Can You Get It Open?

Easy to open packages are not a given

November 4, 2008: Packages should protect the contents, but sometimes they do this almost too well – namely when the consumer either cannot open the package or can do so only with extreme difficulty. This is especially a problem for children and the elderly who have reduced hand function. It is not unusual, however, for healthy, non-handicapped consumers to experience the same problems. Sensory experts from Finland, Sweden, and Denmark – members of the European Sensory Network – researched the reasons behind these problems, and have developed a method to analyse whether and why a package is difficult to open.

You need more than two hands to extricate peanuts from their aroma-protecting, shrink-rapped packaging. Some frustrated souls end up trying to rip it open with their teeth. In the worst case, the transparent plastic wrapping suddenly explodes open and an avalanche of nuts pours out onto the table, lap, and floor. It is highly unlikely that these consumers will buy that particular brand the next time they have a craving for peanuts. The manufacturer should have been more aware of the trappings that surround the selling of his product.

A typical example – the contents are enticing, the packaging looks good – but how do you open it? Packaging should ensure that the contents reach the consumer in perfect condition. Most products achieve this objective, but it is at this point that the problems begin: lids are hard to open, snap-locks clamp, pop-top aluminium can pull-rings break off, plastic foil rips off at the wrong place, re-sealing mechanisms are either unrecognisable or user-unfriendly. There is a long list of obstacles…

Testing the ease of opening

How to systematically tackle this problem? How can one objectively test the degree of ease by which the wide variety of packages can be opened, and at the same time ascertain the various package characteristics that need to be improved. Researchers from the VTT Technical Research Centre of Finland, the Swedish Institute for Food and Biotechnology (SIK), and the Danish Technological Institute (DTI) solve these problems with the help of classic sensory methods, including the combined input from consumer panels and panels of sensory experts.

The research was done in connection with the Nordic Innovation Centre-financed EASYOPENPACK-study, a study that will be the scientific background for a later EU Standardisations Authority’s development of international standards (CEN). The researchers concentrated on one of the major target groups – older consumers who have complained that in their day to day lives they have difficulties with opening packages. The participants were shown pictures of eight packages with diverse sorts of opening mechanisms. The consumers were then asked to sort the pictured packages into two groups, according to the perceived ease in opening. They were then asked to explain to an interviewer, referring back to their own experiences, the reasons why a particular package was easy or difficult to handle. Their comments were listed and counted with the help of a laddering technique. The researchers chose twelve descriptive terms from this list as the basis for the sensory profiling to be conducted by a panel of experts. The members of this trained sensory multi-product panel were tested to make sure that they had no impairment of hand function. After they participated in a training session to familiarise themselves with the chosen terms, the panel rated the product characteristics on a graphic scale from 0-10. They chose the following attributes as especially relevant to whether or not the package was easy to open:

  • visibility and clarity of the opening mechanism
  • ease of gripping the opening mechanism
  • tightness and breakage of the opening mechanism
  • strength needed to open the package
  • need to use both hands
  • rigidity and slipperiness of the packaging material
  • keeping grip of the package
  • package remaining intact when opening
  • degree of the product that stays inside the package after opening

 SIK’s Annika Åstrom emphasized that, “As opposed to purely mechanical test procedures that admittedly are inexpensive and easy to perform, the results garnered from descriptive sensory profiling not only illuminate single characteristics, such as the force needed to undo a zipper or open a seal; they shine a light on the totality of a product’s traits and qualities. This is the only way to clearly identify actual problems that arise when the consumer deals with a product. The ease with which a product can be opened is more than just a question of strength or dexterity.”

More than one hand needed?

Of the packages used in this study, coffee packaging proved to be the most difficult to open in several aspects: the seal was so tight that considerable effort and both hands were needed to open the package. It was not easy to grip either the package or the package opening. The packaging material was slippery, and the seal, as well as the package itself often broke apart when opened. The opening mechanism on the bonbon bag was difficult to see or find, and, as was the case with the biscuit rapping, the bag was unstable, causing a portion of the contents to spill out upon opening. The milk container and the aluminium can with the pop-top ring were given positive ratings relating for five important characteristics: the milk container had a clearly visible, clearly defined, easy to grip opening. When opened, the container and the contents remained intact. The can’s opening mechanism was also clearly visible and easy to grab, the can itself was stabile, not slippery, and easy to hold. Of course these results can not be generalised for all packages, e.g. coffee or milk cartons, but every package needs individual testing to clarify how easy it is to open.

Consumers with special handicaps

In the course of the study, it was shown that diverse sub-groups of consumers with specific handicaps had special problems opening packages. With the help of focus group discussions, the researchers delved deeper into the questions these problems brought up. For instance, it was shown that five out of 22 people with rheumatism were not able to open the aluminium pop-top cans because they either lacked the necessary finger dexterity to pull open the pop-top ring, or did not have the necessary strength to pull the top off. These people often preferred using a can opener, which unfortunately could not be used with the type of can that was tested. Also, some of those with rheumatism had difficulty with the milk carton’s foldaway spout, and with opening medicine bottle caps. Only two out of the eight packages tested were shown to be easy to open for rheumatics who had an impairment of hand function of over 50%.

Raija-Liisa Heiniö from VTT points out that, “If we want to do something against a situation in which approximately every other woman over 75 finds every second product package either difficult or impossible to open, we must orient package design around the abilities and disabilities of these people. Analysis of the descriptive attributes listed above can be extremely useful in designing new packages. When we direct design towards the weakest link in the chain, every consumer benefits in the end. Sensory analysis methods can help to reach this goal.”


 Annika Åström
SIK - The Swedish Institute for Food and Biotechnology
Sensory and Flavour Science
Box 5401, SE-402 29 Göteborg, Sweden

 PhD Raija-Liisa Heiniö
VTT Technical Research Centre of Finland
Food Biotechnology/ Flavour Design
P.O. Box 1000 (Tietotie 2), FI-02044 VTT, Finland