Overview and Basic Principles. Physiological and Psychological Foundations of Sensory Function. Principles of Good Practise. Discrimination Testing. Discrimination Theories and Advanced Topics. Threshold Testing as a Special Case of Discrimination Tests. Scaling Models and Numerical Measurement. Time Intensity Methods. Context Effects and Biases. Descriptive Analysis. Texture. Color and Appearance Measurement. Acceptance and Preference Testing - Laboratory Applications. Acceptance and Preference Testing - Consumer Tests Outside the Laboratory. Qualitative Research Methods. Data Relationships & Multivariate Applications. Strategic Research. Overview and Recap. Statistical Appendices.

Sensory Evaluation of Food: Principles and Practices

Texture is a sensory property

The structural and mechanical properties of gels formed from biopolymers are discussed both in terms of the techniques used to characterise these systems, and in terms of the systems themselves The techniques included are spectroscopic, chiroptical and scattering methods, optical and electron microscopy, thermodynamic and kinetic methods and rheological characterisation The systems considered are presented in order of increasing complexity of secondary, tertiary and quaternary structure, starting with gels which arise from essentially ‘disordered’ biopolymers via formation of ‘quasicrystalline’ junction zones (eg gelatin, carrageenans, agarose, alginates etc), and extending to networks derived from globular and rod-like species (fibrin, globular proteins, caseins, myosin) by a variety of crosslinking mechanisms Throughout the text, efforts are made to pursue the link (both from experiment and from theory) between the structural methods and mechanical measurements As far as we are aware this is the first major Review of this area since that of J D Ferry in 1948 — The interest shown by polymer physicists in more complex biochemical systems, and the multi-disciplinary approaches now being applied in this area, make the format adopted here, in our opinion, the most logical and appropriate

Structural and mechanical properties of biopolymer gels

Proteins for foods, in addition to providing nutrition, should also possess specific functional properties that facilitate processing and serve as the basis of product performance. Functional properties of proteins for foods connote the physicochemical properties which govern the behavior of protein in foods. This general article collates the published information concerning the major functional properties of food proteins, e.g., solubility, binding properties, surfactant properties, viscogenic texturizing characteristics, etc. The effects of extraction and processing on functional properties and possible correlations between structure and function are discussed, in relation to practical performance in food systems. Modification of proteins to improve functional characteristics is briefly mentioned.

Functional properties of proteins in foods: A survey

SUMMARY
Definition of texture is reviewed, and a system for classification of textural characteristics of foods is described. The system is based on fundamental rheological principles, and at the same time is suitable for routine use. Textural characteristics are defined and classified into mechanical and geometrical qualities as well as those related to the moisture and fat content of a product. The mechanical characteristics are subdivided into the primary parameters of hardness, cohesiveness, viscosity, elasticity, and adhesiveness, and into the secondary parameters of brittleness, chewiness, and gumminess. It is pointed out that popular terms used to describe texture often denote degrees of intensity of these characteristics. The proposed classification lends itself to use with both objective and subjective methods of texture characterization.

Classification of textural characteristics

SUMMARY
A new recording instrument, the “texturometer,” gave good correlation between instrumental values and subjective evaluation by a trained texture profile panel. It was applied to measurement of the mechanical textural parameters: hardness, cohesiveness, viscosity, elasticity, adhesiveness, brittleness, chewiness, and gumminess. Subjective definitions of these parameters are interpreted in terms of physical measurement characterized by the texture “profile.” Examples of representative profiles are included.

The Texturometer—A New Instrument for Objective Texture Measurement

SUMMARY
Standard rating scales of hardness, brittleness, chewiness, gumminess, viscosity, and adhesiveness were established for quantitative evaluation of food texture. The scales cover the entire intensity range found in food products and may be expanded at any desired point for greater precision in a narrower range. Each point on the scale is represented by a food product selected on the basis of availability, familiarity, constancy of textural characteristics, and other criteria. Using the developed scales, correlation was good between sensory and instrumental (texturometer and viscosimeter) evaluations of texture.

Development of standard rating scales for mechanical parameters of texture and correlation between the objective and the sensory methods of texture evaluation

. A texture profile panel is a valuable tool for describing and quantifying textural characteristics of food products when the panel is carefully selected, trained and maintained. Guidelines to accomplishing this goal are presented.

Alina S. Szczesniak

Papers

Texture is a sensory property

Classification of textural characteristics

The Texturometer—A New Instrument for Objective Texture Measurement

Development of standard rating scales for mechanical parameters of texture and correlation between the objective and the sensory methods of texture evaluation

Guidelines to training a texture profile panel