Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
  • G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
  • G01N31/223—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating presence of specific gases or aerosols
  • G01N31/225—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating presence of specific gases or aerosols for oxygen, e.g. including dissolved oxygen
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
  • A23L3/003—Control or safety devices for sterilisation or pasteurisation systems
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L3/00—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs
  • A23L3/34—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals
  • A23L3/3409—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor
  • A23L3/3418—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O
  • A23L3/3427—Preservation of foods or foodstuffs, in general, e.g. pasteurising, sterilising, specially adapted for foods or foodstuffs by treatment with chemicals in the form of gases, e.g. fumigation; Compositions or apparatus therefor in a controlled atmosphere, e.g. partial vacuum, comprising only CO2, N2, O2 or H2O in which an absorbent is placed or used
  • A23L3/3436—Oxygen absorbent

Definitions

• the invention relates to an oxygen scavenger / - indicator containing at least one oxygen sorbent of a metal or a metal compound, which is convertible by oxygen in a higher oxidation state.
• a complexing agent or redox indicator for the sorbent and an electrolyte are also included.
• the indicator effect is effected by a change in the physical properties of the oxygen sorbent, which is triggered by complex formation and / or interaction with the redox indicator.
• O 2 scavengers are substances that can sorb oxygen.
• sorption are meant all known sorption possibilities, eg adsorption, absorption, chemisorption and physisorption.
• the systems which are currently established according to the prior art can be used primarily for the O 2 scavenger Substrate and qualify for their initialization mechanism. Here one differentiates the following groups:
• inorganic O 2 scavengers eg iron-based or sulfide-based systems
• O 2 scavengers are initialized either by UV radiation or by moisture. This means that the O 2 scavenging function is only available after exposure to UV radiation or water, ie air humidity.
• Indicator systems can generally be classified into Time-Temperature-Indicator (TTI), Gas / Leakage-Indicator and Freshness-Indicator systems.
• TTI Time-Temperature-Indicator
• Gas / Leakage-Indicator Gas / Leakage-Indicator
• Freshness-Indicator systems can generally be classified into Time-Temperature-Indicator (TTI), Gas / Leakage-Indicator and Freshness-Indicator systems.
• a TTI integrates the time-temperature history of a product and thus makes a direct statement about its storage conditions.
• the indicator effect is effected by a chemical reaction or by opposite diffusion of two dyes.
• Gas leakage indicators detect the gas concentration of O 2 , CO 2 or H 2 O in the packaging space. They thus make an indirect statement about the quality of the product.
• the indicator effect is caused by a chemical reaction with the reactants O 2 , CO 2 or H 2 O.
• Freshness indicators detect the metabolic products of microorganisms and thus make a direct statement about the quality of the product.
• the indicator effect is caused by a chemical reaction of the metabolites.
• O 2 scavenger / indicator systems are not currently known in the art.
• the O 2 scavenger operates independently of the O 2 indicator, ie the O 2 indicator merely signals that a certain O 2 concentration has been exceeded.
• an object of the present invention to provide an O 2 scavenger / indicator system, which is the exceeding of a certain 0 2- concentration, exceeding a certain 0 2- concentration period as well as exceeding a certain amount of oxygen absorbed the O 2 - Scavengers can signal visually or measurably.
• an oxygen scavenger / indicator which contains at least one oxygen scavenger. contains substance sorbent from a metal or a metal compound. The metal or the metal compound can be converted into a higher oxidation state by means of oxygen, ie with oxygen present in the environment. Furthermore, the oxygen scavenger / indicator contains at least one complexing agent and / or redox indicator for the metal or the metal compound in the oxidized form. The complex formation and / or the interaction with the redox indicator triggers a change of at least one physical property of the oxygen sorbent. As a further component, the oxygen scavenger / indicator contains an electrolyte that supports the electron transfer of the redox reaction.
• the oxygen sorbent can change one of its physical parameters under oxygen exposure. With regard to the physical properties concerned, there are no restrictions if they represent a visual or metrologically evaluable change.
• the oxygen sorbent is a magnetic or specifically magnetized material, such as elemental iron, which is reacted by contact with oxygen to a non or less magnetic compound, such as Fe x O y .
• the occurring change in permeability or remanence can be detected by eg a sensor.
• a magnetometer can be used here, while the change of the permeability can be determined by an inductance measurement. can be tektiert.
• the oxygen sorbent is an electrically conductive material, such as elemental iron, and is converted by exposure to oxygen to a no or less electrically conductive compound, such as Fe x Oy.
• the change in the electrical conductivity can be detected for example by means of a sensor.
• the coupling of the current takes place on inductive or capacitive ways.
• the detection in the inductive coupling can be carried out preferably via an eddy current measuring technique.
• detection may preferably take place according to the capacitor principle.
• Another preferred variant provides that the electromagnetic absorption of the oxygen sorbent changes.
• elemental iron is used as the oxygen sorbent, which is reacted with exposure to oxygen to form an oxidic compound, for example Fe x O y .
• This can be detected, for example, by means of a sensor.
• photometers or IR measuring devices are used as detectors for the UV / IR range. Detection is also possible in the VIS range as well as in the microwave range. Particularly preferred is a visually perceptible color change of the oxygen sorbent.
• the trigger for the reaction with oxygen is preferably water, ie the air humidity in the environment.
• the humidity causes the electrolyte to liquefy, causing the electron trans- fer is made possible for the redox reaction. From a certain relative humidity, the initialization of the system takes place, whereby the relative humidity of the initialization can be determined by the choice of the electrolyte.
• a typical value when using sodium chloride as electrolyte for the triggering of the O 2 scavenger / -Indikatorsystems is ⁇ 75% humidity.
• the oxygen scavengers / indicators according to the invention are based on materials consisting of a redox couple or a metal and a complexing agent which combine both the O 2 scavenger and the O 2 indicator function.
• the O 2 scavenger and indicator has the same reaction kinetics.
• this has the further advantage that the correlation of the absorbed oxygen quantity of the O 2 scavenger with the color change of the O 2 indicator is independent of the temperature.
• the at least one oxygen sorbent is preferably present in solid or disperse dissolved form.
• the oxygen sorbent is a metal selected from the group consisting of iron, zinc, aluminum, cobalt, nickel, copper, magnesium, chromium and tin.
• redox indicator or complexing agent for the oxygen sorbent all compounds which can bring about a color change in the sense of an oxygen scavenger / indicator are suitable. These are thus all compounds which serve as redox indicator for the corresponding metal or the metal compound or compounds which can be used as a complexing agent for the metal or the metal compound.
• Preferred as redox indicator or complexing agent are those compounds selected from the group consisting of 2, 2'-bipyridine, 1,10-phenanthroline, 1, 10-phenanthroline hydrochloride, ethylenediaminetetraacetic acid (EDTA), potassium hexacyanoferrate (II), potassium hexacyanoferrate (III) , Potassium thiocyanate, salicylic acid, methyl salicylate, sulfosalicylic acid, acetylsalicylic acid, ethylacetoacetate, phosphoric acid, catechol, catechol, hydroquinone, resorcinol, gallic acid and pyrogallol.
• electrolyte all compounds are suitable which support the electron transfer of the redox reaction. Preference is given to using compounds from the group of alkali metal and alkaline earth metal halides. Likewise, it is also possible to use metallic and non-metallic sulfates and phosphates, but also non-metallic halides, such as ammonium chloride.
• electrolytes can be in both liquid and solid form.
• the oxygen scavenger / indicator contains a polymer electrolyte and / or a gel electrolyte.
• Polymers in combination with salts can be used in particular as polymer electrolytes, such as, for example, polyethyloxide (PEO) with LiPF 6 , polypropylene oxide (PPO) with LiCF 3 FO 3 or polyethylene oxide with LiClO 4 and optionally TiO 2 .
• a preferred embodiment of the oxygen scavenger / indicator provides that this additionally contains an activator for the oxygen sorbent.
• an activator compounds from the group of chromium, silver, copper or tin are particularly preferred.
• a first preferred oxygen scavenger / indicator consists of iron as the oxygen sorbent, which is then combined with a redox indicator for the oxidation of Fe (O) to Fe (II) or with a complexing agent for Fe (II).
• the iron is oxidized by the oxygen in the environment to Fe (II), which in turn forms a complex with the complexing agent, which is perceived as a color change for the observer.
• Another system is based on the use of iron as the oxygen sorbent, with the redox indicator being a redox indicator for the oxidation of Fe (II) to Fe (III) or a complexing agent for Fe (III) is included.
• the color change is effected in that either the redox indicator is discolored during the oxidation to Fe (III) or forms a colored Fe (III) complex.
• a third particularly preferred variant is based on an Fe (II) salt as an oxygen sorbent, which is combined with a redox indicator for the oxidation of Fe (II) to Fe (III) or a complexing agent for Fe (III).
• the color change is effected by the redox indicator in the oxidation to Fe (III) or by the formation of a colored Fe (III) complex.
• iron is present as an oxygen sorbent, with this containing a redox indicator for the oxidation of Fe (O) to Fe (II) and a redox indicator for the oxidation of Fe (II) to Fe (III) combined.
• a redox indicator for the oxidation of Fe (O) to Fe (II) and a redox indicator for the oxidation of Fe (II) to Fe (III) combined.
• Another possibility is the combination with one complexing agent each for Fe (II) and Fe (III). In essence, the color change is achieved here by the oxidation of Fe (O) to Fe (III).
• a preferred embodiment of the oxygen scavenger / indicator according to the invention consists of 60 to 94.5% by weight of the at least one oxygen sorbent, 5 to 30% by weight of the at least one redox indicator or complexing agent and 0.5 to 10% by weight .-% of the at least one electrolyte together. These figures are based on the total weight of the oxygen scavenger / indicator.
• composition there is a second preferred embodiment of the sow according to the invention.
• scavenger / indicator at 15 to 69.5 wt .-% of the at least one oxygen sorbent, to 30 to 75 wt .-% of the at least one redox indicator or complexing agent and 0.5 to 10 wt .-% from the at least one electrolyte.
• a third preferred embodiment relates to an oxygen scavenger / indicator comprising from 30 to 70% by weight of an oxygen sorbent, from 10 to 20% by weight of the Fe (II) complexing agent and from 20 to 40% by weight .-% consists of the Fe (III) complexing agent.
• the oxygen scavenger / indicator according to the invention has the peculiarity that the weight ratio of oxygen sorbent to redox indicator or complexing agent and electrolyte is adjustable so that the oxygen scavenger / indicator at a defined time, the residual capacity of the oxygen sorbent reflects at least one of its physical properties changes. This particularly preferably includes a color change point.
• a further variant according to the invention provides that the weight ratio of oxygen sorbent to redox indicator or complexing agent and electrolyte is adjusted so that the oxygen scavenger / indicator at least one of its at a defined time, which indicates the exceeding of a certain Sauerstoffkonzentrati- physical properties changes.
• These physical properties include in particular a color change point of the oxygen scavenger / indicator.
• a third variant provides that the weight ratio of oxygen sorbent to redox indicator or complexing agent and the at least one electrolyte is set so that the oxygen scavenger / - indicator has a change in its physical properties at a defined time, indicating the exceeding of a certain Sauerstoffkonzentrati- onszeitspanne.
• a preferred physical property is also the electromagnetic absorption, ie the change in the color of the sorbent. By means of the color change point, a defined residual capacity of the oxygen sorbent is to be signaled visually or with the aid of a measurement.
• At least one of the components of the oxygen scavenger / indicator is contained in encapsulated form.
• the oxygen scavenger / indicator can be present in two variants, ie as a non-visible and visible variant.
• the visible variant enables a visual perception and evaluation, which is generally sufficient with regard to qualitative evaluations.
• the invisible variant is in turn based on the change of other physical properties, which, as described above, can be evaluated with appropriate measuring instruments and thus can additionally provide quantitative results.
• the information is often important, how the headspace atmosphere in the packaging behaves.
• knowledge about the residual consumption capacity of the scavenger in the packaging including the time of packaging, of the greatest interest.
• a composite system which contains at least one carrier layer and at least one oxygen scavenger / indicator as described above.
• the at least one oxygen scavenger / indicator is sandwiched between the at least one carrier layer and at least one further layer.
• the at least one oxygen scavenger / indicator may be e.g. be arranged in solid, disperse or dissolved form punctiform between the layers. It is also possible for the at least one oxygen scavenger / indicator to be present in solid, disperse or dissolved form, flat between the layers, e.g. in the form of a film is arranged.
• the dot-shaped arrangement of the oxygen scavenger / indicator it is possible to arrange an oxygen scavenger / indicator spatially separated from each other with an oxygen scavenger. The number of such spatially separated systems is not limited.
• the at least one further layer can be modified by foaming and / or stretching. In this way it is possible subsequently to influence the oxygen permeability of the composite system.
• the at least one oxygen scavenger / indicator may be embedded in a polymer layer, eg of polyethylene. It is likewise possible for the at least one oxygen scavenger / indicator to be embedded in a laminating adhesive layer, a lacquer layer or printing ink layer.
• the described composite systems are eminently suitable as packaging films for any packaged goods, in particular foods, as well as individual films within a technical, electrical device.
• the applications include the food industry, pharmaceutical products and devices, the electronics industry, the chemical industry as well as cultural and military sectors.
• FIG. 1 shows the oxygen uptake and the color change of oxygen scavenger / indicators according to the invention on the basis of a diagram.
• FIG. 2 shows the oxygen uptake over the time of an oxygen scavenger / indicator according to the invention, which is incorporated into a composite system according to the invention.
• FIG. 3 shows by means of a diagram the dependence of the electrical resistance of an oxygen scavenger / indicator according to the invention on the amount of oxygen consumed.
• 4 shows, by way of a diagram, the dependence of the UV / VIS absorption of an oxygen scavenger / indicator according to the invention on the amount of oxygen consumed.
• Table 1 shows investigations on powder mixtures of iron with sodium chloride (1.5% by weight, based on the iron mass) and various additives (in each case 3% by weight, based on the iron mass).
• additives in each case 3% by weight, based on the iron mass.
• Table 2 shows powder mixtures of iron with 1.5% by weight of sodium chloride (based on the iron mass) and 3% by weight of FeSO 4 (based on the iron mass). The degree of discoloration is dependent on the amount of oxygen absorbed (capacity 300 cm 3 / g).
• Table 3 shows powder mixtures of iron with 1.5% by weight of sodium chloride (based on the iron mass) and 3% by weight of CaO (based on the iron mass). The degree of discoloration is dependent on the amount of oxygen absorbed (maximum 300 cm 3 / g).
• Table 4 shows polyethylene extrudates of iron with sodium chloride at various sodium chloride concentrations (in terms of iron mass). The table shows the interaction of the sodium chloride concentration with the degree of discoloration at an ingested oxygen amount of 20 cm 3 / g. Table 4
• FIG. 1 shows the oxygen uptake and the color change (white to purple) of the powder mixtures gallic acid + Fe, gallic acid + Fe + NaCl and salicylic acid + Fe + NHCl + NaOH.
• the oxygen uptake kinetics and the maximum oxygen uptake can be influenced. Furthermore, this can the color change can be adjusted depending on the amount of oxygen absorbed. By means of suitable powder mixtures, the oxygen uptake kinetics, the maximum oxygen uptake and the color change can be set for a certain amount of oxygen absorbed.
• Table 6 shows the time to color change of the tested blends by the number of small colored boxes. The time scale was determined as follows:
• both color and induction time vary greatly depending on Fe (II) salt and Fe (III) complexing agent.
• Fe (III) complexing agent although the Fe (III) complex has a characteristic color, the hue depends on the cation of the iron salt used.
• Gallic acid forms a light blue to black complex with oxidized iron (II) salts
• sulfosalicylic and salicylic acids form relatively pale pink to luscious complexes
• potassium thiocyanate rapidly forms dark red complexes
• potassium hexacyanoferrate forms complexes in various shades of turquoise.
• Fe (II) oxalate is very inert, it will not change color even after a week.
• the mixtures with Fe (II) gluconate, and ascorbate change their color only slightly, since the salts themselves already look brownish.
• the remaining mixtures have induction times of less than 1 hour to more than 18 hours.
• the turnover point of the O 2 scavenger / indicator can be set via the additive to scavenger ratio as well as via the indicator to scavenger ratio.
• this dependence is exemplified for a Fe scavenger with gallic acid as an indicator of various NaCl concentrations.
• the system is located in the acrylate-based laminating adhesive (KK) system used to produce the multi-layer packaging, PET / SiO x / KK / PA.
• the acrylate-based adhesive system contains 10% by weight of iron with 5% by weight of gallic acid and various NaCl concentrations. Table 7 shows the interaction between color change and the amount of oxygen taken up.
• the system is incorporated into the laminating adhesive (KK) of the multi-layer packaging, which consists of PET / SiO x / KK / PA.
• FIG. 3 shows the dependence of the electrical resistance of an iron-based oxygen-consuming PE film on the amount of oxygen consumed, ie the exhausted capacity.
• the bulk resistance through the film decreases as the amount of oxygen consumed by the oxygen scavenger increases.
• Another possibility is to determine the residual capacity of the O 2 scavenger / indicator system by detecting the electromagnetic absorption in the UV / VIS range as a function of the absorbed oxygen quantity of the O 2 scavenger system.
• FIG. 4 shows the dependence of the UV / VIS absorption of an iron-based oxygen-absorbing PE film on the amount of oxygen consumed, ie the exhausted capacity.
• the consumed amount of oxygen or the residual capacity of the O 2 scavenger can be detected by measurement.

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• 2005
  • 2005-11-22 DE DE102005055634A patent/DE102005055634A1/de not_active Withdrawn
• 2006
  • 2006-11-17 JP JP2008541622A patent/JP2009516836A/ja active Pending
  • 2006-11-17 WO PCT/EP2006/011075 patent/WO2007059900A1/de active Application Filing
  • 2006-11-17 US US12/093,165 patent/US20080300133A1/en not_active Abandoned
  • 2006-11-17 EP EP06818643A patent/EP1952139A1/de not_active Withdrawn
  • 2006-11-17 CA CA002629262A patent/CA2629262A1/en not_active Abandoned

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