APPLICATION OF EMERGING TECHNIQUES TO THE EVALUATION OF FOOD SENSORY PROPERTIES

Developing methods and procedures for the rapid techniques in foods quality control is an ongoing challenge and a high priority. A variety of methods based on the conventional analytical tools such as chromatographybased techniques which can provide both qualitative and quantitative analysis, are used in order to evaluate food quality. Analytical techniques can be complex, expensive, time consuming and they require a well-equipped analytical laboratory and a skilled staff. The consumption of food is typically based on a multimodal experience, for this the organoleptic aspect plays a strategic role in food choice. This aspects are, often, evaluated with sensory analysis (or sensory evaluation), a discipline that applies the principles of experimental design and statistical analysis to the use of human senses (sight, smell, taste, touch and hearing). Smell and taste are the most important senses. At its most basic, flavour captures both sensations of taste and olfaction, taste is perceived by the tongue alone, while aroma is perceived by the nose alone. The olfactory system is by far the more complex and contains thousands of receptors that bind odor molecules and can detect some odors at parts per trillion levels and include between 10 and 100 million receptors. The brain interprets the signals and makes a judgment and/or classification to identify the substance consumed, based in part, on previous experiences or neural network pattern recognition. The human olfactory can smell 10.000 different scents even if most of us would be hard pressed to describe any one of them without comparing it to something else, or even to itself. The human tongue contains sensors, in the form of 10.000 taste buds of 50–100 taste cells each, for sweet, sour, bitter, salty and umami. Human Sensory analysis is normally conducted by a panel of experts provides the evaluation of a different matrix as a whole, resulting from the impact of its odors/taste on human senses. A skilled sensory panel, even accurate, is very costly and there is a limit to the number of replicate samples, which can be evaluated because of olfactory adaptation to odors and can be adversely affected by external parameters such as illness or fatigue. The sensory panel is, lastly, limited to odors that are not toxic or obnoxious. New trends are occurring in sensory research, based on the use of non-destructive techniques as the artificial sensory system, better known as electronic noses (e-noses) and electronic tongue (e-Tongue). Both electronic noses (e-noses) and electronic tongues (e-tongues) mimic the human smell and taste sensors (gas and liquid sensors) and their communication with the human brain. These systems are multi-sensor assays that recognize odour or taste patterns as a whole, without decomposing the odor/taste, as it occurs during chromatographic analysis and identify the odor/taste profile of the samples in the same way as the human senses. Sensors interact in a non-selectively mode with molecules to produce a simple pattern of sensorial responses as outputs form of signal response. The interpretation of the complex data sets from e-nose and e-tongue signals is accomplished by use of multivariate statistics to obtain a specific ‘fingerprint’ associated with the different samples in analysis. Odor/taste databases must be built up and a multivariate data analysis is performed in order to discriminate the different samples. Despite the limitations regarding the chemical information of the matrix aroma/taste composition, the electronic artificial senses offers some advantages, such as simple operation procedures and rapid analysis suitable for online monitoring for food safety. This presentation will concentrate on applications of e-nose and e-tongue technology for edible products and same pharmaceutical and natural extract quality control uses.