Different types of Sensory Evaluation Ranking Tests

Introduction:

The main purposes of Sensory test are:

· Select qualified judges and study human perception of food attributes

· Correlate sensory with chemical and physical measurement

· Study processing effects, maintain quality, evaluate raw material selection, establish storage stability or reduce costs

· Evaluate quality or

· Determine consumer reaction

Ranking: 

Ranking tests are rapid and can be performed  with relatively little training and  familiarization with the attribute under test. 

Ranking tests have wide application, but with sample sets above three they do not discriminate  well compared to scaling tests.

In ranking method two or more samples are provided to the panelists who are asked to arrange them in an ascending or descending order of intensity of a specific attribute, e.g. sweetness.

 Ranking is often used for screening inferior from superior samples in product development. This method is also suited for comparison of market samples of different brands.  

Samples may be ranked in order of degree of acceptability or in order of general quality or by a specific attribute.

Scoring:

The most frequently used of all sensory testing systems is scoring because of its diversity,apparent simplicity, and ease of statistical analysis. 

Scoring methods havemost extensively been used by the dairy industry for product development and improvements, shelf life studies and assessing suitability of packaging materials. 

Score cards base on 100 points are generally used for judging andgrading of dairy products. Most recently 25 points score cards have been suggested.

It is believed that numerical rating tests give more complete information than either ranking tests or descriptive rating test. But the judges must be trained. 

Since there is no indication of liking to the test product, palatability norms should be established. 

The score card must be properly developed giving due weight age to all the sensory attributes.

Hedonic scale:

The nine point hedonic scale has been used extensively since its development with awide variety of products and with considerable success. 

The scale is easily understood by naive consumers with minimal instruction and the product differences are reproducible with different groups of subjects. 

The results from use of this scale are most informative since computations will yield means, variance measures and frequency distributions, all by order of presentation and magnitude of difference between products by subject and by panel and the data can be converted to ranks as well, which yields product preferences. An example of the scale is given below.

• Like extremely 9

• Like very much 8

• Like moderately 7

• Like slightly 6

• Neither liked nor disliked 5

• Dislike slightly 4

• Dislike moderately 3

• Dislike very much 2

• Dislike extremely 1

The subject task is to circle the term that best represents their attitude about the product. 

The responses are converted to numerical values for computational purposes, e.g. like extremely 9; dislike extremely 1; in a 9-point scheme.