chapter  1
Optical Properties
Pages 20

The various properties or parameters that define the

sensory quality of food products can be divided into

three groups: visual parameters, texture parameters,

and flavor and aroma parameters (1). By visual

parameters we understand those that we perceive with

the sense of sight. The various properties perceived by

the sense of sight can be further divided into three

subgroups: optical properties, properties depending on

physical form, and properties depending on the method

of presentation (2). By optical properties we understand those that

depend on geometrical or chromatic modification of

the light striking the product in question. These

properties are: color, gloss, translucency, and the

uniformity of these properties on the surface of the

product. If the reader should ask why we measure color and

what importance it has, the answer is that with the sense

of sight we obtain 83% of the information we receive

about our environment, while a mere 17% is obtained

from the other senses. Also, visual evaluation of

appearance precedes the evaluation of other parameters

(flavor, aroma, and texture), so that it may have an

excluding effect. If we reject a food product on the basis

of a visual examination, we do not go on to evaluate its

other properties, however excellent they may be. This

importance is recognized by food legislation in all

countries, where color always appears in the description

of any foodstuff and also features as a quality factor to

distinguish between different quality levels for a

particular product. The first and longest part of this chapter is devoted

to color, followed by a description of the measurement

of gloss, translucency, uniformity, and defects.