Requirements for Sensory Evaluation

A successful implementation of sensory evaluation programme requires three major components:

i) Proper laboratory facilities

ii) Sensory panels/evaluators, and

iii) Rigrous training programme

The first requirement, that is, proper laboratory facilities is discussed in this unit, and the other two will be dealt in unit 2.

i. Sensory Evaluation Laboratory

Many designs of the sensory evaluation laboratory are available. One such designs has been shown in Fig.. Generally sensory laboratory should include a briefing room, an office, testing booths and sample preparation room. Irrespective of the design, the most important considerations for a sensory laboratory are location, ventilation, lighting, traffic pattern, sample preparation and presentation, evaluators communications and experimental comfort.

 

Design of a Sensory Evaluation Laboratory

 a) Briefing Room: All the sensory evaluators are first assembled here. They are briefed by the organizer/leader of the project about the objective of the sensory work, scorecard and its use and give other instructions. This room should be adjoining to testing booths and have facilities for comfortable sittings. If enough space is not available for a separate office for sensory leader or organizer, briefing room should also serve as office.

b) Testing Booths/Area: This is the area where panel members carry out actual sensory evaluation of dairy products. Testing area shall be located separately but in the immediate vicinity of the preparation area. This area is normally divided in to small booths (number of booths between 5 to 10) so that each panel member can independently evaluate the product. Following conditions have to be maintained in testing area for obtaining best results:

- The temperature and relative humidity shall be constant, controllable and comfortable for evaluators. A temperature of about 20oC and 62% relative humidity are considered to be optimum.

- Noise level shall be kept to a minimum during the tests. The movement of persons shall also be restricted in the area.

- The testing area shall keep free from odours. A slight positive pressure may be created in the testing area to reduce inflow of odorous air from other area.

- Lighting is very important in all sensory testing. It is particularly important in colour examination of dairy products. Lighting particularly in testing booths shall be uniform, shadow free, controllable and of sufficient intensity to permit effective evaluation of the colour and appearance of samples. In most cases, lights having a correlated colour temperature of 6500 K (or 110 candle foot light) are desirable. In order to mask differences in colour and other appearance characteristics special lighting devices, such as a dimmer device, colored lamps/filters or sodium vapour lamps, may be provided.

- The size of each testing booth shall be sufficiently large to accommodate the samples, utensils, sink, rinsing agents and score sheet/card. An area of 0.9 m wide and 0.6 m deep is considered optimum for this purpose.The height of working space in the booth should be appropriate to allow comfort to the evaluator.

- A counter on the serving/distribution area side shall be provided. Openings, covered by sliding doors, of convenient size may be provided for supplying samples into the booths from the serving counter. A system, such as light bulb on the counter side, is devised for evaluator to signal to the operator when he is ready for a sample.

c) Preparation Room: A laboratory (or kitchen) for the preparation of samples shall be located adjacent to the testing area. Its location shall be such that the evaluators do not have to pass through testing area. The preparation area shall be well ventilated so that odours emanating from the samples preparation are removed. The type of equipment required in this area depends on the range of products, which will be processed here. The main components of the preparation room for dairy products are: working space, sink, cooking range, oven,refrigerator, deep freeze, blender, scoops, knives, balance, dishes, spoons, and cleaning and storage facilities. Utensils and cutlery used in sample preparation and presentation shall be of the materials, which do not impart any odour or taste to the product.