using values resulting from these simulations as an answer (having checked beforehand the scope and the hypotheses of these models if possible, for example checking whether the models/predictions take into account mixtures with a variable number of compounds, or only binary/tertiary mixtures).

This combination of techniques (simulations and experimental plan) can make it possible to quickly identify a formulation area of interest (by carrying out the minimum number of simulations for a maximum gain in information on the experimental field, rather than a "random" search by iterations), and to validate its relevance and robustness by a few experiments.

While doing some research, I came across the Aw Designer software (paid). 

• Here is a presentation found: Aw Designer water activity calculation software (slideshare.net)
• And the official website: Aw designer – Adria, agri-food expertise center

@Francoise , did the option I gave you for your ellipse topic on the Community solve your problem: Re: graph with ellipse - JMP User Community

[#8]

bjr,  

il y a eu bcp de modélisation faite, surtout dans l'application de la microbiologie prévisionnelle., c à d pour voir l'impact de l'aw sur le développement des bactéries, en particulier les pathogènes.

la première étape du plan d'expérience passe par le recueil de l'état de l'art et des connaissances, donc par une bibliographie entre autre. Aujourd'hui, avec internet, vous pouvez trouver bcp d'informations (articles scientifiques,  livres, présentations pdf ou pwp,...)

cdlt

[#9]

Hello
I did research on the ingredients to use in the recipe but not on the prediction of aw, because it is according to the ingredients that I will put, it can change.

[#10]

Hello
If I understood correctly what you mean, it is that with the aw software I can eliminate several experiments resulting from plan of experiment. But what I didn't understand is how to verify the model's prediction.
I've never done an experiment plan other than the central composite plan so I don't know too much about the realization of the other plans.

Best regards