People pose for photos at the Frankfurt Apple Wine Festival in Frankfurt, Germany, on Aug. 9, 2019. The Frankfurt Apple Wine Festival is held here from Aug. 9 to 18. Frankfurt's apple wine culture has played an important role in the city's social life for hundreds of years. (Xinhua/Lu Yang)

Apple wine is filled into the "bembel", a blue-grey earthenware jug in which apple wine is traditionally served, at the Frankfurt Apple Wine Festival in Frankfurt, Germany, on Aug. 9, 2019. The Frankfurt Apple Wine Festival is held here from Aug. 9 to 18. Frankfurt's apple wine culture has played an important role in the city's social life for hundreds of years. (Xinhua/Lu Yang)

People visit the Frankfurt Apple Wine Festival in Frankfurt, Germany, on Aug. 9, 2019. The Frankfurt Apple Wine Festival is held here from Aug. 9 to 18. Frankfurt's apple wine culture has played an important role in the city's social life for hundreds of years. (Xinhua/Lu Yang)

People enjoy apple wine at the Frankfurt Apple Wine Festival in Frankfurt, Germany, on Aug. 9, 2019. The Frankfurt Apple Wine Festival is held here from Aug. 9 to 18. Frankfurt's apple wine culture has played an important role in the city's social life for hundreds of years. (Xinhua/Lu Yang)

A giant model of the "bembel", a blue-grey earthenware jug in which apple wine is traditionally served, is seen at the Frankfurt Apple Wine Festival in Frankfurt, Germany, on Aug. 9, 2019. The Frankfurt Apple Wine Festival is held here from Aug. 9 to 18. Frankfurt's apple wine culture has played an important role in the city's social life for hundreds of years. (Xinhua/Lu Yang)

People visit the Frankfurt Apple Wine Festival in Frankfurt, Germany, on Aug. 9, 2019. The Frankfurt Apple Wine Festival is held here from Aug. 9 to 18. Frankfurt's apple wine culture has played an important role in the city's social life for hundreds of years. (Xinhua/Lu Yang)