JP7439360B2 - Multilayer paper for food and beverages - Google Patents

Description

The present invention relates to multilayer paper for food and beverages.

The slurry (aqueous dispersion) used to make paper contains nutrients such as pulp and additives, and is an environment suitable for the growth of microorganisms. When microorganisms proliferate in the slurry, they form a biofilm called slime, which causes a problem of quality deterioration due to contamination with foreign substances derived from this slime. Slime control agents and disinfectants are used to suppress the growth of microorganisms in slurry (Patent Documents 1 and 2).

Food and beverage paper that comes into contact with food and beverages, etc., is required to meet very high food hygiene standards, for example, it is required that the number of bacteria in the paper be kept below a certain number. Food and beverage paper is made using the slime control agents and disinfectants mentioned above at high concentrations, but it is difficult to reduce the number of bacteria in the paper to zero, and although the number is below the standard value, microorganisms may still be mixed in. There are cases where this happens.

When the present inventors investigated food and beverage paper containing microorganisms, it was found that most of the microorganisms were spore-forming bacteria. Spore-forming bacteria become dormant by turning into spores under high stress, and when the environment becomes suitable for growth, they germinate from the spores and become active again. Spore bacteria in the spore state have excellent chemical resistance, heat resistance, etc., and can survive in harsh environments. It is thought that by turning into spores, the spore-forming bacteria withstood exposure to disinfectants during the paper-making process and the high heat during drying, and became mixed into paper for food and beverages.

As a result of further investigation, it was found that many spore bacteria were present in the aqueous dispersion of interlayer starch during lamination. As spore bacteria are widely distributed in the soil, they adhere to raw materials such as corn, potatoes, and cassava, and survive the processing process from these raw materials into papermaking starch in a spore state and become mixed into interlayer starch. It is presumed that he did. On the other hand, although internally added starch and externally added starch are also used during paper making, spore-forming bacteria did not inhabit the aqueous dispersion of internally added starch and externally added starch. This is because internally added starch and externally added starch are made into paste by the steaming process, and the spore-forming bacteria are also sterilized by exposing them to high temperatures of approximately 130°C in this steaming process, whereas intercalated starch is This is presumed to be due to the fact that there is no process that can sterilize spore bacteria.

Japanese Patent Application Publication No. 2002-294591 Japanese Patent Application Publication No. 2014-176801

An object of the present invention is to provide a multilayer paper for food and beverages that is excellent in food hygiene.

Means for solving the problems of the present invention are as follows.
1. It has multiple paper layers and a starch adhesive between the layers,
A multilayer paper for food and beverages, characterized in that the number of bacteria in the paper is 250 cells/g or less.
2. 1. The starch-based adhesive contains modified starch processed by a dry method. A multilayer paper for food and beverages as described in .
3. 1. The starch-based adhesive is characterized in that it contains one or more of the following: urea phosphoester starch, phosphate ester starch, dry low-molecular-weight hydroxyethylated starch, and roasted dextrin. or 2. A multilayer paper for food and beverages as described in .

The multilayer paper for food and beverages of the present invention has a small number of bacteria in the paper even though it uses a starch adhesive, and is excellent in food hygiene. Modified starch processed by the dry method reduces the number of spore bacteria when it is heated in the dry method, so even when used as an interlayer adhesive for multilayer paper for food and beverages, it is difficult to suppress the number of microorganisms that get mixed into the paper. can.

- Multilayer paper for food and drink The present invention relates to multilayer paper for food and drink, which has a plurality of paper layers and a starch-based adhesive between the layers, and has a bacterial count of 250 cells/g or less.
In the multilayer paper for food and beverages of the present invention, the number of bacteria in the paper is preferably 200 cells/g or less, more preferably 150 cells/g or less, and still more preferably 100 cells/g or less. preferable.

In the present invention, the number of bacteria in paper is a value measured by the following method with reference to "Food Hygiene Inspection Guidelines - Microorganism Edition" supervised by the Ministry of Health, Labor and Welfare.
1. Cut the portion of the food/beverage paper other than the outer 5 cm into 0.5 cm squares, collect a sample of 0.3 to 0.5 g, and accurately weigh it.
2. Phosphate buffer (pH 7.2) was added to the sample so that the concentration was 1% by weight, and after stirring thoroughly using a homogenizer until the pulp was disintegrated, the sample was heated at 100°C for 10 minutes to eliminate bacteria other than heat-resistant spore-forming bacteria. Sterilize and obtain sample stock solution.
3. 1 ml of the obtained sample stock solution is dispensed into a Petri dish containing 9 ml of a standard agar medium prepared and sterilized in advance, and allowed to stand at 32° C. for 48 hours.
4. After standing, the number of colonies developed on the Petri dish is taken as the number of bacteria, and the number of bacteria in the paper (cells/g) is determined from the dilution ratio and the weight of the accurately weighed sample.

<Paper layer>
In the present invention, the paper layer is a sheet made of pulp, filler, various auxiliary agents, and the like.
Pulps include chemical wood pulps such as softwood bleached kraft pulp (NBKP), unbleached kraft pulp (NUKP), hardwood bleached kraft pulp (LBKP), unbleached kraft pulp (LUKP), and sulfite pulp (SP). , ground pulp (GP), refined ground pulp (RGP), stone ground pulp (SGP), chemical ground pulp (CGP), semi-chemical pulp (SCP), thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP) Mechanical pulp of wood such as kenaf, bagasse, bamboo, hemp, straw, etc., non-wood pulp obtained from wood such as kenaf, bagasse, bamboo, hemp, straw, etc., waste paper pulp made from waste paper and the ink contained in the waste paper removed through a deinking process, etc. It is possible to mix and use the pulp as appropriate. Among these, chemical pulps such as LBKP and NBKP, which are less susceptible to foreign matter contamination, are preferred, and it is also preferred that the amount of waste paper pulp blended is small. Specifically, the amount of chemical pulp mixed with respect to the total amount of pulp is preferably 80% by weight or more, more preferably 90% by weight or more, and most preferably 100% by weight.

Fillers include talc, kaolin, calcined kaolin, clay, heavy calcium carbonate, light calcium carbonate, white carbon, zeolite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, aluminum hydroxide. , inorganic fillers such as calcium hydroxide, magnesium hydroxide, zinc hydroxide, barium sulfate, and calcium sulfate, and organic fillers such as urea-formalin resin, polystyrene resin, phenol resin, and micro hollow particles. I can do it. In addition, in the laminate of the present invention, the paper layer does not need to use filler, and preferably does not use filler.

Various auxiliary agents include various internal sizing agents such as rosin, alkyl ketene dimer (AKD), and alkenylsuccinic anhydride (ASA), various nonionic, cationic, and amphoteric retention improvers, and freeness improvers. , paper strength improvers, various starches, polyacrylamide, urea resin, melamine resin, epoxy resin, polyamide resin, polyamide, polyamine resin, polyamine, polyethyleneimine, vegetable gum, polyvinyl alcohol, latex, polyethylene oxide, hydrophilic cross-linked polymer Particle dispersions and their derivatives or modified products, basic aluminum compounds such as aluminum sulfate, aluminum chloride, sodium aluminate, basic aluminum chloride, basic polyaluminum hydroxide, and water-soluble alumina sol that easily decomposes in water. Examples include polyvalent metal compounds such as ferrous sulfate and ferric sulfate, silica sol, antifoaming agents, colored dyes, colored pigments, pH adjusters, pitch control agents, slime control agents, etc. They can be selected and used as appropriate.

<Multilayer paper for food and beverages>
Multilayer paper for food and beverages has the above-described paper layers and a starch-based adhesive between the layers. The number of paper layers constituting the multilayer paper for food and beverages may be selected from two or more layers depending on the desired thickness, etc., but in order to simplify the manufacturing process, it is recommended that the number be between two and five layers. Preferably, two or three layers are more preferable. In addition, in the multilayer paper for food and beverages of the present invention, the paper layers may have the same or different raw materials, basis weight, density, etc.
The thickness of the multilayer paper for food and beverages is not particularly limited, but is preferably 100 μm or more, more preferably 120 μm or more, and even more preferably 140 μm or more. The upper limit of the thickness of the multilayer paper for food and beverages is not particularly limited, but is preferably 600 μm or less, more preferably 550 μm or less, and even more preferably 500 μm or less.

<Adhesive>
The present invention has a starch-based adhesive between the paper layers. The starch adhesive used preferably contains a small number of microorganisms, especially spore bacteria. As such a starch-based adhesive, it is possible to use starch or modified starch known in the paper manufacturing field that has been sterilized by gas sterilization, gamma ray sterilization, high-pressure steam sterilization, intermittent sterilization, or the like. In addition, modified starches used in the paper manufacturing field are roughly divided into those processed by a wet method in which the starch is reacted in a starch slurry, and those processed by a dry method in which the solid state is heated and reacted. Processed starch can be suitably used because it is exposed to high temperatures during the process and has a small number of bacteria even without a special sterilization process. Examples of the dry processed starch include urea phosphorylated ester starch, phosphoric ester starch, dry low molecular weight hydroxyethylated starch, and roasted dextrin. In the starch-based adhesive used in the present invention, the number of bacteria per gram measured in the same manner as the number of bacteria in paper is preferably 90 cells/g or less, and 60 cells/g or less. The number is more preferably 30 pieces/g or less, and most preferably 15 pieces/g or less.

・Manufacturing method Multi-layer paper for food and beverages is manufactured by forming a first wet paper layer by making paper containing pulp, fillers, auxiliary agents, etc., and applying starch-based adhesive on top of the first wet paper layer. Step B of applying or spraying an aqueous dispersion containing the agent, Step C of forming a second wet paper layer on the surface onto which this aqueous dispersion has been applied or sprayed, as necessary, Step B, Step It can be manufactured by repeating step C.

・Process A
The first wet paper layer is manufactured by a known papermaking method.
Paper making may be carried out using methods such as hand-making or machine-making, and examples of machine-making include fourdrinier paper machines, twin wire paper machines, Yankee paper machines, cylinder paper machines, and cylinder and short screen combination paper machines. A known paper machine such as a paper machine can be appropriately selected and used. In the present invention, it is preferable to use a multilayer paper machine from the viewpoint of work efficiency. In particular, a papermaking net, an upstream headbox provided upstream of the papermaking net, one or more downstream headboxes provided downstream of the upstream headbox, and a papermaking net provided between the upstream headbox and the downstream headbox. Further, it is preferable to use a paper machine equipped with a supply device for supplying an aqueous dispersion containing a starch-based adhesive to supply the paper stock from an upstream head box to a papermaking screen to form a wet paper layer.

・Process B
In step B, an aqueous dispersion containing a starch adhesive is applied or sprayed onto the first wet paper layer. The solid content concentration of the starch adhesive in the aqueous dispersion is not particularly limited as long as it has a viscosity that allows coating or spraying and has an adhesive effect, and is preferably 0.5 to 10% by weight, and 1 The amount is more preferably .0 to 7.0% by weight, and even more preferably 2.0 to 5.0% by weight.

A known device such as a dispenser can be used for application. Further, for spraying, a known device such as a spray nozzle can be used. From the viewpoint of increasing interlayer adhesive strength, the amount (solid content) of the starch adhesive to be applied or sprayed is 0.001% by weight or more and 30% by weight or less based on the solid content of the wet paper layer formed in Step A. , preferably 0.01% by weight or more and 30% by weight or less, more preferably 0.05% by weight or more and 10% by weight or less, and even more preferably 0.1% by weight or more and 5% by weight or less. The solid content of the wet paper layer is the solid content obtained by drying the wet paper layer.

As described in Step A, it is preferable to use the above-mentioned paper machine in the present invention. In this case, the aqueous dispersion containing the starch-based adhesive is applied or sprayed onto the first wet paper layer obtained in step A via a feeding device. Specifically, the supply device is a dispenser or a spray nozzle, and it is preferable to use a spray nozzle to spray. Further, the aqueous dispersion containing the starch adhesive is applied or sprayed over the entire width of the wet paper layer in the width direction of the paper machine. When an aqueous dispersion containing a starch-based adhesive is applied or sprayed across the entire width of the paper machine, the starch-based adhesive forms a very thin layer and is present on the entire surface between the paper layers, resulting in higher interlayer adhesive strength. .

・Process C
In step C, a second wet paper layer is formed on the surface onto which the aqueous dispersion obtained in step B was applied or sprayed.
The method for forming the second wet paper layer is not limited, and for example, a wet paper layer is prepared in the same manner as in step A, and then placed opposite to the surface on which the aqueous dispersion obtained in step B was applied or sprayed. A second wet paper layer can be formed by laminating the sheets in this manner. Alternatively, the second wet paper layer may be formed by supplying paper stock onto the surface onto which the aqueous dispersion obtained in step B has been applied or sprayed. The stock used in step C may be the same as the stock used in step A, or may be different.
As already explained, in the present invention, it is preferable to use the paper machine, so paper stock is supplied from the downstream head box onto the surface onto which the aqueous dispersion obtained in step B has been applied or sprayed, and the second It is preferable to form a wet paper layer of.

After this step C, by repeating steps B and C as necessary, a multilayer paper for food and beverages having a desired number of layers can be manufactured. At this time, the paper stock of the wet paper layer to be laminated may be the same as or different from the paper stock that formed the first and second wet paper layers.

-Other Steps The multilayer body containing at least the layers obtained in Steps A to C undergoes known steps such as a pressing step, a drying step, a calendering step, etc., and becomes a multilayer paper for food and beverages. The pressing step can be performed by a known method such as a plain press, a suction press, or a shoe press. The drying step can be carried out using a known method such as a steam heater, gas heater, infrared heater, electric heater, hot air heater, microwave, or cylinder dryer. The calendering process can be carried out by a known method such as a super calender, a gloss calender, a soft nip calender, a thermal calender, a shoe calender, or the like.

Furthermore, the multilayer paper for food and beverages of the present invention can be provided with a thermoplastic resin layer to enable heat-sealing, a coating layer of water-resistant varnish, water repellent, etc., if necessary.
As the thermoplastic resin, polyethylene, polypropylene, polyvinyl acetate polymer, etc. can be used, and polyethylene and polypropylene are preferably used from the viewpoint of productivity during heat sealing and barrier properties. The method of laminating the thermoplastic resin layer is not particularly limited, but known methods such as a conventional melt extrusion lamination method, a dry lamination method using a film, and a direct melt coating method can be used.
It is preferable to use water-resistant varnishes, water repellents, etc. that are compatible with food safety, such as those that have been approved as food additives as raw materials or have been FDA certified.For example, petroleum-based resins (styrene,・Butadiene-based, acrylic-based, etc.), petroleum-based wax, etc. can be used. The coating method is not particularly limited, and known methods such as air knife coating, bar coating, blade coating, curtain coating, etc. can be used.

In the multilayer paper for food and beverages of the present invention, the basis weight of the paper layer is preferably 20 g/m ² or more, more preferably 30 g/m ² or more. Further, it is preferably 300 g/m ² or less, more preferably 270 g/m ² or less.
The basis weight of the multilayer paper for food and beverages of the present invention is preferably 100 g/m ² or more, more preferably 150 g/m ² or more. Further, it is preferably 500 g/m ² or less, more preferably 450 g/m ² or less.

The multilayer paper for food and beverages of the present invention has a small number of bacteria in the paper, and can be used for various purposes as food and beverages. For example, it can be suitably used for food containers, beverage containers, yogurt containers, paper plates, paper cups, paper sheets, and the like.

"Example 1"
Urea phosphorylated ester starch (number of bacteria per 1 g of starch: less than 10) produced by a dry method was dispersed in water at 100° C. to a solid content of 3% to produce interlayer starch.
Using 100% softwood kraft pulp raw material, the wire part of a multi-layer paper machine has a basis weight of 50 g/m ² for the back layer, 2 g/m ² interlayer starch, 156 g/m ² for the middle layer, and 2 g/m 2. A wet paper was obtained by sequentially laminating and spraying starch between ^{the two} layers to form a surface layer of 50 g/m ² .
Thereafter, the obtained wet paper paper was squeezed and dried so that the water content in the paper became 8%, to obtain a multilayer paper for food and beverages with a basis weight of 260.2 g/m ² .

The obtained multilayer paper for food and beverages was evaluated as follows. The results are shown in Table 1.
- Basis weight: Measured according to JIS P 8124.
- Paper thickness: Measured according to JIS P 8118.
・Number of bacteria in paper: The number of bacteria in paper was measured by the above method.

“Comparative Example 1”
A multilayer paper for food and beverages was produced and evaluated in the same manner as in Example 1, except that the interlayer starch used was acetylated starch produced by a wet method (number of bacteria per 1 g of starch: 160).

The multilayer paper for food and beverages of the present invention had a small number of bacteria in the paper and was hygienic.

Claims (3)

It has multiple paper layers and a starch adhesive between the layers,
Multilayer paper for food and beverages, characterized in that the number of bacteria in the paper is 250 cells/g or less (excluding those containing antibacterial agents by coating) . The multilayer paper for food and beverages according to claim 1, wherein the starch-based adhesive contains modified starch processed by a dry method. 3. The starch adhesive according to claim 1 or 2, wherein the starch adhesive contains one or more of urea phosphorylated ester starch, phosphoric ester starch, dry low molecular weight hydroxyethylated starch, and roasted dextrin. Multilayer paper for food and beverages.