Contribution of sugars and volatile components to perceived sweetness of apple

Correlation between soluble solid content (SSC) and sweetness in apple is weak. Nevertheless SCC is commonly used as an estimation of sweetness because is easily measurable. We also found poor correlation between sugars (total or single sugars) and perceived sweetness in apple. Starting from the concept that sweetness perception is influenced by other sensory characteristics we explored the possible influence of volatile compounds on sweetness in apple. A combination between sensory and instrumental approach was used for this purpose. Single sugars (sucrose, glucose, fructose, xylose), sorbitol, malic acid, SSC and volatile compounds were measured in 40 apple batches and compared with sweetness as measured by a trained sensory panel. Using regression models we found that sugars, sorbitol, acids and SSC explain less than 60 % of perceived sweetness. Including volatile compounds into the model is possible to account for 92 % of sweetness variance in apple. In particular, several esters that are associated with fruity aroma positively contribute to the model for sweetness while other compounds such as 1-octen-3-one, 1-octen-3-ol, 6-methyl-5-hepten-2-ol and cis-3-hexen-1-ol associated to earthy-fungal or green-herbaceous odours give a negative contribution to sweetness. These results are a clear example of how sensory perception is regulated by multisensory response.