DESC:FIELD OF THE INVENTION

The present invention relates to a food antioxidant packaging materials, capable of holding the food product and allows the antioxidant to migrate into the food product in a sustained manner and its process of preparation.

BACKGROUND OF THE INVENTION

Oxidation is the second most important cause of food deterioration after that induced by microbiological contamination. Food products are often susceptible to oxidation. Oxidation of food is a destructive process, causing loss of nutritional value and changes in chemical composition, leading to unhealthful compounds. Oxidation of fats and oils involves a free radical chain mechanism which leads to rancidity, discoloration, and off-flavors. Oxidation reactions happen when chemicals in the food are exposed to oxygen in the air.

Two principal types of oxidation that contribute to food deterioration are “autoxidation” and “enzyme-catalyzed oxidation”.

Autoxidation of unsaturated fatty acids involves a reaction between the carbon-carbon double bonds and molecular oxygen (O2) that produces highly reactive free radicals which causes the off-flavours and off-odours, characteristics of oxidative rancidity. Antioxidants that react with the free radicals (free radical scavengers) can slow the rate of autoxidation. These include the naturally occurring tocopherols (vitamin E derivatives) and the synthetic compounds butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tertiary butylhydroquinone (TBHQ).

Specific enzymes also carry out the oxidation of many food molecules, which leads to quality change in the food. For example, enzymes called phenolases catalyze the oxidation of certain molecules (e.g., the amino acid tyrosine) when fruits and vegetables, such as apples, bananas, and potatoes, are cut or bruised. The product of these oxidation reactions collectively is known as enzymatic browning. Antioxidants that inhibit enzyme-catalyzed oxidation include agents that bind free oxygen (i.e., reducing agents), such as ascorbic acid (vitamin C), and agents that inactivate the enzymes, such as citric acid and sulfites.

An age-old technique for preserving food was to “cure” it with salt (used mostly with meat and fish). Sugar was also added to fruits to prevent spoilage. There are certain spices and herbs that are used in preservation methods. Vinegar and vitamins (such as vitamins C & E) can also be used as preservatives.

A squeeze of lemon juice on cut fruit or veggies staves off enzymatic browning for a time. The citrus changes the pH level of the product, in turn neutralizing the enzymes and preventing the browning process, which means better looking and fresher tasting fruits and veggies.

Common preservation techniques to slow oxidation, without adding flavors, are: drying, freeze drying, freezing, vacuum packing, canning, preserving in syrup, sugar crystallization and adding preservatives or inert gasses such as carbon dioxide or nitrogen.

Air-tight packaging, using inert gases like nitrogen, vacuum packing and refrigeration can all be used to delay the oxidation process. However, these can still be inefficient and adding antioxidants can be an effective way of extending the shelf life of a product.

Antioxidants are used to retard the oxidation of chemicals in the food. The main purpose of using an antioxidant as a food additive is to maintain the quality of that food and to extend its shelf life rather than improving the quality of the food. Antioxidants are an especially important class of preservatives. Unlike bacterial or fungal spoilage of food, oxidative damage can occur even in refrigerated and sealed food items which can be prevented by the use of antioxidants.

Antioxidants prevent the formation of peroxides and slow the process of the spoilage of the food. Some antioxidants react with oxygen itself and so prevent the formation of peroxides.

Antioxidants are often added to fat-containing foods in order to retard the development of rancidity due to oxidation.
Natural anti-oxidants include flavonoids, polyphenols, ascorbic acid (vitamin C) and tocopherols (vitamin E).

Synthetic antioxidants include butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate etc.

The natural antioxidants tend to be short-lived, so synthetic antioxidants are used when a longer shelf life is preferred.

Several attempts have been made in the art for sustained release of antioxidants into the food composition. Some of the references are summarized below.

CN102450724B discloses a fat-containing food antioxidative hydrogen sustained-release material comprises zinc powder, iron powder, citric acid, and calcium chloride in the ratio of 0.2:1.25:0.75-1.25:0.5-0.75 respectively. The quality guarantee period of the fat-containing food antioxidative hydrogen sustained-release substance is within 6 months.

CN103435894A discloses sustained-release antioxidant food packaging and preparation method that comprises film substrate, high density polyethylene and ethylene-vinyl acetate copolymer blend, diatomite, and quercetin. The antioxidant food packaging film has high antioxidant retention, good mechanical properties and oxygen resistance.

US2007/0010632A1 discloses a method of controlled delivery of an antioxidant to a subject, involves the coupling of antioxidants to each of the plurality of biodegradable monomers which are then enzymatically polymerized. The resultant antioxidant coupled polymer will degrade over time and deliver the antioxidant at a controlled rate.

US2012/0276357A1 describes a method for controlling tocopherol migration. This is achieved by adding to the polymer an adequate quantity of tocopherol, and a food grade surface modifier agent that can be glycerol monostearate, erucamide, or any other food grade surface modifier agent.
Previously antioxidants were added to the packaged foods/ oils to scavenge the oxygen radicals. However, this process is also associated with adverse side effects such as allergies, carcinogenic effects etc.

To solve this problem, antioxidants were added or coated on to the packaging materials. However, these antioxidants often lack high retention rate and effective utilization, it is difficult to form long-lasting antioxidant protection and also causes high production costs.

Polymers like HDPE are often used in food product packaging. Generally, additives like talc are added to the polymer system for structuring of polymer. These additives increase the strength, stiffness and reduce the cost. One of the major concerns of using such mineral additives in structuring polymers for packaging of food product is that they sometime increase the oxidation of oil due the presence of pro-oxidative metal ions present in it.

In order to overcome the above mentioned disadvantages involved in the prior art technology, the present invention aims to introduce antioxidant into the polymer composition along with the structurant. The antioxidant gets migrated into the food products in a slow and sustained manner and prevents the oxidation and increases the shelf life of the food product. This process involves the addition of steam treated talc so as to render antimicrobial properties to the packaging.

OBJECT OF THE PRESENT INVENTION

The principle object of the invention is to provide packaging materials that release the antioxidants in a sustained manner to the food present in it.

Another object of the present invention is to provide a manufacturing process for packaging material for food/ oils which are susceptible to oxidation.

Yet another object of the present invention is the use of antioxidants in food compositions to stabilize flavor components, maintain colour, prevent the formation of off odors, and increase the shelf life of the processed product.

Still yet another object of the present invention is to provide a process of adding steam treated talc to render antimicrobial properties to the packaging.

The above objectives are achieved by introducing antioxidants into the polymer composition along with the structurant. The antioxidant gets migrated into the food products in a slow and sustained manner and prevents the oxidation thus enhancing the shelf life of the food product.

SUMMARY OF THE INVENTION

The present invention relates to the structuring of polymers with antioxidants for sustained release of antioxidants into the food present in packaging materials and preparation method thereof.

The present invention provides an active food packaging material comprising of
i. 1 - 30% of structurant;
ii. 1 - 2% of antioxidant;
iii. 68 - 98% of virgin plastic;
iv. 1 - 2% flow modifiers; and
v. 1-2% of pigments.

The present invention provides a process which involves the blending of structurants with the antioxidants to form a premixed composition. The premixed composition is then blended with pigment and a suitable flow modifier to form master batch.

The master batch is diluted with virgin plastic to required composition and is moulded into variously shaped bottles or containers. Food product is filled into the container and packed off.

The structurant particle along with the antioxidant will migrate into the product in a sustained manner. The rate of migration depends upon the chemical nature of the food product. The food product now contains the antioxidants which are migrated from the container and the oxidation of the food product is prevented.

It should be understood that alternatives for the present invention could be realized. The following discussion describes merely exemplary embodiments illustrating the principles of the present invention, the scope of which is recited in the claims. Those skilled in the art will readily recognize from the description and claims that numerous changes and modifications can be made without departing from the spirit and scope of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flow chart showing the steps involved in the process of preparation of packaging materials.
FIG. 2 is a graphical representation showing the delivery of vitamin C (ascorbic acid) from plastic materials.

DETAILED DESCRIPTION

The present invention provides an active food packaging material comprising of
i. 1 - 30% of structurant;
ii. 1 - 2% of antioxidant;
iii. 68 - 98% of virgin plastic;
iv. 1 - 2% of flow modifiers; and
v. 1-2% of pigments.

Non-limiting examples of structurants include talc, kaolin, mica, montmorillonite and silicate minerals which are compatible for food grade packaging.

Non-limiting examples of antioxidants include propyl gallate (PG), ascorbic acid, sucrose acetate isobutyrate (SAIB), tert-butyl hydroquinone (TBHQ), citric acid, 2 and 3-tert-butyl-4-hydroxyanisole, 2,3-tert-butyl-4-methoxyphenol (BHA), 3,5-di-tert-butyl-4-hydroxytoluene (BHT), sodium erythorbate (monohydrate of D-isoascorbate sodium or -lactone), sorbic acid (SBA), phytic acid [(myo-inositol hexakis (dihydrogen phosphate)].

Non-limiting examples of polymers include High density polyethylene (HDPE), Low density polyethylene (LDPE), Linear low-density polyethylene (LLDPE), Polypropylene (PP), Nylons, polyolefins and polyamides.

The pigments or flow modifiers that could be used in the present invention include all the potential pigments or flow modifiers that can be used for food grade plastics. The exhaustive list is available in the following standard (IS 9833 - List of pigments and colourants for use in plastics in contact with foodstuffs, pharmaceuticals and drinking water).

Flow modifiers could include ethyl vinyl acetate (EVA), very low-density polyethylene, mineral oils and the like. According to this invention, packages or plastic articles are used to preserve, store and/or transfer the food products such as flowable foods, particularly liquids including oils.

The present invention provides a process for the preparation of food packaging materials for sustained release of antioxidants into the food present in it.

The process of preparation of packaging materials of the present invention has been illustrated in figure 1. The process comprises of the following steps:
a) blending of the structurant with the nutrients (antioxidants);
b) addition of pigments/ suitable flow modifier to the above composition to form the master batch;
c) dilution of the master batch with virgin plastic; and
d) moulding of the composition to various shaped plastic bottles and containers.

According to this invention, the structurants with a particle size of 50 microns or less are subjected to super-heated steam treatment at a temperature of 150°C for 1 hr in order to make it free of microbes. The blending of the both structurant and the antioxidant are done thoroughly to ensure proper mixing of the both. The premixed composition of structurant and antioxidant are blended with the pigment and suitable flow modifier to form master batch.

The master batch is diluted with the virgin plastic to required composition and is moulded into variously shaped bottles or containers. Food product is filled into the container and packed off.

The structurant particle along with the antioxidant will migrate into the product in a sustained manner. The rate of migration depends upon the chemical nature of the food product. The food product now contains the antioxidants which are migrated from the container and the oxidation of the food product is prevented.

According to the present invention, the antioxidant blend time is from 30 to 45 min.

According to the present invention, the moulding temperature ranges from about 150-180 °C.

According to the present invention, the resident time of the composition in the extruder is 10-20 seconds.

EXPERIMENTAL DETAILS

EXAMPLE 1
To demonstrate the delivery of vitamin from the plastic materials disclosed in the present invention, the material was prepared with and without vitamin (e.g. vitamin C). The moulded plastic materials were cut into small pieces and delivery of the vitamin C from these pieces was evaluated using the following process and the results are graphically presented in Fig 2.
Step 1. 100 ml water was taken in a container with a lid;
Step 2. A piece of plastic material (2 gm) was placed in the water mentioned in step 1 and stirred;
Step 3. Aliquots were drawn at different time intervals, scanned and measured the absorbance of the aliquot at 264 nm (which is the ?max of vitamin C in water); and
Step 4. Calculated the concentration of vitamin C from a standard curve constructed using known concentration of vitamin C

The characteristic absorption peak associated with the ascorbic acid present in the aliquot of the plastic material is indicative of the migration of vitamin C from the plastic material to the food product.

While this invention has been described with reference to an illustrative embodiment, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiment will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention. ,CLAIMS:
1. An active food packaging material comprising of
i. 1 - 30% of structurant;
ii. 1 - 2% of antioxidant;
iii. 68 - 98% of virgin plastic;
iv. 1 - 2% of flow modifiers; and
v. 1 – 2% of pigments.

2. The active food packaging material according to claim 1, wherein the said structurant is selected from the group consisting of talc, kaolin, mica, montmorillonite, silicate minerals and any material that would be compatible for food grade packaging, and combinations thereof.

3. The active food packaging material according to claim 1, wherein the said antioxidant is selected from the group consisting of propyl gallate (PG), ascorbic acid, sucrose acetate isobutyrate (SAIB), tert-butyl hydroquinone (TBHQ), citric acid, 2 and 3-tert-butyl-4-hydroxyanisole, 2,3-tert-butyl-4-methoxyphenol (BHA), 3,5-di-tert-butyl-4-hydroxytoluene (BHT), sodium erythorbate (monohydrate of D-isoascorbate sodium or -lactone), sorbic acid (SBA), phytic acid [(myo-inositol hexakis (dihydrogen phosphate)].

4. The active food packaging material according to claim 1, wherein the particle size of structurant is in the range of 50 microns or less.

5. An active food packaging material of claim 1, wherein the said material comprising the structurant migrates the antioxidant into the food product in a sustained manner.

6. A process of manufacturing an active food packaging material comprising of
a) blending of a structurant with the nutrients (antioxidants);
b) addition of flow modifiers and pigments to the above composition to form the master batch;
c) dilution of the master batch with virgin plastic; and
d) moulding of the composition to bottles and containers of desired shape.
7. The process of claim 1, wherein the blend time of the antioxidants is 30 to 45 min.

8. The process of claim 1, wherein the moulding temperature is in the range of about 150-180 °C.

9. The process of claim 1, wherein the resident time of the composition in the extruder is 10-20 seconds.