Quality sensory analysis

Unfortunately, the two basic techniques used to assess flavor/fragrance quality— sensory analysis and conventional GC/MS—are generally too time-consuming, complex, and labor-intensive for routine quality control application. In fact, many of the test procedures and sample preparation methods described in this book are inappropriate for routine quality control testing. In industrial quality control applications, the need for speed and the large number of samples to be tested significantly impact the type of testing procedures and instrumentation that can be used. 

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]. 

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. 

Sensory. Sensory analysis is one of the oldest accepted methods forjudging seafood quality and freshness. Although fairly accurate, it unfortunately requires trained, experienced panelists to attain accuracy. Perez-Villarreal (( u evaluators experienced in sensory analysis of fish to judge freshness and quality. Results of the study showed sensory scores were better correlated with microbiological analyses, especially total viable counts, than with chemical analyses such as trimethylamine or enine nucleotide decomposition (6). 

Aroma compounds in distilled spirits and liqueurs, their levels, odour attributes, and thresholds are most important for quality and authenticity. Using gas chromatography and mass spectrometry, especially the composition of volatile aroma compounds in distilled spirits has been widely investigated [4-8]. By direct injection of an alcoholic distillate it is possible to determine more than 50 components within levels between 0.1 and 1,000 mg L b special methods of extraction can be used to increase this number up to more than 1,000 volatile substances [6]. However, sensory analysis is still indispensable to describe and evaluate spirit drinks. 

Sensory. Although the basis for multivariate analysis was developed in the early 1900 s, its use in sensory analysis is relatively recent. These types of statistics, however, have been valuable in dealing with two fundamental problems which occur in sensory testing. First there are difficulties encountered when one attempts to breakdown complex sensory parameters into single semantic terms which can be rated, and second it is difficult to achieve the goal of every panelist having the same internal understanding of each term. Approaches to minimize these difficulties included 1) evaluation of semantic terms used by the panel to determine if the variables are unique or can be condensed to a new set of unique variables 2) evaluation of the panelists use of semantic terms to determine inconsistencies as well as the relative importance of the terms to food quality or discrimination.(8)... 

In concomitance to the sensory analysis with external experts, different analytical investigations were performed in order to select few indices for the definition of the quality characteristics for both the typologies of cheese. 

Example 9-7. Sensory analysis of a C02 containing mineral water showed that a loss of 15 % or more from the initial quantity of C02 led to a significant quality decrease in the form of a flat taste. A 1.5 liter plastic bottle has an initial fill pressure of 3.8 bar. A tightly sealed bottle has a total permeability of Q = 6 mg/day at 20 °C. How long can this bottle be stored before a noticeable sensory change takes place in the mineral water ... 

Sensory analysis The odour of an essential oil can be evaluated by conducting investigations on the evaporation of an essential oil under standardized conditions and comparing this to a standard sample of the oil. This is sometimes referred to as odour purity but is a rather subjective method. It involves putting the essential oil and a standard sample onto separate smelling strips and allowing them to evaporate to a final dry-out under the same environmental conditions and time scale. This, along with a visual inspection of the oil, is the only immediate quality control measure available to the aromatherapist. 

Sensory Analysis of the Saumur and Anjou Wines as Related to Phenolic Composition. Sensory analysis of the Saumur and Anjou wines. Figure 8, allowed to distinguish a third group of wines (namely SCI and GRA), characterized by strong astringency, in addition to the higher quality and poorer quality wines mentioned above. 

Characterization of essential oils must include three kinds of analysis sensory analysis determination of physicochemical properties such as specific gravity (20°C), refractive index, optical rotation, aldehyde and carotenoid contents and solubility spectroscopic properties (UV and IR) and chromatographic analysis. In Table 5.10, the main analytical determinations that can be carried out in the quality control of essential oils are summarized. The ranges of values for each analytical parameter of essential oils from oranges are also shown. 

In contrast, under appropriate conditions, sensory analysis or sensory quality testing of flavourings is ... 

The problem in quality testing is the number of assessors. In Sensory Analysis, which is closely allied with statistics here, between 7 and 11 panelists are normally required for this type of testing. But no company carries out initial quality testing with over 7 people. So a compromise has to be found. 

In 1966, Le Magnen proposed a designation of the organoleptic qualities of coffee. A choice of tests for the organoleptic valuation of coffee has been presented by Depledt (1968) and a sensory analysis of coffees and instant coffees has also been published by Van Roekel (1976). Vitzthum et al. (1976) were the first to use the sniffing -technique in the analysis of coffee volatiles. 

After an avalanche of analytical results, mainly with a view to discover a maximum number of new and typical constituents, some research groups focused their attention on the key constituents , arranging them in order of decreasing flavor contribution. This approach has been particularly conducted during the last two decades, thanks to the development of new concepts in sensory analysis and to the general tendency to improve the quality of foodstuffs. Moreover, the application of sensory analysis allowed, in collaboration with chemical methods, the identification of the compounds responsible for the aroma and, notably, determination of the intensity of individual odors of the fractions separated by chromatography. 

White (1995), not for a sensory analysis but mainly with a view to determining coffee adulterations, used the data of combined headspace GC and high-performance LC for multivariate analysis. Principal component analysis visualized the relationship between samples, and the outlying samples could be identified. The method could be an additional tool for classification and quality control of coffee products. 

During lipid oxidation, the primary oxidation products that are formed by the autoxidation of unsaturated lipids are hydroperoxides, which have little or no direct impact on the sensory properties of foods. However, hydroperoxides are degraded to produce additional radicals which further accelerates the oxidation process and produce secondary oxidation products such as aldehydes, ketones, acids and alcohols, of which some are volatiles with very low sensory thresholds and have potentially significant impact on the sensory properties namely odor and flavor [2, 3]. Sensory analysis of food samples are performed by a panel of semi to highly trained personnel under specific quarantined conditions. Any chemical method used to determine lipid oxidation in food must be closely correlated with a sensory panel because the human nose is the most appropriate detector to monitor the odorants resulting from oxidative and non-oxidative degradation processes. The results obtained from sensory analyses provide the closest approximation to the consumers approach. Sensory analyses of smell and taste has been developed in many studies of edible fats and oils and for fatty food quality estimation [1, 4, 5]. 

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