Abstract: Top or bottom structure for a paper container with a flat type top or bottom having opposed outside bottom plates formed of board paper having thermal adhesive plastic layers on both front and back surfaces and opposed inside bottom plates having folding lines of isosceles triangular shape. A first end piece (10) extending from a first outside bottom plate (6), disposed at the outermost side during assembling and shaping, extends further than other end pieces (11, 12, 13). A second end piece (12) of a second outside bottom plate (8) is formed in a tongue shape by first and second cutouts at right and left sides, which first and second cutouts are equal in depth to adjacent additional cutouts extending 2/5 of the length along the inside bottom plates. Third and fourth cutouts (26, 27) are formed on the second outside bottom plate at the right and left sides of the second end piece, and an assembling and folding line (30) is formed between the points of greatest cutting depth of said third and fourth cutouts.

Abstract: Packing material for foodstuff is sterilized with hydrogen peroxide. Residual hydrogen peroxide on the material is then removed by contacting the material with an anti-oxidant or reducing agent which is an approved food additive. L-ascorbic acid is preferred.