Is lemon juice permitted?
The ingredient list is questionable. Concentrates are always on the questionable list, plus this has added ingredients. You're safer going with a company that uses lemons not from concentrate, with a clean ingredient list, such as this one: https://www.wellbees.com/organic-lemon-juice.html.
and what about "kosher select lemon juice"?
Was an error with the photo, see it here, the ingredients are "natural lemon juice, antioxidant potassium metabisulfite."