Sensory panel tests

Following previous works on physico-chemical characterisation of sunflower low-methoxyl pectins (Alarc o-Silva, 1990, Leitao at al., 1995) and technological utilisation in the manufacture of low calorie gels (Alarc o-Silva et al., 1992), this investigation was carried out to test the suitability of that pectin to the confection of grape juice reduced calorie jellies in comparison with two types of commercial pectin. Aiming at the optimisation of low-calorie jelly formula, based on consumers preferences, the jellies were submitted to a sensory panel test judgement and instrumental texture-analysis. 

When many data sets for the same set of products (objects) are available it is of interest to look for the common information and to analyze the individual deviations. When the panellists in a sensory panel test a set of food products one might be interested in the answer to many questions. How are the products positioned, on the average, in sensory space Are there regions which are not well... 

Fig. 16.5 Correlation between the technical quality index and sensory score (overall judgement) in blind sensory panel tests.

Evaluating Synthetic Sweeteners. Evaluation of new sweeteners, unlike that of most functional food ingredients, is not possible using totally objective means, There arc no general rules leading to structurc/function relationships for all classes of sweeteners. The principal judgments must rely on human sensory panel tests. The training and administration of sensory panels for sweeteners are beyond the scope of this volume. 

Taste of amino acids was studied using the taste sensor [23]. Taste of amino acids has had the large attention so far because each of them elicits complicated mixed taste itself, e.g., L-valine produces sweet and bitter tastes at the same time. Thus, there exist detailed data on taste intensity and taste quality of various amino acids by sensory panel tests [26]. The response of the sensor to amino acids was compared with the results of the panel tests, and response potentials from the eight membranes were transformed into five basic tastes by multiple linear regression. This expression of five basic tastes reproduced human taste sensation very well. 

Because most foods are complex disperse systems, there are great difficulties in establishing objective criteria for texture measurement. It is also difficult in many cases to relate results obtained by instrumental techniques of measurement to the type of response obtained by sensory panel tests. 

This approach is most closely related to flavor evaluation and suitable for comparison with results of sensory panel tests. Although it is more precise than sensory methods, the results vary with different unsaturated oils, and with different additives such as antioxidants and metal inactivators. This method provides useful data on the origin of volatiles and flavor precursors. While total and individual volatiles can be correlated between oxidation time (Table 7.2)... 

The gas chromatographic determination of individual carbonyl compounds appears to be a method suitable for conparison with findings of sensory panel tests. Analytical methods for the odorants causing aroma defects is still in the early stages of development because only a few fats or fat-containing foods have been examined in such detail that the aroma substances involved are clearly identified. 

S. de Jong, J. Heidema and H.C.M. van der Knaap, Generalized Procrustes analysis of coffee brands tested by five European sensory panels. Food Qual. Pref., 9 (1998) 111-114. 

It is often too expensive to have or maintain an inhouse descriptive sensory panel. Therefore, other ways of measuring flavor need to be developed. Off-flavor in many foods have been measured by using gas chromatography to assess the level of lipid volatiles associated with off-flavor development Chapters 5, 6, 9) such as hexanal or by direct chemical determination of thiobarbituric acid reactive substances Chapters 5, 6) as a marker of the degree of lipid peroxidation. A new method being tested for use in the assessment of food qu ity is impedance technology. This method is showing promise for use in the seafood industry Chapter 20),... 

Two kinds of mixed solutions were provided to test the hypothesis. One was a mixed solution of D-phenylalanine and L-phenylalanine. The second was a mixed solution of sucrose and L-phenylalanine. While the chemical properties of d- and l-phenylalanine are the same, for the most part, they do possess different tastes. Sucrose has a structure and taste that is significantly different from L-phenylalanine. The sensory data obtained from a five member sensory panel is shown in Table ni. 

Klinger et al. (31) reported that extensive taste panel tests of chicken breast meat or leg meat irradiated to 3.7 kGy and cooked by boiling in water showed no loss in sensory quality immediately after treatment. The sensory quality of the irradiated chicken deteriorated during refrigerated storage over a period of 3 to 4 weeks. Irradiated chicken breast meat was acceptable for about three weeks however, quality of unirradiated chicken was retained for only about four days during chilled storage. 

In the case of pineapples, the 12 odorants listed in Table 16.7 were dissolved in water in concentrations equal to those determined in the fruit [50]. Then the odour profile of this aroma model was evaluated by a sensory panel in comparison to fresh pineapple juice. The result was a high agreement in the two odour profiles. Fresh, fruity and pineapple-like odour notes scored almost the same intensities in the model as in the juice. Only the sweet aroma note was more intense in the model than in the original sample [50]. In further experiments, the contributions of the six odorants showing the highest OAV (Table 16.7) were evaluated by means of omission tests [9]. The results presented in Table 16.8 show that the omission of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, ethyl 2-methylbutanoate or ethyl 2-methylpropanoate changed the odour so clearly that more than half of the assessors were able to perceive an odour difference between the reduced and the complete aroma model. Therefore, it was concluded that these compounds are the character-impact odorants of fresh pineapple juice. 

Cone penetrometry has the advantages of being simple and economical to use. Also, its results correlate well with testing by sensory panels (Dixon, 1974 Rousseau and Marangoni, 1999). In addition, standardized tests and commercial standards of design are available. The most widely used method is that of the American Oil Chemists Society (AOCS) (Cc 16-60) (AOCS, 1960). According to this method, the depth (d) (in increments of 0.1 mm) to which the cone penetrates the sample is read (AOCS, 1989). This depth is an indicator of consistency and can be related to some structural parameter of the material. Penetrometry results, for example, are often translated into spreadability or hardness values. For example, spreadability (S), as... 

Most mechanical tests developed for fats are empirical in nature and are usually designed for quality control purposes, and they attempt to simulate consumer sensory perception (3, 4). These large-deformation tests measure hardness-related parameters, which are then compared with textural attributes evaluated by a sensory panel (3, 5). These tests include penetrometry using cone, pin, cylinder and several other geometries (3, 6-12), compression (13), extrusion (13, 14), spreadability (15, 16), texture profile analysis (2), shear tests (13), and sectility measurements (14). These methods are usually simple and rapid, and they require relatively inexpensive equipment (3, 4, 17). The majority of these tests are based on the breakdown of structure and usually yield single-parameter measurements such as hardness, yield stress, and spreadability, among others (4, 17-20). The relationship between these mechanical tests and the structure of a fat has, however, not been established. The ultimate aim of any materials science endeavor is to examine the relationship between structure and macroscopic properties. 

Standard practices have been developed for conducting sensory panels in order to minimize psychological errors and physical testing conditions that can influence human judgment. By controlhng these factors, reliable sensory results can be achieved. The following sections outhne the most common psychological errors and how they can be minimized. 

American Society for Testing and Materials, STP 758 Guidelines for the Selection and Training of Sensory Panel Members, ASTM, Philadelphia, Peimsylvania, 1981. 

Within the meaning of Sensory sensory in combination with other attributes additionally means performing actions with sensory panels. Therefore Sensory Testing means testing with a sensory panel. 

After 3 days a preliminary chemical (TVOC) test and sensory irritation test with a panel of persons. If the TVOC concentration is higher than 5 mg/m and/or more than 10% of a panel of persons perceive sensory irritation, no label is given. 

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... 

A range of soaps was profiled by the sensory panel and the results were analysed to give a two-dimensional map, showing the relative similarities in odour character of the perfumes tested (Figure 8.5). 

Sensory panel The panel employed in all sensor measurements in tliis work was composed of eighteen persons university students Port winemakers and laboratory personnel. The panel is permanent and receives weekly training. Tests were performed in individual booths, using tulip glasses containing 30 mL of wine at room controlled temperature of 20 °C. 

Sensory Evaluation. Odor thresholds were determined as previously described, using Teflon squeeze bottles for panel testing (17). 

Reiners et al. employed a sensory analysis to check whether the results of the instrumental analyses were in agreement with their flavor profiles. The sensory panel used, consisted of nine experienced assessors, seven males and two fanales, aged 25-35 years. The sample was sniffed by the panelists (nasal evaluation) and then rinsed into the mouth (retronasal evaluation). The intensities of the odor characteristics of the olive oils scored as above on a category scale from 0 to 3.0. After an outlier test, the results were expressed as means (standard deviations). Apple-like and green notes were characteristic for the Italian oil, whereas the Spanish oil smelled intensely like black currants and the flavor of the Moroccan oil came close to eating black olives. Olive oils of several types and cultivars were sensory evaluated for main attributes by various composition panels giving important results. 

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