(+)-(S)-Alapyridaine--A General Taste Enhancer?

Abstract

N-(1-Carboxyethyl)-6-hydroxymethyl-pyridinium-3-ol inner salt (alapyridaine), recently identified in heated sugar/amino acid mixtures as well as in beef bouillon, has been shown to exhibit general taste-enhancing activities, although tasteless on its own. Differing from other taste enhancers reported so far, racemic (R/S)-alapyridaine and, to an even greater extent (+)-(S)-alapyridaine, the physiologically active enantiomer, are able to enhance more than one basic taste quality. The threshold concentrations for the sweet taste of glucose and sucrose, for the umami taste of monosodium L-glutamate (MSG) and guanosine-5'-monophosphate (GMP), as well as the salty taste of NaCl, were significantly decreased when alapyridaine was present. In contrast, perception of the bitter tastes of caffeine and L-phenylalanine, as well as of sour-tasting citric acid, was unaffected. Furthermore, alapyridaine was shown to intensify known taste synergies such as, for example, the enhancing effect of L-arginine on the salty taste of NaCl, as well as that of GMP on the umami taste of MSG. The activity of (+)-(S)-alapyridaine could be observed not only in solutions of single taste compounds, but also in more complex tastant mixtures; for example, the umami, sweet and salty taste of a solution containing MSG, sucrose, NaCl and caffeine was significantly modulated, thus indicating that alapyridaine is a general taste enhancer.

Systematic studies of structure and physiological activity of alapyridaine. A novel food‐born taste enhancer

“…In order to investigate the taste enhancing potential of these compounds, the influence of the pyridinium betaines 1 -3 on the oral recognition thresholds for the umami-tasting monosodium glutamate, the sweet-tasting sucrose, and the salty-tasting sodium chloride was evaluated by a trained sensory panel using triangle tests. Confirming the results of previous studies [24], the human recognition threshold of aqueous solutions of sucrose (12.5 mmol/L), monosodium glutamate (1.5 mmol/L), and sodium chloride (20 mmol/L) were found to be significantly decreased in the presence of equimolar amounts of racemic alapyridaine (1); for example, the threshold for monosodium glutamate dropped by a factor of 4 from 1.5 to 0.4 mmol/L when compound 1 was present in equimolar amounts (Table 1). In contrast, the sensory threshold for the umami taste of aqueous solutions containing either the pyridinium betaine 2, or compound 3 in mixture with monosodium glutamate was determined to be 1.5 mmol/L, which is the recognition threshold of monosodium glutamate (Table 1).…”

“…Twelve subjects (five women and seven men, age 25-38 years) with no history of known taste disorders were trained to evaluate the taste of aqueous solutions (2 mL each) of the following standard taste compounds by using a triangle test as described in the literature [24]: sucrose (50 mmol/L) for sweet taste; lactic acid (20 mmol/L) for sour taste; NaCl (20 mmol/L) for salty taste, caffeine (1 mmol/L) for bitter taste, sodium glutamate (3 mmol/L) for umami taste, and gallustannic acid (0.05%) for astringency. The assessors had participated earlier at regular intervals for at least two years in sensory experiments and were, therefore, familiar with the techniques applied.…”

“…This so-called alapyridaine, which was recently found to occur naturally in beef bouillon [23], does not show any taste on its own, but is able to enhance the sweetness of sugars, amino acids, and the artificial sweetener aspartame. While well-known taste enhancers, such as, e. g., monosodium glutamate, guanosine-59-monophosphate or maltol, intensify single taste modalities only, the (+)-(S)-enantiomer of 1 was recently demonstrated to act as a multivalent taste modifier significantly decreasing the human taste thresholds for various sweet, umami, and salty compounds [24,25]. It is, however, yet not known which structural elements are essential for the physiological activity of that molecule.…”

New Developments in Umami (Enhancing) Molecules

“…Originally, it was found to be sweet-enhancing, but later it was published to enhance salt and umami taste as well [30]. A clear disadvantage of alapyridaine was the fact that it was required at equimolar quantities compared with the other tastant which made it a very expensive solution.…”

Die molekulare Welt des Lebensmittelgenusses: Auf den Geschmack gekommen

“…Dabei gelang es erstmals, eine Substanz zu lokalisieren, die den Süßgeschmack von Zuckern signifikant verstärkt, und mit Hilfe von PrecursorExperimenten und instrumenteller Messtechnik als das innere Salz des N-(1-Carboxyethyl)-6-hydroxymethyl-pyridinium-3-ols (Alapyridain) zu identifizieren (Abbildung 16) [18]. Studien zum Einfluss der Stereochemie ergaben (+)-(S)-Alapyridain als die physiologisch aktive Wirkform, während das (-)-(R)-Enantiomer keine geschmacksverstärkende Aktivität aufzeigte [19,20].…”