Effect of sucrose on oxygen uptake of ascorbic acid in a closed aqueous system

Abstract

The effect of sucrose on the oxygen uptake kinetics of ascorbic acid (A) in a closed aqueous system was studied at different temperatures (26.5,30, and 33 "C) and pH levels (3.0-5.0). The reactions generally followed a pseudo-first-order reaction with respect to dissolved oxygen. The activation energy of A oxidation in sucrose solutions was greater than that in solutions containing no sucrose at all pH levels. Approximately 1 mol of oxygen was used per mole of A at the early stage of the noncatalyzed oxidation of A in various solutions. Two effects of sucrose on the A oxidation in the closed homogeneous system were suggested. First, a pH-independent physical hindrance effect retarded A oxidation and, second, a pH-dependent catalytic effect accelerated oxidation due to metal impurities found even in analytical grade sucrose.Sucrose is commonly present as a sweetening ingredient in fruit juices and drinks containing ascorbic acid. The effect of sugar on the stability of ascorbic acid in liquid media has been studied. Sucrose has long been reported to inhibit ascorbic acid oxidation in Cu-catalyzed or noncatalyzed reactions, and the mechanism of this protective effect was attributed to either the viscosity or the Cu-binding power of the sugar (Birch and Pepper, 1983;Lin and Agalloco, 1979;Kyzlink and Curda, 1970; Miller and Joslyn, 1949a,b;Chamrai, 1941). Recently, Hsiehand Harris (1987a) found that in an open-air system a t pH 3.2 sucrose accelerated the degradation of ascorbic acid when ita viscosity effect was diminished by vigorous shaking. This destructive effect of sucrose was attributed to the trace amounts of metal impurities found in sucrose because metal ions, e.g., cupric ion, have been shown to have great catalytic effect on the oxidation of ascorbic acid even a t trace levels (Silverblatt et al., 1943) and it is very difficult to completely eliminate the metal impurities and their catalytic effect from water and food ingredients in liquid systems. Furthermore, the study (Hsieh and Harris, 1987a) shows that the destructive effect of sucrose on ascorbic acid was much more pronounced in coppercatalyzed solutions containing 1-5 ppm of added copper. Sucrose (10%) did not show any Cu-binding ability, as was postulated in early literature, but enhanced the catalytic effect on ascorbic acid oxidation by its physical bulking effect and decreased water activity in solutions which increased cupric ion activity (Hsieh and Harris, 1987b). These results shed new light on former studies that illustrated the effect of sucrose on ascorbic acid oxidation in a heterogeneous oxygen-diffusion mediated system. To clearly define the reaction mechanism of the effect of sucrose on ascorbic acid oxidation, it is also important to investigate the effect of sucrose in a closed homogeneous nondiffusion mediated aqueous system. Therefore, the present research was designed to study oxygen uptake in the early stages of ascorbic acid oxidation in a closed homogeneous aqueous system which simulated the practical quiescent condition o...

Qualidade de balas de gelatina fortificadas com vitaminas A, C e E

“…A gelatina contém menos de 30 ppm de ferro e menos de 10 ppm de cobre e estes metais estão presentes, mesmo que em baixas concentrações, na bala. Para HSIEH e HARRIS [7] a sacarose tem efeito destrutivo no ácido ascórbico e este se deve a impurezas presentes na sacarose em pHs na faixa de 3, o que também vem de encontro com as condições presentes na bala de gelatina. Segundo BALL, RYLEY e KADJA [2,18], a utilização de gases inertes, a minimização de espaços vazios na embalagem, o uso de embalagens com permeabilidade controlada ao oxigênio e luz e o uso de agentes sequestrantes como o EDTA, citratos, sulfitos, BHA e BHT protegem a vitamina C.…”

Apple polyphenoloxidase inactivation during heating in the presence of ascorbic acid and chlorogenic acid

“…Moreover, owing to its thermolability, AA is often used as a nutritional quality marker of food processing treatments (Nicoli, Anese, & Parpinel, 1999). The rate of its degradation in model systems depends on the reaction conditions; temperature, pH, dissolved oxygen concentration, presence of enzyme and sugar (Eison-Perchonok & Downes, 1982;Giannakourou & Taoukis, 2003;Hsieh & Harris, 1993;Rojas & Gerschenson, 1997).…”

Biopolymer/candelilla wax emulsion films as carriers of ascorbic acid – A comparative study

“…However, in some cases a zero-order (Kennedy, Rivera, Lloyd, Warner, & Jumel, 1992;Janjarasskul et al 2011a) or second-order (Singh, Heldman, & Kirk, 1976;Hsieh & Harris, 1993) seemed to describe the kinetics as well.…”