Is sourdough starter made from barley or whole wheat flour mixed with water and dates, and left to ferment, considered permissible (halal) and permissible to use?

It is not possible to prove that a certain product contains pork fat except with a sharia-compliant evidence or widespread news that makes its truth highly probable. Additives in food and medicine that originate from impure or unlawful sources become permissible by sharia law through transformation (istiḥāla) or consumption (istihlāk). Natural yeast has been used since ancient times without objection.