Comparative taste dilution analysis

Ottinger el al.2S6 have applied their comparative taste dilution analysis (cTDA) to examine the extractable products from heated aqueous D-glucose and L-alanine that were not solvent-extractable. One HPLC fraction proved to be a strong sweetness enhancer. It was isolated and submitted to LC-MS and NMR, both ID and 2D the results, together with its synthesis from HMF and alanine, unequivocally identified it as the inner salt of /V-( I -carboxycthyl)-6-(hydroxy-methyl)pyridinium-3-ol (alapyridaine, Structure 45). It has no taste on its own, which in many applications would be an advantage. Depending on the pH, it lowers the detection threshold of sweet sugars, amino acids, and aspartame, the... 

H. Ottinger, T. Soldo, and T. Hofmann, Discovery and structure determination of a novel Maillard-derived sweetness enhancer by application of the comparative taste dilution analysis (cTDA), J. Agric. Food Chem., 2003, 51, 1035-1041. 

Aimed at investigating taste enhancers in beef bouillon, taste activity-guided fractionation combined with the comparative taste dilution analysis led to the discovery of the presence of a sweet enhancing compound. Model Maillard reactions, spectroscopic and synthetic experiments revealed the previously unknown 1 - 1 -carboxyethyl)-5-hydroxy-2-... 

The comparative taste dilution analysis revealed a high TD factor of 16 for sweetness in fraction III (Figure 1). As this fraction showed no sweetness in the absence of sucrose, this fraction was assumed to contain a reaction product enhancing the sweetness of the sucrose solution by a factor of eight. Because sweetness enhancing compounds were not yet reported in beef bouillon, the following identification experiments were focused on the sapid taste modifier present in GPC fraction III (Figure 1). 

In order to further resolve GPC fraction III into distinct sensory active compounds and to rate them in their relative taste impacts, this fraction was then separated by RP-HPLC (Figure 2) into 16 subfractions. Application of the comparative taste dilution analysis using sucrose as the basic tastant revealed the highest TD factor for sweetness for fraction III-5, thus indicating the presence of a sweetness enhancing compound in that fraction. 

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