Effect of Ascorbic Acid or Acyl Ascorbate on the Stability of Catechin in Oil‐In‐Water Emulsion

Abstract

The degradation of (?)-catechin in an oil-inwater emulsion using methyl dodecanate as an oil phase with or without ascorbic acid or acyl ascorbate was kinetically examined at 40°C. The rate constant, k, of the firstorder kinetics for the degradation with ascorbic acid or octanoyl ascorbate depended on the added amount, whereas the k value with hexadecanoyl ascorbate was independent of the amount. The k value for a smaller oil droplet with each ascorbate was lower than that for a larger oil droplet. Catechin did not partition well into the methyl dodecanate phase, but did adsorb slightly onto the interface between the methyl dodecanate and water. The suppressive effect of acyl ascorbate on the catechin degradation in the emulsion was lower than that of hydrophilic ascorbic acid at the low concentration, but the peroxidative ability also was lower. Most of the catechin molecules in the emulsion degraded in the water phase. The catechin degradation in the emulsion with small oil droplets depended on the acyl chain length of the ascorbates more than in large oil droplets.

Factors affecting formulation characteristics and stability of ascorbic acid in water‐in‐oil creams

“…Various studies have earlier reported a similar order of reaction for the degradation of AA in o/w and w/o emulsions, multiple emulsions, etc. . It appears that the pH and formulation characteristics of creams greatly affect the rate of reaction, and hence these factors are discussed in the following sections.…”

Engineering aspects of rate-related processes in food manufacturing

“…Finally, (+)-catechin degradation in O/W emulsions with and without added ascorbic acid or acyl ascorbate has also been kinetically analyzed. 59) The first-order rate constant depended on the amount of the additive present; however, hexadecanoyl ascorbate addition had no effect on rate constant, regardless of amount. The rate constant with each ascorbate for smaller oil droplets was lower than that for larger droplets.…”

Preparation and Characterization of Water-in-Oil-in-Water Emulsions Containing a High Concentration ofL-Ascorbic Acid

“…This behavior have been reported by different research groups for O/W emulsions containing L-ascorbic acid in the outer aqueous phase. 38) The factors affecting the retention kinetics of L-ascorbic acid in different systems include the concentration of L-ascorbic acid (active ingredient), the pH and viscosity of the liquid phase and the preparation process. The release pattern of L-ascorbic acid follows zero-order kinetics in W/O and O/W/O emulsions.…”