Effects of noble rot on juice composition

cinerea utilizes a significant part of the grape s assimilable nitrogen content, including ammonium and amino acids. In some studies, a significant decrease (by 30-80%) in the total amino acid content has been reported in Botrytis-affected grapes, compared to the healthy grapes (Dittrich and Sponholz, 1975 Dittrich et ah, 1975 Rapp and Reuther, 1971). 

TABLE 6.4 Effect of Botrytis cinerea on some nitrogen compounds of the grape juice 

Reference n Grape Total amino Ammonium acid (mg/l) (mg/l) Proline (mg/l) Assimilable (N mg/l) Protein (mg/l) 

Reuther, 1971). Relative to vitamins, thiamin and pyridoxine contents are seriously reduced in botrytized must (Dittrich and Sponholz, 1975). 

Most of the studies on Botrytis-specific aroma compounds have investigated the aroma composition of wines (Table 6.7). Only a few have focused on what occurs in the grape. On synthetic media, the main odorous compounds produced by B. cinerea are aromatic aldehydes (benzaldehyde, phenylacetaldehyde), and furfural (Kikuchi et al., 1983). Sarrazin et al. (2007a) confirmed the higher concentration of phenylacetaldehyde in noble-rotted grapes. 

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