It is widely recognized that smelling food results in a mouth-watering feeling 
and influences appetite. However, besides changes in volume, little is known 
about the effects that food odours have on the composition of saliva. The aim of 
the present study was to access the effects that smelling bread has on saliva 
proteome and to compare such effects with those of chewing and ingesting it. 
Besides a significant increase in saliva flow rate, together with a decrease in 
total protein concentration, bread odour induced changes in the proportion of 
different salivary proteins. The expression levels of two spots of cystatins and 
two spots of amylase increased due to olfactory stimulation, similar to what 
happened with bread mastication, suggesting that odour can allow anticipation of 
the type of food eaten and consequently the physiological oral changes necessary 
to that ingestion. An interesting finding was that bread odour increased the 
expression levels of several protein spots of immunoglobulin chains, which were 
decreased by both bread or rice mastication. This may be of clinical relevance 
since food olfactory stimulation of salivary immunoglobulins can be used to 
potentiate the oral immune function of saliva. Moreover, the effects of bread 
odour in the levels of salivary proteins, previously observed to be involved in 
oral food processing led to the hypothesis of an influence of this odour in the 
sensory perception of foods further ingested. Further studies are needed to 
elucidate this point, as well as whether the changes observed for bread odour 
are specific, or if different food odours lead to similar salivary proteome 
responses.