Sensory analysis flavor studies

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. 

Recent developments In microcomputers, sensory analysis and experimental design have made it possible to efficiently evaluate and optimize products. This paper focuses on the conduct and analysis of a study to optimize the flavor constituents of an alcoholic "digestive" liqueur. It illustrates the use of the panel data, and the contributions of the microcomputer as both a tool for gathering data, and as an inexpensive replacement for mainframe computers in statistical computations. 

Many varieties of red pepper, derived from plants of the genus Capsicum, are used in different cuisines around the world for their sensory properties of oral chemical "heat", volatile flavor and color. Determination of the degree of heat in a pepper sample has been a difficult problem for both sensory and instrumental analysts of flavor. Furthermore, the literature concerning the sensory physiology and perceptual responses of the "common chemical sense" (as defined later) has lagged behind other areas of study of the chemical senses. The purpose of this paper will be to review recent developments in two areas, the development of a standard method for sensory analysis of ground red pepper heat and the psychophysical characterization of observers responses to oral chemical Irritation induced by spice-derived compounds. 

Cabernet wine comparison. One of the objectives of the study was to identify the odoi active compounds of wines with "Brett" flavor through sensory analysis and gas chromatography-olfactometry (GCO). Wines identified by their respective winemakers as having "Brett" character were evaluated by a trained expert sensory panel also, using the technique CharmAnalysis (92-94) for GCO analysis, along with gas chromatography-mass spectrometry (GC-MS), odor-active compounds were identified by their respective Kovats retention indices (95). Contained below is a... 

Electronic noses have also been used to analyze meat flavor. Warmed-over flavor (WOE) in beef was studied by 32 conducting polymer sensors [30]. The meat was processed by vacuum cook-in-bag/tray technology (VCT) and stored in a refrigerator. The VCT process involves treatment at 50°C for 390 minutes. The authors indicated that electronic noses can be readily utilized for WOE identification in beef and can be a useful addition to sensory analysis. 

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]. 

In other flavor perception studies, the PTR mass spectra of the headspace of seven different brands of mozzarella cheese held at 36 C have been first compared with the judge panel flavor profile [157]. A PCA of the mass spectral data was used to discriminate different cheese types. And a trained panel of sensory judge was employed to give qualitative and quantitative analysis of mozzarella cheese. It was found that there was an interesting and clear similarity between the classical sensory and the instrumental analysis. More recently, a robust and reproducible model was developed to predict the sensory profile of espresso coffee, and the model was derived from 11 different espresso coffees, which had been analyzed by a trained panel and PTR-MS, and further validated using eight additional espressos [158]. Flavor studies of whey [159], custard desserts [160], other types of cheeses [148,161], milk [162], wine [163,164], apples [165],olive oils [166],bread [167], and butter and butter oil [168,169] were also conducted by the PTR-MS system. 

Challenges in the characterization of flavor compounds rest, at least in part, on olfactory and/or gustatory assessment. However, in sensory analysis studies, the measuring instrument is the human element [34—35]. That is the reason why it appears very important to know, as well as possible, the capabilities of this measuring instrument. ... 

In the present chapter, we have thus chosen to study the influence of the nature of fat and protein on the aroma release by solid-phase microextraction measurements and on the flavor perception by time-intensity sensory analysis. 

Flavor Description. TypicaHy, a sensory analyst determines if two samples differ, and attempts to explain their differences so that changes can be made. The Arthur D. Litde flavor profile (FP), quantitative descriptive analysis (QDA), and spectmm method are three of the most popular methods designed to answer these and more compHcated questions (30—33). AH three methods involve the training of people in the nominal scaling of the flavor quaHties present in the food being studied, but they differ in their method for quantitation. 

Human perception of flavor occurs from the combined sensory responses elicited by the proteins, lipids, carbohydrates, and Maillard reaction products in the food. Proteins Chapters 6, 10, 11, 12) and their constituents and sugars Chapter 12) are the primary effects of taste, whereas the lipids Chapters 5, 9) and Maillard products Chapter 4) effect primarily the sense of smell (olfaction). Therefore, when studying a particular food or when designing a new food, it is important to understand the structure-activity relationship of all the variables in the food. To this end, several powerful multivariate statistical techniques have been developed such as factor analysis Chapter 6) and partial least squares regression analysis Chapter 7), to relate a set of independent or "causative" variables to a set of dependent or "effect" variables. Statistical results obtained via these methods are valuable, since they will permit the food... 

Very limited information has been published on this subject. Using a sensory panel which employed quantitative descriptive analysis, Rouseff (2 ) was able to demonstrate that heated off-flavor was the major quality factor in determining the perceived quality of the juice. Some flavor descriptors used in this study are shown in Figure 3. Panelists evaluated each flavor descriptor using a 10-cm line anchored with weak and strong on the ends, and overall quality, previously defined using a 100-point... 

Preliminary GC analysis revealed that there are more number of peaks in roasted samples compared to plain cashews. Also selective extraction method was found to be slightly superior to the SDE method under the conditions of the experiment adopted in this study. However, the compounds in oven-roasted and oil-roasted samples did not differ much, qualitatively and quantitatively. In total, 26 compounds have been identified in plain cashews and 3 compounds in roasted samples. The identified peaks constituted 70 percent of the total peaks registered in GC analysis of the individual samples. The descriptive flavor profile of the eluting peaks of the plain and roasted samples were studied. Since the flavor isolate from oven roasted cashew nuts contained the flavor components of plain cashews also and since analysis showed that there was not much difference between the flavor constituents of oven-roasted and oil-roasted samples, the aromagram of the oven-roasted cashew nuts (SDE) was taken as representative. Fig.l gives the GC profile of oven roasted cashew nuts and the sensory properties of the numbered peaks are included in Table III. 

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). 

Guth, H. (1998) Comparison of different white wine varieties in odor profiles by instrumental analysis and sensory studies. In Waterhouse, A.L., Ebeler, S.E. (eds.) Chemistry of Wine Flavor, ACS Symposium Series 714, pp. 39-52... 

Schlich et al. (1987) proposed a new approach to selecting variables in principal component analysis (PCA) and getting correlations between sensory and instrumental data. Among other studies, Wada et al. (1987a,b) evaluated 39 trade varieties of coffee by coupling gas chromatographic data with two kinds of multivariate analysis. The objective classification was compared with the sensory data (cup test), directly or after statistical treatment. The results were concordant. Murota (1993) used qualitative sensory data to interpret further the results of GC data and canonical discriminant analysis. He could thus suggest which were the components responsible for the flavor characteristics in different coffee cultivars. 

Recent studies of photooxidized butter and butter oil identified by aroma extract dilution analysis, 3-methylnonane-2,4-dione, a potent volatile compound derived from furanoid fatty acids (see Section C.4) (Figure 11.7). Six different furanoid fatty acids were established as dione precursors, and were found in various samples of butter made from either sweet cream (116 76 mg/ kg), or from sour cream (153-173 mg/kg), or from butter oil (395 mg/kg). Similar precursors of the dione were identified in stored boiled beef and vegetable oils. This flavor defect arising by photooxidation of butter or butter oil is apparently different from the light-activated flavor in milk,that involves the interaction of sulfur-containing proteins and riboflavin. However, more sensory comparisons are needed to distinguish between these two flavor defects due to light oxidation. 

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