Foods sensory properties

Sensory perception is both quaUtative and quantitative. The taste of sucrose and the smell of linalool are two different kinds of sensory perceptions and each of these sensations can have different intensities. Sweet, bitter, salty, fmity, floral, etc, are different flavor quaUties produced by different chemical compounds the intensity of a particular sensory quaUty is deterrnined by the amount of the stimulus present. The saltiness of a sodium chloride solution becomes more intense if more of the salt is added, but its quaUty does not change. However, if hydrochloric acid is substituted for sodium chloride, the flavor quahty is sour not salty. For this reason, quaUty is substitutive, and quantity, intensity, or magnitude is additive (13). The sensory properties of food are generally compHcated, consisting of many different flavor quaUties at different intensities. The first task of sensory analysis is to identify the component quahties and then to determine their various intensities. 

Commercial interest in the sensory properties of foods during the past decade has led to a great increase in basic knowledge of the phenomenon. 

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]. 

In paired comparison tests two different samples are presented and one asks which of the two samples has most of the sensory property of interest, e.g. which of two products has the sweetest taste (Fig. 38.3). The pairs are presented in random order to each assessor and preferably tested twice, reversing the presentation order on the second tasting session. Fairly large numbers (>30) of test subjects are required. If there are more than two samples to be tested, one may compare all possible pairs ( round robin ). Since the number of possible pairs grows rapidly with the number of different products this is only practical for sets of three to six products. By combining the information of all paired comparisons for all panellists one may determine a rank order of the products and determine significant differences. For example, in a paired comparison one compares three food products (A) the usual freeze-dried form, (B) a new freeze-dried product, (C) the new product, not freeze-dried. Each of the three pairs are tested twice by 13 panellists in two different presentation orders, A-B, B-A, A-C, C-A, B-C, C-B. The results are given in Table 38.3. 

The experimental designs discussed in Chapters 24-26 for optimization can be used also for finding the product composition or processing condition that is optimal in terms of sensory properties. In particular, central composite designs and mixture designs are much used. The analysis of the sensory response is usually in the form of a fully quadratic function of the experimental factors. The sensory response itself may be the mean score of a panel of trained panellists. One may consider such a trained panel as a sensitive instrument to measure the perceived intensity useful in describing the sensory characteristics of a food product. 

Sensory quality can be defined as texture, flavour (taste), aroma and visual aspect. The sensory properties of milk are highly influenced by its fat content (Phillips et al., 1995a). As a result, research has examined the effects of various food additives on sensory quality when used as a substitute for fat in milk (Philips et al., 1995b). Frpst et al. (2001) showed that a combination of thickener, whitener and cream aroma in 0.1% fat milk was successful in mimicking the sensory quality of 1.3% fat milk. With the interest in the production of milk enriched with cis-9, trans-l 1 CLAs, owing to their relevance to human health (Tricon et al., 2004), recent research has examined the effects of CLA on the sensory quality of dairy products and found that it is possible to produce CLA-enriched dairy products with acceptable sensory characteristics (Jones et al., 2005). 

Schmidt, S.J. 1999. Probing the physical and sensory properties of food systems using NMR spectroscopy. In Advances in Magnetic Resonance in Food Science (P.S. Belton, B.P. Hills, and G.A. Webb, eds), pp. 79-94. Royal Society of Chemistry, Cambridge, UK. 

The main unique feature of osmotic dehydration, compared to other dehydration processes, is the penetration of solutes into the food material. Through a calculated incorporation of specific solutes into the food system, it is possible, to a certain extent, to change nutritional, functional, and sensory properties, making it more suitable to processing by... 

In summary, there have been several physical/mechanical means developed to improve the functionality, safety, and sensory properties of psyllium. These previous investigations have indicated the possibility to improve the physicochemical, sensory, biological properties of psyllium for its optimal applications in foods. However, none of them could sufficiently solve the strong gelling and extreme water-uptake problems of psyllium. 

Krajewska A, Powers J (1988) Sensory properties of naturally occurring capsaicinoids. J Food Sci 53 902-905... 

Assmann, S., Medeiros, D. M., and Chambers, E. (2003). Fortification with calcium citrate malate may not influence the sensory properties of an orange flavored beverage. /. Food Qual. 26, 395 07. 

The technological feasibility of a food irradiation treatment depends on how much irradiation the food withstands without adversely changing its qualities, i.e., how much useful effect can be achieved without significant change to the chemical composition, nutritional value, and sensory properties of the product. Generally, there is a minimum dose requirement. Whether every mass element of a food requires irradiation will depend... 

Lesschaeve, I. and Noble, A.C., Polyphenols factors influencing their sensory properties and their effects on food and beverage preferences. Am. J. Clin. Nutr., 81, 330S, 2005. 

Canet, W., Alvarez, M. D., Fernandez, C., Tortosa, M. E. (2005b). The effect of sample temperature on instrumental and sensory properties of mashed potato products. Int. J. Food Sci. Technol.,40,481-493. 

As mentioned before, the sensory properties of the various heterocyclic compounds discussed in this contribution are one of the important factors determining food quality. The data on sensory characteristics of the various numerous compounds formed through the reaction of aldehydes with ammonia or ammonium sulfide, in the presence or in the absence of acetoin, are scattered in the literature (57) and thus are not easy to find. At the same time, information on sensory characteristics of compounds of this type is of primary importance to food chemists. Sultan (29) has compiled much of this information which is presented here in Table IV where also the appropriate references to the original literature are given. 

While in ancient times, the sensorial properties of a flavour for foodstuffs were of major importance, modern flavours have to perform like multifunctional systems. Physical form, chemical and mechanical stability and controlled release mechanisms are meanwhile essential criteria for the flavour quality. All these properties have to be addressed by a flavourist in close cooperation with technologists. Therefore, knowledge about food product properties must lead to a careful and intelligent evaluation of the flavour system as an important driver for the success of the final product. 

---