GB2025894A

GB2025894A - Mushroom spawn bag

Info

Publication number: GB2025894A
Application number: GB7920348A
Authority: GB
Original assignee: PERRIER HEINZ SA
Current assignee: PERRIER HEINZ SA
Priority date: 1978-06-16
Filing date: 1979-06-12
Publication date: 1980-01-30
Also published as: FR2428583A1; FR2428583B1; CA1133411A; NL7904646A; GB2025894B

Abstract

A sterilizable bag for use in the production of mushroom spawn is made of plastics sheet material and has, located between two perforated areas (2,3) of the plastics sheet material, a panel (7) of microporous sheet material having pores of size less than 0.5 mu m. This panel (7) is edge-welded (8) to the two perforated areas (2,3) and acts as a bacterial filter. <IMAGE>

Description

SPECIFICATION Mushroom spawn bag This invention relates to sterilizable bags for use in the production of mushroom spawn.

The particular use of such bags is for mycelium growing medium which is usually innoculated with mycelium and fed into the bag. The bag is then sealed and stored under incubating conditions for growth of the mycelium resulting in a bag of mushroom spawn which can be shipped directly for use by the mushroom grower and is a convenient package for sale. Innoculation may be carried out with the growing medium already in the bag.

In United Kingdom Patent No. 1,520,51 1 there is described a sterilizable bag having at least a panel of microporous plastics sheet material which is a good bacterial filter and which permits passage of oxygen and carbon dioxide. Such a bag may have a wall of transparent plastics sheet material which is perforated and is lined with a panel of microporous plastics sheet material.

It is a main object of the present invention to provide an improved sterilizable bag having increased strength and which permits the use of a variety of different microporous sheet materials as the bacterial filter.

According to the invention there is provided a sterilizable bag of plastics sheet material for use in the production of mushroom spawn, which bag has a panel of microporous sheet material which has pores of size less than 0.5 ym and which is a bacterial filter, characterised in that the microporous panel is located between and has its edges welded to, two perforated areas of the plastics sheet material.

In a preferred embodiment the bag is formed from a sheet of the plastics sheet material which has said perforated areas at opposite sides, by folding the sheet so that the perforated areas overlap, inserting the microporous panel between the overlapping perforated areas, and peripherally welding together the triple layer so formed, and then welding one end of the bag.

To isolate the spaces within the triple layer from the main part of the bag the edges of the triple layer may be welded together along the open end of the bag.

Preferably the plastics sheet material is transparent or translucent polypropylene, nylon or polyethylene.

The microporous sheet material may be microporous polypropylene or polyethylene.

Alternatively the microporous sheet material is a microporous paper composite including polymeric fibres to facilitate welding to the plastics sheet material.

In order that the invention may be more clearly understood an embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a plan view of a sterilizable bag according to the invention looking down on the side of the bag which embodies a bacterial filter, Figure 2 is a section on line Il-Il of Figure 1 indicating how the bag will appear when full of mycelium growing medium, and Figure 3 is a detailed view of part of Figure 2, showing the bacterial filter construction in more detail.

The sterilizable bag illustrated in the drawings is formed from a sheet of translucent or transparent plastics material for example polyethylene, polypropylene or nylon sheet of thickness in the range 50 to 125 Mm. The sheet 1 has perforated areas 2 and 3 at opposite sides which perforated areas are of substantially equal width corresponding to the width of the bacterial filter to be formed in one wall of the bag. When the bag is full of mycelium-growing material indicated at 4 in Figure 2, the bag lies on a shelf 5 with the bacterial filter uppermost during incubation of mycelium.

The perforations in the areas 2 and 3, which perforations are indicated at 6 are of pin-hole size produced by mechanical perforation of the areas of the sheet. The perforations aliow free passage fair.

The sheet 1 is folded over to tubular form so that the perforated areas 2 and 3 overlap and a panel-7 of microporous sheet material is inserted between the overlapping perforated areas 2 and 3 to form a triple layer.

The microporous polypropylene of thickness in the range 58 to 125 cm and having pores of size less than 0.5 ,um so that the material is a good bacterial filter, and bacteria do not enter the bag during growth of the mycelium although oxygen can be drawn into the bag through the microporous panel 7 and carbon dioxide resulting from the growth of mycelium in the growing medium can be expelled.

In a preferred embodiment the panel 7 of microporous sheet material is of a microporous paper composite including polymeric fibres which impart weld strength to the paper composite and facilitate welding of the edges of the microporous sheet material to the plastics sheet material. The paper composite has pores of size less than 0.5 ,um.

In this preferred embodiment the plastics sheet material 1 is polypropylene and the microporous panel is a paper composite containing polypropylene fibres so that the finished bag can be sterilizedpy heat.

The microporous panel 7 is inserted between the overlapping perforated areas as just described and the triple layer thus formed is welded peripherally as indicated at 8 along the length of the bag and one end of the bag is welded as indicated at 9 to close that end and form the bottom of the bag. The triple layer comprising the overlapping perforated areas 2 and 3 and the bacterial filter panel 7 may also be welded along the Qpen end of the bag as indicated at 10 in Figure 1 in order to close up that end of the triple layer while leaving the end of the bag open, in order to ensure that when the bag is filled with growing medium the growing medium does not enter into the layer and interfere with the bacterial filter.

In another embodiment when the sheet 1 of plastics material is polyethylene, the panel 7 of paper composite may contain polyethylene fibres and the bag can be sterilized by radiation.

The provision of polymeric fibres in the paper composite ensures a good weld around the periphery of the panel 7 so that the bag is safely sealed and the bacterial filter is protected by the perforated areas 2 and 3, either from damage by the growing medium in the bag or from the outside of the bag. This protected bacterial filter thus forms an integral part of the bag structure.

Claims

1. A sterilizable bag of plastics sheet material for use in the production of mushroom spawn, which bag has a panel of microporous sheet material which has pores of size less than 0.5 jum and is a bacterial filter, characterised in that the microporous panel is located between and has its edges welded to, two perforated areas of the plastics sheet material.

2. A bag according to Claim 1, characterised in that the bag is formed from a sheet of the plastics sheet material which has said perforated areas at opposite sides, by folding the sheet so that the perforated areas overlap, inserting the microporous panel between the overlapping perforated areas, and peripherally welding together the triple layer so formed and then welding one end of the bag.

3. A bag according to Claim 2, characterised in that the edges of the triple layer are welded together along the open end of the bag.

4. A bag according to any one of Claims 1 to 3, characterised in that the plastics sheet material is transparent or translucent polypropylene, nylon or polyethylene.

5. A bag according to any one of Claims 1 to 4, characterised in that the microporous sheet material is microporous polypropylene or polyethylene.

6. A bag according to any one of Claims 1 to 4, characterised in that the microporous sheet material is a microporous paper composite including polymeric fibres to facilitate welding to the plastics sheet material.

7. A sterilizable bag of plastics sheet material for use in the production of mushroom spawn, substantially as herein described with reference to the accompanying drawings.