The flavor often described when there is excess sodium bicarbonate is alkaline. A chalkiness on the teeth, and or a burning sensation on the palette.
If you have a pH meter you can grind up a sample of the product and mix with distilled water to get a reading and an idea of what to adjust.
This can also be tested in baked goods using an indicator solution used in the self rising flour and cornmeal muffin/bread mix production. The solution changes color based on the pH of the product. More yellow is acid base, orange is neutral, fuschia is alkaline, and the variations in between. Innophos is the company that makes the concentrate, and it must be diluted 9:1 with distilled water. Just a few drops with a pipette on the crumb of the product provides the best indication. Innophos can provide a chart with color indication examples that approximate pH.
Here is a link to the Innophos website with information on the solution. It can be ordered from them directly. https://www.innophos.com/products/indicator-solution