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Packaging: thousands of solutions to preserve produce

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A retail store with a variety of packaged products. Iamge credit: Cold Link Africa

A retail store with a variety of packaged products. Iamge credit: Cold Link Africa

Compiled by Benjamin Brits

From times of past, packaging has evolved to include many elements of both engineering and science. The understanding of produce has simultaneously grown too.

The world of packaging is really vast, and comprises not only numerous types of equipment and ways of handling goods, it also includes many different material-types. So, from the farm all the way through to the consumer, you will encounter several solutions, no matter if processed by hand, semi-autonomous, or fully autonomous systems. In addition, what you could expect to find would depend on the particular point in the supply chain cycle that you look at.

Having attended the recent Propak Africa exhibition to learn more about the packaging sector – it was indeed an eye-opening experience to see the different equipment and machines, designs and systems used in this space. A lot of attention was naturally placed on bulk produce handling, sorting and measuring, sustainability, health and quality. Other highlights were the upholding of standards and professionalism, and another factor that is important globally – waste reduction. Quite a list of things for packaging clients to take in.

As the world is on the cliffs-edge of yet another food crisis according to the Food and Agricultural Organisation, mounting pressure is evident – particularly as waste continues to see double digit figures annually and on the back of the ongoing conflict between Russia and the Ukraine [current at time of publishing], food supply chains have already been severely impacted – notably a large portion to Africa where the poorest communities are most affected.

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As delays have hence become the norm – one would expect that packaging manufacturers and scientists are looking at as many ways of preserving produce shelf life as possible – and yes, this is the case along the entire cold chain. Reducing waste is a critical theme particularly with fresh fruit, vegetables, and medicines. Utilising the correct packaging and systems for perishables is now more important than ever as supply chains to all corners around the world are really getting put under the magnifying glass. Maintaining the cold chain is aided by interventions, and this is where developments in the packaging space are adding immense value.

A significant influence over packaging has come from the consumer and the quickly diversified solutions required for changed, and changing behaviour. This has reportedly been driven by new purchasing platforms and an increased expectation of quality and value. As we know today, quality receives a premium rate.

The “right” fresh produce packaging solutions therefore offer substantial gains in processing time, logistics and presentation. It further plays an important role today in a company’s brand and product perception – be that through transportation or when it lands on the retail shelf. Safety requirements are a given and the concept of packaging has moved solidly within the post-harvest category as a lot of produce science or understanding how certain produce reacts in different environments and under different conditions assists the cold chain.

In certain regions, however, some traditional methods of packaging and storage are still the best solution given a particular setting – such as in remote desert areas – where for example one would still see the use of clay chambers that get sealed and opened to preserve fresh fruit and vegetables.

The line-up of the types of packaging materials could include any, or a combination, of paper, wood, cardboard, plastics, fabric or cloth, glass, steel, and synthetics that would be used as the raw materials for manufacturing of packaging products that come in various configurations, including:

  • Nets
  • Bags
  • Films
  • Trays
  • Cups
  • Boxes
  • Crates
  • Bins
  • Baskets
  • Cartons
  • Pallets
  • Bottles
  • Shells
  • Punnets
  • Seatings
  • Etc

Worth noting is that there is a strong common goal to reduce, rework, recycle, recover and renew packaging materials in order to achieve a significant decrease in the total packaging carbon footprint globally. It has therefore become important for clients and consumers alike as to the choice of material, design, manufacturing process, and even the choice of print or branding methods used by suppliers. Subsequently, the views on certain raw materials have received a lot of attention for some years now in terms of pollution and ability to degrade naturally.

Interestingly, various sources then indicate that a country’s total packaging sector can be used as a lead indicator of the strength of the economy – owing to the fact that almost everything sold today is packaged in some or other form. The packaging sector in South Africa is still considered “small” given its noted contribution to GDP – being slightly shy of two percent of the South African total. However, with the increasing demand of South African produce and capacity building in several perishable categories such as fresh produce and pharmaceuticals, this is one sector with huge untapped potential for growth.

Packaging influence in markets

Under the reflections of commercial and environmental pressure to meet targets and scientifically developed best practices, packaging design continues to reduce its impact on energy needs and material quantities, bettering handling, logistics and storage, and the contribution to pollution and landfills.

The cold chain packaging market size has been reported that it will reach USD34.7-billion globally within the next five years. This directly relates to increasing demand for packaging solutions from the food processing industry, the changing lifestyle of the consumers, a rising population, and rapid urbanisation in emerging economies. In addition, the increased use of processed food items such as meat, frozen fruits and vegetables, seafood, and dairy products has played into this increased demand. Furthermore, the packaging sector continues to gain momentum from the fast-growing pharmaceutical sector and global trading conditions of these products.

A major restraint, however, has been recorded as the stringent regulation and high costs involved in product development that have affected market growth until now. Cold chain packaging is comparatively more expensive than standard packaging. To keep best quality products and to meet required specification and the use of technically advanced raw materials, a skilled workforce is required thus driving up costs. Increasing global regulatory aspects such as health and safety protocols, environmental impacts, and product treatments also continue to create hurdles for packaging to the cold supply chain.

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Local factors of consideration

Wastage or spoiled produce owing to poor packaging choices, incorrect design or simply the choice to save a few rand at the producer has far-reaching consequences. One would need to look at resultant waste from a holistic perspective. When a ton of fresh produce is lost owing to poor/unsaleable condition it is not just the product lost which role players need to be cognisant of – what must be taken into account is also the natural resources such as water that went into production, fertiliser, manpower, energy consumption in cooling, processing and storage, harvesting costs, and the diesel to move the product around – besides the impact of those activities on the environment and the impact of the actual produce that must be discarded or destroyed.

South Africa is able to boast a thriving fresh produce market with a healthy local demand and sufficient supply to participate in exports of significant volumes to international destinations. Many fresh fruits and vegetables particularly have seen an increased international demand and so significant growth as consumer preferences change with each season. Ensuring produce quality will be one of the biggest factors driving the consumer’s choice – and so producers and retailers alike will need to up their game to reduce returns or rejections, and where waste can be mitigated.

Correct packaging choice coupled to precise production, harvesting and post-harvest logistics should also protect the produce along the supply-chain journey above the function of preservation. No consumer enjoys a situation where they bite into a bruised, partially decayed or soft item that is spoilt or has a bad taste – this could deter their future support of a particular brand, and this is definitely important today with the variety of brands seen on the shelf – that is growing annually too. Now, although producers are scared of “input costs”, a small additional fee can mean the difference between excellent financial returns, having to reduce a sale price or worst case – a total loss.

Packaging solutions that are available, and the incorporation of modified atmosphere environments, technology such as laser perforated films, resealable containers, and produce “breathing” features available to the local market not only mitigate the degradation of produce, they have also opened up the doors to more easily managed participation in the supply chain for astute sellers. It enables that in times of oversupply to the markets that portions or entire harvests can be delayed to market and this in turn gains additional revenue being able to sell a quality product at a premium. The technology in packaging is in fact so advanced at this point in time that it is possible to control, quite precisely, the rate at which these controlled environments can slow down or stop ripening according to individual fresh produce respiration rates, and without the product losing moisture.

These features can also enable an extended period for consumers to purchase produce designated as “sellable” before price reduction to get rid of stock – this could further result in massive increases of profits. For the export markets – as we know shipping has become a thorn in the side of many with up to two-week periods of additional lead times added to an already long delivery process. With the right packaging solutions this too can now be accommodated to ensure produce still arrives at its destination in top quality condition.

Requirements for fresh produce: simple guidelines

Packaging of fresh fruits and vegetables as we can see is one of the more important steps in the often-complicated journey from the producer to the consumer while this journey involves several steps in processing and logistics – it is also today A LOT about product marketing.

In the US, as an example, more than 1500 different types of packaging are used for produce and this number continues to increase as the industry introduces new materials and concepts to meet the market needs. Although for most industries, standardisation is one way to reduce cost, trends in recent years have definitely moved toward providing a wider range of packaging to try and accommodate the diverse needs of all that include other than the consumers – wholesalers, food service buyers, and processing operations as they all strive to have a unique selling proposition in a highly competitive trading environment.

It is important that role players in the cold chain as well as consumers have a solid understanding of the wide range of packaging options available, as well as the impact that packaging can have. One such aspect is the impact of container failure. Another significant impact is the management of moulds and pests that all affect a product’s saleability. In essence, packaging needs to fulfil a multi-pronged solution of protection, preserving quality, appropriate design and function, meet the consumer’s aesthetic needs that sway them to purchase, and provide easy identification of contents.

 Use and function

Any “container” should enclose the produce in a convenient “unit” for suitable handling throughout distribution and retail steps. Produce should fit well with little wasted space. Small produce items that are spherical or oblong (such as potatoes, onions, and apples) may be packaged efficiently utilising a variety of different package shapes and sizes. However, many produce items such as asparagus, berries, or soft fruit may require containers specially designed for that item. Produce commonly handled by hand is usually limited to certain maximum manageable weights – eg 4.5kg or 9kg, etc.

Protection

The packaging unit must obviously protect produce from mechanical damage and poor environmental conditions during a journey. Torn, dented, or collapsed packaging usually indicates a lack of care in handling the contents but also most often results in reduced sales prices.

Almost all produce packages are palletised at some point in the chain and so containers should have sufficient stacking strength to resist crushing in a low temperature, high humidity environment prevalent in the cold chain. Although the cost of packaging materials has escalated in recent years, poor quality, lightweight containers that are easily damaged by handling or moisture are no longer accepted by many packers, buyers or retailers as they don’t want to be liable should containers fail in their hand or control.

Produce destined for export markets requires containers to meet very specific criteria. Air-freighted produce may require other steps to be included such as insulation. Companies that intend to export fresh produce should consult with authorities around such special requirements.

Containers should be “produce friendly” – thus assisting to maintain an optimum environment for the longest shelf life possible. This may include materials to slow the loss of water from the produce, insulation materials to keep out heat, or engineered plastic liners that maintain a favourable mix of oxygen, carbon dioxide or nitrogen.

Identification

There is a general requirement that any packaged product must identify and provide useful information about the particular produce. It is customary (and may be legally required in some cases) to provide information such as the produce name, brand, size, grade, variety, net weight, count, grower, shipper, and country of origin.

It has also become a standard to be able to find nutritional information and other useful information directed specifically at the consumer. In consumer marketing, package appearance has also become an important part of point-of-sale displays.

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Universal Product Codes (UPC or bar codes) are generally included – particularly for export produce. A UPC used in the food industry consist of a ten-digit machine readable code. The first five digits are a number assigned to the specific producer (packer or shipper) and the second five digits represent specific product information such as type of produce and size of package. Although no price information is included, UPCs are used more and more by packers, shippers, buyers, and retailers as a fast and convenient method of inventory control and cost accounting. Efficient use of UPCs requires coordination with everyone who handles the produce.

It would be impossible to cover all of the types of packaging available in South Africa, so we have chosen a few of the most common ones that would be used and seen in the supply chain.

Types of packaging materials

  • Pallets

Pallets literally form the base on which most fresh produce is delivered to the consumer. The produce industry uses billions of pallets per year globally. In South Africa, unlike many other countries with very high ratios of single-use pallets, this product carries multiple uses and comes in standard wood and plastic – produced locally which is also a very big industry here. Standardisation of sizes further encourages re-use, which has many benefits above reducing cost, standard size pallets make efficient use of transport space and can accommodate heavier loads than single-use options.

Depending on the size of produce packaged, a single pallet can carry many individual packages. Because these packages are often loosely stacked to allow for air circulation, or are bulging and difficult to stack evenly, they must be secured to prevent shifting during handling and transit. Although widely used, plastic straps and tapes may not have completely satisfactory results. Plastic or paper corner tabs should always be used to prevent the straps from crushing the corners of packages.

Plastic film or wrap is also widely used to secure produce packages. A good film must stretch, retain its elasticity, and cling to the packages. Plastic film may conform easily to various size loads. It helps protect the packages from loss of moisture, makes the pallet more secure and can be applied using partial automation. However, plastic film severely restricts proper ventilation. A common alternative to stretch film is plastic netting, which is much better for stabilising some pallet loads, such as those that require forced-air cooling. Used stretch film and plastic netting particularly is difficult to properly handle and recycle after use.

  • Wooden crates

Wooden crates, once extensively used for apples, stone fruit, potatoes and tomatoes have been almost totally replaced by other types of containers. The relative expense of the container, a greater concern for overall weight contribution, and advances in material handling have reduced their use to a few specialty items, such as expensive tropical fruit.

  • Corrugated board

Corrugated board (often mistakenly called cardboard) is manufactured in many different styles and weights. Because of its relativity low cost and versatility, it is the dominant produce container material and will probably remain so in the near future. The strength and serviceability of corrugated boards have been improving in recent years.

Most corrugated board is made from three or more layers of paperboard. To be considered paperboard, the paper must meet specific criteria thickness. The grades of paperboard are differentiated by their weight (generally in grams per square meter – GSM) and their thickness. This paper-type typically made from unbleached pulp has a characteristic brown colour and is exceptionally strong by ratio. This product, as manufactured in other countries, may also include a portion of synthetic fibres added for additional strength, and other materials to give it “wet strength” and then printability.

Although most corrugated boards contain some recycled fibres, it must be noted that minimum amounts of recycled materials may be specified by local and international standards. Tests have shown that cartons of fully recycled pulp have only about 75 percent of the stacking strength of virgin fibre containers. The use of recycled fibre products will thus lead to the implementation of thicker walled containers.

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Double-faced corrugated board is the predominant form used for produce containers. It is produced by sandwiching a layer of corrugated board between an inner and outer liner of paper-board. The inner and outer liner may be identical, or the outer layer may be pre-printed or coated to better accept printing. The inner layer may also be given a special coating to assist in moisture resistance. Heavy-duty shipping containers, such as corrugated bulk bins that are required to have high stacking strength, may have double- or even triple-wall construction.

Corrugated board manufacturers can print certificates on the bottom of containers to certify certain strength characteristics and limitations. Both cold temperatures and high humidities reduce the strength of this packaging. Unless the container is specially treated, moisture absorbed from the surrounding air and their contents can reduce the strength of the container by as much as 75 percent. Anti-moisture coatings are available to substantially reduce the effects of moisture.

Waxed cartons may be required for certain products and destinations but are generally used for produce items that must be either hydrocooled or iced. The main objection to wax cartons is disposal after use— wax cartons cannot be recycled as per standard cartons.

In many applications for corrugated containers, the stacking strength of the container may be a minor consideration. For example, canned goods carry the majority of their own weight when stacked. Fresh produce usually cannot carry much of the vertical load without some damage. Therefore, one of the primarily desired characteristics of corrugated containers is stacking strength to protect the produce from “crushing or bruising”. Most of the stacking strength of corrugated containers is carried by the corners. For this reason, hand holes and ventilation slots should never be positioned near the corners of produce containers.

Interlocking the packages (cross stacking) is universally practiced to stabilise pallets. Cross stacking places the corner of one produce package at the middle of the one below it, thus reducing its stacking strength. To reduce the possibility of collapse, the first several layers of each pallet should be column stacked (one package directly above the other). The upper layers of packages may be cross stacked as usual with very little loss of pallet stability.

In South Africa, there are numerous styles of corrugated containers or carton boxes as commonly referred to. Research has shown that there are in excess of 20 manufacturers in this packaging type alone. This is not surprising given the fact the exports cumulatively from this country exceed 900 million boxes of produce annually. The box carton locally has received quite a lot of attention of late owing to the fact that there are so many manufacturers and each wants to implement their own design. More around this can be viewed in prior issues of Cold Link Africa.

Almost all corrugated containers are shipped to the packers flat and assembled at the packing house. To conserve space, assembly is usually performed just before use. Assembly may be by hand, machine, or a combination of both. Ease of assembly should be carefully investigated when considering a particular style of carton.

For many years, labels were printed on heavy paper and glued or stapled to the produce package. The high cost of materials and labour has all but eliminated this practice. The ability to print the brand, size, and grade information directly on the container is one of the greatest benefits of corrugated board containers today. There are basically two methods used to print corrugated board containers: post printed – when the liner is printed after the corrugated container has been formed, and the process is known as post-printing. Post printing is the most widely used printing method for corrugated containers because it is economical and may be used for small press runs. However, post-printing produces graphics with less detail and is usually limited.

Pre-printed high quality, full-colour graphics may be obtained by pre-printing the linerboard before it is attached to the corrugated paperboard. Whereas the cost more, the eye catching quality of the graphics makes it very useful for many situations. The visual quality of the package influences the perception of the product because the buyer’s first impression is of the outside of the package. Produce managers especially like high quality graphics that they can use in supermarket floor displays.

Pre-printed cartons are, however, usually reserved for the introduction of new products or new brands. Market research has shown that exporters may benefit from sophisticated graphics. The increased cost usually does not justify use for mature products in a stable market, but this may change as the cost of these containers becomes more competitive.

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  • Paper and mesh bags

Consumer packs of potatoes and onions are about the only fresh produce items you will still see packed in paper bags. The more sturdy mesh bag has much wider use. In addition to potatoes and onions, cabbage, turnips, citrus, and some specialty items are packed in mesh bags. Sweet corn may still be packaged in mesh bags in some markets. In addition to its low cost, mesh has the advantage of un-inhibited air flow. Good ventilation is particularly beneficial to products like onions. Supermarket produce managers like small mesh bags because they make attractive displays that stimulate purchases.

However, bags of any type have several serious disadvantages. Large bags do not palletise well, and small bags do not efficiently fill the space inside corrugated containers. Bags do not offer protection from rough handling. Mesh bags provide little protection from light or contaminants. In addition, produce packed in bags is correctly perceived by the consumer to be less than the best grade. Few consumers are willing to pay premium price for bagged produce.

Paper bags are now also increasing being used by retailers for purchasers but where you will also see the use of paper packaging is in freshly made confectionary items and even the use of ready to eat foods such as pies and baked goods.

  • Plastic bags

Plastic bags are the predominant material for fruit and vegetable consumer packaging. Besides the very low material costs, automated bagging machines further reduce the packing costs. Film bags are clear, allowing for easy inspection of the contents, and readily accept high quality graphics. Plastic films are available in a wide range of thicknesses and grades and may be engineered to control the environmental gases inside the bag. The film material “breathes” at a rate necessary to maintain the correct mix of gasses and water vapor inside the bag.

Since each produce item has its own unique requirement for environmental gases, modified atmosphere packaging material must be specially engineered for each item. Research has shown that the shelf life of fresh produce is extended considerably by this packaging. The explosive growth of pre-cut produce seen on any supermarket shelf these days is due in part to the availability of modified atmosphere packaging that slows or eliminates the natural process of oxidisation.

In addition to engineered plastic films, various patches and valves have been developed that affix to low-cost ordinary plastic film bags. These devices respond to temperature and control the mix of environmental gases. They also enable the consumer to manage multiple uses of the product.

  • Plastic bins

Plastic bins are used extensively in fruit and vegetable packhouses at the starting point of the cold chain. They are available in vented and solid configurations with smooth interior surfaces that can reduce waste and downgrade. Various ventilation designs also reduce cooling time and therefore saves energy. Their clean, non-porous surfaces eliminate many HACCP risks associated with wood bins. They can weigh up to 45% less than wooden bins for quicker, safer handling and stacking and can also be stacked up to eight units high. They have optimal compatibility with most handling equipment and certain manufacturing practices such as on-piece products reduce maintenance and cleaning. Capacities can be as little as a few litres up to thousands of litres capacity.

  • Shrink/cling wrap

One of the newest trends in produce packaging is the shrink wrapping of individual produce items. Shrink wrapping has been used successfully to package a variety of fresh fruit and vegetables as well as ready to eat foods. Shrink wrapping with an engineered plastic wrap can reduce shrinkage, protect the produce from disease, reduce mechanical damage and provide a good surface for stick-on labels. Shrink wrapping material also comes in different types such as on rolls and in sleeves.

Cling film is another very popular packaging material for a variety of goods and as a versatile solution has applications across the cold supply chain from pallet wrapping to the wrapping of certain produce individually.

  • Rigid plastic packages

Packaging with a tops and bottoms that are heat-formed from one or two pieces of plastic are known as clamshells. Clamshells have gained in popularity because they are inexpensive, versatile, provide excellent protection to the produce, and present a very pleasing consumer package. It would be plausible to accept that this is the most common type of produce packaging used in South Africa for fresh fruits and vegetables.

Clamshells are most often used with consumer packs of high value produce items like small fruit, berries, mushrooms, etc., or items that are easily damaged by crushing. Clamshells are used extensively with pre-cut produce and prepared salads, as well as baked goods.

  • Foil trays

Aluminium foil trays are yet another major packaging solution for produce and along with treated cardboard lids are used in a lot of frozen foods, ready to eat meals, takeaways and packaged pre-cut fresh foods.

The list goes on to include polystyrene, boxes for frozen goods, sandwiches, wooden food containers, plastic and paper cups, glass, and so on.

As environmental pressures continue to grow, the disposal and recyclability of packaging material of all kinds will become an increasingly important aspect. Common polyethylene, for example, may take from 200 to 400 years to breakdown. The addition of as little as six percent starch will reduce that time to 20 years or less. Packaging material companies are developing several starch-based substitutes that will break down in a landfill as fast as ordinary paper and will be seen more and more as developments progress.

The move to biodegradable or recyclable plastic packaging materials may be driven by cost in the long term, but by legislation in the near term. Some authorities have already proposed a total ban on plastics and some retailers locally have also already transitioned to more environmentally friendly packaging and delivery of produce in containers that can be re-used at the consumer level – thus also reducing what gets thrown away.

Standardisation

Produce package standardisation is interpreted differently by different groups. The wide variety of package sizes and material combinations is a result of the market responding to demands from many different segments of the produce industry. For example, many of the large-volume buyers of fresh produce are those most concerned with the environment. They demand less packaging and the use of more recyclable and biodegradable materials, yet would also like to have many different sizes of packages for convenience.

Packers aim to limit the variety of packaging they must carry in stock, yet they have driven the trend toward pre-printed, individualised containers. Shippers and trucking companies want to standardise sizes so the packages may be better palletised and handled.

Produce buyers are not a homogeneous group. Buyers for chain stores have different needs than buyers for food services. For grocery items normally sold in bulk, processors want largest size packages that they can handle efficiently – to minimise unpacking time and reduce the cost of handling or disposing of the used containers. Produce managers, on the other hand, want individualised, high-quality graphics to entice retail buyers with in-store displays.

Selecting the right container for one’s produce is actually not as simple as dumping it in a box anymore. For each commodity, the market has shown that it demands certain standards and technology, market acceptability, and disposal regulations are constantly on the change.

When choosing a package for produce, role players must actually be actively consulting the market, and in fact all role players in the chain such as facility managers, refrigeration engineers, logistics companies etc, to understand how each process influences or is influenced by the selection.

Article Sources:

  • Food and Agricultural Organisation
  • General industry engagement
  • Global Cold Chain Alliance
  • Mpact Plastic Containers
  • NC State University cooperation paper
  • NNZ Packaging
  • StePac
  • Tecra Automation
  • The Institute of Packaging (SA)
  • United Exports
  • Vantage Market Research
  • World Health Organisation

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