|
|
|
You can get e-magazine links on WhatsApp. Click here
|
|
|
|
|
|
Sensory evaluation:understanding the basics
|
|
Friday, 16 October, 2009, 08 : 00 AM [IST]
|
|
|
Taste is the ultimate criterion of the desirability of any food product. Other food attributes like color, appearance, flavour etc play an equally important role in either enhancing or reducing the acceptability of food. For example, raw egg is a rich source of proteins but how many of us would really like to consume it? Most of us would prefer a boiled egg or an omelet as these products taste better and are also believed to be free from bacterial contamination. Organoleptic properties of food like colour, appearance, aroma etc are judged by human sensory organs and evaluation of theses attributes is therefore called as Sensory Evaluation. The best food quality would be a perfect blend of chemical, microbiological and sensory parameters and which is evaluated by objective and sensory means.
Objective evaluation measures the chemical and microbiological goodness of a food product. This evaluation involves testing of parameters like measurement of pH, sugar, cholesterol, cis-trans fat, protein, pathogens etc. from food. However, we all will agree that a product passing all objective evaluations if fails in the sensory evaluation, acceptability of that product would be certainly poor. While a lot has already been written about objective evaluation of food products for the benefit of layman, very little is written about sensory evaluation.
Why Carry Out Sensory Evaluation?
Sensory evaluation is a critical requirement of food industry because it is a means of determining how consumers will approve a food product. There are five important sense organs in the human body, Nose, Ear, Tongue, Eyes and Skin. These sense organs help us to evaluate various sensory characteristics of food like appearance, color & flavor.
Unlike the objective tests, sensory evaluations do not need any sophisticated equipment. They provide a quick and ready reference to the quality of product.
Who should carry out sensory evaluation tests?
Sensory evaluations should be carried out by all the food producers during various stages of food production. These evaluations can benefit the food producers in following ways. It helps them
■ To understand the consumer preferences in case of new product developments
■ To understand the effect of process variation on organoleptic properties of a food product. Process variation may be necessary for better storage stability, better packaging options or for process simplification of a product.
■ To detect off-quality of raw materials and/or products during manufacturing, packaging and marketing
■ To determine the shelf-life of a food product
What are the prerequisites for conducting the sensory tests?
■ Trained panel members
The panel members should be healthy, physically as well as mentally. They should have normal organoleptic sensory capacities and should be trained adequately so that they can differentiate in specific quality characteristics based on different stimuli & intensity of differences. Such trainings are offered at national food institutions like Central Food Technology Research Institute (CFTRI), Mysore.
Testing laboratory Testing laboratory should consist of following units
■ Reception & briefing room where the panel members are assembled, registered, given the evaluation cards & briefed about the sensory test.
■ Sample preparation room where samples are prepared.
■ Test booths where the actual sensory evaluation is carried out. These booths are located adjacent to the reception & preparation rooms. Test room environment should be pleasant. The entire laboratory should be air- conditioned, free from noise & extraneous odors. Lighting system of the laboratory should be appropriate for the sample being tested. Coloured lights may be used to mask the colour of sample & thereby eliminate the bias.
What are the critical points of sensory evaluation test?
■ Identical method of preparation: All processing variables for a product like temperature, time of boiling, quantity & composition of water, blending, etc. should be controlled to ensure sample uniformity
■ Uniformity in sample presentation: Variation in sample size, temperature and serving utensils should be strictly avoided. Coding should be done to obscure the identity of the sample & proper order of presentation as per the experimental design should be followed when test involves more than one sample.
■ Special techniques of smelling & tasting of product: These should be used to perceive the aroma & taste more clearly.
■ Ideal testing time is generally 10-12 in the morning when the panel members are fresh. The tests can also be carried out one hour before lunch.
■ Number of samples: Number of samples served in any one session should be optimum and should not produce any kind of fatigue for the panel member which may lead to errors in results.
■ The design of the experiment: It should be decided on the basis of the accuracy needed & the amount of sample available.
How to conduct sensory evaluation tests?
There are different types of sensory tests employed for food evaluation.
■ Hedonic rating test: It is a 9 point scale ranging from "like extremely" to "dislike extremely". Scales with other phrases can also be used like in case of texture characteristics it may range from "extremely soft" to "extremely hard". These tests are carried out either to rate the sample or to find the difference between two samples on the basis of sensory characteristics. This is the most widely used evaluation food industry.
■ Triangle Test: This test consists of two samples which are identical and one sample which is different. This type of testing is useful in assessing the competitor product or in case of assessing a new product attribute for an existing product.
■ Numerical Scoring Test: In this case the various sensory attributes of product are rated as being poor, fair, good, very good and excellent. The questionnaire should be prepared carefully for each test.
There are other sensory evaluation tests like Duo Trio Test, Multiple Paired Comparison, Composite Scoring Tests, and Sensitivity Tests etc.
After the evaluation is over a suitable statistical analytical technique is used to measure variables & establish the significance of results.
Which sensory evaluation test should be chosen?
The selection of test method will depend on the objective of the test, accuracy desired & personnel available for conducting the evaluation.
How to interpret the data obtained from sensory tests?
Differences in perception of individuals, error of habituation, logical error; emotional burden/stress etc. may influence an individual's ability to assess a product without bias. Therefore sensory evaluation tests alone should never be used to determine the quality of a food product. Only when the subtle correlation between sensory and objective tests is understood we can say that the sensory evaluation is beneficial for the food manufacturer.
Authors: Manjiri Satam & Dr. Priti N. Amritkar
Envirocare Labs Pvt. Ltd
Email: priti.a@envirocare.co.in
|
|
|
|
|
|
|
|
|
|