The human brain and its relationship with flavour

Perhaps the single key realisation that changed the understanding of flavour was when scientists investigating its perception became aware of the then comparatively new field of experimental psychology dealing with the multisensory processing of signals to the brain. Knowledge of the brain and how it processes information has grown dramatically with the development of non-invasive imaging techniques and in particular magneto-encephalography (MEG), positron emission tomography (PET) and...

The development of the human brain in infancy

In comparison with all other mammals the human infant is essentially born too soon in the sense that it is quite helpless for a long time and relies for survival totally on adults for several years. It has been argued that this essentially premature delivery is a consequence of the unusually large size of human brains and heads, if fully developed before birth they would require the mother to have a cervix impossibly wide to support her weight when standing on two legs. The growth and...

A unique study of spontaneous food selection

There is evidence that children left to their own choice will select foods which their bodies need. In a classic study which was reported 65 years ago and which would be virtually impossible to repeat today, 15 infants from 6 to 11 months of age were allowed to self-select their diets over a period of six years (Davis 1939). Each day there were three or four meal occasions when the children were offered the range of 34 different foods shown in Table 17.1. The supervisory staff who were present...

The role of carers in flavour learning by the child

The Department of Human Development and Family Studies at The Pennsylvania State University have shown another interesting consequence of bottle feeding on later food consumption (Fisher, Birch et al. 2000). In this case comparisons were made between toddlers which had either been breast fed or bottle fed earlier in life. One of the main conclusions of this work was that breast feeding in the first year showed benefits on food intake and feeding style which persisted into the toddler phase....

Psychological interactions

Psychological processes involved in flavour perception were recently reported in detail by Prescott (2004). Various sensory information perceived during the ingestion of food or drink through the mouth or only by smelling give us important information about identification of the product. These are olfactory, gustatory, visual and tactile sensations. The combination of these or some of these sensations, when we ingest a food or a drink are generally integrated and it is difficult to separate (or...

Changes in food preferences after infancy

Up until now we have discussed how and when young children form their likes and dislikes for foods. We now need to consider what happens after childhood and how adults change food preferences during life. It is not difficult to understand why neophobia in humans should exist, what is much more difficult to understand is the fact that human beings both individually and collectively change their food preferences throughout their lives. Even for young children we see behaviour which is hard to...

Driving principles applied in the elaboration of strategies

A large proportion of flavour components contained by food emulsions may look underemployed. In systems operating normally, the larger share of aroma compounds is not even given a chance to escape the bowl at any moment throughout the mouth stay. However, these molecules, although not carried forth in the nosespace, are not idle material as they find themselves, at one time or the other, in a position to influence overall balance of partial pressures. Oil-in-water emulsion is a remarkable model...

The discriminative power of early olfaction

Discrimination level of early olfaction Several experimental strategies have appraised the capacities of newborns to segregate olfactory qualities. The most global, used by early experimenters, consisted in merely spotting different motor responses following presentation of distinct odorants. They noticed that the frequency, amplitude, latency and duration of the odour-induced movements vary for contrasting olfactory qualities (Stirnimann 1936, Engen et al. 1963, Self et al. 1972). More...

Conclusions and future trends

In humans, as in other mammals, nasal chemoreception is already functional before birth and it can then contribute to the behavioural and physiological adjustments necessary to adaptive transitions in the postnatal period (cf. Schaal 2005). Chemosensory systems are comprehensive in nature, i.e. they can detect a large spectrum of odorants and flavorants, and are open to early influences, as attested by the variety of stimuli influencing behaviour and the variety of rewarding means and contexts...

Olfactory preferences established independently of postnatal experience

The demonstration of the remarkable malleability of postnatal olfactory acquisitions in no way attenuates the importance of the results presented above and which are recalled here. First, certain unfamiliar smells appear to be immediately more pleasant than others for newborn babies (Steiner 1979, Soussignan et al. 1997). Second, the 'naive newborn' model, which consists in analysing the responses of subjects confronted for the first time with a given odorant, reveals that infants deprived of...

Memory and plasticity of olfactory function in early life 1841 Early postnatal shaping of odour preferences

The fact that human infants can be familiarised with a novel odorant by mere exposure, i.e. without any apparent reinforcement, has already been mentioned above (see page 416, Dimensions of olfactory stimulation discriminable to newborns). This form of passive acquisition seems to prepare more complex and more specific olfactory acquisitions. Thus, the repeated pairing of an initially neutral odorant with maternal contact leads to the progressive development of a preference. Delaunay-El Allam...

Sensitivity of early olfactory detection

Which nasal chemoreceptive systems are involved In humans, at least four chemoreceptive systems are located in the nasal cavities the main olfactory, the trigeminal, the accessory olfactory or vomeronasal, and lastly the terminal systems (cf. Doty 2003). The functional status of vomeronasal 1. Alliesthesia defines the change in the level of pleasure associated with sensory stimulation, depending on the physiological and metabolic state of the organism (Cabanac 1971). Negative alliesthesia...

The learning of flavour by the neonate

About eleven weeks after a baby is conceived it has developed an olfactory epithelium (Doty 1992). At this stage the only source of any olfactive stimulus is from the amniotic fluid surrounding the baby, however, this is in contact with the mother's blood and there is considerable evidence that volatile flavour molecules from the mother's diet can reach the baby in utero (Schaal, Marlier el al. 1998, 2000). As the baby grows and its brain develops it experiences more and more olfactive stimuli...

The relevance of propriosense to flavour learning

Before we leave the discussion about our five senses we should mention the other very important flow of information to our brain that probably plays the single most important part in whether we remember the flavour of the food or drink just consumed as good or bad. I refer to what is sometimes described as propriosense that incorporates all the information received by the brain about the state of the body. Many sensory channels are involved in this, both nervous, for example, the information...

The role of all the senses in flavour perception

For us humans sight is the most far reaching sense that we have and we usually first become aware of potential food sources because of it. It may seem unusual that we discuss vision in the context of flavour but there is now convincing evidence that the appearance of an object can influence our perception, recognition and liking of its flavour (Zellner and Kautz 1990). There is also the much publicised study that showed that experienced wine tasters were quite unable to correctly describe and...

References

BALOGH, R.D. and PORTER, R.H. (1986) Olfactory preferences resulting from mere exposure in human neonates. Infant Behavior and Development, 9, 395-401. BARTOCCI, M., WINBERG, J., RUGGIERO, C. et al. (2000) Activation of olfactory cortex in newborn infants after odor stimulation a functional near-infrared spectroscopy study. Pediatric Research, 48, 18-23. BEAUCHAMP, G.K., COW ART, B.J. and SCHMIDT, H.J. (1991) Development of chemosensory sensitivity and preference. In T.V. Getchell, R.L. Doty,...

Future trends

There is no doubt that advances in brain scanning techniques have greatly improved our knowledge of how the brain develops and functions. The present generation of body scanners have, of course, been designed with medical diagnostic applications as the first priority but they are not wholly suitable for studies on eating and drinking. Most fMRI scanners are configured such that the subject lies prone and is introduced into the magnet coil horizontally. Consuming foods and beverages when lying...

Trigeminal chemosensitivity chemesthesis 241 Fibres and receptors

In combination with tastes and aromas, oral and nasal irritation contributes to the flavour profile elicited by a food or a beverage. The term 'irritation' encompasses a broad range of discriminable sensations that involve the action of a cranial nerve, nerve V or trigeminal nerve, belonging to the somatosensory system and providing most of the innervation of the face, including the nasal and oral cavities along with the cornea and conjunctiva of the eye. Two branches of the trigeminal nerve,...

Conculation Encapulation

The retention of aroma compounds in a polysaccharidic matrix is mainly due to two factors 1. Diffusion of aroma compounds in the matrix, which increases when the temperature of the matrix or its water content increases and when the size or the molecular weight of the volatile compound decreases. Furthermore, in the presence of water, diffusion increases with water solubility of aroma compounds. 2. Physicochemical interactions between the aroma compounds and the matrix. The higher the affinity...

The sense of taste

The basic taste qualities contribute differently to the assessment of the value of food Skramlik 1926 . Sweet taste is predominantly elicited by carbohydrates and indicates energy-rich food sources Drewnowski 1995 . The broth-like umami taste, that is mainly triggered by glutamate and enhanced by ribonucleotides such as inositol monophosphate IMP , identifies protein-rich food Bellisle 1999, Yamaguchi and Ninomiya 2000 . Both taste qualities indicate valuable food components, and thus sweet and...