Tastes, structure and solution properties of D-glucono-1,5-lactone

Area of Science:

• Carbohydrate Chemistry
• Physical Chemistry
• Sensory Science

Background:

• D-glucono-1,5-lactone, a cyclic ester of D-gluconic acid, possesses a sweet taste due to its intact alpha-glycol group.
• In aqueous solutions, it undergoes autohydrolysis, forming D-gluconic acid and D-glucono-1,4-lactone, which lowers the pH.

Purpose of the Study:

• To investigate the relationship between the autohydrolysis of D-glucono-1,5-lactone and the resulting changes in taste perception.
• To correlate solution property changes with taste modifications during the hydrolysis process.

Main Methods:

• Monitoring the autohydrolysis of D-glucono-1,5-lactone in water solution at room temperature.
• Measuring changes in solution pH, apparent specific volume, and apparent isentropic compressibility over time.
• Correlating these physical changes with perceived taste qualities (sweet, sour, bitter).

Main Results:

• The ratio of generated hydronium ions to unchanged lactone correlated with taste quality shifts from sweet to sour within the first 28 minutes.
• Observed changes in specific volume and compressibility indicated increased solute-solvent interactions and water structure disturbance.
• These physical changes align with the sweet-to-sour taste transition but do not fully explain the accompanying bitterness.

Conclusions:

• The autohydrolysis of D-glucono-1,5-lactone leads to a predictable sweet-to-sour taste transition driven by pH reduction.
• Physical changes in the solution reflect molecular interactions and water structure alterations during hydrolysis.
• Further research is needed to elucidate the mechanism behind the observed weak bitterness.