ascorbic-acid and sodium-bisulfite

The microbial production of methylglyoxal in cheese has been linked to the formation of brown pigmentation and distinctive volatiles. This study investigated methods for preventing methylglyoxal-induced browning in Parmesan cheese through the addition of reducing agents. Cheeses were treated with the reducing agents sodium bisulfite, glutathione, and erythorbate at 2:1 and 4:1 molar ratios with added methylglyoxal, and then incubated at 10 °C. Colorimetric methods were used to determine degree of browning at 0, 3, and 6 d. Sodium bisulfite and glutathione inhibited the browning reactions of methylglyoxal compared with the control. Erythorbate was much less effective than the other compounds at inhibiting browning, yet was significantly less browned than the control. These reducing agents are thought to act as strong nucleophiles that can form thiohemiketals and thioketals at the carbonyl carbons of methylglyoxal.

Topics: Ascorbic Acid; Cheese; Colorimetry; Food Preservation; Glutathione; Maillard Reaction; Pyruvaldehyde; Reducing Agents; Sulfites

Stimuli response behaviors of cystamine-core dendrimer in the presence of several reducing agents including vitamin C, sodium bisulfite, and DL-Dithiothreitol are described. A competitive redox cleavage and supramolecular aggregate formation model is proposed based on PFG NMR and (1)H NMR titration experiments. Furthermore, reduction-responsive release of guest molecules from interior pockets of the cystamine-core dendrimer is confirmed by NOE studies. The results suggest that cystamine-core dendrimer is a versatile scaffold or precursor in the design of reduction-sensitive polymeric nanocapsules for biomedical purposes.

Topics: Ascorbic Acid; Cystamine; Dendrimers; Deoxycholic Acid; Diffusion; Dithiothreitol; Magnetic Resonance Spectroscopy; Nanocapsules; Oxidation-Reduction; Reducing Agents; Sulfites

In a system which consisted of luminol (3-aminophthalhydrazide), cobalt sulfate (CoSO4), alkaline buffer and the mixture of NaSO3 and sodium bisulfite (NaHSO3) (sulfite and bisulfite=3:1, m/m), a strong chemiluminescence (CL) was observed using a BPCL ultra-weak luminometer. The CL signals resulted from 3-aminophthalate (the product of oxidized luminol), and were affected by the buffer pH, buffer medium and the concentrations of luminol, CoSO4 and the NaSO3-NaHSO3 mixture. The observation that the CL intensities were inhibited by superoxide dismutase (SOD), Vitamin C (Vc) and glutathione (GSH) in a dose-dependent manner suggested that superoxide radical (O2*-) was involved in the CL reaction and responsible for oxidation of luminol.

Topics: Ascorbic Acid; Cobalt; Glutathione; Hydrogen-Ion Concentration; Kinetics; Luminescence; Luminol; Sulfites; Superoxide Dismutase

The effects of potato variety (Van Gogh, Bintje and Fambo), washing with browning prevention chemicals in place of sodium bisulfite, percentages of CO2, O2, and N2 in the package headspace, and storage time (1, 4, and 7 days) on the sensory and microbiological quality of potato slices were examined. Citric acid and ascorbic acid (at 0.1% each and at 0.5% each) were used as browning prevention chemicals. In the packaging atmosphere the percentage of N2 was 75 or 80%, the percentage of O2 was 5 or 0%, and the percentage of CO2 was 20% at the beginning of storage. Packed potato slices were stored in the dark at 5 degrees C. Darkening was the most important factor limiting the sensory quality of raw potato slices. Darkening occurred quickly with Fambo slices; it seems that Fambo is not a suitable potato variety if slices are to be stored. Water-washed and cooked Van Gogh slices were still acceptable for retailing after a storage period of 7 days. After 7 days of storage the best sensory quality of both raw and cooked Bintje slices was obtained with washing solutions containing 0.1 to 0.5% citric and ascorbic acids and with the gas mixture containing 20% CO2 and 80% N2. The number of microorganisms was higher in samples stored in the atmosphere containing 5% O2 than samples stored in the atmosphere containing 0% O2. Washing of potato slices with browning prevention chemicals decreased the number of microorganisms compared to potato slices not washed or potato slices washed with water after 7 days of storage.

Topics: Ascorbic Acid; Bacteria, Aerobic; Carbon Dioxide; Citric Acid; Enterobacteriaceae; Food Handling; Food Packaging; Food Preservation; Lactobacillus; Maillard Reaction; Nitrogen; Odorants; Oxygen; Solanum tuberosum; Sulfites; Temperature

We have reported previously that toxic concentrations of isoproterenol caused severe alterations in the structural integrity of the sarcolemma and mitochondria found in primary cultures of rat myocardial cells [8, 9]. Mitochondrial injury was observed 1.5 h after exposure to isoproterenol, whereas leakage of intracellular ions and enzymes was observed only after prolonged exposures (greater than 4 h). Ascorbic acid and sodium bisulfite prevented the cytotoxic effects of isoproterenol in our cell culture system. Takeo et al. [13] suggested that adrenochrome (an oxidative metabolite of epinephrine) specifically inhibits the activity of the sodium/potassium ATPase. Other investigators have shown that an indole metabolite of epinephrine inhibited actomyosin ATPase [1, 4]. These inhibitory actions may result from an interaction between the oxidative metabolites and sulfhydryl groups present in the enzyme [13]. Inhibition of the sodium/potassium ATPase is associated with an increase in the intracellular concentration of Na+ and Ca2+ and a decrease in intracellular K+. Changes in the intracellular concentration of these ions are commonly seen in heart cell damage and contractile failure [2]. The present study was designed to determine if isoproterenol, a synthetic catecholamine, inhibits the sodium/potassium ATPase activity in a primary culture system of rat myocardial cells.

Topics: Animals; Antioxidants; Ascorbic Acid; Culture Techniques; Electrolytes; Isoproterenol; Mitochondria, Heart; Myocardium; Rats; Rats, Inbred Strains; Sarcolemma; Sodium-Potassium-Exchanging ATPase; Sulfites

Ascorbic acid (100 mg/ml) and sodium bisulfite (0.5 and 20 mg/ml) prevented more than 10% oxidation of apomorphine hydrochloride in water maintained at room temperature over 1-3 days. Refrigeration at 5 degrees prevented oxidation of apomorphine hydrochloride in aqueous solutions for 1 week. Neither ascorbic acid nor sodium bisulfite affected murine stereotyped cage climbing or hypothermia induced by apaomorphine.

Topics: Animals; Antioxidants; Apomorphine; Ascorbic Acid; Body Temperature; Drug Interactions; Drug Stability; Mice; Motor Activity; Sulfites