Stability of Saturated Acyl L-Ascorbates in Aqueous Solution

Abstract

acid, which was formed through the hydrolysis of the ester bond in the ascorbate, was measured at pH decanoic acid, which was formed through the hydrolysis of the ester bond in the ascorbate, was measured at pH decanoic acid, which was formed through the hydrolysis of the ester bond in the ascorbate, was measured at pH decanoic acid, which was formed through the hydrolysis of the ester bond in the ascorbate, was measured at pH decanoic acid, which was formed through the hydrolysis of the ester bond in the ascorbate, The initial concentration of the ascorbate scarcely affected its decomposition at pH 5 and 40 The initial concentration of the ascorbate scarcely affected its decomposition at pH 5 and 40 The initial concentration of the ascorbate scarcely affected its decomposition at pH 5 and 40 The initial concentration of the ascorbate scarcely affected its decomposition at pH 5 and 40 The initial concentration of the ascorbate scarcely affected its decomposition at pH 5 and 40°C. The decompo-°C.The decompo-°C.The decompo-°C.The decompo-°C. The decompositions of acyl ascorbates with acyl chain lengths of 6, 8, 10, and 12 were measured at pH 5 and at different sitions of acyl ascorbates with acyl chain lengths of 6, 8, 10, and 12 were measured at pH 5 and at different sitions of acyl ascorbates with acyl chain lengths of 6, 8, 10, and 12 were measured at pH 5 and at different sitions of acyl ascorbates with acyl chain lengths of 6, 8, 10, and 12 were measured at pH 5 and at different sitions of acyl ascorbates with acyl chain lengths of 6, 8, 10, and 12 were measured at pH 5 and at different temperatures. The temperature dependency of the rate constant for the decomposition of each ascorbate was temperatures. The temperature dependency of the rate constant for the decomposition of each ascorbate was temperatures. The temperature dependency of the rate constant for the decomposition of each ascorbate was temperatures. The temperature dependency of the rate constant for the decomposition of each ascorbate was temperatures. The temperature dependency of the rate constant for the decomposition of each ascorbate was analyzed by the Arrhenius equation, and it was shown that the enthalpy-entropy compensation held for the analyzed by the Arrhenius equation, and it was shown that the enthalpy-entropy compensation held for the analyzed by the Arrhenius equation, and it was shown that the enthalpy-entropy compensation held for the analyzed by the Arrhenius equation, and it was shown that the enthalpy-entropy compensation held for the analyzed by the Arrhenius equation, and it was shown that the enthalpy-entropy compensation held for the decomposition of the ascorbates. decomposition of the ascorbates. decomposition of the ascorbates. decomposition of the ascorbates. decomposition of the ascorbates. K K K K Keywor eywor eywor eywor eywords: acyl ascorbate ds: acyl ascorbate ds: acyl ascorbate ds: acyl ascorbate ds: acyl ascorbate, decomposition, , decomposition, , decomposition, , decomposition, , decomposition, W W W W Weibul...

Enzymatic Synthesis of l‐Ascorbyl Fatty Acid Esters Under Ultrasonic Irradiation and Comparison of Their Antioxidant Activity and Stability

“…Saturated derivative esters were more stable than the unsaturated ones both in acidic and neutral conditions. In acidic condition, L‐AD and L‐AP showed better stability than L‐AA, this result was in agreement with a previous study that L‐AD was more stable than L‐AL and L‐AN at pH 3 (Kuwabara and others ). In neutral condition, L‐AP showed the best stability among the saturated derivative esters and showed a similar stability as L‐AA.…”

“…Previous studies reported that derivatives of L‐AA such as l ‐ascorbyl benzoate and l ‐ascorbyl palmitate (L‐AP), with good solubility in hydrophobic medium, showed similar or even better antioxidant effects than L‐AA (Burham and others ). Some researchers reported that l ‐ascorbyl fatty acid esters like L‐AP and l ‐ascorbyl stearate (L‐AS) could be used to replace the traditional antioxidants in food and cosmetic industry (Humeau and others ; Kuwabara and others ). l ‐Ascorbyl fatty acid esters were normally synthesized by chemical method in corrosive solvent containing sulfuric acid or hydrofluoric acid.…”

“…Previous studies mainly focused on the optimization of the chemical synthesis method of l ‐ascorbyl derivatives (Kuwabara and others ). Although, there is few study about the synthesis of l ‐ascorbyl fatty acid esters by using enzymatic catalization under ultrasonic irradiation.…”

Enhancing operational stability and exhibition of enzyme activity by removing water in the immobilized lipase‐catalyzed production of erythorbyl laurate

“…Two possible explanations exist for this observation. One is degradation of the erythorbyl moiety of the erythorbyl laurate, and the other possibility is hydrolysis of the ester bond in the erythorbyl laurate . Therefore, to investigate the instability of erythorbyl laurate at a high temperature, the degradation of the compound was monitored during storage at 70°C and 90°C using HPLC.…”

“…One is degradation of the erythorbyl moiety of the erythorbyl laurate, and the other possibility is hydrolysis of the ester bond in the erythorbyl laurate. 35 Therefore, to investigate the instability of erythorbyl laurate at a high temperature, the degradation of the compound was monitored during storage at 70 C and 90 C using HPLC. A peak of released erythorbic acid or lauric acid from erythorbyl laurate was rarely detected during the storage (data not shown), indicating the low storage stability of erythorbyl laurate at such high temperatures, which was likely due to thermal degradation, rather than hydrolysis of the ester bond.…”