Determination methods sensory

Food colorants are analyzed either by direct inspection (sensorial analyses) or by physical or physicochemical instrumental methods. Direct inspections determine the sensorial attribute of color, frequently combined with assessments of smells and flavors. Visual color assessment is subjective and may be used with reliable visual evaluations controlling multiple variables. 

Pal, S., Sachdeva, S., and Singh, S. 1995. Methods for determination of sensory quality of foods. A critical appraisaL J. Food. Set Technol. 32, 357-367. 

The effectiveness of the appropriate FRI combination in stabilizing oils, normally sprayed onto expanded cereals, snacks and pet food is shown in Figure 3. The application of com oil to an expanded pet food at a level of 5% posed an unusual stress. The oil is stressed by the high surface area of the expanded food. Inclusion of oleoresin rosemary or ethoxyquin, or a patented ascorbic acid (Todd, 1989, 1992) provides varying degrees of improvement in shelflife as determined by sensory evaluation of the aroma, a key factor in dog foods. Aroma development correlated well with the Active Oxygen Method (AOM) for peroxide value determination. 

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. 

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. 

Picking fruit at an optimal harvest date is also an important factor affecting the nutritional and sensory quality and storability of fruit. Regardless of the production method, a fruit grower needs precise information on the seasonal (e.g. climate) and site-specific parameters that determine the optimal harvest... 

Decomposition of the primary products of lipid oxidation generates a complex mixture including saturated and unsaturated aldehydes such as hexanal. Hexanal is the most commonly measured end product of lipid oxidation, and both sensory and physicochemical methods are used for its determination. Where other antioxidant activity tests may be nonspecific, physicochemical measurement of hexanal offers the advantage of analyzing a single, well-defined end product. 

The physicochemical nature of the oil phase components in a cosmetic emulsion, the emollients, determines the skin-care effects, such as smoothing, spreading, sensorial appearance. Test methods have been developed to characterize and classify the numerous emollients available on the market, such as silicones, paraffins, and oleochemical-based products. The latter include glycerides, esters, alcohols, ethers, and carbonates with tailor-made structures, depending on the performance needed (Table 4.8). However, especially with regard to additional effects, there is still a demand for new products with unique performance properties. 

Comprehensive studies of this technique have been made at JTI and KI. In one of these studies comparisons were carried out between different spreading and burial methods for pig manure. The odour determinations were made in a mobile laboratory especially constructed for sensory measurements of air pollutants (1). The laboratory mainly consists of an airconditioned test-room with three exposure hoods. Fig. 3 shows a general outline of the mobile laboratory with the sampling equipment. 

Assessment of taste is achieved by sensory analysis, from very simple experiments such as triangular tests aiming at determining detection thresholds to complex descriptive analysis approaches. A method referred to as time-intensity that consists in recording continuously the intensity of a given sensation over time under standardized conditions has been applied to study flavonoid bitterness and astringency properties. 

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),... 

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. 

Currently available methods for determining seafood freshness have been reviewed (2,3,4,5). In general, sensory and microbiological quality of seafoods are the standards most often utilized for determining freshness. There are, however, several limitations with these methods such as the need for trained technicians, problems with subjectivity, or long analysis times. Consequently, several new methods have been proposed using chemical indices of freshness that attempt to overcome these difficulties. The purpose of the present paper is to first review these methods with particular emphasis on shrimp freshness determinations and, secondly, to present experimental evidence showing that impedance can be used to denote shrimp freshness. 

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