For those who require very specific media, Flystuff offer the separate ingredients. This allows for individual customisation for your facility.

Propionic acid, sodium salt is a safe, simple and economical alternative to propionic acid as a fly food preservative. This odourless white powder is easily water soluble and is not considered a hazardous material. No loss of performance has been reported by the kitchens who have changed to the salt form of propionic acid, making propionic acid, sodium salt the best overall decision in food production.

To make 1L of 1M propionic acid from propionic acid, sodium salt, dissolve 96.06g of propionic acid salt (sodium propionate) in 500mL of distilled water to make 2M sodium propionate solution. Add 500mL 2M HCl to 2M sodium propionate solution to make 1L.