Check-All-That-Apply (CATA) Test to Investigate the Consumers’ Perception of Olive Oil Sensory Properties: Effect of Storage Time and Packaging Material

The article titled “Check-All-That-Apply (CATA) Test to Investigate the Consumers’ Perception of Olive Oil Sensory Properties: Effect of Storage Time and Packaging Material” published on the international scientific journal “Foods” ( by our sensory analysis laboratory team, is the result of a project that lasted almost two years and was made possible thanks to the Italian National Consortium for the Recycling and Recovery of Steel Packaging (RICREA – Consorzio Nazionale per il Riciclo e il Recupero degli Imballaggi in Acciaio ( an UNISG supporting member. The purpose of the research was to systematically study how the perception of different oils packaged in different materials changed in a period of nineteen months. 

The experimental plan was long and complex. In the study took part both consumers and trained assessors (‘panelists’).  This double participation was important because normally for the evaluation of oils from only  the group of experts is involved to evaluate the quality of oils, according to the directives and guidelines of the IOC (International Olive Oil Council). Often, however, the perception of experts differs from the perception of the consumers, even if consumers play a very important role in the consumption and sale of oil and must therefore be listened too. So far, in the academic studies little attention is paid to study the point of view of consumers and their perception of quality on oils.

During the shelf-life, the packaging acquires a very important role as it keeps the product intact, it slows down the oxidative and degradative processes, but it also has an important function of communication being the packaging (including material, label, etc.) the first thing that the consumer sees at the time of purchase. It is therefore interesting to better understand what the consumer’s perception of the product’s quality is, both including sensory and non-sensory characteristics. In fact, the concept of quality usually includes “intrinsic” aspects linked to sensory analysis (for example the odour, the taste, the texture, etc.), and some “extrinsic” aspects such as the price, the availability of a product, and also the packaging, that includes also the material. 

As mentioned above, the opinions of an expert may  differ from the one of a consumer. For example, several studies showed indeed how some attributes indicating high quality and freshness of oil, such as bitterness and pungency, due to a high content of polyphenols, may not be appreciated by consumers and may even be mistakenly considered as defects. Consumer acceptability of oils is also influenced by many factors such as the level of knowledge about the product and its familiarity with it. 

This research consisted in the sensory evaluation of the impact of the material on the perceived quality of two types of oils (olive oil and extra virgin olive oil), studying how in a time span of nineteen months the sensory perception of the consumers changed. Thus, the dual impact of storage time and of the packaging material was evaluated . The experimental plan involved 150 consumers, including students and UNISG staff, and included liking tests (a testing in which the degree of liking was asked to participants considering appearance, smell, taste, flavour and overall liking) and a check-all-that-apply (CATA) test that requires the selection from, a given list, of the attributes considered suitable to describe the sample tasted. The same types of oils (olive oil and extra virgin olive oil) were bottled in three different materials (green glass, transparent plastic – PET, and tinplate) at the same time. All samples were stored in a temperature-controlled cell at 22°C and tasted at three different control times (after two, 10 and 19 months). Tests were conducted at the Sensory Analysis Laboratory of the University of Gastronomic Sciences ( The six samples (three packages for each type of oil) were presented in blind condition (without giving any information about the brand or the type of oil tasted) to avoid influencing the assessors.

At the end of the research, no evident effects on consumer liking were found with regard to the packaging material. However, the results showed a clear negative effect of time on the perceived quality of the oils, that was expected which resulted from a slight decay of the sensory properties and which decreased the overall liking, demonstrating the ability of consumers to perceive the degradation of the product over time.

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