Sensory analysis production

Discriminant Sensory Analysis. Discriminant sensory analysis, ie, difference testing, is used to determine if a difference can be detected in the flavor of two or more samples by a panel of subjects. These differences may be quantitative, ie, a magnitude can be assigned to the differences but the nature of the difference is not revealed. These procedures yield much less information about the flavor of a food than descriptive analyses, yet are extremely useful eg, a manufacturer might want to substitute one component of a food product with another safer or less expensive one without changing the flavor in any way. Several formulations can be attempted until one is found with flavor characteristics that caimot be discriminated from the original or standard sample. 

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. 

The determination and analysis of sensory properties plays an important role in the development of new consumer products. Particularly in the food industry sensory analysis has become an indispensable tool in research, development, marketing and quality control. The discipline of sensory analysis covers a wide spectrum of subjects physiology of sensory perception, psychology of human behaviour, flavour chemistry, physics of emulsion break-up and flavour release, testing methodology, consumer research, statistical data analysis. Not all of these aspects are of direct interest for the chemometrician. In this chapter we will cover a few topics in the analysis of sensory data. General introductory books are e.g. Refs. [1-3]. 

P. Lea, T. Naes and M. R0dbotton, Analysis of Variance for Sensory Data. Wiley, London, 1997 D. H. Lyon, M. A. Francombe, T. A. Hasdell and K. Lawson, Guidelines for Sensory Analysis in Product Development and Quality Control. Chapman and Hall, London, 1990. 

Flavour is of increasing importance when food is sufficiently abundant for consumers to exert choice. Sensory analysis, using trained laboratory panels, has been developed to profile fruit flavours, and describe relationships between products with a marked de ee of confidence but is time-consuming, requiring d icated obs ers who appreciate the nuances of individual character. Many, if not most, consumers, however, do not discriminate between fruit flavours. In dried orange juices, sweetness has been shown to be the major factor determining preference in canned juices, sourness and in frozen juices the interaction between sweetness and sourness is the significant factor (77). 

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. 

Rancidity measurements are taken by determining the concentration of either the intermediate compounds, or the more stable end products. Peroxide values (PV), thiobarbituric acid (TBA) test, fatty acid analysis, GC volatile analysis, active oxygen method (AOM), and sensory analysis are just some of the methods currently used for this purpose. Peroxide values and TBA tests are two very common rancidity tests however, the actual point of rancidity is discretionary. Determinations based on intermediate compounds (PV) are limited because the same value can represent two different points on the rancidity curve, thus making interpretations difficult. For example, a low PV can represent a sample just starting to become rancid, as well as a sample that has developed an extreme rancid characteristic. The TBA test has similar limitations, in that TBA values are typically quadratic with increasing oxidation. Due to the stability of some of the end-products, headspace GC is a fast and reliable method for oxidation measurement. Headspace techniques include static, dynamic and solid-phase microextraction (SPME) methods. Hexanal, which is the end-product formed from the oxidation of Q-6 unsaturated fatty acids (linoleate), is often found to be a major compound in the volatile profile of food products, and is often chosen as an indicator of oxidation in meals, especially during the early oxidative changes (Shahidi, 1994). 

Wold, J.P., Veberg, A., Nilsen, A., Iani, V., Juzenas, P., Moan, J. 2005. The role of naturally occurring chlorophyll and porphyrins in light-induced oxidation of dairy products. A study based on fluorescence spectroscopy and sensory analysis. Int. Dairy J. 14, 343-353. 

The second product is changed in yet another way, but is found not to be different from the newest (third) product. However, the third product may be different from the first product. The best way to avoid product drift is to intimately know a product. This means knowing exactly what sensory characteristics are present in your product and at what intensities. This type of sensory analysis requires the use of descriptive analysis techniques. Because descriptive analysis involves using a trained peine 1, developing a set of descriptors, and rating their intensities, it can be very expensive, but so can product drift. 

To illustrate descriptive analysis, I will draw from both the wine and beer industry. Oregon State University s Sensory Science Laboratory, located in the Department of Food Science and Technology, is heavily involved in wine and beer research. The principle problems and solutions in the sensory analysis of wine and beer should be transferable to other products. Common wine descriptors, such as soft, hard, fat, are ambiguous. What do soft or hard mean when referring to wine The goal of descriptive analysis is to use precise terms, even referring to specific chemical entities when possible. In the wine industry, objective sensory analysis must overcome the historical romance of wine. 

Oxidative stability of edible oils depends primarily on their fatty acid composition and, to a lesser extent, in the stereospecific distribution of fatty acids in the triacyl-glycerol molecules. The presence of minor components in the oils also affects their oxidative stability. A detailed discussion of oxidative processes in fats and oils is provided elsewhere in this series. Oxidation may occur via different routes and includes autoxidation, photo-oxidation, thermal oxidation, and hydrolytic processes, all of which lead to production of undesirable flavor and products harmful to health. Flavor and odor defects may be detected by sensory analysis or by chemical and instrumental methods. However, chemical and instrumental procedures are often employed in the processing and during usage of edible oils. Indicators of oxidation are those that measure the primary or secondary products of oxidation as well as those from hydrolytic processes or from thermal oxidation, including polymers and polar components (15). 

A professional description of flavours uses as precise descriptors as possible. Chemical analytical results are combined with sensory analysis of the identified components to assess the relative importance and contribution to the flavour profile. Key ingredients or character impact compounds (CIC) are important components sine qua non to impart the typical, product characteristic, flavour, e.g. anethol for anise, eugenol for clove, 3-methyl butyl acetate for banana or ethyl butyrate to improve the juiciness of orange juice. 

Rice bran protein concentrate can be effectively acid hydrolyzed to produce RB-HVP having a unique free amino acid profile, with a slightly reduced monosodium glutamate balance conqiared to soy and wheat HVPs. The majority of the character-inq)act conqjonents of RB-HVP were derived via Strecker degradation of the available free amino acids, with some potential off-notes being caused by presence of 2-methoxyphenol and 2,6-dimethoxyphenol. In order to fully imderstand the potential of RB-HVP, it is recommended that the product be further characterized by sensory analysis and evaluated in an actual process flavor application. 

Despite years of research on irradiation odor, many questions remain unanswered. There is no systematic descriptive sensory analysis of irradiation-induced odor and aroma in RTE meat products. The description of off-odor has been mostly reported for raw meats. Limited studies have indicated that the off-odor is not always found in low dose irradiation-induced RTE products. The descriptive analysis may be conducted on RTE products irradiated in higher doses, so distinguished odors can be detected. 

Sensory analysis is concerned with quantifying human responses to stimuli. It is a precise, descriptive and measuring technique that characterizes the stimulus. In this case, the particular concern is to evaluate the odour of a perfume, perfume ingredient or perfumed product. This is an important process in enabling the perfumer to understand and quantify the sensory characteristics of the product, as only then can they be manipulated in a controlled way as part of the creative process. 

The evaluative and subjective associations made by the consumer must be understood when assessing a product these are measured using market research techniques. If the market is understood, fragrances can be developed to match or enhance the image of a particular product or market segment. Sensory analysis is also an important tool in this process. Using powerful statistical techniques, the odour relationships between different products or perfumes can be characterized and quantified, and the results combined with market research to enable the subjective associations to be interpreted in odour terms. 

Sensory analysis and market research rely on verbal or conscious measurement of an odour or perfumed product by a human respondent. Emotion is another aspect of product perception which is difficult... 

Sensory analysis involves using human subjects as a measuring tool. This presents an immediate problem, as individuals are innately variable, not only as a result of their experiences or expectations, but also as a result of their sensitivity. Thus, each person could genuinely perceive the same product quite differently. It is therefore essential in... 

---