Information on creating nutrition labels

I recently switch companies, going from frozen seafood (module 11) to RTE imitation seafood (module 9)
At the new company, we apply nutrition labels on product. Is there a website where I can learn more about creating nutrition labels?
We do use an outside lab to create them, but for minor ingredient changes, they are changed inhouse. 
I'd like to be more knowledgeable about the process.

Also, if a label states "no preseratives" but uses trace amounts of ingredients, such as ascorbic acid, what are the requirements there?
Again, if there is a website or link, that would be great.

Thanks!

The actual regulations regarding nutritional info and labeling in general are nausiating to read.    I have pasted a link below to a simple label guidance (it has some nutritional panel info)  that has reference to the regulations.  I believe a new one is suppose to be out soon.    

When I created nutritional panels I used reputable software such as ESHA genesis.   It helps ensure you are complaint.   you still have to be aware of colors, sizes, orientation, placement, etc.  

Exemptions from labeling are covered in 21 cfr 101.100.    I don't think what you are doing is Ok as they would appear to have a "functional effect".  

In general labels can not be misleading.   claiming no preservatives when preservatives are present would be misleading / misbranding

There are also a bunch of seafood specific labeling rules that I am not super knowledgeable on.   

My best advice would be to start studying the regulation and / or find a comprehensive labeling class (sorry I don't know one of them either).  

https://www.fda.gov/.../81606/download

21 CFR 101 is indeed mind-numbing, but the labeling guide that is posted to the FDA's website has not yet been updated to reflect the nutrition labeling changes that went into effect this year.  I strongly suggest that you rely on the regulation itself rather than the guidance document.  

If your company belongs to an industry association such as National Fisheries Institute, check with their technical experts.  These groups may occasionally also provide classes on labeling.  There are also consultants (such as me!) who can help you navigate the complexities of the labeling regulations, albeit for a fee .