What is meant by "Istihalah" (transformation) in alcohol, and how can ordinary people assess whether it is intoxicating or not to determine its impurity, considering the scientific terms written on product labels?

Transformation (Istihala) means the change of a substance into another, entirely different substance. The transformation of alcohol means the removal of its name as an intoxicant (khamr (definition)) and the loss of its intoxicating effect, such that it no longer causes intoxication even if consumed in large quantities. If it still intoxicates when consumed in large quantities, then it remains khamr and is forbidden. Transformation is achieved by treating the alcohol until its intoxicating effect is completely removed, and the reference for this is the specialists in the field. If there is doubt about whether transformation has occurred, the default assumption is that the impurity remains until certainty of purity and the occurrence of transformation are established.