WO2016033659A1

WO2016033659A1 - Food preservation

Info

Publication number: WO2016033659A1
Application number: PCT/AU2015/050525
Authority: WO
Inventors: Andrew David Scully; Pablo JULIANO; Kai KNOERZER; Thambaramala V. GAMAGE; Netsanet Shiferaw TEREFE; Rangika WEERAKKODY; Tanoj Kumar SINGH
Original assignee: Commonwealth Scientific And Industrial Research Organisation
Priority date: 2014-09-05
Filing date: 2015-09-04
Publication date: 2016-03-10
Also published as: AU2015311625A1

Abstract

The present disclosure relates to packaged food or therapeutic products and packages that prevent, reduce or delay non-enzymatic browning of the food or therapeutic substances upon storage. Methods of preventing, reducing or delaying non-enzymatic browning and increasing shelf life of products are also described.

Description

FOOD PRESERVATION

FIELD

[0001] The present disclosure relates to packaged food or therapeutic products and packages that prevent, reduce or delay non-enzymatic browning of the food or therapeutic substances upon storage. Methods of preventing, reducing or delaying non-enzymatic browning and increasing shelf life of products are also described.

BACKGROUND

[0002] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0003] Non-enzymatic browning is a known problem in packaged foods, particularly packaged fruit products. Treatment of foods and therapeutic products for preservation by processes such as thermal processing, high pressure processing and high pressure thermal processing are effective in reducing or eliminating harmful microorganisms such as bacteria, yeasts and moulds and also better preserves the natural quality attributes of the packaged product. However, foods such as fruits that are subject to such processing undergo discolouration over time and this limits the storage time and shelf life of these products.

[0004] Food products have been processed and packaged in metallic cans such as aluminium cans, tin-coated steel cans and enamel-coated tin cans. However, more recently food has been packaged in flexible or semi-rigid packaging, which is lighter and more environmentally friendly. In some instances, the packaging is at least in part transparent, allowing the consumer to view the product prior to purchase.

[0005] Transparent packaging results in the consumer electing not to purchase products that have discolouration. Non-transparent packaging results in consumer dissatisfaction if a discoloured product is purchased. [0006] High pressure thermal processing (HPTP) was found to be effective in reducing microbial counts which are detrimental to pear quality, and maintained suitable pear texture during storage at 30°C for 16 weeks. However, two non-enzymatic browning products, acetic acid and furfural, were detected immediately after HPTP, suggesting such processing initiated non-enzymatic browning. The in-pack non-enzymatic browning of the pear product limited shelf life to 4 weeks at 30°C indicating that longer shelf life requires refrigeration (Gamage et al., poster presentation, International Non-Thermal Food Processing Workshop - FIESTA 2012, 16-17 October 2012, Melbourne, Australia).

[0007] A solution to the problem of in-pack browning of fruits and vegetables has been proposed in US 2013/0236611 by coating the interior of a package with a first metal and a second metal, each metal having different galvanic properties. However, this solution requires the presence of two different metals exposed to the food product.

[0008] There is a need for methods and packaging for foods that allow effective preservation of food products but provide a simple, effective and safe means of controlling non-enzymatic browning and thereby extending storage times and shelf life.

SUMMARY

[0009] The present disclosure is predicated at least in part on the discovery that inclusion of a single metal, for example, as a coating, in a particulate or piece form or dissolved in a liquid or a food or therapeutic product prevents, reduces or delays the non-enzymatic browning process thereby extending storage time and shelf life of the products.

[0010] In a first aspect, the present disclosure provides a packaged product comprising: i) a food or therapeutic substance that comprises one or more amino-containing compounds and one or more carbonyl-containing compounds;

ii) a non-metallic package having an internal volume containing the food, or therapeutic substance, and

iii) a metal, wherein the metal is in contact with the food or therapeutic substance and the metal is substantially the only metal in the packaged product that is in contact with the food or therapeutic substance. [0011] In particular embodiments, the metal forms a coating on at least a portion of an internal surface of the package, forms a coating on a material added to the internal volume of the package, is in particulate form or in pieces in the internal volume of the package, or is in solution in the food or therapeutic substance. In particular embodiments, the metal is tin or magnesium.

[0012] In another aspect of the disclosure there is provided a non-metallic package having an internal volume, said internal volume comprising a metal, wherein the metal is substantially the only metal in or in contact with the internal volume.

[0013] In particular embodiments , the package is formed from polymeric material and the metal is coated on an internal surface of the package or in particulate form or in the form of pieces in the internal volume of the package.

[0014] In a further aspect of the disclosure, there is provided a method of preventing, reducing or delaying non-enzymatic browning in a food or therapeutic substance that comprises one or more amino-containing compounds and one or more carbonyl-containing compounds, said method comprising:

providing a non-metallic package having an internal volume;

providing the food or therapeutic substance to the internal volume of the package; providing a metal to the internal volume of the package, wherein the metal is substantially the only metal in the internal volume of the package and the metal is in contact with the food or therapeutic substance; and

sealing the package.

[0015] In particular embodiments, the metal is tin or magnesium and the metal is coated on at least a portion of an internal surface of the package, forms a coating on a material added to the internal volume of the package, is in particulate form or in pieces in the internal volume in the package, or is in solution in the food or therapeutic substance in the package. In particular embodiments, the method further comprises exposing the sealed package to a process selected from thermal processing, high pressure processing, high pressure thermal processing or electromagnetic, microwave or ohmic heat processing. DETAILED DESCRIPTION

[0016] The singular forms "a", "an" and "the" include plural aspects unless the context clearly dictates otherwise.

[0017] G5. The term "invention" includes all aspects, embodiments and examples as described herein.

[0018] In a first aspect, there is provided a packaged product comprising:

i) a food or therapeutic substance that comprises one or more amino-containing compounds and one or more carbonyl-containing compounds;

ii) a non-metallic package having an internal volume containing the food or therapeutic substance, and

iii) a metal, wherein the metal is in contact with the food or therapeutic substance and the metal is substantially the only metal in the packaged product that is in contact with the food or therapeutic substance.

[0019] The food or therapeutic substance is a food or substance that comprises one or more amino-containing compounds and one or more carbonyl-containing compounds and is therefore able to undergo non-enzymatic browning (NEB). The NEB is initiated during processing by heating and/or pressure and results from the Maillard reaction occurring between the amino groups and carbonyl groups. Examples of suitable amino-containing compounds include, but are not limited to, amino acids, peptides, oligopeptides and proteins. Examples of suitable carbonyl-containing compounds include, but are not limited to, reducing sugars such as glucose, glyceraldehyde, galactose, lactose, maltose and starches including hydrolysed starch. In some embodiments, the amino-containing compound and the carbonyl- containing compound are different compounds. In other embodiments, the amino-containing compound and the carbonyl-containing compound are a single compound having both amino group and carbonyl group.

[0020] In some embodiments, the product is a food, especially food consisting of or comprising one or more of fruit, vegetables, dairy products, meat or fish. In further embodiments the food consists of or comprises fruit.. [0021] In some embodiments, the fruit is selected from one or more of pears, apples, peaches, plums, nectarines, apricots, nashi pears, pineapple, passion fruit, cherries, kiwi fruit, exotic fruits such as mangos, guava, lychees, jakfruit, durian, mangosteen, papaya, abiu, breadfruit, star fruit, giant granadilla, Malay roseapple, mamey sapote, matisia, ramboi, rambutan, custard apple, rollinia, salak, soursop, wax jambu and white sapote and citrus fruits such as lemons, oranges, blood oranges, mandarin, grapefruit, tangerines, limes, pummelo, Clementines, finger limes, kumquats and tangelos.

[0022] In some embodiments, the food consists of or comprises a vegetable. Suitable vegetables include, but not limited to, one or more of, carrots, corn, mushrooms, asparagus, celery, brussels sprouts, broccoli, tomatoes, potatoes, onions, olives, parsnips, turnips, kumara, radishes, yams, swede, cabbage, cucumber, gherkin, artichokes and legumes such as peas, green beans, butter beans, broad beans, kidney beans, lima beans, chick peas, black eyed beans and haricot beans.

[0023] In some embodiments, the food product consists of or comprises a dairy product. Suitable dairy products include, but are not limited to, infant formula, milk concentrates and evaporated milk.

[0024] In some embodiments, the food product consists of or comprises a meat or fish product. Suitable meat or fish products include, but are not limited to, ham, bacon, salami, corned beef, cooked meats such as roast beef, lamb, pork and chicken, salmon, tuna, sardines, kippers and mackerel.

[0025] In some embodiments, the food is packaged in a liquid such as water, syrup, brine, juice, sauce or gravy. In particular embodiments, the liquid has a pH less than 8, especially a pH of 7 or less or a pH of 6 or less or 5 or less, more especially an acidic pH. In particular embodiments, the pH is between 2.5 and 5. In embodiments where the product is a therapeutic substance, the pH may be in the range of 2.5 to 12 and will depend on the identity of the therapeutic substance.

[0026] In some embodiments, the food or therapeutic substance is a liquid. Examples of suitable liquids include fruit juices, fruit purees, vegetable juices, vegetable purees, dairy based drinks, blood serum liquid ingredients and analogue drinks such as those containing protein

[0027] In some embodiments, the therapeutic substance may be selected from syrups, infusions, solutions, suspensions or liquid mixtures in dossifiers or syringes. In some embodiments the therapeutic substance is a plant derived material, which may not be edible, such as leaves, stems, bark, fruit, nuts, sap or exudate, and which may be cut into pieces by slicing, chopping or grating, ground, macerated, pulped or an extract thereof, Each therapeutic substance comprises an amino-containing compound and a carbonyl-containing compound.

[0028] In some embodiments, the food or therapeutic substance may be subject to further treatment with an enzymatic browning inhibitor prior to sealing the package, for example, by soaking, spraying dusting, coating or dipping into an enzymatic browning inhibitor or solution thereof. Examples of enzymatic browning inhibitors include ascorbic acid and ascorbates, citric acid and citrates (e.g. lemon juice), sulphites (e.g sodium bisulfite), phosphoric acid and phosphates, chelating agents (e.g. EDTA) glutathione and cysteine.

[0029] The non-metallic packaging is any non-metallic packaging that is suitable for packaging food or therapeutic substances and is suitable for use in thermal, high pressure, high pressure thermal, electromagnetic heating, or ohmic heating processes. Examples of suitable packaging include glass and flexible packaging such as plastic pouches, plastic bags, plastic cups, plastic tubs or other plastic containers. In particular embodiments, the packaging is flexible packaging, such as plastic pouches, bags, cups, tubs and other plastic containers, the cups and tubs and other plastic containers including spouts, caps, lids or sealed plastic covers.

[0030] Glass packaging is suitable for use in thermal processes, electromagnetic, microwave or ohmic heating processes but is not suitable for use in high pressure processes including high pressure thermal processes.

[0031] In some embodiments, the food or therapeutic substance is subject to processing, such as thermal processing, high pressure processing, high pressure thermal processing, electromagnetic or ohmic heat processing, after packaging has occurred. In other embodiments, the food or therapeutic substance is subject to processing prior to being packaged, and after processing is placed in the package aseptically.

[0032] In some embodiments, the flexible packaging is made of a polymeric material. The polymeric material must be a polymeric material that is a food grade polymeric material that is safe for use in contact with food or therapeutic materials. Examples of suitable polymeric materials include polyethylene polymers, polypropylene polymers, polystyrene polymers, polyvinyl chloride polymers, polyvinyl polymers, poly aery lie acid polymers, ionomers, polyamide polymers, polyacetyl polymers, halogenated olefin polymers, polyester polymers, polyacetal polymers, polyether polymers, polyurethane polymers, polysulfide polymers, polysulphone polymers, silicone polymers, polyallyl ester polymers, silicone rubbers, epoxide resins, petroleum resins, alkyd resins, amino resins or combinations thereof. Suitable polymers include, but are not limited to, polyethylene (PE), polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), biaxially oriented polypropylene (BOPP), retortable cast polypropylene (R-CPP), cast polypropylene (CPP), polystyrene (PS), expanded polystyrene (EPS), general purpose polystyrene (GPPS), styrene butadiene rubber (SBR), polyvinyl chloride, ethylene vinyl acetate (EVA), ethylene vinyl alcohol (EVOH), polyvinyl acetate (PVA), polymethylmethacrylate (PMMA), polyacrytonitrile (PAN), polyethylene oxide (PEO), polyoxymethylene (POM), polyamide (PA), aliphatic polyamide, aromatic polyamide, acrylonitrile butadiene styrene (ABS) and polybutylene terephthalate. In particular embodiments, the polymeric material is selected from polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyvinyl chloride and combinations thereof.

[0033] In some embodiments, the package is in the form of a laminate of more than one polymeric material. There are many possible combinations of two or more layers of polymeric materials and adhesive layers suitable for use in this invention, but by way of non-limiting examples, the package may comprise a laminate of PET and PP, PET and PE, PE and PP, PS and EVOH, PET/Metal/LLDPE, PET/Metal/PA, A-PET/PE (PEEL), BOPP/PE, BOPP/PET/PE, HDPE/foil, PE/EVOH/PE, PP/EVOH/PP, PE/PA/PE, PA/Al/PP, PET/oriented nylon (ON)/Al/R-CPP and PET/A1/CPP, or PET and oriented PA and PP, where interspersed between each layer may be an adhesive.

[0034] In some embodiments, the laminate includes an oxygen transmission barrier (OTB). The OTB may be included between two layers of polymeric material in the laminate and provides a barrier to oxygen entering the internal volume of the package. The presence of oxygen in the internal volume of the package can result in oxidation of the food or therapeutic substance contained in the internal volume, causing deterioration of the food or substance and contributing to discolouration of the product. Non-limiting examples of suitable oxygen transmission barriers include thermoplastic polymer materials such as ethylenevinyl alcohol copolymers (EVOH), polyvinylidene chloride (PVDC), polyamide (PA), polyvinylalcohol (PVOH) and nylon meta-xylenediamine (MXD6) copolymers; metal foils such as aluminium foil, and others such as oxides of aluminium (Al_xO_y) and silicon (SiO_x).

[0035] The metal in contact with the food or therapeutic substance is disposed in the internal volume of the non-metallic package, and is substantially the only metal in contact with the food or therapeutic substance. By the term "substantially the only metal in contact with the food or therapeutic substance" is meant that it is the only metal intentionally included in the internal volume of the package. This term does not exclude the presence of metal contaminants that may be present in small or insignificant amounts in the packaging material or the food or therapeutic substance or metals that may be present in the food or therapeutic product, for example as nutrients, or the presence of metals internally placed within in a laminate or on the external surface thereof, but not forming part of the internal surface of the internal volume of the package.

[0036] By "in contact with the food or therapeutic substance" is meant that the metal is contained in the internal volume of the package where it is able to be in contact with the food or therapeutic substance. In some embodiments, the metal is at least in part constantly in contact with the food or therapeutic substance. In other embodiments, the metal is completely in contact with the food or therapeutic substance. The metal may be disposed within the internal volume so as to be in contact with the food or therapeutic substance for at least a portion of the subsequent processing time, or for the duration of the processing time. [0037] In some embodiments, the metal is present in the liquid that forms the food or therapeutic substance or part of the food or therapeutic substance. For example, the metal may be present in a liquid food such as a fruit or vegetable juice, or may be present in the liquid, syrup, brine, sauce or gravy that forms part of the food or may be present in the liquid therapeutic substance.

[0038] In some embodiments, the metal is present in the internal volume of the package containing the food or therapeutic substance in particulate form or as pieces. For example, the metal may be in the form of metallic granules or metallic foil pieces or strips. The particulate metal may be attached to a surface of the internal volume of the package or may be suspended in the food or therapeutic substance. When the metal is in particulate form or in pieces, it may be contained within a permeable container such as a permeable membrane or tea bag type container suspended in the food or therapeutic substance or attached to the internal surface of the package. When the metal is in the form of metal pieces or strips, the pieces or strips may be suspended in the food or therapeutic substance or may be attached at least in part to the internal surface of the package.

[0039] In some embodiments, the metal is coated on at least part of an internal surface of the package. In some embodiments, the metal is coated on one internal surface of the package. In other embodiments, the metal is coated on part or all of more than one internal surface of the package. The internal surface may be, for example, one or more of the bottom of the cup, tub or other container, one or more of the side walls of a cup, tub or other container, or the lid or sealing material of the cup, tub or other container or the sides of a pouch or bag. The metal may be applied to the internal surface of the package prior to manufacture of the package, during manufacture of the package or after manufacture of the package. The metal may be applied by any suitable means for example, sputter coating, electron-beam evaporation, chemical vapour deposition, plasma-enhanced chemical vapour deposition, plasma spray deposition, atomic layer deposition, electrolytic deposition, autocatalytic deposition and the like. The thickness of the metal coating will depend on the size of the package and the portion of the package coated as well as the desired time of storage of the product, but can be in the order of 0.01 μιη to 700 μιη, especially 0.01 μιη to 500 μιη, 0.01 μιη to 250 μιη, 0.01 μιη to 100 μιη, 0.01 μιη to 50 μιη or 0.01 μιη to 10 μιη, 0.01 μιη to 2.0 μιη. In some embodiments, the thickness of the metal coating is in the range of 0.1 μιη to 1.0 μιη. In some embodiments, the thickness of the metal coating is about or greater than 0.6 μιη, such as about or greater than 0.7 μιη, or about or greater than 0.8 μιη, or about or greater than 0.9 μιη, or about or greater than 1.0 μιη, or about or greater than 1.1 μιη, or about or greater than 1.2 μιη, or about or greater than 1.3 μιη, or about or greater than 1.4 μιη, or about or greater than 1.5 μιη.

[0040] In some embodiments, the metal is coated on at least part of a food- and/or therapeutic substance- grade material present in the internal volume of the package (by which is meant a substance which is safe for use with the food or therapeutic substance. In some embodiments the material is polymeric material, such as described herein, and may be in the form of sheets, films, pieces, strips, fibres, granules or beads. The metal may be applied by any suitable means for example, sputter coating, electron-beam evaporation, chemical vapour deposition, plasma-enhanced chemical vapour deposition, plasma spray deposition, atomic layer deposition, electrolytic deposition, autocatalytic deposition and the like. The thickness of the metal coating will depend on the size of the package and the portion of the package coated as well as the desired time of storage of the product, but can be in the order of 0.01 μιη to 700 μιη, especially 0.01 μιη to 500 μιη, 0.01 μιη to 250 μιη, 0.01 μιη to 100 μιη, 0.01 μιη to 50 μιη or 0.01 μιη to 10 μιη, 0.01 μιη to 2.0 μιη. In some embodiments, the thickness of the metal coating is in the range of 0.1 μιη to 1.0 μιη. In some embodiments, the thickness of the metal coating is about or greater than 0.6 μιη, such as about or greater than 0.7 μιη, or about or greater than 0.8 μιη, or about or greater than 0.9 μιη, or about or greater than 1.0 μιη, or about or greater than 1.1 μιη, or about or greater than 1.2 μιη, or about or greater than 1.3 μιη, or about or greater than 1.4 μιη, or about or greater than 1.5 μιη. The metal coated material may be attached to a surface of the internal volume of the package or may be suspended in the food or therapeutic substance. The metal coated material may be contained within a permeable container such as a permeable membrane or tea bag type container suspended in the food or therapeutic substance or attached to the internal surface of the package. Alternatively, the metal coated material may be suspended in the food or therapeutic substance or may be attached at least in part to the internal surface of the package. It will be understood that the material may be a laminate as described herein, and which may include an internal metal layer, however, the internal metal layer does not make contact with the food or therapeutic substance in the package. [0041] The metal may be any metal that is able to prevent reactions that lead to non- enzymatic browning and is considered safe for human consumption. There may be regulations or guidelines as to how much metal may be present in the food or therapeutic product at the point of consumption. In some embodiments, the metal is selected from one of tin, magnesium, copper, iron, zinc, nickel, cobalt, aluminium or chromium. In further embodiments, the metal is tin or magnesium. In still further embodiments, the metal is tin.

[0042] The metal may be present in elemental form or as a metal salt or oxide and may be disposed in the internal volume of the package in solid or solution form as appropriate. Thus in some embodiments, the metal is selected from elemental tin, magnesium, copper, iron, zinc, nickel, cobalt, aluminium or chromium and/or a salt thereof and/or an oxide thereof. In some embodiments the metal is present in elemental form. In some embodiments the elemental metal has a purity of at least 95%, such as at least 97%, 98%, or 99%. In still further embodiments, the metal is elemental tin or magnesium and has a purity of at least 98 or 99%.

[0043] In some embodiments, the metal is tin and is present in the package either coated on at least a portion of an internal surface of the package, or coated on a food- or therapeutic substance-grade material present in the internal volume of the package. In still further embodiments thereof, the package is a pouch, such as a retort pouch, or bag.

[0044] The amount of metal present in the internal volume of the package depends on

(i) the size of the package;

(ii) the quantity of food or therapeutic substance in the package;

(iii) the length of time the food or therapeutic substance requires storage before consumption;

(iv) the storage conditions, such as temperature;

(v) the regulations relating to the amount of the metal that may be present in a consumable item;

(vi) the processing conditions of the thermal, high pressure, high pressure thermal or electromagnetic or ohmic heat processing;

(vii) the composition of the food product, especially pH, dissolved oxygen level and the presence of nitrites, nitrates, anthracyanins and sulfur compounds. [0045] The amount of metal present is calculated taking into account these factors, so that the desired storage time can be achieved while not exceeding the maximum amount of metal allowed in the consumable product. In some embodiments, the amount of metal does not exceed about 200 ppm.

[0046] The packaged product may be for retail purposes to be sold in supermarkets or during food service in cafes and restaurants and the like, or may be prepared for specific purposes such as for institutions including hospitals, prisons or nursing homes or for combat rations such as Military Ready to Eat (MRE) meals.

[0047] In another aspect of the disclosure, there is provided a non-metallic package having an internal volume, said internal volume comprising a metal, wherein the metal is substantially the only metal in or in contact with the internal volume.

[0048] The non-metallic package is useful in the packaged product described above.

[0049] The package may be any suitable size and shape to package the food or therapeutic substance. In some embodiments, the package may be in the form of a pouch, such as a retort pouch or stand-up retort pouch, a bag, a cup, a tub or a bottle, and may be, for example, cylindrical, frustoconical, bursiform, square tubular or tray shaped. The package may contain a pouring or dispensing means such as a cap or spout. The package may be sealed by any suitable means, for example, by use of a lid, cap or peel-back covering for cups, tubs or bottles or, as in the case of pouches or bags, the two upper edges may be sealed using an adhesive or heat such as known in the art, optionally incorporating a cap or spout. In some embodiments, the pouch or bag may be vacuum sealed.

[0050] In some embodiments, the package or at least part of the package is transparent, translucent or opaque. At least part of the package may be transparent if it is desirable to have manufacturer, retailer or consumer visual inspection of the food or therapeutic substance inside the package.

[0051] The package may have an internal volume of a size suitable to store the desired amount of product. The package may be of a size suitable for a single serve of food or dose of therapeutic substance or multiple servings of food or doses of therapeutic substance. Alternatively, the package may be of a size suitable for bulk storage, for example, after harvest or preparation where the product may be processed or semi-processed such as by washing, until the time the product is repackaged for retail or medical purpose.

[0052] In yet another aspect of the disclosure, there is provided a method of preventing, reducing or delaying non-enzymatic browning in a food or therapeutic substance that comprises one or more amino-containing compounds and one or more carbonyl-containing compounds, said method comprising:

providing a non-metallic package having an internal volume;

sealing the package.

[0053] The method makes use of the package and forms the packaged food described above.

[0054] In some embodiments, the method further comprises a step of treating the sealed package with a process selected from thermal processing, high pressure processing, high pressure thermal processing and electromagnetic (microwave or radiofrequency) or ohmic processing, especially thermal processing, high pressure thermal processing and high pressure processing, more especially high pressure thermal processing. In other embodiments, the food or therapeutic substance is treated with a process selected from thermal processing, high pressure processing, high pressure thermal processing and electromagnetic (microwave or radiofrequency) or ohmic processing before being provided to the internal volume of the package, wherein filing the internal volume of the package occurs under aseptic conditions. In some embodiments, processing occurs before the package is sealed. In other embodiments, the processing occurs after the package is sealed.

[0055] In some embodiments, the methods of preventing, reducing or delaying non- enzymatic browning in a food or therapeutic substance, is a method of extending or increasing the shelf life of the food or therapeutic substance. In some embodiments, the shelf life may be extended to 20-fold, 15-fold, 10-fold, 8-fold or 5-fold the length of time compared to packaged food or therapeutic substance that does not include the metal in the internal volume of the package. In some embodiments, the packaged food or therapeutic substance may refrigerated (for example at 4-10°C) , or be stored at room temperature or without refrigeration for a desired period of time, such as at least 4 weeks, or 2-3 months, or 6 months, 12 months or more, depending on the nature of the food or therapeutic substance.

[0056] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[0057] Throughout this specification and the claims which follow, unless the context requires otherwise, the phrase "consisting essentially of", and variations such as "consists essentially of" will be understood to indicate that the recited element(s) is/are essential i.e. necessary elements of the invention. The phrase allows for the presence of other non-recited elements which do not materially affect the characteristics of the invention but excludes additional unspecified elements which would affect the basic and novel characteristics of the invention.

[0058] The disclosure will now be described with reference to the following examples that illustrate some non-limiting aspects thereof. However, it is to be understood that the particularity of the following description is not to supersede the generality of the preceding description.

BRIEF DESCRIPTION OF THE FIGURES

[0059] Figure 1 provides graphical representations of the visual colour change in pear samples with tin foil or SnCl₂ at varying concentrations (0-300 ppm) during storage at (a) 4°C and (b) 37°C.

[0060] Figure 2 provides graphical representations of the instrumental colour (lightness) change in pear samples with tin foil or SnCl₂ at varying concentrations (0-300 ppm) during storage at (a) 4°C and (b) 37°C.

[0061] Figure 3 provides graphical representations showing the effect of tin foil and tin coated film on visual colour index of High Pressure Thermal treated pears during storage at (a) 4°C, (b) 20°C and (c) 37°C.

[0062] Figure 4 provides graphical representations showing the effect of tin foil and tin coated film on instrumental colour change of High Pressure Thermal treated pears during storage at (a) 4°C, (b) 20°C and (c) 37°C.

[0063] Figure 5 provides graphical representations showing the visual colour index of commercially heat treated pears during storage at 4°C, 20°C and 37°C.

[0064] Figure 6 provides graphical representations showing the instrumental colour change of commercially heat treated pears during storage at (a) 4°C, (b) 20°C and (c) 37°C.

[0065] Figure 7 provides a graphical representation of the visual colour change in high pressure thermally treated pear samples with added tin-coated film having various tin surface areas and nominal tin concentration per package (0-296 ppm) after storage at 37°C.

[0066] Figure 8 provides a graphical representation of the visual colour change in pear samples with added tin-coated film at various tin surface areas and nominal tin concentration per package (0-296 ppm) after storage at 20°C.

[0067] Figure 9 provides a graphical representation of the visual colour change in pear samples with added tin-coated film having various tin-coating thickness per package (0, 0.1, 0.2, 0.5, 0.8, and 1 μιη) after storage at 37°C. [0068] Figure 10 provides a graphical representation of the visual colour change in retorted pear samples with added tin-coated film (tin coating thickness: 1 μηι) having a tin surface area of 100 cm and a nominal tin concentration per package of 222 ppm after storage at 37°C.

[0069] Figure 11 provides the chromatogram from headspace solid phase micro- extraction (SPME)- gas chromatography mass spectrometry (GCMS) analysis in HPT treated pear samples without metal addition, with tin foil and with Mg metal foil, respectively indicating the formation of Maillard reaction compounds furfural and acetic acid after processing.

EXAMPLES

Example 1: Effect of tin foil and dissolved tin salts on non-enzymatic browning of pears during storage after high pressure thermal treatment

[0070] Packham pears were dipped in 200 ppm chlorine solution at 20°C for 2 min. Pears were peeled, cored and quartered manually, and submerged in 1000 ppm ascorbic acid solution to prevent enzymatic browning. The syrup (20° Brix) was prepared by using sucrose (2 kg) and potable water (10 L). The pH of the syrup was adjusted to < 3 using 10 g ascorbic acid. Calcium chloride (25 g) was added to the syrup to improve the texture of the final product. The syrup was heated to 85°C using a steam operated kettle. Stand-up-retort pouches ( 140 mm x 185 mm x 80 mm) made of 3-ply laminate (PET ( 12 μιη), ALOX / ADH / PRINT / OPA (15 μηι) and ADH / CLEAR PP (70 μιη) were used.

[0071] Tin pieces were cut into squares with a surface area required for each experiment. The tin foil had a purity of 99% and 0.25 mm thickness. A stannous chloride stock solution with a concentration of 20 mg/mL was made using stannous chloride salt and deionised water.

[0072] Three pear pieces and syrup (1: 1 w/w) were placed in retort pouches to make 200 g packs, vacuum sealed and stored at 30°C until high pressure high temperature (HPT) treatment. The following treatments were applied to pear packages:

• Treatment 1 - Control - No additional treatment was applied.

• Treatment 2 - A tin foil piece with a surface area of 87 cm was placed inside each pack in addition to pear and syrup.

• Treatments 3 - 100 ppm SnCl₂ per package.

• Treatment 4 - 200 ppm SnCl₂ per package.

• Treatment 5 - 250 ppm SnCl₂per package.

• Treatment 6 - 300 ppm SnCl₂per package. [0073] Ten packs were made with each treatment combination for the storage trial. Samples were sealed using a vacuum sealer at a vacuum level of -0.8 bar. Pear packs were placed in the upper compartment of the insulated carrier cage and preheated at 95 °C in a heating tower. During the preheating stage the product reached 85°C after 20 min. The high pressure vessel was heated to 90°C and the water in the vessel was heated to 85°C prior to the high pressure runs. The preheated insulated cage at 85°C was transferred to the high pressure processing unit and the high pressure process was carried out at 600 MPa for 3 min.

[0074] Samples from each treatment were stored at either 37°C or at 4°C. Samples were photographed and colour was measured instrumentally (Minolta CR 200, Japan) and visually scored during a 6-month period.

[0075] The temperature of the pear packs reached 105- 109°C during the HPT process at 600 MPa for 3 min. Addition of tin foil to HPT pear packs was effective in preventing non- enzymatic browning up to 51 days at 37°C and decreased browning rate during further storage at 4° and 37°C as shown by the visual scores and instrumental colour values in Figures 1 and 2. The colour of the treated pear packages containing tin foil was retained during 24 weeks at 4°C. However, SnCl₂ at various concentrations initially inhibited browning within the first two weeks only.

[0076] Volatile markers of non-enzymatic browning were detected in all samples soon after processing. At 37°C storage for 2 months, key pear flavour compounds (esters) were lost in all samples. Marker compounds for non-enzymatic browning (acetic acid and furfural) were detected in all processed samples. Low levels of acetic acid and furfural were detected in the sample containing tin foil as compared to other treatments, indicating the effect of added tin on non-enzymatic browning inhibition.

Example 2: Effect of tin foil and tin coated film on non-enzymatic browning of pears during storage after high pressure thermal treatment

[0077] Samples of pear were prepared and subject to high pressure thermal (HPT) treatment following the procedure described in Example 1 with the exception that a higher temperature was used in the HPT processing. Each sample package contained one piece of pear (30 g) and 30 niL of syrup. The following treatments were applied to the pear packages before sealing:

• Treatment 1 - Control - No additional treatment was applied

• Treatment 2 - A tin foil with a surface area of 24.5 cm was placed inside each pack in addition to pear and syrup.

• Treatment 3 - One internal side of the package was coated with a tin film (49 cm ) in addition to pear and syrup. Tin film was prepared by sputter coating a flexible packaging material with tin metal at a thickness of 0.2 μιη.

[0078] Twelve packs were made for each treatment combination for the storage trial. Samples were sealed using a vacuum sealer at a vacuum level of -0.8 bar and stored for ~ lhr at 30°C until high pressure high temperature treatment. Replicate HPT runs were performed at 90°C initial temperature and 600 MPa for 3 min. Four replicate samples from each treatment were stored at 4°C, 20°C, and 37°C. Samples were evaluated at 7 -10 day intervals. Samples were photographed, colour was measured instrumentally (Minolta CR 200, Japan) and subjective score was assigned.

[0079] Temperature of pear packs reached >115°C during HPT run at 600 MPa for 3 min. Addition of tin foil to HPT pear was effective in preventing non-enzymatic browning and decreased browning rate during further storage as shown by the instrumental colour, visual scores and L values (lightness) in Figures 3 and 4. At 4°C the colour of HPT pear with tin foil, film and control maintained a visual score < 3 during the 123 days of storage. At 20°C and 37°C addition of tin foil delayed browning for 84 and 49 days (score < 3). However, at 20°C and 37°C the addition of tin coated film could only delay browning initially and a visual score < 3 was maintained for 59 and 10 days, respectively. However, the colour differences observed with visual score were not as clearly seen with the instrumental colour measurements.

[0080] During HPT treatment, tin completely dissolved from the deposited film into the syrup/product. The amount of tin included in the form of tin film was 117 ppm and this is ~ 50% less than the amount of tin allowed in canned products which is 200 ppm and this may be the reason for observing non-enzymatic browning at 20°C and 37°C after 59 and 10 days respectively. In addition, a higher temperature during the HPT may have caused the formation of larger concentrations of non-enzymatic browning precursors or products.

Example 3: Evaluation of colour stability of commercial pears heat processed in flexible packaging, without metal addition

[0081] Commercial thermally treated pear packs (pear pieces and syrup packed in sealed cups) were obtained from a local supermarket. The packs were obtained from two different processing batches (B 1 and B2). Four replicate samples from each batch were stored at 4°C, 20°C and 37°C.

[0082] Samples were evaluated at 7-10 day intervals for 56 days. Samples were photographed, colour was measured instrumentally (Minolta CR 200, Japan) and a subjective score was assigned.

[0083] At the time of purchase the commercial samples had a visual colour score of 2.0 and 2.5 for batches B l and B2, respectively. According to the visual score, the colour of commercial samples gradually increased at 37°C. The colour scores of samples stored at 37°C ranged between 3.5 and 4.0 after 56 days. Colour values at 4°and 20°C were stable and fluctuated between a visual score of 2-3 (Figure 5). Differences detected visually were not seen in instrumental measurement of lightness (L value) graph (Figure 6).

Example 4: Effect of thickness and surface area of tin coated films added to pear packs on NEB after high pressure thermal and retort treatments.

[0084] Pear packages were prepared as described in Example 1. Before sealing the sample packages, tin coated film prepared by sputter coating were added in-coated plastic film pieces to sample packages. The various tin-coating thicknesses on the plastic film were as follows:

• Treatment 1 - Control; no tin coating was applied

• Treatment 2 - Film coated with 0.1 μιη tin thickness (140 cm ); nominal tin

concentration per pack: 207 ppm 2

• Treatment 3 - Film coated with 0.2 μιη tin thickness (140 cm ); nominal tin

concentration par pack: 207 ppm

• Treatment 4 - Film coated with 0.5 μιη tin thickness (100 cm ); nominal tin

concentration per pack: 185 ppm

• Treatment 5 - Film coated with 0.8 μιη tin thickness (70 cm ); nominal tin

concentration per pack: 207 ppm

• Treatment 6 - Film coated with 1 μιη tin thickness (30 cm ); nominal tin

concentration per pack: 111 ppm

• Treatment 7 - Film coated with 1 μιη tin thickness (60 cm ); nominal tin

concentration per pack: 222 ppm

• Treatment 8 - Film coated with 1 μιη tin thickness (80 cm ); nominal tin

concentration per pack: 296 ppm

[0085] Samples were subjected to high pressure thermal (HPT) treatment following the procedure described in Example 1 with the exception that 600 MPa and 110°C process temperature for 3 min was used in the HPT processing. A separate set of pear samples was retorted at 95°C for 18 min.

[0086] Triplicate samples from each treatment were stored at 20°C and 37°C. A trained panel used a hedonic scale ranging from 1 -9 to rate colour development in the samples at 7 - 10 day intervals. In most cases, sample colour was followed for a period of 6 months. A score of 2.5 has been designated as the threshhold limit of acceptable colour based on the collective assessment of the trained panel for commercial shelf stable pears.

[0087] Treatments 7 and 8 produced a 25 day delay in reaching the threshold limit of acceptable colour compared to the HPT (no tin) control during accelerated storage at 37°C (Figure 7). This is supported by colour data of HPT treated pears stored at 20°C (Figure 8), where the control (Treatment 1) reached a score higher than the acceptability threshold limit after 2 months storage, and tin added samples could preserve an acceptable colour for at least a testing period of 6 months. [0088] Addition of tin-coated film having a thickness greater than 0.1 μιη allowed the pear colour to remain below the acceptability threshold for an additional month (Figure 9). Films coated with lower tin thickness were more prone to releasing almost all of the tin coating into the syrup on completion of the HPT processing step. Addition of tin-coated film at 222 ppm (Ιμιη thickness and 100 cm ) provided similar protection to retorted samples (Figure 10), with samples containing added tin-coated film or metallic tin remaining within the acceptability threshold during a storage period of 28 days at 37°C.

Example 5: Effect of Mg metal foil on Maillard browning of pears during storage after high pressure thermal treatment

[0089] Pear packages were prepared as described in Example 1. Before sealing the sample packages, Mg metal pieces or tin metal pieces of 8 cm x 6.25 cm (total metal surface area 100 cm ) were added to pear in syrup packages. Samples were subjected to HPT treatment following the procedure described in Example 1 with the exception that 600 MPa and 110°C process temperature for 3 min was used in the HPT processing. Headspace solid phase micro- extraction (SPME)-GCMS analysis was used to analyse the volatile compounds in 0.5 g of untreated and processed samples after treatment.

[0090] Maillard browning compound precursors (furfural/acetic acid) were detected in HPT treated samples without metal addition and with added tin foil. However, formation of these compounds were absent upon addition of Mg metal foil in the package after HPT processing.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A packaged product comprising:

i) a food or therapeutic substance that comprises one or more amino-containing compounds and one or more carbonyl-containing compounds; ii) a non-metallic package having an internal volume containing the food or therapeutic substance, and

2. The packaged product according to claim 1 wherein the one or more carbonyl- containing compounds is one or more reducing sugars.

3. The packaged product according to either of claim 1 or claim 2 wherein the packaged product comprises a food.

4. The packaged product according to claim 3 wherein the food comprises fruit, vegetable, dairy, meat or fish.

5. The packaged product according to either of claim 3 or claim 4 wherein the food is a liquid.

6. The packaged product according to any one of claims 1 to 5 wherein the non- metallic package is glass.

7. The packaged product according to any one of claims 1 to 5 wherein the non- metallic package is a flexible package.

8. The packaged product according to claim 7 wherein the flexible package comprises a polymeric material.

9. The packaged product according to claim 8 wherein the flexible package comprises a laminate of polymeric materials.

10. The packaged product according to claim 9 wherein the laminate of polymeric materials further comprises an oxygen transmission barrier.

11. The packaged product according to any one of claims 1 to 10 wherein the metal is selected from tin, magnesium, copper, iron, zinc, nickel, cobalt, aluminium and chromium.

12. The packaged product according to claim 11 wherein the metal is tin or magnesium.

13. The packaged product according to any one of claims 1 to 12 wherein the metal is incorporated in the food or therapeutic substance.

14. The packaged product according to any one of claims 1 to 13 wherein the metal is present in the food or therapeutic substance in particulate form.

15. The packaged product according to claim 14 wherein the metal is in the form of one or more metallic pieces.

16. The packaged product according to any one of claims 1 to 12 wherein the metal is coated on one or more internal surfaces of the package.

17. The packaged product according to any one of claims 1 to 16 which has been treated by a process selected from thermal processing, high pressure processing, high pressure thermal processing and electromagnetic heat processing or ohmic heat processing.

18. A non-metallic package having an internal volume, said internal volume comprising a metal, wherein the metal is substantially the only metal in or in contact with the internal volume.

19. The package according to claim 18 wherein the package is formed from glass.

20. The package according to claim 18 wherein the package is formed from polymeric material.

21. The package according to claim 20 wherein the polymeric material is in the form of a laminate.

22. The package according to claim 21 wherein the laminate of polymeric materials further comprises an oxygen transmission barrier.

23. The package according to any one of claims 17 to 22 wherein the metal is in particulate form.

24. The package according to claim 23 wherein the metal is in the form of one or more metallic pieces.

25. The package according to any one of claims 17 to 24 wherein the metal is coated on one or more surfaces of the internal volume.

26. A method of preventing, reducing or delaying non-enzymatic browning in a food or therapeutic substance that comprises one or more amino-containing compounds and one or more carbonyl-containing compounds, said method comprising:

providing a non-metallic package having an internal volume;

sealing the package.

27. The method according to claim 26 wherein the metal is in particulate form.

28. The method according to claim 27 wherein the metal is in the form of one or more pieces of metallic foil.

29. The method according to claim 26 wherein the metal is coated on one or more surfaces of the internal volume of the package.

30. The method according to any one of claims 26 to 29 wherein the metal is selected from tin, magnesium, copper, iron, zinc, nickel, cobalt, aluminium and chromium.

31. The method according to claim 30 wherein the metal is tin or magnesium.

32. The method according to any one of claims 26 to 31 wherein the one or more carbonyl- containing compounds is one or more reducing sugars.

33. The method according to any one of claims 26 to 32 wherein the food comprises fruit, vegetables, dairy, meat or fish.

34. The method according to any one of claims 26 to 33 further comprising a step of treating the sealed package with a process selected from thermal processing, high pressure processing, high pressure thermal processing, electromagnetic heat processing and ohmic heating processing.