Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B2/00—Preservation of foods or foodstuffs, in general
  • A23B2/70—Preservation of foods or foodstuffs, in general by treatment with chemicals
  • A23B2/704—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
  • A23B2/721—Preservation of foods or foodstuffs, in general by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere comprising other gases in addition to CO2, N2, O2 or H2O
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B4/00—Preservation of meat, sausages, fish or fish products
  • A23B4/14—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12
  • A23B4/16—Preserving with chemicals not covered by groups A23B4/02 or A23B4/12 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23B—PRESERVATION OF FOODS, FOODSTUFFS OR NON-ALCOHOLIC BEVERAGES; CHEMICAL RIPENING OF FRUIT OR VEGETABLES
  • A23B7/00—Preservation of fruit or vegetables; Chemical ripening of fruit or vegetables
  • A23B7/14—Preserving or ripening with chemicals not covered by group A23B7/08 or A23B7/10
  • A23B7/144—Preserving or ripening with chemicals not covered by group A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor
  • A23B7/152—Preserving or ripening with chemicals not covered by group A23B7/08 or A23B7/10 in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere comprising other gases in addition to CO2, N2, O2 or H2O ; Elimination of such other gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B23/00—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose
  • B32B23/04—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B23/08—Layered products comprising a layer of cellulosic plastic substances, i.e. substances obtained by chemical modification of cellulose, e.g. cellulose ethers, cellulose esters, viscose comprising such cellulosic plastic substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
  • B32B27/304—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl halide (co)polymers, e.g. PVC, PVDC, PVF, PVDF
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
  • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/08—Cellulose derivatives
  • C08L1/10—Esters of organic acids, i.e. acylates
  • C08L1/12—Cellulose acetate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2553/00—Packaging equipment or accessories not otherwise provided for

Definitions

• Sulphur Dioxide Film The present invention relates to a film which releases sulphur dioxide, and in particular to the use of such films in packaging materials.
• Sulphites are commonly used as preservatives in food and other industries. They have been used to prevent enzy ic and non-enzymic browning as well as growth of spoilage microorganisms, for over two thousand years.
• sulphur dioxide can cause severe respiratory disfunction in asthmatics and its reaction with components of biological systems has led to concern that its use as a preservative may be harmful to health. Toxicity of sulphur dioxide to the human respiratory system has received considerable attention since it was demonstrated that it is a major contributor to smogs.
• Packaging materials incorporating a sulphur dioxide-liberating sulphite(s) have now been proposed which liberate sulphur dioxide upon permeation of water vapour. By avoiding the direct contact of the sulphite compounds with the produce, these materials offer a higher level of safety. However, to be useful these materials must be able to generate sulphur dioxide over extended periods so as to compensate for the loss of sulphur dioxide caused by its reactivity with food components such as oxygen.
• the packaging material comprises two sheets of synthetic or other material pervious to water vapour and sulphur dioxide, laminated together with a suitable substance such as paraffin wax. Dispersed within the laminating substance is a material which, in the presence of moisture, liberates sulphur dioxide.
• This packaging material does however, have a number of disadvantages including a rather complex manufacture and a limited range of applications. Further, the packaging material described does not allow for the fact that different types of produce consume sulphur dioxide at varying rates and thus, the packaging material may not be suitable for some types of produce.
• the present inventors have now developed a packaging material which aims to provide advantages over the prior art or ameliorate at least one of the disadvantages mentioned above.
• the present invention provides a polymeric film material for use in the packaging of produce incorporating a sulphur dioxide-liberating compound(s) and one or more of the following additives:
• Suitable sulphur dioxide-liberating compounds for use in the present invention include those listed by the United States Food and Drug Administration under 21 CFR Ch.l - Part 182, including sodium sulphite, sodium hydrogen sulphite, sodium metabisulphite.
• Other suitable sulphur dioxide-liberating compounds include calcium sulphite, calcium hydrogen sulphite, calcium metabisulphite, salts of thiosulphuric acid and organic sulphur dioxide-liberating agents. Mixtures of these materials may also be suitable.
• non-hygroscopic salts such as calcium sulphite.
• Suitable acid compound(s) may vary depending upon the other components, but may include those acidulants typically used in food processing such as stearic acid, benzoic acid, citric acid, ascorbic acid, succinic acid, tartaric acid, sorbic acid, acetic acid, propionic acid, adipic acid, fu aric acid, lactic acid, malic acid, phosphoric acid and their salts.
• Mixtures comprising stearic acid can also be useful because the stearic acid acts as a coupling agent between the other acid(s) and the polymer and sulphur dioxide-liberating compound(s).
• the identity(ies) and quantity of the acid(s) used can be selected to achieve a predetermined rate of sulphur dioxide liberation.
• Suitable hygroscopic compounds include hygroscopic salts such as salts of acetic acid, salts of hydrochloric acid, salts of carbonic acid, polyhydric alcohols such as glycerol and propylene glycol and hygroscopic polymers. These compounds may be used to control the sulphur dioxide liberation rate because they absorb moisture which, in turn, triggers the liberation of sulphur dioxide.
• Suitable polymers which degrade to produce an acid include neoprene, poly(lactic acid), poly(glycolic acid) and co-polymers, poly(anhydrides) and poly(ortho-esters) .
• Other materials, such as anhydrides, lactones or lactide, which become acid in a humid environment, may also be used to achieve a predetermined, controlled liberation of sulphur dioxide due to their different rates of hydrolysis and different acidities.
• Suitable polymers for the production of the films include members of the polyolefin family due to their high permeability to sulphur dioxide.
• Low temperature processing, low density polyethylene are particularly preferred polyolefins (e.g. Compol 4202 and LDPE 4203).
• Other polymers with acid functional groups such as acid co-polymers EAA or EMAA may also be suitable carriers of the sulphur dioxide-liberating compound(s). These polymers have superior adhesion to aluminium foil and greater toughness when compared to LDPE.
• Polymers such as poly(vinyl chloride), ethylene-vinyl alcohol, cellulose acetate, ethyl cellulose or starch may also be used.
• Ionomers such as Dupont' s SURLYN resins may also be used.
• the most preferred polymer is poly (vinyl alcohol) due to the high loadings of sulphur dioxide-liberating compounds that can be achieved with this polymer.
• Poly (vinyl alcohol) is also biodegradable and recyclable.
• the polymeric film material according to the invention may be a single-layer or multi-layer film.
• the sulphur dioxide-liberating compound(s) and one or more additive(s) may be present within each or separate layers of the film. This latter arrangement offers an advantage in that direct contact between the produce and the layer containing the sulphur dioxide-liberating compound(s) may be avoided.
• poly (vinyl alcohol) films need to be made from aqueous solutions. The addition of the sulphur dioxide-liberating compound(s) and the additive(s) to the aqueous poly (vinyl alcohol) solution can cause an unwanted release of sulphur dioxide.
• This difficulty may be overcome by producing a multi-layer film wherein the film layers containing the sulphur dioxide-liberating compound(s) or additive(s) are made separately, and subsequently laminated together.
• a similar result may be achieved where one or more of the layers used comprises paper or other porous material.
• the present invention provides a material for use in packaging of produce, comprising at least two laminated layers, wherein at least one layer incorporates a sulphur dioxide-liberating compound(s) and at least one other layer incorporates one or more of the following additives:
• the packaging material according to the second aspect of the invention comprises at least two laminated polymeric film layers. More preferably, it comprises at least two laminated poly (vinyl alcohol) film layers.
• the amount and identity(ies) of the additive(s) may be selected to provide a predetermined, controlled rate of sulphur dioxide liberation.
• the invention further relates to a method for producing a multi-layer film or material according to the first or second aspect, comprising separately forming at least one layer incorporating the sulphur dioxide-liberating compound(s) and at least one layer incorporating the one or more additives, and thereafter laminating the film layers together.
• Polymeric film materials according to either aspect of the invention may be used to wrap the produce prior to surrounding with typical packaging material such as corrugated cardboard to provide greater mechanical strength.
• typical packaging material such as corrugated cardboard
• the polymeric film materials may be used as a lining for typical packaging material.
• the term "produce” is used in its broadest sense and is intended to cover all forms of produce including but not limited to wine, flowers, grapes, dried fruits such as apricots, peaches and pears, marine produce in particular prawns, cut flowers and the like.
• the materials of the present invention are also useful in reducing peroxide in cases where peroxide is used to sterilise the film or where hydrogen peroxide is formed in oxygen scavenging applications, for example those applications using oxidation of ascorbic acid.
• the sulphur dioxide saps up hydrogen peroxide.
• oxidant agent(s) include copper sulphate and iron sulphate.
• the film was cast onto a glass plate with the solution using a glass rod as a screed.
• Ethanol was added to PVC powder (Corvic) in a conical flask and mixed thoroughly. At this stage the polymer was wetted and may be swollen.
• Tetrahydrofuran was added to the polymer. The mixture was stirred intensively for at least 6 hours. At this stage, the solution was clear and very viscous. No particles were visually detectable inside the solution.
• a film was cast onto a glass plate with the solution using a glass rod as a screed.
• PVOH was dissolved in water using a microwave oven to heat the mixture to the boiling point. The mixture was stirred with a glass rod to remove large lumps. At this stage, the solution is very viscous but not very clear and small particles are visually detectable.
• An inorganic sulphite salt was either suspended (for calcium sulphite) or dissolved (for sodium disulphite) into the solution over the water bath.
• a film was cast onto a PVC board with the solution using a glass rod.
• the sulphite salt-containing film was dried at room temperature in a fume cupboard. 5.
• a film containing an organic acidulant was made in the same fashion.
• films according to the invention may be cast using vented extruders fitted with a Blown film die (1") and film take-off tower. The take-off tower governs the rate at which the blown film is drawn from the die, thereby controlling film thickness. C. Examples of films
• Air from a cylinder is passed through Fisher Mulligan wash bottles.
• the first bottle is filled with water and the second is filled with potassium sulfate to provide constant relative humidity (approximately 98%).
• the air is then passed through two test tubes connected in series at approximately 30ml/min.
• the film or material to be tested is placed in the first test tube and the second test tube is filled with 3% hydrogen peroxide solution. Released sulphur dioxide will be absorbed and oxidized to sulfuric acid. The resulting acid is titrated with sodium hydroxide.
• Table 5 shows that three-layer poly (vinyl alcohol) films using ascorbic acid and benzoic acid produced a low level of sulphur dioxide liberation.
• the same film construction using lactone showed a vastly greater sulphur dioxide liberation over the duration of the experiment (80.7 days). Steady state release of sulphur dioxide was achieved with this film after about 21 days.
• Table 6 shows that in single layer PVC films, greater levels of sulphur dioxide liberation with citric acid and a citric acid-succinic acid mixture than with succinic acid alone.
• Two-layer poly (vinyl alcohol) demonstrated much higher rates of liberation than the PVC single layer films.
• the use of citric acid in the poly (vinyl alcohol) gave greater rates of release than with succinic acid.
• Table 7 provides results of three-layer poly (vinyl alcohol) at 15 C.
• Film including citric acid showed very high rates of liberation for 22.9 days.
• Film including succinic acid showed a steadily increasing rate of liberation over the duration of the experiment (92.2 days) .
• films or materials according to the present invention may be tailored to provide a sulphur dioxide liberation rate suitable for different produce having widely varying requirements.
• the liberation rate may be ca. 30 mg of sulphur dioxide per kilogram of produce per day.
• Some grapes such as the thick skinned Ohanez may require a lower rate whereas thinner skinned Thompson seedless would require a higher rate of liberation.
• the liberation rate may be about 2mg per litre per day.
• sulphur dioxide is generally regarded as being without any toxicity hazard at the usual levels but it does pose an important nutritional problem.
• the bisulphite (hydrogen sulphite) ion reacts readily and destructively, with the vitamin thiamine. Vegetables such as potatoes which are often stored in sulphite solutions at intermediate stages of processing will lose considerable proportions of their thiamine content. A further investigation by the user would be to determine that the foodstuffs packaged by this material are not the major source of thiamine.
• Agricultural films e.g. mulch films - Wine casks to prevent secondary fermentation and oxidation
• Shrimp melanosis commonly termed “black spot” is a surface discoloration caused by enzymatic formation of precursor compounds which can polymerize spontaneously and/or react with cellular constituents to form insoluble pigments. This results in a cosmetic problem analogous to browning of potatoes, apples, avocados and grape juice resulting in reduced commercial value and consumer acceptance of the products.
• the endogenous shrimp enzyme, polyphenol oxidase (PPO) which catalyzes the initial step in black spot formation, remains active throughout post-harvest processing unless the shrimp are frozen or cooked. The PPO activity can resume in raw shrimp upon thawing. Likewise, the detrimental black pigments persist through processing and preparation unless bleached or marked.
• Sulphiting agents were introduced in the 1950 's to inhibit blackspot formation. Treatment of shrimp is by dipping them into a 1/25% sodium metabisulphite solution with an allowable sulphite residual of 10 pp . Currently, this dip procedure is employed on commercial vessels followed by storage on crushed ice or brine freezing of the sulphited shrimp for subsequent transport and handling.
• the present invention has significant impact for storage of the shrimp after the initial dipping described.
• Extended storage of grapes demands the control of decay arising from the infection by Botr ⁇ tis cinerea spp.
• Sulfur dioxide is currently the only acceptable chemical to control decay.
• the chemical is applied to the grapes in commercial practice through a dual release system.
• the release system consists of kraft paper impregnated with sodium disulphite and a series of sachets containing about 0.3g of sodium disulphite.
• the migration of water activates the release of sulfur dioxide rapidly from the Kraft paper and more slowly from the sachets.
• These release systems are extremely sensitive to condensation and temperature abuse. If the temperature of the grapes is allowed to rise significantly above 5°C then the pads release the sulphur dioxide rapidly resulting in severe bleaching of the crop and short storage life because there is no sulfur dioxide available in the sachet.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Polymers & Plastics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Food Science & Technology (AREA)
• Zoology (AREA)
• Wood Science & Technology (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Organic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Wrappers (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Laminated Bodies (AREA)
• Compositions Of Macromolecular Compounds (AREA)

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• 1993
  • 1993-10-29 NZ NZ257311A patent/NZ257311A/en not_active IP Right Cessation
  • 1993-10-29 CA CA002147872A patent/CA2147872A1/fr not_active Abandoned
  • 1993-10-29 WO PCT/AU1993/000562 patent/WO1994010233A1/fr not_active Application Discontinuation
  • 1993-10-29 JP JP6510471A patent/JPH08502772A/ja active Pending
  • 1993-10-29 EP EP93923980A patent/EP0666883A4/fr not_active Withdrawn

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