保持密封 meaning in Chinese

keetight

Moon cakes should be properly sealed and kept clean . they should also be consumed before the expiry date
此外，月饼必须保持密封和清洁，并须于食用期限前进食。
Reliable seal : the squeezing and cutting action of eccentric for sphere and valve seat on opening and closing can remove scale and adhesive matters on sealing suface effectively to keep tight seal
蜜蜂可靠：启、闭时，球面与阀座经偏心的挤切作用，能有效切除密封面上的结垢及粘连物，保持密封严紧。