Masking Bitter Taste by Molecules Jakob P.Ley Received: 21 November 2007 / Accepted: 24 January 2008 / Published online: 13 February 2008 # 2008 Springer Science + Business Media, LLC AbstractCombating bitter taste in food, pharmaceuticals, and beverages remainsa hugechallenge. In the past, bitterness reduction was focused on pharmaceuticals and drugs; however, more recently, the most intense research is performed on the reduction of bitter or astringent taste in functional food or beverage applications. These foods and beverages possess inherent off-tastes due to fortification with healthy butpoor-tasting actives. During thelast 10 years, tremendous progress in the elucidation of bitter taste reception and transduction on the cellular levelwas made and many new molecules and compounds to reduce bitter off-tastes were reported. The following review will be focused on theadvances, in the areaof bitter-masking molecules, during the last 10 years. It will notcover other debitteringstrategiesuchasprocessoptimizationor biotransformations to reduce the amount of bitteringre- dients,encapsulation, and otherphysicalformulation technologies. The review will close with a short compar- ative study of various bitter maskers and some suggestions for flavor development of poor-tasting ingredients. Keywords Off-taste . Bitter Taste . Masking Technologies . Taste Masking Abbreviations AMP adenosine monophosphate ATP adenosine triphosphate CMP cytosine monophosphate cTDA comparative taste dilution analysis dATP 2-deoxyadenosintriphosphate FLIPR fluorescence-induced plate reader GRK G protein-coupled receptor kinases HEK293 human embryonic kidney cells type 293 IP 3 inositoltriphosphate L-DOPA L-3,4-dihydroxyphenylalanine Leu-Trp L-leucinyl- L-tryptophan γ-PGA poly-γ-glutamic acid PDE phosphodiesterase PLCβ2 phospholipase C subtype β2 TRC taste receptor cells TRPM5 transient receptor potential channel, type M5 T2R taste receptor type 2 Introduction Bitter taste is a major problem in the food and pharmaceu ticalindustriesdueto its negativehedonicimpacton ingestion (Drewnoswki 2001;Drewnoswki and Gomez- Carneros 2000).Only in rare cases, consumers prefera strong bitter taste forfood and beverages, e.g.,in black coffee,black or green tea,beer,red wine,grapefruit products, or bitterlemon.In mostothercases, the bitter taste isnot desirable and has to be eliminated from or masked in the product. As an example, mostlegumes, fruits,and staple foods were extensively optimized using breeding and cultivation technology to become less bitter astringent, or sour variants over the course of time. Anoth example is in the juice industry, whereby raw orange juice are processed to bedebittered by cleaving the bitter naringin to thelessbitternaringenin ornaringin-7-O- glucoside. Most cloudy raw apple juicesare treated to remove most of the polyphenols, which can taste bitter or astringent to yield clear beverages (Oszmianski et al. 2007). Chem.Percept. (2008) 1:58–77 DOI 10.1007/s12078-008-9008-2 J. P. Ley (*) Flavor & Nutrition Research & Innovation, Flavor Research, Symrise GmbH & Co. KG, P.O.Box 1253, 37601 Holzminden, Germany e-mail: jakob.ley@symrise.com