An in-house made product is not regulated by the FDA.
FDA regulates all foods and food ingredients introduced into or offered for sale in interstate commerce, with the exception of meat, poultry, and certain processed egg products regulated by the U.S. Department of Agriculture (USDA).
Examples of Food businesses NOT regulated by FDA:
Retail food establishments (i.e. grocery stores, restaurants, cafeterias, and food trucks), which are regulated by state and local governments.
(Bolding added) From FDA
If your goal is to have the store looked at so they change their ways, you would have a better chance with the California Health Department. In this case, the grocery store is a retail food establishment*, like a cafe. I am taking your assumption as correct that the juice is being made in the store.
Retail Food Facilities (e.g. restaurants, food trucks, cafés, etc.)
The local environmental health department (EHD) is responsible for the initial investigation of consumer complaints regarding foods served or sold at retail food facilities (e.g. restaurants, food trucks, cafés, etc.).
To file a consumer complaint regarding a retail food facility, click here to contact the EHD (PDF).
From California Public Health
If your goal is to "cash in", you are on your own.
*Edit: I mean that they are regulated like a cafe for the part of the store that makes and sells its own food.