(57) The apparatus comprises a horizontal drawer (3) with an opening (103) through which
the body of the tray to be packaged can pass, said tray with its edge (B) resting
on the upper, horizontal and flat side of an annular rim (1) which surrounds the said
opening and, around this rim, the drawer has a continuous annular channel (4), the
outer shoulder (104) of which has a height greater than that of the inner shoulder
and opens out on the upper side (203) of the said drawer which is thus at a height
greater than that of the said rim (1) and the upper edge (B) of the tray positioned
on the latter. Means are envisaged for extending over the upper side of the said drawer
with the tray inside it a length of barrier film (112) and foil-pressing means (17)
are envisaged for pressing, when operated, the film onto the upper side of the drawer
(3), at a due distance from the outer shoulder of the said annular channel (4), all
of which so as to form a packaging chamber (C) which is substantially closed with
respect to the exterior and is defined at the bottom by the tray (V), at the top by
the said barrier film and along the sides by the said annular channel (4) which has
along at least one side one or more openings (7) through which, upon operation, the
modified atmosphere may be blown into the said chamber (C), while on the opposite
side of the said annular channel (4) one or more discharge openings (10) are provided,
through which openings firstly the air contained inside the tray, pushed by the front
edge of the incoming modified atmosphere, is able to pass out and also part of the
said modified atmosphere can pass out. Once packaging of the said chamber has been
completed, a heat-welding plate (21) is lowered and pushed onto the edge (B) of the
tray so as to heat-weld onto the latter the said closing film (112) and trap in the
packaging thus formed the quantity of modified atmosphere useful for conserving the
product, following which, after the heat-welding, cutting means (27) are activated
and separate from the film the closed tray.
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