NAME LYNETTE CHIRIDZA
COURSE SENSORY SCIENCE
PROGRAM FOOD PROCESSING TECHNOLOGY
LECTURER MR MPOFU
Describe and explain the working principle of electronic noses and their application in the food industry.
Analysis of odour and flavour in food has traditionally been performed either by a trained sensory panel or by head-space gas chromatography mass spectrometry. These methods are time consuming and costly and there is need in the food industry for objective automated non-destructive techniques that can characterize odour and flavour in food. New methods should allow a high number of samples to be analysed within a ...view middle of the document...
In this way the signals from individual sensors represent a pattern which is unique for the gas mixture measured and is interpreted by multivariate pattern recognition techniques like artificial neural network, the brain of the instrument. Samples with similar sensor odorous show differences in their patterns when the sensor patterns for a series samples are compared, differences can be correlated with the perceived sample odour (Russell et al, 2001).
The sensor array of an electronic nose has a very large information potential and will give a unique overall pattern of the volatile components. In principle, both the electronic and human nose operates by sensing simultaneously a high number of components giving rise to a specific response pattern. However, there are two basic differences between the human nose and the electronic nose that should be kept. The electronic nose has both large differences in sensitivity and selectivity from the human nose. The sensors of an electronic nose respond to both odorous and odourless volatile compounds. The electronic nose can be applied to any product that gives off volatiles with or without smell provided that this occurs within the sensitivity range of the sensors.
The results are plotted on a histogram with each sensor represented by a vertical bar whose height is the intensity of response. In some ways, this resembles a mass spectrum and in fact mass spectrometers are the basis of some electronic noses. The data from the histogram of responses from different samples are then assessed statistically and differences between samples can be plotted. Electronic noses can also be trained to detect certain types of odour pattern (Baigrie, 2003)
Application of the electronic nose has been expanded dramatically for a variety of areas in the food industry. The electronic nose can be used to predict sensorial descriptors of food quality as determined by a panel. In some instances, it can be used to reduce or replace panels of human experts. In other cases, electronic noses can be used to reduce the amount of analytical chemistry. Adulteration of food products, involving replacement of expensive ingredients with cheaper substitutes can be detected using the electronic nose. Adulterations are easily carried out with corn germ oil, soybean oil, sunflower oil and maize oil. In order to evaluate an...