Sensory assessment

In any flavor development project it is necessary to carry ont a continnons sensory assessment of trial samples in order to establish the nature and extent of differences between the trial and the target flavor profile. While the final evalnation of a flavoring is done in the Flavor Applications laboratory, there is a need to have a simpler, faster 

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Industry has standardized procedures for the quantitative sensory assessment of the perceived olfactory intensity of indoor malodors and their relationship to the deodorant efficacy of air freshener products. Synthetic malodors are used for these evaluation purposes. These malodors should be hedonicaHy associated to the "real" malodor, and must be readily available and of consistent odor quaUty. These malodors should be tested in various concentrations and be representative of intensities experienced under normal domestic conditions. 

Penetrometers are easy to use giving good results and correlating well with the sensory assessment of gels etc. Nevertheless these instruments yield a purely empirical method working on the principal of linear compression, penetration or back extrusion. 

During the past 5 years, our institute has done extensive research on biological and toxicological surface and drinking water quality assessment and its relation to chemical pollution (8). Scientists discerned that water, along with other sources, has become the victim of the indifference of humans. One of the first multidisciplinary approaches of a water contamination problem was introduced in the thesis, Sensory Assessment of Water Quality (9). 

In recent years, large consumer panels have been employed for sensory assessments of drinking water. As a result of these assessments, water treatment methods have been adjusted. 

Zoeteman, B. C. J. Sensory Assessment of Water Quality Pergamon Oxford, 1980. 

The use of colorimetry for evaluating discoloration in fresh meat is well established and has been reviewed elsewhere (Francis and Clydesdale, 1975 Hunt, 1980). In general, a values are most commonly reported, as they indicate the degree of redness in meat. Several colorimetric parameters correlate very well with sensory assessment of meat discoloration and hue angle, as shown in Figure F3.3.3. 

Figure F3.3.3 Comparison of subjective sensory assessment (A percent discoloration) and objective colorimetric evaluation (B hue angle). Beef was obtained from cattle supplemented with 0 (E-0), 500 (E-500) or 2000 (E-2000) IU a-tocopherol acetate per head per day. The a-tocopherol demonstrated a color preservation effect. Hue angle was calculated as [tan-1(b7a )] (36072rc). Standard error bars are indicated. Adapted from Chan et al. (1995), with permission from the Institute of Food Technologists.

As the flavour and odour of a soft drink or fruit juice are very important elements of a product they should be closely controlled. This is generally carried out by trained panellists who have been screened to ensure that they have an aptitude for this type of assessment they are often quality assurance personnel or workers from the factory. Sensory assessments should be carried out in surroundings where the panellists can concentrate without distractions. 

In contrast to the mechanical and rheological properties of materials, which have defined physical meanings, no such definitions exist for the psychophysical assessment of equivalent textural properties of foods. To identify material properties, or combinations of these, which are able to model sensory assessments requires a mixture of theory and experimentation. Scientific studies of food texture began during the twentieth century by the analysis of the rheological properties of liquid or semi-solid foods. In particular Kokini14 combined theoretical and experimental approaches in order to identify appropriate rheological parameters from which to derive mathematical models for textural attributes of liquid and semi-solid foods, namely, thickness, smoothness and creaminess. 

A further complication arises from the different food breakdown paths sustained by different individuals, both in the extent and the rate of breakdown30, both of which may be important in sensory assessment of various textural characteristics. 

Untrained consumers and trained panellists may agree on the categorisation of most textural characteristics, and the foods which exemplify these characteristics38. Discrepancies are more likely to become apparent when considering small scale differences between products. Although variability among untrained individuals in their sensory assessments of food products are commonly found, few studies have addressed these (see 39,4°), or compared the results of trained and untrained subjects41,42. 

Kapsalis, J.G. and Moskowitz, H.R. (1978). Views on relating instrumental tests to sensory assessment of food texture. Applications to product development and improvement. J. Texture Studies 9, 371-393. 

The volatile isolate desorbed and sensorially assessed at our odor port was described as typical of processed black truffle, showing that the Tenax had adsorbed and desorbed volatile components responsible for canned black truffle aroma. 

Official quality parameters comprise acidity, peroxide value, halogenated solvents, ultraviolet adsorption and sensory assessment. In addition to these official parameters important roles and high values are attributed to the content of the chlorophyll and carotene pigments and phenol antioxidants, as well as to the correlated induction time value. The significance of olive oil quality parameters is explained in Table 2.1. The phenol content and the related induction period, defined as the delay in the commencement of oxidation in an oil , merits particular comment the longer the induction period, the better the oil. Resistance... 

Sensations perceived in the mouth during mastication may vary between subjects, but their acceptability will certainly reflect cultural as well as physiological and psychological differences. Tests for sensory assessment of texture aim at understanding how the food feels in the mouth. They may be classified into those where consumers are constrained to record only their perception of in-mouth stimuli (e.g., trained panel assessment) in other words, they are asked to perform as an analytical instrument. Alternatively, consumers are asked to record their judgment against requirements of quality (e.g., preference testing) where perceptions are related to expectation. Sensory assessment of texture is described in many texts, for example, Kilcast (2004). 

Crispness is a desirable sensory property in many cereal foods such as toast, the crust of bread, crispbreads, crisps, biscuits, extruded snacks and breakfast cereals. Since it is a subjective sensory assessment crispness is difficult to define unambiguously and its perception varies greatly between individuals and also between countries (Bourne 2002). In general it is known that crisp foods are at low moisture, in the brittle or glassy state well above Tg and fracture rapidly (see also Chapters 5 and 7). We can... 

The third and fourth influential factors on wine aroma chemistry arise from the problems caused by the matrix on both the isolation and preconcentration of molecules and on the sensory assessment of the role played by the impact odorants. The presence of major volatiles, such as ethanol and fusel alcohols, complicates the isolation of the other wine odorants, particularly of those present at low levels. This has a marked influence on the way in which the extracts for screening and for further qualitative or quantitative studies should be prepared. On the other hand, ethanol and the major fermentation volatiles have also a deep influence on the way in which the odor chemicals are released and perceived. 

Because much work was done with viscosity expressed in poise in sensory assessment of viscosity, the same tradition will be continued in Chapter 7 on sensory assessment of viscosity. 

The flow of some materials may not commence until a threshold value of stress, the yield stress (ao) (see Figures 1-2 and 1-3), is exceeded. Although the concept of yield stress was questioned recently (Bames and Walters, 1985), within the time scales of most food processes the concept of yield stress is useful in food process design, sensory assessment, and modeling. Shear-thinning with yield stress behavior... 

Role of Rheological Behavior in Sensory Assessment of Foods and Swallowing... 

Figure 7-1 A Set of Four Fluid Foods that Could be Arranged in a Matrix for Sensory Assessment, Based on Shama et al. (1973). Each arrow points to the less viscous sample.

Figure 7-5 Stimuli Controlling the Sensory Assessment of Viscosity by Oral Methods. Lines of Constant Viscosity are shown (Shama and Sherman, 1973).

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