The present invention regards a package for food products comprising a flexible container having a first wall and a second wall opposite each other and peripherally sealed along at least the respective side edges, a space inside said walls containing, optionally in sterile conditions, a food product, and a gusset element extended between the upper edges of said first wall and of said second wall, said gusset element defining a pocket turned towards the interior of said flexible container, characterized in that it comprises an opening and closing device housed in said pocket and constrained to said flexible container, said opening and closing device comprising a pourer body associated with an opening and closing cap, and cutting means suitable to perforate said flexible container at the time of the first opening of said packaging. The invention also regards a method for packaging a food product, in particular in sterile conditions, in a package of the aforesaid type, a flexible container for a package of the aforesaid type as well as a method for producing such container.