Hello, Yes it is possible that gas may originate from the esophagus in achalasia, due to undescended food. However, the cause for the pressure feeling in the chest is not known and fully understood, therefore, whether the opening of LES is the reason for the relief felt after burps is not very clear. It is very possible, though, that the pressure created by the burps on the walls of the food pipe, may also force the LES to open, thus allowing the remaining food from the esophagus to go to the stomach, by emptying the former. Beer may cause frequent burping, but it may also cause heartburn, which in turn may worsen the symptoms. I hope my answer was helpful. All the best.