Principles and Instrumentation for the Physical Measurement of Food Quality with Special Reference to Fruit and Vegetable Products

This chapter organizes the development of instrumental methods for measuring food quality as a distinct discipline by dividing quality measurements into categories of appearance as observed by the eye; kinesthetics as felt by hand or mouth; and flavor as tasted and smelled by the mouth and nose.

Abstract

This chapter organizes the development of instrumental methods for measuring food quality as a distinct discipline. As food quality is ultimately evaluated by the human consumer, it appears logical to organize the material in accordance with the human senses involved in the evaluation. Thus, quality measurements may be classified into categories of: appearance as observed by the eye; kinesthetics as felt by hand or mouth; and flavor as tasted and smelled by the mouth and nose. Factors that are included in the appearance category are items such as size, shape, pattern, wholeness, and consistency. Most of these may be measured easily by relatively simple devices such as scales, screens, micrometers, planimeters, sedimentation tests, consistometers, or displacement in liquid media. Another approach is through the employment of photographs, models, and drawings. For measuring color and gloss, methods such as munsell color system, hunter color and color difference meter, and abridged methods have been adopted. Viscosity or consistency is an appearance factor of great importance with food products such as catsup, juices, creams, fruit preserves, jams, jellies, gelatins, oils, and dough. Of the many instruments in existence for the measurement of viscosity and consistency, one of the most widely used methods for determining the viscosity of pure fluids is Poiseville. Various measuring units for size and shape have been illustrated. As defects are another factor of quality evaluated by the consumer's eye, the chapter discusses its classification and available instruments for measuring the defect factor. Kinesthetics characteristics that deal with the sense of feel have been discussed and its classification has been described. Measurement of specific flavor constituents that are divided into taste and odor categories have also been discussed.