I recently called the Star-K to ask if we could use fruit concentrates without a kosher sign, and they explain that although technically it would be OK, we do need a kosher sign as the processing plant might also be processing grape products, which do need a reliable hechsher. So the answer ended up being no.
So y’all I found a fabulous source for these wonderful fruit concentrates: Dynamic Health It sounds very pricey but a little goes a very long way. I use them constatnly in my salad dressings, smoothies, sauces etc…. Beside being absolutely delicious, they are nutritional powerhouses! More about them in my cookbook: Working hard on it, it will come out beginning of next year I”YH!