Analysis Sensory

Sensory analysis involves using human subjects as a measuring tool. This presents an immediate problem, as individuals are innately variable, not only as a result of their experiences or expectations, but also as a result of their sensitivity. Thus, each person could genuinely perceive the same product quite differently. It is therefore essential in 

A purpose-built sensory panel suite enables testing to be carried out in an environment free of noise or movement, and in rooms that are painted a neutral colour and are fitted with individual booths for each panellist. When testing is carried out, all samples are presented unlabelled so that the panellists do not receive any cues concerning the nature of the product, and the sample appearance is identical the only variable (as far as possible) is the smell. 

A purpose-built sensory panel suite enables testing to be carried out in an environment free of noise or movement, and in rooms that are 

---

More recently, studies of wine and beer have initiated techniques of statistically vaUd sensory analysis. Scientific studies involving wine continue in these areas, building on past discoveries. Natural phenols as desirable dietary components and monitors of storage and aging reactions are currently active fields. Viticultural research, as well as enological, continues to improve grapes and the wines made from them (11). 

Sensory perception is both quaUtative and quantitative. The taste of sucrose and the smell of linalool are two different kinds of sensory perceptions and each of these sensations can have different intensities. Sweet, bitter, salty, fmity, floral, etc, are different flavor quaUties produced by different chemical compounds the intensity of a particular sensory quaUty is deterrnined by the amount of the stimulus present. The saltiness of a sodium chloride solution becomes more intense if more of the salt is added, but its quaUty does not change. However, if hydrochloric acid is substituted for sodium chloride, the flavor quahty is sour not salty. For this reason, quaUty is substitutive, and quantity, intensity, or magnitude is additive (13). The sensory properties of food are generally compHcated, consisting of many different flavor quaUties at different intensities. The first task of sensory analysis is to identify the component quahties and then to determine their various intensities. 

Discriminant Sensory Analysis. Discriminant sensory analysis, ie, difference testing, is used to determine if a difference can be detected in the flavor of two or more samples by a panel of subjects. These differences may be quantitative, ie, a magnitude can be assigned to the differences but the nature of the difference is not revealed. These procedures yield much less information about the flavor of a food than descriptive analyses, yet are extremely useful eg, a manufacturer might want to substitute one component of a food product with another safer or less expensive one without changing the flavor in any way. Several formulations can be attempted until one is found with flavor characteristics that caimot be discriminated from the original or standard sample. 

The development of precise and reproducible methods of sensory analysis is prerequisite to the determination of what causes flavor, or the study of flavor chemistry. Knowing what chemical compounds are responsible for flavor allows the development of analytical techniques using chemistry rather than human subjects to characterize flavor (38,39). Routine analysis in most food production for the quaUty control of flavor is rare (40). Once standards for each flavor quaUty have been synthesized or isolated, they can also be used to train people to do more rigorous descriptive analyses. 

This example demonstrates the most challenging problem of flavor chemistry, ie, each flavor problem may require its own analytical approach however, a sensory analysis is always required. The remaining unknown odorants demand the most sensitive and selective techniques, and methods of concentration and isolation that preserve the sensory properties of complex and often dehcate flavors. Furthermore, some of the subtle odors in one system will be first identified in very different systems, like o-amino acetophenone in weasels and fox grapes. 

Advances in the technology of chemical analysis and the abiUty to analy2e for trace amounts of complex compounds now make it possible to combine analytical information with sensory analysis to identify taste characteristics and faciUtate process control. 

British Standard Institution, Methods for the Sensory Analysis of Foods, BS 5929-10 1999/ISOl 1037 1999, London, 1999. 

The determination and analysis of sensory properties plays an important role in the development of new consumer products. Particularly in the food industry sensory analysis has become an indispensable tool in research, development, marketing and quality control. The discipline of sensory analysis covers a wide spectrum of subjects physiology of sensory perception, psychology of human behaviour, flavour chemistry, physics of emulsion break-up and flavour release, testing methodology, consumer research, statistical data analysis. Not all of these aspects are of direct interest for the chemometrician. In this chapter we will cover a few topics in the analysis of sensory data. General introductory books are e.g. Refs. [1-3]. 

There are four main types of data that frequently occur in sensory analysis pair-wise differences, attribute profiling, time-intensity recordings and preference data. We will discuss in what situations such data arise and how they can be analyzed. Especially the analysis of profiling data and the comparison of such data with chemical information calls for a multivariate approach. Here, we can apply some of the techniques treated before, particularly those of Chapters 35 and 36. 

P. Lea, T. Naes and M. R0dbotton, Analysis of Variance for Sensory Data. Wiley, London, 1997 D. H. Lyon, M. A. Francombe, T. A. Hasdell and K. Lawson, Guidelines for Sensory Analysis in Product Development and Quality Control. Chapman and Hall, London, 1990. 

T. Naes and E. Risvik (Editors), Multivariate Analysis of Data in Sensory Science. Data Handling in Science and Technology Series, Elsevier, Amsterdam, 1996 J.R. Piggott (Editor), Sensory Analysis of Foods. Elsevier, London, 1984. 

Taylor, B. J. and Walsh, M. K. (2002). Development and sensory analysis of a textured whey protein meatless patty. /. Food Sci. 67,1555-1558. 

Sweeley, C. C., Holland, J. F., Towson, D. S., Chamberlin, B. A. J. Chromatogr. A 399, 1987, 173-181. Interactive and multi-sensory analysis of complex mixtures by an automated gas chromatography system. 

Assessment of taste is achieved by sensory analysis, from very simple experiments such as triangular tests aiming at determining detection thresholds to complex descriptive analysis approaches. A method referred to as time-intensity that consists in recording continuously the intensity of a given sensation over time under standardized conditions has been applied to study flavonoid bitterness and astringency properties. 

Preparation of boiled potatoes for sensory analysis involves peeling and cooking the samples in boiling water for 25-30 minutes or until cooked through as determined by a sharp probe. Hot samples are presented to the panel of assessors whole or prepared as required according to the particular study. The number of assessors, design of the assessments, replication and analysis are determined by the objectives of each experiment. 

Table IV. The Results of Sensory Analysis of Mixed Solution...

Figure 3. Descriptive sensory analysis of beef flavor attributes. Flavor attributes are examined as a function of storage time (days) postmortem.

Alsberg, B. Chemometrics and Intelligent Laboratory Systems 1990, 8, 173-181. Powers, J.J. In Sensory Analysis of Foods Piggott, J.R., Ed. Elsevier Applied Science London, 1988 pp 187-266. 

Flavour is of increasing importance when food is sufficiently abundant for consumers to exert choice. Sensory analysis, using trained laboratory panels, has been developed to profile fruit flavours, and describe relationships between products with a marked de ee of confidence but is time-consuming, requiring d icated obs ers who appreciate the nuances of individual character. Many, if not most, consumers, however, do not discriminate between fruit flavours. In dried orange juices, sweetness has been shown to be the major factor determining preference in canned juices, sourness and in frozen juices the interaction between sweetness and sourness is the significant factor (77). 

Volatile Compounds from Heated Porii Fat. Pork fat was heated at 160°C for 1 hr, fractionated at 207 bar/50°C and at 345 bar/50°C, and analyzed as described by Um et al. (30). The fractions (Figure 6) were analyzed by sensory analysis and the results were similar to those described for beef tallow. Fraction FI was observed to have the strongest "porlty" odor, and the residue had the least... 

Sensory analysis of mixed solutions of MSG and each of four dipeptides was carried out (Table VI). The umami taste of MSG was not changed when it was mixed with peptides containing aspartic acid. On the other hand, Glu-Glu, produced the... 

---