Estimated carboxylic acid ester hydrolysis rate constants for food and beverage aroma compounds

Abstract

Aroma compounds in the Flavornet database were screened for potentially hydrolyzable carboxylic acid ester functionalities. Of the 738 aroma compounds listed in this database, 140 molecules contain carboxylic acid ester groups that may be amenable to hydrolysis in various food and beverage products. Acid- (k~A~) and base- (k~B~) catalyzed and neutral (k~N~) hydrolysis rate constants in pure water at 25°C were estimated for these aroma compounds. Where available, good agreement between theoretical and experimental hydrolytic half-lives was obtained at various pH values. Wide ranges and broad frequency distributions for k~A~, k~B~, and k~N~ are expected among the various hydrolyzable aroma compounds, with estimated k~A~ ranging from 3.7 × 10^-8^ to 4.7 × 10^-4^ M^-1^ s^-1^, estimated k~B~ ranging from 4.3 × 10^-4^ to 43 M^-1^ s^-1^, and estimated k~N~ ranging from 4.2 × 10^-17^ to 7.6 × 10^-9^ M^-1^ s^-1^. The resulting hydrolytic half-lives also range widely, from 10 days to 370 years at pH 2.8, 18 days to 4,900 years at pH 4.0, 1.8 days to 470 years at pH 7.0, and 26 minutes to 5.1 years at pH 9.0. The findings presented herein attest to the importance of considering abiotic hydrolysis and matrix pH when modeling the evolution of sensory characteristics for foods and beverages with carboxylic acid ester based aroma compounds.

A user's guide to degradation testing of polyethylene glycol‐based hydrogels: From in vitro to in vivo studies

“…Based on our results (Figure 2 ), the hydrolytic stability was ranked based on the labile functional endgroups: acrylamide (PEGDAA) > > acrylate ester (PEGDA) > Thio‐β‐ester (PEGDTT). This trend is aligned with the reported half‐life of these groups 38–40 . Urethanes and amides are inherently less reactive than esters with the half‐life of amides is typically longer than 100 years.…”

“…In most cases, the standard deviation is smaller than the bullet size and was not displayed by the software. (B) Hydrolysis reactions and reported half‐life for different chemical bonds 38–40 …”

“…This trend is aligned with the reported half-life of these groups. [38][39][40] Urethanes and amides are inherently less reactive than esters with the half-life of amides is typically longer than 100 years. The decreased hydrolysis rates resulting from a less electrophilic acyl carbon are due to the electron-donating resonance characteristics of the amide nitrogen.…”

“…(B) Hydrolysis reactions and reported half-life for different chemical bonds. [38][39][40] T A B L E 1 Swelling ratio of PEGDTT, PEGDA, and PEGDAA hydrogels. We would like to highlight that the temperatures selected for accelerated degradation need to be moderate to avoid chain scission events that might not be relevant under physiological conditions.…”

Converting Unrefined Birch Suberin Monomers into Vitrimer

“…At pH = 11, however, slow hydrolysis was observed, reaching 5% in 6 weeks. Base-catalyzed hydrolysis of esters is generally faster than acidcatalyzed hydrolysis, 55 which in combination with the hydro-phobicity of suberin polymers, makes them resilient to acidic aqueous media.…”