Packaging extends shelf life, but how?

The increasing globalisation and international trade in the fresh produce sector demands the utmost of the products. The products are transported thousands of miles before they find their way to the consumer. Shelf life during transport is crucial to get a good price for products. One of the factors that can determine the state in which a product reaches its destination is the packaging. Primeur spoke with a number of suppliers of packaging that positively affect shelf life.

There are several ways to extend the shelf life with a packaging. The different packages each address a different problem. The FruitPads prevent the moisture in the packaging from becoming too high, damaging the fruit. These pads are mainly used for soft fruit and prevent mould growth. Clingfilm prevents a product from drying out, which keeps the product fresh. Packaging under a protective atmosphere or with micro-perforation film requires specific knowledge about the influence of air quality on the product. A wrong balance can reduce shelf life or even stimulate growth of bacteria.

“In the past, you’d see a lot of soft fruit was locally marketed,” says Filip Tintchev from McAirlaids. “A shelf life of two to three days was sufficient then. Due to globalisation, you now need a shelf life of 10 to 12 days for soft fruit, that’s a completely new situation.” The German company has much experience in the meat sector with pads; the pad at the bottom of a dish packaging. Despite the fact that these sectors are completely different, their experience was used to access the fresh produce market several years ago.

The second generation of the FruitPad was launched in 2012. In the soft fruit bowls, a lot of bubble film was then often used. Pads of this film were placed at the bottom of the bowls to protect the strawberries and raspberries in transit. “The disadvantage is that these bubble films don’t absorb moisture,” Filip explains. Moisture in the packaging, both fruit juice and condensation through varying temperatures, can damage the fruit and create a favourable climate for the development of moulds. In some cases, the loss during transport of soft fruit could amount to 40 per cent of the products.

The FruitPad was developed to absorb moisture in packaging, reducing the risk of mould growth. “With the FruitPad, the growth of mould is down by fifty percent,” Filip says about the results. “We’ve noticed FruitPads are becoming standard in soft fruit packaging.” Since 2012, FruitPad's market share has increased rapidly to seventy to eighty per cent of the market. Especially strawberries, raspberries and blackberries are placed on FruitPads, although the blueberry sector is also becoming more interested. That coincides with the desire of the blueberry growers to keep the berries in storage longer. “Prices are often better later in the season, so growers want to be able to store the berries. With the FruitPad, the risk of mould is decreased, and the berries can be stored longer.”

McAirlaids takes it one step further with the FreshGuard line. These pads contain an active substance that actively absorbs moisture from the air in the packaging. “The FreshGuard not only absorbs more drops, but also moisture from the air.” The balance needed to keep the fruit from drying out requires a delicate touch. Each product needs a pad with unique characteristics. “We noticed a significant drop in moisture in the packaging,” says Filip. The new pad was tested with fruit from Huelva for the British market, among other things. “We saw with the active pad the humidity stayed in check around ninety per cent, ideal for the fruit.”

This makes the pads complementary to other packaging, such as MAP packaging. “Those types of packaging often don’t regulate the humidity in the packaging, just the atmosphere. Condensation can therefore still be found in the packaging.” The pads are a solution for products that are transported over longer distances especially. From Southern Europe to Northern Europe and Mexico and California, and even further into the US are two trading routes for which the pads are widely used.

McAirlaids invests in research to also use the pads for other products. The tests with rocket are promising. “The test shows the pad doesn’t just absorb the moisture, but the rocket also changes colour less and doesn’t smell as bad,” Filip explains. Additionally, a pad that absorbs ethylene in addition to moisture is being developed. With this so-called Fresh Guard EC (ethylene control), the ripening of, for example, pears, tomatoes, bananas and broccoli is delayed. Another pad, the FreshGuard EHC (ethylene humidity control) combines the function of the two previously mentioned pads. “Tests and studies show promising results.”

Although there’s a general increasing trend towards more packaging, highlighted by factors such as convenience, shelf life and hygiene, clingfilm stands out. Marcus Gillioen from Flexfilm sees the market for this film growing. There are several causes for this.

Firstly, a distinction must be made between stretch film and clingfilm. The difference is in the materials used. Stretch films often use PVC, a material that is increasingly less popular with companies and consumers for environmental reasons (softeners).

Clingfilm consists of two types of PE film and polyolefin film. The difference is in the technical complexity and in the brightness of the film, the latter is brighter than the first and is technically much more high-quality. The clingfilm market is growing, because, among other things, more companies exchange the stretch films, which contain PVC, for an environmentally friendly alternative. “You occasionally see cauliflower or broccoli in stretch film, but most companies choose clingfilm,” Marcus says.

A second factor causing the market to grow: clingfilm is an efficient and attractive packaging, price-wise.

“The films are getting thinner and thinner,” Marcus continues. Flexfilm supplies clingfilm with a thickness between 11 and 15 microns, or 0.011 to 0.015 millimetres. “The films are really very thin. That shouldn’t be underestimated. For example, we pack oxheart cabbage and broccoli in an 11-micron film. This also results in saving.” The calculation is simple: less film is used per packaging. At a film price per kilo, it results in more packaging from the same amount of foil. An additional advantage is the speed at which the products can be packaged. Many Flexfilm customers pack 50 to 60 oxheart cabbages per minute. Another customer reaches a capacity of 120 bell peppers per minute.

For growers, there are several reasons for choosing this type of packaging. Besides the cost aspect, with which the clingfilm is distinctive compared to other packages, the film also has a positive effect on shelf life. “Everyone knows that a broccoli that isn’t wrapped dries out,” says Marcus. By packing the broccoli in clingfilm, shelf life is extended. Other products for which this package is used are, for example, bell peppers, aubergines and cabbage types such as cauliflower and oxheart cabbage. “Cucumbers are often packed in the PE version, because the packers don’t have clingfilm capacity yet,” Marcus explains. “We also see, for example, bunches of bananas wrapped in polyolefin clingfilm, and their shelf life is also extended because of that.”

Products that have a high moisture content and breathe fast are usually packed in anti-condensation film. This film prevents condensation on the inside of the clingfilm, with broccoli for example, when the product is refrigerated on the supermarket shelves or in case of fluctuating temperatures during transport. “For bell pepper and oxheart cabbage you don’t need an anti-condensation film, because the film is tightly wrapped around the product. In this case, the clingfilm ensures hygiene and retaining moisture and weight,” Marcus continues. The watermelons halves and pumpkins are also often protected against dehydration with clingfilm. “When a supermarket receives and sells a new supply of bell peppers every day, clingfilm remains useful for hygiene and presentation.” Clingfilm extends the shelf life of bell pepper up to six days.

The process of packing the products is simple. The vegetables are first packed in a flowpack. The product then passes through a heat tunnel of about 140 degrees Celsius. Because of this, the air in the package expands. The film then shrinks and the film pushes the air out through minuscule holes in the film. The end result is a film that has formed a second skin around the product. This shrinking process means printing becomes specialised. “It's possible, but you really have to know what you're doing,” Marcus says. “We are an experienced specialist in this field. It’s possible and it’s already being done.”

Other trends can also be seen internationally. For instance, in the US there’s a trend in which potatoes are individually packed in clingfilm. “MAP packaging was used for that in the past, but with clingfilm, potatoes can be prepared in microwaves.” For the machine, it doesn’t matter whether a cabbage, bell pepper, or potato is processed. “Clingfilm is an efficient way of packing. Demand is increasing for the packaging and the machines to use the film,” Marcus concludes.

The composition of the air in the packaging can have a major impact on the product. There are two aspects: on the one hand, removing all air from the packaging, or vacuuming, and on the other hand it is possible to adjust the air composition. Both applications aim to extend shelf life. One machine can be used for both techniques. 

In the fresh produce sector, the vacuum packaging is mainly used to pack products which are subsequently cooked in the package. To consumers, the pre-cooked sweet corn and red beets are best known. Wholesalers and kitchens will also know the vacuum packed peeled potatoes. “Whole peeled onions are also packed in this manner,” says Hans Schalkwijk from Multivac. With that product, the bulk consumers will be familiar with that type of packaging as well.

“For packing fresh unprocessed fruit and vegetables, vacuuming is actually not really an option,” Hans continues. “We can pack under protective atmosphere with our deep drawing packing machines and tray-sealers. The atmospheric air is pushed away by creating a vacuum / gassing or flush gassing. We then provide the packaging with a known gas mixture, extending shelf life.” This technique, known as MAP, is similar to EMAP packaging. For that second technique, the product creates its own optimal living environment. “However, it costs a lot of energy for the product at the expense of shelf life. By packing the product under protected atmosphere and providing the top film of the package with laser or micro-perforations, the optimal living environment is created for each product with a good and optimal start.”

There’s much interest from trade in packaging techniques that contribute positively to shelf life. “It gives companies the opportunity to gain time for a delivery. For example, you can produce today and deliver the same shelf life to the final customer the next day.” The composition of the gas mixture used in the packaging requires a delicate touch and is not suitable for each product. “For a firm skin products such as bell pepper, MAP packaging has little effect because the gas mixture does not penetrate into the product,” Hans explains. “For chopped mango, strawberries, raspberries or sliced pineapples, it could have advantages. In short, products with a high respiration content show the best result.”

Each product needs its own gas mixture to achieve the ideal results. Indeed, a wrong ratio could be potentially dangerous. Hans mentions mushrooms as an example. “Mushrooms can be packed under protective atmosphere, but the oxygen content cannot be too low. If oxygen levels are too low, anaerobic bacteria, such as Clostridium, can survive, causing botulism, among other things. You therefore cannot just do everything.” Products such as peeled garlic, bean sprouts and other seed vegetables can also be packed under protective atmosphere. The only constant that applies to practically all products is the lower limit of at least four to five percent oxygen. “If the oxygen percentage is lower, the anaerobic bacteria that affects products develops itself.”

According to Hans, the shelf life of a product is becoming increasingly important, and more experiments are being done and researched. Multivac is a food technologist, at the request of their customers as well, and they are structurally engaged in product-level research to determine the ideal composition of the atmosphere in the packaging. In the wake of the growing interest in MAP packaging, the share of top-seal packaging is growing. “It results in a higher presentation value, better product protection, and you're using less film,” Hans explains. Additionally, in this package the ‘living climate’ is easier to control.

The fact that the advance is serious is also evident from the introduction of the G700, a new Multivac tray-seal packager especially for the fresh produce sector. “With this machine we can pack under natural atmosphere or protected atmosphere like MAP and EMAP to a capacity of 18 cycles per minute. The machine can naturally be combined with the Multivac FreshSafe technology. This means that the package is air permeable, allowing the product to breathe.”

More than ten years ago, laser perforations unleashed a revolution in the sustainability of fruit and vegetables. Despite the fact that the technology has been available for a few years, Perfotec's Ivo Hendriks still meets with some skepticism from some companies. The United Kingdom remains the undisputed leader, but interest on the European continent is increasing.

“In the UK, most of the early potatoes, for example, are packed with our technology,” Ivo explains. “But none in the Netherlands. Although our technique is extremely suitable for counteracting green discolouration and sprouting on potatoes, it’s not used. I think that is remarkable.” The basis of the technology is simple. Fruit and vegetables are live products that keep breathing after harvest. The air composition in the package has a significant impact on shelf life. An atmosphere that is different for each product, provides an extension of shelf life for the fresh products.

Perfotec's technique measures how much the products ‘breathe.’ Based on these results, it is determined how many laser perforations are needed on the packaging. Thanks to these tiny holes that are invisible to the naked eye, the product can breathe and shelf life is improved. In the UK, more and more supermarkets demand that the technology be used. For example, all packaging of soft fruit products at the fresh produce department of Marks & Spencer are provided with micro-perforations by Perfotec's lasers. “M&S experiences the added value of our technology and they focus on consumers,” says Ivo. “Consumers don’t go to the supermarket every day, they want to be able to use the products for longer periods.” In addition, this packaging method is also a solution to internet sales. Because technology extends shelf life, you can offer consumers a longer one. “In the supermarket you can choose whether you want tomatoes or bananas that are ripe or less ripe. That’s not possible online, so the product has to be good.”

The perforations in the packaging extend the shelf life, depending on the product, up to two days. There are several reasons for the reluctance on the European mainland to get started with the technology. The growers might think: I have a good product, why would I need that technique? The limited influence of growers and retailers on the retail sector also plays a role. Finally, there is some conservatism in the sector. “We have many case studies, but many companies still want to see the results themselves and personally experience the effects.”

In the UK, a trend is visible in which top-sealing with micro-perforation is being used more often. Products from countries like Chile, Argentina, Peru and South Africa, such as blueberries and grapes, are shipped to the UK in an open punnet. The punnets are then provided with a top-seal and a label with a ‘best until’ date.

And finally, micro-perforation is not always necessary for all products. Ivo exemplifies: “Grapes have a low oxygen consumption after certain growth conditions and breathe very slowly. At certain times during the season, perforations are not required at all.” For practically all products, the respiration value is now known, so the technique can be used quickly. For exporters, Perfotec technology is being applied more and more. That is interesting for products that are transported over long distances. “In some cases, our technology means the difference between air freight or sea freight. Sea freight is half as expensive in transportation costs,” Ivo concludes.

More information:
McAirlaids
Filip Tintchev
Filip.Tintchev@mcairlaids.com

Flexfilm
Marcus Gilioen
marcus@flexfilm.nl

Multivac
Hans Schalkwijk
Hans.schalkwijk@multivac.nl

Perfotec
Ivo Hendriks