If one is a pastry chef and every time he makes a pastry he has to taste it, and if that pastry has a non-halal gelatin or pork gelatin is it permissible for him to taste that pastry or not ?

He can taste it from the part which does not touch the haram parts. (If the portion he is tasting does not contain harm parts, then it is allowed, otherwise, it is harm, if he is going to swallow it.