Definition Importance and Uses of Sensory Evaluation

i. Definition

Sensory evaluation may be defined as a scientific discipline used to evoke, measure, analyze and interpret results of those characteristics of foods and materials as they are perceived by the senses of sight, smell, taste, touch and hearing.

ii. Importance

A number of quality assurance procedures are used to examine and maintain quality of a dairy product. The testing starts from reception of raw material, for example, milk, to close examination of finished product. These tests are physical, chemical, microbiological and sensory.The sensory evaluation is very important in product evaluation on account of following advantages:

i) It is a simple analytical tool,

ii) It identifies the presence or absence of perceptible differences in terms of flavour, texture, colour and appearance,

iii) These important quality attributes are measured in a fast and quantifiable manner employing sensory techniques. The use of chemical and instrumental methods for examining sensory characteristics are time consuming, complicated and expensive,

iv) It enables identification of a particular problem or defect that cannot be detected by other analytical techniques,

v) Sensory evaluation techniques help in ensuring that the consumers get a non defective and enjoyable product.

In recent years, the competition in food/dairy corporate has tremendously increased.The companies are making very fast changes in their existing product in terms of ingredients, value addition, packaging etc. or developing new products to grab larger market share. In all these situations, sensory evaluation plays a critical role.You can adopt sensory evaluation for following uses.

i) Inspection of Raw Materials: The main raw material for dairy industry is milk. Any defect in quality of milk related to colour, appearance, aroma and taste can be quickly detected on the reception dock by the senses of smell, taste and sight. This will help producing final product of good quality. The other raw materials, such as, sugar, stabilizer, emulsifiers, flavouring and colouring substances and other additives are also examined for colour and flavour.

ii) New Product Development or Improvement of Existing Product:

According to a survey more than 90% of the new products developed result into failure mainly because of poor sensory attributes and rejection by the consumers. The adoption of appropriate sensory methods during new product development is thus inevitable.

iii) Cost Reduction: In addition to eating quality of a dairy product, the cost is also an important consideration for selection of the product by consumers. Hence, dairy product manufacturers always try to reduce the cost by either using low cost ingredients or adopting good management skills. The use of low cost or alterative ingredients may adversely influence the sensory characteristics of the product and may not find good acceptability. The sensory evaluation of product during these modifications is, therefore, highly advantageous.

iv) Quality Control: The modern day concept of “Total-Quality-Control” (TQM) involves sensory evaluation at all stages of product flow. This includes, not only the sensory quality of raw material, but also quality of product during processing and storage. The changes in product quality in terms of colour, flavour and texture during processing and storage has to be regularly monitored using sensory techniques.

v) Selection of Packaging Material: Now the consumers have become very quality conscious and prefer to buy properly packaged processed food. This has resulted into development of various types of packaging materials for food applications. The newer types of packaging materials, particularly in forms of flexible films/pouches/laminates are being extensively used. The suitability of these films for packaging a particular dairy product in respect of containment of product, its non-reactiveness with food ingredients and compatibility to storage conditions has to be examined adopting sensory analysis along with some chemical/ instrumental method.

vi) Shelf Life Studies: Dairy products during storage undergo many types of changes, for example, chemical, bacterial, enzymatic, physical, etc. All these alter the sensory properties, such as taste, colour, flavour, texture and appearance. Application of sensory evaluation not only monitors these changes but also determine the nature and extent of the defects in dairy product during storage so that corrective measures can be adopted. As per the existing rules, the mention of ‘manufacture date’ and “expiry date or use before date” on the label are mandatory. The expiry date has to be determined by using chemical and sensory techniques together.

vii) Establishing Analytical/ Instrumental/ Sensory Relationships: Such relationships are highly useful for quick evaluation of the product quality and for designing new equipment for product manufacturing. Some relationships between sensory properties of milk and dairy products with that of analytical or instrumental techniques have already been established, for example, the titratable acidity of fresh milk ranges between 0.14 to 0.16%, and at 0.17%and above it may impart sour flavour. Similarly the free fatty acid (as oleic acid) in ghee of good quality (no rancidity) should be less than 2.8%. Relationship between sensory textural attributes, hardness, stickiness, chewiness, gumminess and elasticity/ sponginess with that measured by an instrument can also be established.