MODERNIZING EDIBLE OIL & GHEE PACKAGING

S.K ANSARI, SEEMA ANSARI
(feedback@pgeconomist.com)

June 6 - 12, 2011

Oils and fat form an important constituent of human food. In Pakistan, the fats used as cooking media are generally vegetable oil, vanaspati and ghee.

Vegetable oil is derived from seeds of plants. Among the oilseeds cultivated in Pakistan, from which edible oil is obtained, are groundnut, rapeseed, mustard, sesame, safflower, sunflower, niger, soybean, linseed and castor. The other sources of vegetable oil are palm, cottonseed, coconut and rice bran. Generally, the two methods employed for obtaining edible oil are pressing and solvent extraction. The crude oil thus obtained may be refined, bleached, and de-odourised to remove pigments, objectionable odors and flavors and non-triglyceride material. Oil is liquid at room temperature and contains a large proportion of unsaturated fatty acids.

Vanaspati is refined hydrogenated vegetable oil. It is solid at room temperature, as during hydrogenation, the fatty acids get saturated. Ghee is pure clarified fat with especially developed characteristic physical structure and flavor. Ghee is exclusively obtained from milk, cream or butter from various animal sources by means of processes, which result in almost the total removal of moisture and solid-non-fat contents.

COMPOSITION OF EDIBLE OIL AND FAT

The composition of fatty acids in each variety of oil/fat varies considerably.

PARTICULARS SATURATED FATTY ACIDS (%) MONO-UNSATURATED FATTY ACIDS (%) POLY-SATURATED ACIDS (%)
Coconut 90 8 2
Palm 50 39 9
Cottonseed 28 22 50
Groundnut 20 50 30
Rice bran 18 54 37
Sesame 18 53 39
Niger 12 36 52
Sufflower 10 15 75
Butter 63 33 3
Soybean 16 24 60
Sunflower 12 21 67
Mastard/rapseed 6 67 27
Corn Oil 16 29 55
Vanaspati 61 36 3
Ghee 64 33 3

Oil and fat are subject to spoilage due to effect of environmental factors that can affect their stability. These factors are mainly oxygen, moisture, heat, and light. Oxygen is the most critical factor affecting stability. The presence of oxygen leads to oxidation and formation of hydro peroxides. These reactions increase in rate and intensity in the presence of light and heat. Each oil or fat has a different degree of susceptibility to oxidation. This depends on the fatty acids composition of each oil and fat. Oil containing high degree of unsaturated fatty acids such as safflower, soya, and sunflower are highly prone to oxidative rancidity whereas oil with high degree of saturated fatty acids are less susceptible.

In unrefined oil, natural antioxidants are present and, therefore, these are less prone to rancidity than refined oil, where the antioxidants are removed during the process of refining. Very often, the oil manufacturers add antioxidants to refined oil in order to extend the shelf life of the product. In vanaspati and ghee, oxygen sensitivity is low as compared to oil. Oxygen may gain access to the fat/oil in several ways. Atmospheric oxygen may be present in the oil, it may also be present in the headspace of the package, or may enter the package through the body or the seals. Another important factor, which contributes to the deterioration of oil, is moisture. Very small amount of moisture can be detrimental. Hydrolysis of triglycerides results in formation of glycerol and free fatty acids. Off-flavors occur due to hydrolytic rancidity. This is more common in oil and fats with high levels of saturated fatty acids. Moisture may also gain entry through the body or seams by permeation. Light and heat act as initiators of oxidation reactions, which ultimately lead to degradation and, therefore, control of these factors is also important.

PACKAGING SYSTEMS/TYPES OF PACK

Traditionally, oil and fats have been packed in 15 kg square tinplate containers. The other types of packages like plastic containers, lined cartons, and flexible pouches have been recently introduced. Even though packaging has witnessed many changes, till today about 52 per cent of oil and fats continue to be traded in loose/unpacked form. This includes retail selling of loose oil from 15kg tins as well. This allows a lot of scope to pursue the dangerous practice of adulterating the oil with less expensive and unhygienic varieties.

Due to adulteration of oil, deaths have been reported in Spain, Philippines, India and Pakistan. Consequently, the governments in these countries have taken a step forward to encourage use of inexpensive safe and hygienic plastics packaging for edible oil. Plastic packaging provides safe hygienically packed oil at competitive cost to consumers.

It is extremely important that, whatever the packaging material used, it should be food grade and non-toxic. The product package compatibility is the starting point and shelf life follows compatibility.

Packaged oil and fats offer various advantages such as:

* Ease in quick disposal at retail points
* Ease of identification.
* Tamper evident and therefore chances of mixing or adulteration minimized.
* Quality is guaranteed.
* No need for consumer to carry own container.
* Convenience in storage and use by the consumer.
* No wastage due to spillage at retail shops/containers.
* Brand identification can be established.

Packaged oil, vanaspati and ghee are well accepted and the quantity in packed form is growing steadily.

The array and availability of packaging materials, sizes and shapes of package construction are unlimited. In the present day, consumer is willing to try and use new materials. Modern packaging technology provides many opportunities to maintain product protection while reducing the cost.

The main requirements for a packaging system for edible oil, vanaspati and ghee should be:

* Non-toxic and compatible
* Protect against environmental factors
* Machineable
* Leak-proof and transport-worthy
* Easy to store, use and handle
* Printable

PACKAGE TYPES

Tinplate containers are widely used for packaging of edible oil. They ensure a long shelf life and are sturdy. They are also suitable for high filling and packaging operations. However, the disadvantages of using a tinplate container are its high cost and uncertainty about availability. Edible oil is packed in tinplate containers of different capacities - 500g, 1kg, 2kg, 5kg and 15kg. The shape of the container may be round or square.

Of late, tinplate containers of 1 kg, 2 kg and 5 kg capacities are replaced by plastic containers for edible oil and vanaspati, but are still in use for ghee packaging.

GLASS BOTTLES

Though glass bottles provide excellent protection and can also be used for high-speed operation, they are not commonly used for edible oil packaging because of their fragility and high tare weight.

SEMI RIGID CONTAINERS

These are mainly plastic containers made from HDPE (High Density Polyethylene), PET (Polyethylene Terephthalate), and PVC (Poly Vinyl Chloride). The advantage of using these containers is that they provide a moderately long shelf life, are light in weight, and are transport- worthy. Although they do not provide as long a shelf life as the tinplate container, they are economical as compared to a tinplate container, and therefore, suitable for use where very long shelf-life is not required.

PET BOTTLES

With the introduction of PET bottles in the country, edible oil is one of the commodities packed in 1 kg stretch blow molded PET bottles. PET bottles have excellent clarity, are odor free and have good gas barrier properties. PET bottles are also accepted internationally for edible oil packaging.

PVC (POLY VINYL CHLORIDE) BOTTLES

Recently, food grade stretch blow molded PVC bottles have been introduced for packaging of edible oil in the country. PVC bottles have good clarity and excellent oil resistant properties.

OTHER SEMI: RIGID PACKS

The other forms of semi-rigid containers recently introduced in the market are the bag-in-box systems, lined cartons and the tetra packs, for marketing edible oil, vanaspati and ghee. This era will discuss in detail.

FLEXIBLE PLASTIC POUCHES

Flexible pouches may be made from laminates or multi-layered films of different compositions. The pouches may be in the form of pillow or as stand-up-pouches. Limited quantities of edible oil, vanaspati and ghee are packed today in flexible pouches of 1kg, 500 g and 200 g capacity. The main advantage of packaging oil, vanaspati and ghee in flexible pouches is that they are more economical than any other packaging system available for packaging of these products.

The shelf-life factor is interrelated to the product quality when ready to pack as well as to the market environment. It is of utmost importance that an economical optimum medium is chosen and this can only be done if the quality parameters are fixed for the products at the time of packing. If the oil properties at the point of packing are nearer the upper limits, higher is the packaging media specification requirement to achieve the given shelf-life period. Similarly, longer the shelf-life needed, higher would be the material specification. The task becomes more difficult when the above two factors play concurrently. Consequently, the cost of packaging also goes up. Thus, the primary factors that should be fixed are the shelf-life period, market conditions, and initial values of critical parameters of edible oil.

CRITICAL FACTORS: UPPER LIMITS FOR REFINED EDIBLES OIL/GHEE/VANASPATI

PRODUCT PERCENTAGE MOISTURE CONTENT PERCENTAGE FREE FATTY ACID AS OLEIC ACID PEROXIDE VALUE (MILLI-EQUIVALENT OF OXYGEN PER KG)
Vanaspati 0.25 0.25 ---
Sunflower Oil 0.10 0.25 ---
Palm Oil 0.10 0.25 10
Coconut Oil 0.10 0.25 ---
Safflower Oil 0.10 0.25 ---
Soybean Oil 0.10 0.25 ---
Maize Oil 0.15 0.25 ---
Sesame Oil 0.10 0.25 ---
Groundnut Oil 0.10 0.25 ---
Mustard Oil 0.10 0.25 ---
Cottonseed Oil 0.10 0.15 ---
Palmolein 0.10 0.25 10
Nigerseed Oil 0.10 0.25 ---
Rice bran Oil 0.10 0.25 ---
Ghee 0.50 3.00 ---

ANALYSIS OF NEEDS AND SHIFTS

Analysis of results from some studies in flexible packaging materials carried out indicate that flexible with appropriate thickness and specifications could be effectively deployed for edible oil, vanaspati, and ghee packaging, for medium and even for long shelf-life periods. The criteria that need specific consideration are excellent barrier properties, good substrate bond and heat seal property. Amenability to machine run is yet another important criterion.

Currently, flexible packaging for edible oil and vanaspati is used only for 1kg and less quantity. The common materials for producing composite film structures depend on the performance desired and include:

* High Density Polyethylene (HDPE)
* High Molecular High Density Polyethylene (HM-HDPE)
* Low Density Polyethylene (LDPE)
* Linear Low Density Polyethylene (LLDPE C4/C8)
* Nylon 6 (PA-6)
* Ethylene Vinyl Acetate Copolymer (EVA)
* Ethylene Acrylic Acid Copolymer (EAA)
* Polyester (PET)

These polymers are used either in co-extruded films or in laminates.

POLYPROPYLENE STABILIZERS

Polypropylene is a tertiary carbon atoms occurring alternately on the chain backbone. It is particularly susceptible to oxidation at elevated temperature. Since polypropylene is normally processed at temperatures between 220 and 280∞C, it will degrade under these conditions (to form lower-molecule-weight products) unless it is sufficiently stabilized before it reaches the processor. The antioxidants are added at least partially during the manufacturing process and at the least during palletizing. Antioxidant systems in technical use are composed of processing stabilizers, long tem heat stabilizers, calcium-or zinc-stearate, and synergists if necessary.

The most important long-term heat stabilizers for polypropylene are phenols of medium (300-600) and especially high (600-1200) molecular weight, which are frequently used.

POLYETHYLENE STABILIZERS

High-density polyethylene (HDPE) is less sensitive to oxidation than propylene, so low stabilizer concentrations are generally sufficient. As in polypropylene, antioxidants can be added during a suitable stage of manufacture or during palletizing. The antioxidants in technical use are the same as for polypropylene. Phenols of medium and higher molecular weight are so active as long term heat stabilizers. Concentrations between 0.03 and 0.15 per cent are usual.

Low-density polyethylene (LDPE) is extensively used for the manufacture of films. During processing, which is carried out at temperatures of approximately 200∞C, cross-linking and thus formation of gel, can occur through oxidation if the polymer is not stabilized. Such gel particles are visible in the film as agglomerates, known as fisheyes or arrowheads. The processing stabilizers used in LDPE consist of systems commonly used for polypropylene, namely, combination of a phosphite or phosphonite and a long-term heat stabilizer (hindered phenol) in overall concentrations up to 0.1 per cent. Concentrations seldom exceed 0.1 per cent, since the compatibility of any additive in LDPE is considerably lower than in any other polyolefins.

Cable jackets and pipes manufactured from LDPE, medium to high molecular weight grade are used and are frequently cross linked after processing. Long-term heat stabilizer is of primary importance in these applications, since life times of up to 50 years are required (usually at elevated temperatures with short time peaks up to 100∞C for cables). The antioxidants have to be extremely compatible and resistant to extraction. There are stabilizers other than polyolefin which will be non-relevant like Polystyrene, ABS-Copolymers, Nylons, PVC, Polyacetal and rubber will discussed in my other articles.

Co extrusion is used to make multilayer films by extruding several polymers at the one time through a single complex die. Each individual polymer will have its own extruder feeding into a central die. An individual polymer may be included into more than one layer, yet it only needs to come from one extruder. Multilayer films are common despite the complexity of the equipment required for their manufacture. Each layer has a special purpose in the film. The requirements for mechanical protection, diffusion, diffusion barrier properties, subtract and interlayer adhesion, and heat shrinkage cannot all be met through a single polymer. The most suitable polymer for each purpose can be chosen and assembled into the multilayer structure.

In many cases, the best combination of packaging attributes at the lowest cost is achieved by using a combination of materials. Therefore, plastic packaging films are often combined with one another or with other materials such as paper, aluminum, or even glass, through processes such as coating, lamination, co-extrusion and metallization.

POLYOLEFIN BLEND TECHNOLOGY

Polyolefin blend technology is of critical importance to various application including greenhouse films. For instance, the LLDPE/LDPE blend is characterized by reducing haze and better bubble stability. One of the most common blends is LLDPE/ethylene-propylene-diene terpolymer (EPDT) with improved low temperature flexibility, rubbery properties, weathering resistance and high-temperature mechanical properties. The addition of EVA (Ethylene Vinyl Acetate) to LDPE has been commercially utilized to improve environmental stress crack resistance (ESCR), toughness, film tearing resistance, flexibility, and optical properties.

STRUCTURES AND CRITICAL POLYMERS

Based on the requirements, various laminated, 3 and 5 layer co-extruded structures have been developed.

It includes:

* Typical Laminate Structure-PET + Adhesive + 3 Layer co-extruded LD/LLD film with EAA as sealant layer.

* Typical 3 layer co-extruded film consists of LD+ LLD-HM HDPE- EAA.

* Typical 5 layer co-extruded film consists of LD+LLD-Tie-Nylon 6-Tie-Primacor (EAA).

These structures have one common polymer, i.e. Ethylene Acrylic Acid Copolymer for the sealant layer, and it provides an excellent seal integrity through oil contamination, good hot tack, and lower seal temperature. The EAA could also be replaced by octane based LLDPE.

Generally, HDPE blends with LD/LLD provide (low moisture - Vapor - Transmission - Rate) MVTR in the co-extruded film and also avoids excessive stiffness in the film which may result in failure during drop test.

For low (Oxygen - Transmission - Rate) OTR, either Nylon-6 or Polyester or other like polymers can be used depending on the structure and shelf-life required.

CRITICAL POLYMERS

In general, the performance of ethylene acrylic acid copolymers improves with increased percentage of acid copolymers and its characteristics can be summarized as follows:

Seal integrity:

* Excellent sealing through oil contamination
* Minimum seal strength deterioration over the period of shelf life.
* Withstands longer transportation.
* Ease of processing.
* Insensitivity to moisture under normal conditions.
* Low sealing temperature.
* Excellent hot tack.

The success of the flexible pouch for packaging of edible oil and vanaspati has to a large measure, been on account of the LLDPE content in the structure. LLDPE is a narrow molecular distribution copolymer having butene-1 and octane 1. In film form, they have:

* Good impact strength
* Tensile strength
* Good puncture resistance
* Excellent hot tack seal strength

The blending of LLDPE with LDPE resin provides excellent hot tack and seal characteristics.

LLDPE with octane copolymer provides superior performance with regard to tensile strength, toughness, impact strength, stress crack resistance and tear resistance, excellent hot tack and sealing through contamination etc.

* Metallocene Polyethylene

As compared to polyethylene resins made by using standard catalyst, the metallocene technology claims to offer better strength characteristics, better oxygen and moisture barrier characteristics, high clarity and greater toughness.

* Ionomer

The ionomers are tough, transparent, having high tensile strength, low softening point, good abrasion resistance, and good oil resistance. The most important properties of film are:

* Heat sealability and hot tack strength
* Excellent optical properties
* Resistance to oil and co-extrusion with nylon with excellent adhesion.
* Nylon-6 based multi-layer film has unique combination of properties such as:
* High barrier
* Aroma retention
* Puncture resistance
* High burst strength

* Tie Layer: In a 5 layer structure, the tie layer is used for bonding two different polymers such as Nylon-6 and PE. Ethylene Acrylic Acid Copolymer (EAA) can also be used as bonding layer since it offers good adhesion to both Nylon-6 and PE. As Nylon-6 is sensitive to moisture and picks up moisture during processing and weakens bond strength, grafted copolymers are used as tie layer in 5 layer structures, to overcome this.

* Polyester

PET is used for lamination with co-extruded film, which enhances properties such as:

* MVTR/OTR
* Excellent printing
* Aroma retention
* Excellent burst strength in the pouch

A shift to flexible stands to offer many advantages primarily in terms of cost to the consumers and overall economy. One should, however, not lose sight of the critical needs a flexible medium and pouch should satisfy. The other important aspect relates to secondary and tertiary packaging, as unlike the rigid tinplate or plastic containers, the pouch does not offer any contribution in the performance of the total system.

FLEXIBLE PLASTICS AS ECONOMICAL MEDIA

If one compares the product sale cost v/s the packaging cost for various types of packages, the most economical pack would be a flexible pouch.

FLEXIBLE PLASTICS AS EFFECTIVE SOLID WASTE REDUCING MEDIA

While selecting a packaging medium, its effect on the environment needs to be considered, as solid wastes are causing problems. Flexible plastic pouches, in comparison to other packaging systems, stand to offer an advantage in reducing solid waste, as they are lighter in weight. Considering a pack of 1litre, the approximate tare weights of different packaging

media would be:

Tinplate Container: 63 grams
HDPE Container: 40 grams
PVC/PET Container: 22 - 28 grams
Tetra Pack/Lined Carton: 30 - 35 grams
Flexible Plastic Pouch: 9 - 13 grams

Moreover, flexible pouches can be recycled and reproduced for other non-food packaging applications or as building materials etc.

The Bag-In-Box packaging solves problems encountered by producers and consumers of edible oils, affording significant savings in expenses and environmental advantages during use. The Bag-In-Box packaging has many advantages in comparison with the rigid, cumbersome oil containers. The Bag-In-Box packaging is easier to handle, carry, use, and store. Thanks to its form, more units can be contained in a given volume, thus allowing for efficient storage and distribution. Using the pouches for both high and low volumes (five to 1,000 liters) makes for more efficient manufacturing, storage, marketing and consumption. The Bag-In-Box system enables easy pouring in both small and big quantities. The Bag-In-box packaging consists of a multilayer film pouch inside a corrugated cardboard casing. The pouch has flexible, strong walls, designed for the attributes needed during use, storage, and shipment of the oils.

The Bag-In-Box packaging saves 65 per cent of the container shipments and more than 80 per cent of the storage space for empty packaging. The high filling rate of the Bag-In-Box packaging affords a higher manufacturing and packaging capacity.

POURING SYSTEMS

Pouring oils through Bag-In-Box system is a clean, easy process, free of waste and the trouble entailed in pouring from rigid containers. The various Bag-In-Box pouring systems enable oil producers to fulfill the special requirements of their customers.

The Bag-In-Box packaging is environment-friendly, since it can be fully recycled and thus reduces waste volume. Also, it uses 60 per cent less plastic raw materials and contributes to reduced consumption at the source. Corrugated cardboard, which makes up 85 per cent of the Bag-In-Box packaging, can be fully recycled in any recycling center in Israel. It is easy to dislodge from the box and discard. The empty pouch consumes 1/3 of the plastic raw materials contained in any other packaging of similar volume, and when discarded, its volume is 5 per cent of the volume of corresponding rigid containers.

In packaging, a Bag-in-Box or BiB is a type of container for the storage and transportation of liquids. It consists of a strong bladder (or plastic bag), usually made of several layers of metalized film or other plastics, seated inside a corrugated fiberboard box. The bag is supplied to the 'filler' as an empty premade bag. The 'filler' then generally removes the tap, fills the bag, and then replaces the tap. The bags are available as singles for semiautomatic machines or as web bags, where the bags have perforations between each one. These are used on automated filling systems where the bag is separated on line either before the bag is automatically filled or after. Depending on the end use, there are a number of options that can be used on the bag instead of the tap. The bags can be filled from chilled product temperatures up to 100 degrees Celsius. There is also now a technology available called FSF (Form Seal Fill) and pioneered by Scholle where equipment is supplied to the filler who manufactures the bags on-line from reels of film, and then the FlexiTap is inserted then filled on an integral rotary head filler on the Scholle line. This technology is currently limited to the packing of wine products.

OXIDATION BARRIERS TO EDIBLE OIL/COOKING OIL

The main advantage to bag-in-a-box packaging is that it prevents oxidization of the edible oil during dispensing. After opening, edible oil in a bottle or other container can oxidized by air; edible oil in a bag is not touched by air and thus not subject to oxidation until it is dispensed.

However, oxygen transmits through the film and tap at different rates depending on what type of plastics are used and has an unopened shelf life. Most casks will have a best-before date stamped.

ANTISEPTIC PACKAGING

Bag in box is also used extensively in the packaging of processed fruit and dairy products in antiseptic processes. Utilizing aseptic packaging equipment, products can be packed in aseptic packaging. Pasteurized or UHT treated products packed into this format can be "shelf stable", requiring no refrigeration. Some products can have a shelf life of up to two years, depending on the type of bag that is used.

The key to this unique system is that the product being filled is not exposed to the external environment at any stage during the process and as such, there is no possibility of bacterial load being added to the product during the filling process. To ensure there is no contamination from the packaging, it is irradiated as part of the bag manufacturing process. These packs are typically from 10 to 1200 liters and offer the advantage of cheap, disposable, and transport efficient packaging.