Nutrient saturated fat to total fat ratio

[aleene]

Is your feature request related to a problem? Please describe.
The calculation of the NutriScore is now very opaque. Part of the solution is to show which nutrients are used in the calculation. For the fats category this also involves the saturated fat to total fat ratio. This now not displayed as it is not on the package.

Describe the solution you'd like
Add it to the nutrients list, similar to the salt/sodium solution.

Describe alternatives you've considered
none

Additional context
none

[stephanegigandet]

We should not add it to the nutrient form in the product edit form. We could add it when we display the nutrition facts table, but it's really something internal to the Nutri-Score, like the positive points and negative points. I think it would be more interesting to show it when we explain the Nutri-Score computation (which we still have to do).