Sensory Methods

KLARENBEEK, J.V., and BEUMER, S.C.C., (1979). The use of a simple sensory method for odour emission research in intensive livestock keeping. Xnr. 5221. IMAG, Wageningen. (in dutch)... 

Olfactometric or sensory methods which provide information relating to the human response to odours. 

Heilman, T.M., and Small, F.H. Characterization of the odor properties of 101 petrochemicals using sensory methods, J. Air Pollut. Control Assoc, 24(10) 979-982, 1974. 

Antioxidant-Treated Beef Patties. The effect of several primary antioxidants, PG, TBHQ, Tenox 20 (which contains TBHQ and citric acid) and Tenox 4A (which contains BHA and BHT) were also evaluated by instrumental, chemical and sensory methods for their effectiveness in raw/stored and cooked/stored beef, see Tables 1-4. These particular antioxidants were chosen based on their antioxidant effects on MFD as determined previously (14) and because of their GRAS status. Experimental samples were prepared similarly to those of the 0-and 2-day controls, except the antioxidants, either dissolved or suspended in water, were mixed into the raw ground meat. 

Sensory methods have the ability to detect spoilage of either cooked or raw products. Because of this advantage, sensory methods are used as standards by agencies such as the U.S. Food and Drug Administration (FDA) for regulatory purposes. The shortcomings of such procedures are the subjective nature of the evaluations, which typically causes greater deviation than objective evaluations, and the need for trained evaluators. 

Zhang, H., Balaban, M.O., Portier, K., Sims, C.A. (2005) Qrantification of spice mixture compositions by electronic nose Part II comparison with GC and sensory methods. J. Food Sci. 70 E259-E264. 

Choosing a Sensory Test. The types of sensory methods available for citrus evaluation are numerous. Two excellent refer-... 

Two oat varieties were studied with respect to their oil content. The composition of these SCCO2 extracted oils, with regard to fatty acids, free fatty acids, phosphorus and thermal stability has previously been reported (Fors and Eriksson, submitted for publication 1988). Volatile compounds were isolated from the oat oils by molecular vacuum distillation. The fractions obtained were transferred to aqueous alkali and extracted by CH2CI2. The adjustment in pH was made to remove fatty acids which could otherwise interfere with the later work. Moreover, it is well established that many heterocycles are important flavor compounds in heated food items. These compounds are normally isolated in the basic fraction. The isolates were analysed by chemical and sensory methods. 

Samples were reheated at full power for 1 minute in a microwave oven prior to proceeding with flavor volatile analysis (60 C internal temperature). A reproducibility study was carried out on 5 identical, 100 g samples that had been stored for 3 days after cooking, except that they were not reheated in the microwave prior to analysis. An ad hoc panel convened for these experiments consisted of two trained meat flavor panelists who scored the samples for characterization of MFD according to descriptive sensory methods described by Johnsen and Civille (12) and Love (13). The panelists were also active members of a twelve member descriptive sensory panel at the Center. Two duplicate repetitions were carried out for each experiment (4 samples studied). 

The combination of sensory evaluation with analytical approaches is required to identify perceptible changes and to identify the potential chemical changes that may be causing the sensory effect. Low concentrations of compounds responsible for changes in food characteristics may not be detectable by even the most sensitive analytical methods but, in combination with appropriately applied sensory methods, the clues provided by both techniques may help identify the problem, provide indications to the cause, and suggest clues for the source of the problem. 

However, since the act of sensation is an interaction of an observer with a stimulus, the two approaches often end up using similar methods (e.g., scaling) to provide similar information (e.g., observer response as a function of stimulus concentration). Because of this parallel orientation in methods, and because of the concurrent advances recently made in both areas, we have integrated results from the two fields in this paper. The first section will focus on psychophysical characterization of oral chemical irritants. The final section will discuss the development of a new sensory method for evaluation of ground red pepper heat. 

The development of new instrumental methods to replace the troubled Scoville procedure necessitated the design of an improved sensory method for validation of instrumental precision. A new sensory method (4) was designed which offered the following procedural improvements over the Scoville Method 1) a 20 minute aqueous extraction, (2) no ethanol used, 3) reference standard included in each test, 4) trained panelists, 5) timed tasting, rinsing and recess, 6) one dilution for all samples, and 7) use of a graphic line scale to score the heat sensation. 

Furthermore, the new sensory method avoids several problems inherent in the Scoville procedure. Heat build up, fatigue, and increased threshold are minimized by use of a standardized initial sample, as well as timed rinsing between samples. Ethanol bite is avoided by use of an aqueous extraction. The panel data may be manipulated statistically due to the linearity of the scale and the number of panelists. Reference standards are included. Extraction time is reduced from 16 hours to 20 minutes. Reproducibility of results has been demonstrated. The error of central tendency is avoided by not having a "middle sample. The new method is more comparable to normal food usage as it is an aqueous rather than ethanol extraction. 

The new sensory method shows excellent correlation with instrumental determination of capsaicinoid content of red pepper samples, and can be converted to Scoville units for universal understanding. 

Notwithstanding all the limitations involved, the continuous improvement in precision and reproducibility of physical measurement equipment that relate to parameters perceived by human subjects make their use straightforward and they can provide consistent results. It is important to keep in mind that although instruments allow precise and objective measurements if applied to whole foods, they only can account for the initial structural properties contributing to texture perception. A correlative approach using sensory and instrumental techniques is often necessary. Indeed, there is no reason to determine accurately a mechanical property if it is not relevant to human sensory perception. Sensory methods become essential when calibrating instrumental equipment and are fundamental in product development, especially at early stages. 

Houskaet al. (1998) determined the relationships for five sensory methods of oral and non-oral viscosity evaluation between viscosity scores and instrumentally measured dynamic viscosity for Newtonian fluid foods of low and medium viscosities. From those relationships, the effective shear rates for the five the sensory tests were estimated. Highest shear rates were predicted for viscosity perception by compression of samples between tongue and palate, and the lowest for pouring the fluid foods from a teaspoon. Mixing with a teaspoon, slurping and swallowing exhibited nearly... 

Sensory methods are often criticized as being subjective techniques. Part of the problem ties with the failure to acknowledge that two distinct types of sensory tests... 

The sensory method chosen for a test is dependent on the type of information required. The appropriate method can only be selected after the objectives of the test are clearly defined. As illustrated in Table 1, there are a substantial number of test methods available and it is important to be familiar with them in order to apply the correct method to achieve the correct results. Familiarity with the test methods also reduces the likelihood of relying on a single method. Difference and descriptive tests are the main tests used to evaluate fat and oil quality. Both tests require the use of trained panelists, but the level of training is considerably more for descriptive testing. In difference testing, panelists only determine if there is a difference between samples. The degree of difference is not determined. In contrast, descriptive tests allow panelists to rate the intensities of several attributes resulting... 

Fried foods quality is defined by their properties, such as moisture and oil contents, porosity, color, taste, and nutritional content (Dogan et al., 2005). Conventional methods of measuring these properties include physical (instrumental), chemical, and sensory methods (Qiao et al., 2007a). Some of these procedures are subjective, cumbersome, and time-consuming, and often require the destruction or modification of a product. During the past decade, a number of novel methods for determining food properties have been proposed, and some of them are presented below. 

Characteristic aroma components in foods and off-flavor substances in processed foods are called character impact compounds. It would be desirable to develop methods for finding such compounds with sensory methods because such information is useful in the food industry. A compilation of odor and taste threshold values was edited by Fazzalari (7). Olfactory-trigeminal response to odorants was measured using rabbits (2). However, aroma quality can be evaluated only by human sense. In spite of this fact, olfactory judgment by humans can not give constant data like... 

Harper R. (1982) Techniques of analysis of flavours. Sensory methods. In Food Flavours. Part A. Introduction. Morton I.D. and McLeod A.J., Eds, Elsevier Scientific Publishing, Amsterdam, Co, 3A, 79 120. 

Rothe M. and Kruse H.P. (1999) Solving flavor problems by sensory methods. In Flavor Chemistry. Thirty Years of Progress. Teranishi R., Wick E.L. and Hornstein I. Eds, Kluwer Academic/Plenum, New York, pp. 367-75. 

Tciste is determined in drinking waters only by sensory methods and is expressed by description only (salty, fresh, bitter, acid, or also the taste is... 

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