Sensory evaluations

Sensory evaluation provides information most closely associated with the quality of food lipids. Flavor or odor defects may be detected by panelists before they are recognised by chemical or instrumental methods. For example, the fishy and grassy taste produced in linolenic acid-containing oils such as soybean oil occurs at very low levels of oxidation only detected by sensory analyses. The limitations of this method are poor reproducibility and high cost of panelists and the necessary facilities. The recommended approach is to use more reproducible chemical or instrumental methods to complement or support the sensory analyses (Frankel 1998). 

Over the last few decades scientist have developed sensory testing from the earliest individual examinations into a formalised, structured and codified methodology. Subsequently, sensory tests have become valuable, important and precise tools in quality control, which are equivalent to the physical and chemical methods used. However, sensory testing is not only a tool in quality assurance, but also in grading, product development and marketing, as well as for the correlation between specific chemical/physical properties of a food and the effect on the human sensorial perception. 

Besides smell and taste, the sensorial evaluation of raw materials and final products covers trigeminal impressions (e.g. hot) and visual impressions like colour, opacity and particle size. 

In order to obtain reproducible results, special care must be given to panel selection and panel education, testing facilities, sample presentation and the design of each test. Modern sensory facilities display a kitchen/laboratory for sample preparation as well as separate sensory booths with controlled air and lighting. The evaluation of the sensory results can be supported by specialised computer software packages. 

The most frequently used tests in quality control in the flavour industry are paired-sample comparison tests, and triangle tests, which are often combined with the description of deviation from a reference item. For the selection and training of panellists, further test methods are used, for example ranking tests for colour, taste and odour, threshold detections (taste, off-flavour), colour blindness tests and odour identification tests [6]. 

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There is no combination of chemical or physical analyses which can, or is ever likely to, replace human sensory evaluation completely. Sensory examination of wines employs two major approaches detecting differences and evaluating quaUty or, more briefly, analytical and hedonic (16,19). The former can be objective and the latter is inevitably somewhat subjective regardless of the expertise of the judges. 

A. Turk, Basic Principles of Sensory Evaluation, American Society for Testing and Materials Special Technical Pubhcation 433, 1968, pp. 79—83. 

Aldehydes, enals, dienals, ketones, and hydrocarbons, which are responsible for disagreeable odors, generally bok at lower temperatures than fatty acids. Analysis showkig a free fatty acid concentration of less than 0.05% is an kidication that deodorization is sufficientiy complete. Some of the dienals have very low odor thresholds and sensory evaluation of the finished ok is a judicious quaHty assurance step. 

The type of food and its processing affect flavoring efficiency therefore, flavor materials must be taste-tested in the food itself. Because there has been a lack of standardization of testing techniques, a committee on sensory evaluation of the Institute of Food Technologists has offered a guide (112) which is designed to help in developing standard procedures. 

A General Guide to Sensory Evaluation, McCormick and Co., Hunt Valley, Md., 1978. 

To predict the comfort of a material, a combination of hand evaluation, eg, using the Kawabata system, as well as deterrnination of the heat and moisture transport properties, is necessary. Often, these values are correlated with a sensory evaluation of the tactile qualities of the material by a human subject panel. A thorough discussion of the many physical and psychological factors affecting comfort is available (134,135). 

Tyler, L.D., Acree, T.E., and Smith, N.L., Sensory evaluation of geosmin in juice made from cooked beets, J. Food Sci., 44, 79-81, 1979. 

Three attributes characterize color hue, lighmess (or value), and saturation (or chroma) and they are graphically represented in color solids (e.g., Munsell solid. Hunter solid). The Munsell Color Notation is a rapid, portable, widespread, and economical system of color determination. However, as it depends on sensory evaluation by panels, many laboratories prefer when possible to replace human judgment by instrumental techniques that are easier to handle. The CIELAB established by the Commission International d Eclairage (CIE) has become widely used with the availability of reflectance spectrophotometric instrumentation. 

Miettinen, S.M. et al.. Effect of emulsion characteristics on the release of aroma as detected by sensory evaluation, static headspace gas chromatography, and electronic nose, J. Agric. Food Chem., 50, 4232, 2002. 

Using these rhelogical methods laboratories for quality control and research and development have good tools to characterize pectins in gels and solutions. The most important points are the reproducable handling, pretreatment, and measurement of the samples and the knowledge which information can be derived from the measured data regarding the texture, the production parameters, and the sensory evaluation of the product. 

Keywords hypocaloric jelly analysis sensory evaluation. 

The jellies (20 sets) were submitted to a sensory panel (ten panellists from the laboratory staff with some experience in sensory evaluation) requested to give a score (from low to high in a non-structured 10 cm scale) to each of the following characteristics aroma (intensity), taste (sweet, acid and intensity), texture (hardness, spreadability) and overall acceptance. 

In this study we intend to investigate if a correlation between sensory evaluation and instrumental measurements of the low-methoxyl pectin jellies could be established. 

The data from sensory evaluation and texture profile analysis of the jellies made with amidated pectin and sunflower pectin were subjected to Principal component analysis (PC) using the statistical software based on Jacobi method (Univac, 1973). The results of PC analysis are shown in figure 7. The plane of two principal components (F1,F2) explain 89,75 % of the variance contained in the original data. The attributes related with textural evaluation are highly correlated with the first principal component (Had.=0.95, Spr.=0.97, Che.=0.98, Gum.=0.95, Coe=0.98, HS=0.82 and SP=-0.93). As it could be expected, spreadability increases along the negative side of the axis unlike other textural parameters. 

M. Meilgaard, G.V. Civille and B.T. Carr, Sensory Evaluation Techniques, 2nd Edition. CRC Press, Boca Raton, FL, 1987. 

H. Stone and J.L. Sidel, Sensory Evaluation Practices, 2nd ed. Academic Press, San Diego, 1993. 

M. O Mahony, Sensory Evaluation of Foods. Statistical Methods and Procedures. Marcel Dekker, New York, 1986... 

The purpose of preparative-scale liquid chromatography is the isolation of materials conforming to a specified purity in cUBOunts that depend on the intended use of the product [8,570-572]. Possible uses Include the isolation of materials for structural elucidation, for biological or sensory evaluation, for organic synthesis or commercial applications. The scale of the... 

Haglund A, Johansson L and Dahlstedt L (1998) Sensory evaluation of wholemeal bread from ecologically and conventionally grown wheat . Journal of Cereal Science, 27, 199-207. 

Haglund A, Johansson L, Berglund L and Dahlstedt L (1999) Sensory evaluation of carrots from ecological and conventional growing systems . Food Quality and Preference, 10, 23-29. 

Alternatively produced products have in common that their unique selling proposition is not directly visible to the consumer. Only additional information will identify the nature of the origin or the production process of these foods (Oude Ophuis, 1993). Within a sensory evaluation of free range pork under different conditions of experience and awareness, labelling and prior experience of the product have favourable influence on the sensory evaluation of free range pork for a number of attributes. The author assumes that contextual elements are very important in the sensory evaluation of fresh foods. 

Oude Ophuis PAM (1993), Sensory evaluation of free range and regular pork meat... 

Williams, U.P., J.W. Kiceniuk, and J.R. Botta. 1985. Polycyclic Aromatic Hydrocarbon Accumulation and Sensory Evaluation of Lobsters (Homarus americanus) Exposed to Diesel Oil at Arnold s Cove, Newfoundland. Canada Tech. Rep. Fish. Aquatic Sci. 1402. 13 pp. 

Boehm, T. and Zufall, F. (2006) MHC peptides and the sensory evaluation of genotype. Trends Neurosci. 29, 100-107. 

Field Pea Flour in Other Baked Products. When McWatters (44) substituted 8% field pea flour and 4.6% field pea concentrate for milk protein (6%) in baking powder biscuits, sensory attributes, crumb color, and density of the resulting biscuits were adversely affected. No modifications were made in recipe formulation when pea products were incorporated. The doughs were slightly less sticky than control biscuits that contained whole milk. This might be due to lack of lactose or to the different water absorption properties of pea protein or starch. Panelists described the aroma and flavor of these biscuits as harsh, beany and strong. Steam heating the field pea flour improved the sensory evaluation scores, but they were never equivalent to those for the controls. 

During the CEC-seminar in Bad Zwischenahn, Kowalewsky (1) concluded that NH3 is suitable for use as a main component. He defined a main component as a compound whose concentration correlates with the sensory evaluation of odour intensity. 

To minimise the influence of variables that are inherent to sensory evaluation, such as... 

A forced-choice detection method should be used to reduce the influence of variables that are inherent to sensory evaluation, such as anticipation, decision criteria, doubt and adaption, etc. 

On the basis of a sensory evaluation, the air in cowsheds using peat was slightly fresher than that in the other cowsheds. The same result was obtained in the farm interviews. 

LINDVALL, T. 1970. On sensory evaluation of odorous air pollutant intensities. Nordisk Hygienisk Tidskrift, Supplementum2 l-181, Stockholm. 

Most of the odours coming from livestock production units are associated with the biological degradation of the animal wastes (35), the feed and the body odour of the animals (1). Volatile fatty acids and phenolic compounds were found to contribute mostly to the strong, typical odour of animal houses by the help of sensory evaluations parallel to the chemical analysis (29), (30). 

When comparing the dust-borne concentrations of butyric acid and p-cresol with the odour thresholds it seems that the concentrations are too small to be relevant for an odour nuisance. However, if the dust is removed from the gas phase of the air from animal houses the odour disappears (39), (40), (14). This supports the opinion of HAMMOND et al. (40) that the odor is concentrated on the dust particles. The authors conclude from their data that the concentration of the two odorants butyric acid and p-cresol is about 4TO7 greater on an aerosol particle than it is in an equal volume of air. Thus, an aerosol particle deposited on the olfactory organ carries odour equivalent to a much greater volume of air (40). These considerations indicate that dust from animal houses should be taken into account in connection with odour emission/immission measurements not only by chemical analysis but by sensory evaluations using olfactometers without dustfilters, as well. 

SugawaraY, Kara C, Tamura K, FujiiT, Nakamura K, MasujimaT, AokiT, Sedative effect on humans of inhalation of essential oil offinalool Sensory evaluation and physiological measurements using optically active finalools, Anal Chim Acta 365 293-299, 1998. 

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