**Sensory Analysis of Virgin Olive Oils**

Innocenzo Muzzalupo, Massimiliano Pellegrino and Enzo Perri

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/51721

**1. Introduction** 

222 Olive Germplasm – The Olive Cultivation, Table Olive and Olive Oil Industry in Italy

geographical origin, *Food Chemistry* Vol. 89: 561–568.

27.

Vinha, A. F., Ferreres, F., Silva, B. M., Valentao, P., Gonçalves, A., Pereira, J. A., et al. (2005). Phenolic profiles of Portuguese olive fruits (Olea europaea L): Influences of cultivar and

Viola, P. (1997). Olive Oil and Health. *International Olive Oil Council*, Madrid Spain, pp. 26-

The evaluation of the sensory properties and determination of the importance of these properties in consumer product acceptance represent a major accomplishment in sensory analysis.

Most of the sensory evaluation carried out by a trained *panel* involves measurement in two main areas, difference testing and descriptive analysis. Sensory difference tests are procedures used to determine whether judges can distinguish between two similar stimuli. In terms of food, the two stimuli are two very similar food samples. These evaluations are used to determine whether slight changes occur due to either product reformulation or the change in technological processing. Difference tests are particularly well adapted to the assessment of vegetable oils during their processing, being used to control refining efficiency.

Furthermore, they may be used to measure slight flavour variation determined by changes in storage or packaging. There are many different methods for sensory difference testing. They are described in detail in several texts (Amerine *et al.*, 1965; Lawless and Heymann, 1998; Meilgaard *et al.*, 1999).

Descriptive analysis, the other main area of sensory evaluation, precisely describes and measures the sensory attributes of food. It follows that this can be done only with trained judges. There are various methodologies that can be used. One procedure is the Quantitative Descriptive Analysis (QDA) developed by the Tragon Corporation of Palo Alto, California (Stone *et al.*, 1974). Judges examine the food and list all the relevant sensory properties. They then use standards to obtain agreement on the descriptive terms being used. By using a scaling procedure, the judge estimates the intensity of each sensory attribute considered. The raw data obtained are then evaluated through common statistic techniques.

There are several applications for descriptive analysis: product development and assessment, comparison of the sensory properties of products which cannot be compared

simultaneously (e.g., fresh olive virgin oil from consecutive years), shelf-life studies, correlation of instrumental and sensory properties, studies of the effects of technological processing on the sensory characteristics of a product, quality assurance, certification of a preset quality standard, etc.

Sensory Analysis of Virgin Olive Oils 225

sheet used within the European Union to establish the sensory profile of virgin olive oil is shown below (Fig. 1). The values, expressed as centimetres, are statistically processed to

calculate the median of each positive and negative characteristic.

**Figure 1.** Sheet for sensory analysis

Another branch of sensory analysis is represented by consumer science. Generally, people eat and drink food because they like it. But, food intake is not completely driven by hedonic motives. Other factors such as market segmentation, advertising, price, packaging, opinions and beliefs play a role too. The sensory perception of sensory quality is an important factor in motivating consumer choice. It derives from the intrinsic properties of the product, perceived by the consumer at the moment of buying (colour, shape, aspect, etc) and subsequently from direct individual experiences (odour, taste). The measurement of liking is necessary before a product is launched onto the market, with substantial capital being needed. This can therefore save investing in a product that may not be liked due to a deficiency of sensory qualities.

The most frequently used method to measure acceptability and preference is the 9-point hedonic scale, developed in 1955 (Jones *et al.*, 1955). The subjects that take part in the sensory testing are not trained, and should be relatively naive to this kind of task.
