Flavour improvement of water solutions comprising bitter amino acids

Abstract: The aim of this project was to improve taste of a liquid food product, comprising extremelybitter and unpalatable amino acids and one unrevealed ingredient. The amino acids were Lleucine,L-isoleucine, L-valine, L-threonine and L-lysine monohydrochloride. Experimentaldesign was set up as a screening of water solutions comprising these ingredients (called BCAAsolutions) and added ingredients with potential to improve flavour. BCAA solution withingredients that were potential bitterness suppressors were evaluated in flavour, bitternessand/or palatability. Solutions of separate amino acids were also studied. Sensory panelscomprised untrained assessors with varying capability of detecting bitterness. Palatability andbitterness were rated on hedonic scales in sensory analysis. Sensitivity to bitterness variesgreatly between individuals, which together with varying preferences of bitterness andflavours caused significantly differing answers. This resulted in difficulties to obtainsignificant results using Tukey’s pair-wise comparison. A decreased content of leucine in theBCAA solution was indicated favourable, as well as replacing lysine monohydrochloride withlysine. Ingredients that indicated moderate bitterness reduction were aspartic acid andglutamic acid, both giving sour solutions but the latter being regarded as unpalatable.Ingredients indicated to reduce bitterness a little were carbonic acid, isomaltulose and someflavours. Opinions of bitterness reducing effect of flavours differed greatly, perhaps becauseof individual preferences or differences in bitterness sensitivity. The choice of water, morespecifically the composition of minerals and salts, might considerably affect flavour qualitiesand bitterness of BCAA solution. The amino acid concentrations in the BCAA solution wereprobably too high for successful bitterness reduction using added ingredients inconcentrations that would not alter flavour characteristics in any other undesired way. Apromising alternative, that was not studied, would be to modify the branched chain aminoacids (BCAAs) Leu, Ile and Val by acetylation of the N-terminal.