scholarly journals The Copper-Catalysed Oxidation of Ascorbic Acid in Fruitand Vegetable Suspensions

1948 ◽  
Vol 1 (1) ◽  
pp. 50 ◽  
Author(s):  
FE Huelin ◽  
I Myee Stephens
Keyword(s):  
Ascorbic Acid ◽  
Protective Factors ◽  
Atmospheric Oxygen ◽  
Oxidation Catalysts ◽  
Catalysed Oxidation ◽  
The Stability ◽  
And Storage ◽  
Different Tissues

Considerable attention has been given to the retention of ascorbic acid byfruit and vegetables, both fresh and processed. The stability of ascorbic acid tooxidation can vary greatly in different tissues and under different conditions ofprocessing and storage. The factors concerned in this stability include (a) accessof atmospheric oxygen, as determined by the structure of the tissue and by processingprocedures; (b) oxidation catalysts, including enzymes, copper, and othersubstances in the tissues; and (c) "protective" factors.

scholarly journals The effect of freezing-drying, cloudiness and concentration on the keeping quality of various blackcurrant products

1964 ◽  
Vol 36 (1) ◽  
pp. 161-180
Author(s):  
Taina Kuusi
Keyword(s):  
Ascorbic Acid ◽  
Relevant Literature ◽  
Organoleptic Properties ◽  
Black Currant ◽  
Organoleptic Evaluation ◽  
Freeze Dried ◽  
Juice Concentrate ◽  
The Stability ◽  
And Storage

Experiments have been made in the development of various new black-currant products, such as cloudy juice, juice concentrate and various freeze-dried preparations, along with a study of the effect of these different methods of preparation on the initial quality and storage properties. The quality was assessed from the stability of ascorbic acid and colour, the aroma number, and organoleptic evaluation. Storage lasted up to 8 months. It was established that the cloudiness exercised a slight protective effect on ascorbic acid. However, the instability of the cloud meant that the appearance of the cloudy juice was less attractive than that of the clear juice. No well-founded advantage of the cloudy juice could be demonstrated. Concentration proved less suitable, as there occurred harmful changes in ascorbic acid, colour and organoleptic properties. The freezing-drying method was excellent with respect to ascorbic acid and colour. In contrast, considerable losses in aroma occurred, with consequent weakening of the organoleptic properties. This method would be of advantage only in combination with aroma recovery, and solution of the financial problems involved. The results are discussed in the light of relevant literature.

Factors affecting measurement of urinary oxalate.

1984 ◽  
Vol 30 (8) ◽  
pp. 1339-1343 ◽  
Author(s):  
B C Mazzachi ◽  
J K Teubner ◽  
R L Ryall
Keyword(s):  
Ascorbic Acid ◽  
Room Temperature ◽  
Alkaline Ph ◽  
Ascorbic Acid Concentration ◽  
Factors Affecting ◽  
The Stability ◽  
Gas Chromatographic Method ◽  
And Storage ◽  
Urine Specimens ◽  
Positive Interference

Abstract Using a gas-chromatographic method, we examined the effects of phosphate concentration, added calcium chloride, and pH on precipitation of oxalate from urine. All three factors are important, but the pH of precipitation is particularly so, especially in the presence of even normal concentrations of ascorbic acid. At pH 8, increases in measured oxalate ranged from 20% at an ascorbic acid concentration of 1 mmol/L to more than 300% at 15 mmol/L. Ascorbic acid is rapidly converted to oxalate at alkaline pH. We also investigated the stability of both untreated and acidified urine containing ascorbic acid during storage for up to one month at -70, -20, and 4 degrees C, and room temperature. After one month, untreated collections were stable at -70 degrees C and acidified collections at -20 and -70 degrees C. We recommend conditions for assay and storage of urine specimens that are to be assayed for oxalate under which positive interference by ascorbic acid is minimized.

scholarly journals Factors Affecting the Stability of Vitamin C in Tropical Fruit Juices and Nectars

1969 ◽  
Vol 48 (1) ◽  
pp. 1-12
Author(s):  
Abdul R. Rahman ◽  
J. Anziani ◽  
J. R. Cruz-Cay
Keyword(s):  
Ascorbic Acid ◽  
Vitamin C ◽  
Fruit Juices ◽  
Tropical Fruit ◽  
Factors Affecting ◽  
Synthetic Vitamin ◽  
The Stability ◽  
And Storage

Studies were conducted on the effect of certain factors such as temperature, pH, degrees Brix, concentration of vitamin C, and storage in sealed as well as in open containers, on the stability of vitamin C in tropical fruit juices and nectars. They were fortified with different quantities of synthetic vitamin C (1-ascorbic acid) ranging between 10 and 4,000 mg. per 100 ml.

Sorbitol enhances the physicochemical stability of B12 vitamers

2020 ◽  
Vol 90 (5-6) ◽  
pp. 439-447 ◽  
Author(s):  
Andrew Hadinata Lie ◽  
Maria V Chandra-Hioe ◽  
Jayashree Arcot
Keyword(s):  
Ascorbic Acid ◽  
Uv Light ◽  
Heat Exposure ◽  
Water Soluble ◽  
Uv Exposure ◽  
Physicochemical Stability ◽  
Before And After ◽  
The Stability

Abstract. The stability of B12 vitamers is affected by interaction with other water-soluble vitamins, UV light, heat, and pH. This study compared the degradation losses in cyanocobalamin, hydroxocobalamin and methylcobalamin due to the physicochemical exposure before and after the addition of sorbitol. The degradation losses of cyanocobalamin in the presence of increasing concentrations of thiamin and niacin ranged between 6%-13% and added sorbitol significantly prevented the loss of cyanocobalamin (p<0.05). Hydroxocobalamin and methylcobalamin exhibited degradation losses ranging from 24%–26% and 48%–76%, respectively; added sorbitol significantly minimised the loss to 10% and 20%, respectively (p < 0.05). Methylcobalamin was the most susceptible to degradation when co-existing with ascorbic acid, followed by hydroxocobalamin and cyanocobalamin. The presence of ascorbic acid caused the greatest degradation loss in methylcobalamin (70%-76%), which was minimised to 16% with added sorbitol (p < 0.05). Heat exposure (100 °C, 60 minutes) caused a greater loss of cyanocobalamin (38%) than UV exposure (4%). However, degradation losses in hydroxocobalamin and methylcobalamin due to UV and heat exposures were comparable (>30%). At pH 3, methylcobalamin was the most unstable showing 79% degradation loss, which was down to 12% after sorbitol was added (p < 0.05). The losses of cyanocobalamin at pH 3 and pH 9 (~15%) were prevented by adding sorbitol. Addition of sorbitol to hydroxocobalamin at pH 3 and pH 9 reduced the loss by only 6%. The results showed that cyanocobalamin was the most stable, followed by hydroxocobalamin and methylcobalamin. Added sorbitol was sufficient to significantly enhance the stability of cobalamins against degradative agents and conditions.

Preparation, Stabilization and Some Properties of Purified Human Plasmin*

1964 ◽  
Vol 11 (01) ◽  
pp. 075-084 ◽  
Author(s):  
Daniel L Kline ◽  
Jacob B Fishman ◽  
Keyword(s):  
Plasminogen Activator ◽  
Stable Form ◽  
Neutral Ph ◽  
The Stability ◽  
And Storage

Summary1. Lysine increased the solubility, decreased the SK requirement and increased the stability of plasmin prepared from purified plasminogen by SK activation.2. A procedure is presented for the rapid and quantitative conversion of plasminogen to plasmin and storage of the plasmin in stable form at neutral pH as a lyophilized powder.3. Approximately 10% for the plasminogen molecule was split off during its activation. No carbohydrate was lost.4. The plasmin isolated was homogeneous in the ultracentrifuge at pH 2.5 and was quantitatively convertible to plasminogen activator by the addition of SK.

Evaluation of the quality and the stability of human samples for analysis and storage in biorepository

2018 ◽  
Vol 50 (1) ◽  
Author(s):  
Leonardo André Lange ◽  
Caroline Galgowski ◽  
Anna Cecília Roncalio ◽  
Fabiana Sehnem ◽  
Grabriela Borgmann ◽  
...  
Keyword(s):  
Human Samples ◽  
The Stability ◽  
And Storage

Label-free proteomic analysis revealed the mechanisms of protein oxidation induced by hydroxyl radicals in whiteleg shrimp (Litopenaeus vannamei) muscle

2021 ◽  
Author(s):  
Hui-min Lin ◽  
Xue-er Qi ◽  
Shan-shan Shui ◽  
Soottawat Benjakul ◽  
Santiago P. Aubourg ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Hydroxyl Radicals ◽  
Litopenaeus Vannamei ◽  
Protein Oxidation ◽  
Proteomic Analysis ◽  
Muscle Proteins ◽  
Label Free ◽  
Whiteleg Shrimp ◽  
The Stability ◽  
Oxidative Effects

The oxidative effects of hydroxyl radicals derived from a FeCl3/ascorbic acid/H2O2 system on the stability of muscle proteins in peeled shrimp (Litopenaeus vannamei) were investigated.

scholarly journals Spatio-temporal selection of reference genes in the two congeneric species of Glycyrrhiza

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yuping Li ◽  
Xiaoju Liang ◽  
Xuguo Zhou ◽  
Yu An ◽  
Ming Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Developmental Stage ◽  
Reference Genes ◽  
Developmental Stages ◽  
Individual Factors ◽  
Congeneric Species ◽  
Spatio Temporal ◽  
The Stability ◽  
Different Tissues ◽  
Selection Of

AbstractGlycyrrhiza, a genus of perennial medicinal herbs, has been traditionally used to treat human diseases, including respiratory disorders. Functional analysis of genes involved in the synthesis, accumulation, and degradation of bioactive compounds in these medicinal plants requires accurate measurement of their expression profiles. Reverse transcription quantitative real-time PCR (RT-qPCR) is a primary tool, which requires stably expressed reference genes to serve as the internal references to normalize the target gene expression. In this study, the stability of 14 candidate reference genes from the two congeneric species G. uralensis and G. inflata, including ACT, CAC, CYP, DNAJ, DREB, EF1, RAN, TIF1, TUB, UBC2, ABCC2, COPS3, CS, R3HDM2, were evaluated across different tissues and throughout various developmental stages. More importantly, we investigated the impact of interactions between tissue and developmental stage on the performance of candidate reference genes. Four algorithms, including geNorm, NormFinder, BestKeeper, and Delta Ct, were used to analyze the expression stability and RefFinder, a comprehensive software, provided the final recommendation. Based on previous research and our preliminary data, we hypothesized that internal references for spatio-temporal gene expression are different from the reference genes suited for individual factors. In G. uralensis, the top three most stable reference genes across different tissues were R3HDM2, CAC and TUB, while CAC, CYP and ABCC2 were most suited for different developmental stages. CAC is the only candidate recommended for both biotic factors, which is reflected in the stability ranking for the spatio (tissue)-temporal (developmental stage) interactions (CAC, R3HDM2 and DNAJ). Similarly, in G. inflata, COPS3, R3HDM2 and DREB were selected for tissues, while RAN, COPS3 and CS were recommended for developmental stages. For the tissue-developmental stage interactions, COPS3, DREB and ABCC2 were the most suited reference genes. In both species, only one of the top three candidates was shared between the individual factors and their interactions, specifically, CAC in G. uralensis and COPS3 in G. inflata, which supports our overarching hypothesis. In summary, spatio-temporal selection of reference genes not only lays the foundation for functional genomics research in Glycyrrhiza, but also facilitates these traditional medicinal herbs to reach/maximize their pharmaceutical potential.

scholarly journals Complexes of Copper and Iron with Pyridoxamine, Ascorbic Acid, and a Model Amadori Compound: Exploring Pyridoxamine’s Secondary Antioxidant Activity

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 208
Author(s):  
Guillermo García-Díez ◽  
Roger Monreal-Corona ◽  
Nelaine Mora-Diez
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Rate Constant ◽  
Stable Complex ◽  
Aqueous Environment ◽  
Oh Radicals ◽  
Bidentate Ligands ◽  
Superoxide Radical Anion ◽  
Amadori Compound ◽  
The Stability

The thermodynamic stability of 11 complexes of Cu(II) and 26 complexes of Fe(III) is studied, comprising the ligands pyridoxamine (PM), ascorbic acid (ASC), and a model Amadori compound (AMD). In addition, the secondary antioxidant activity of PM is analyzed when chelating both Cu(II) and Fe(III), relative to the rate constant of the first step of the Haber-Weiss cycle, in the presence of the superoxide radical anion (O2•−) or ascorbate (ASC−). Calculations are performed at the M05(SMD)/6-311+G(d,p) level of theory. The aqueous environment is modeled by making use of the SMD solvation method in all calculations. This level of theory accurately reproduces the experimental data available. When put in perspective with the stability of various complexes of aminoguanidine (AG) (which we have previously studied), the following stability trends can be found for the Cu(II) and Fe(III) complexes, respectively: ASC < AG < AMD < PM and AG < ASC < AMD < PM. The most stable complex of Cu(II) with PM (with two bidentate ligands) presents a ΔGf0 value of −35.8 kcal/mol, whereas the Fe(III) complex with the highest stability (with three bidentate ligands) possesses a ΔGf0 of −58.9 kcal/mol. These complexes can significantly reduce the rate constant of the first step of the Haber-Weiss cycle with both O2•− and ASC−. In the case of the copper-containing reaction, the rates are reduced up to 9.70 × 103 and 4.09 × 1013 times, respectively. With iron, the rates become 1.78 × 103 and 4.45 × 1015 times smaller, respectively. Thus, PM presents significant secondary antioxidant activity since it is able to inhibit the production of ·OH radicals. This work concludes a series of studies on secondary antioxidant activity and allows potentially new glycation inhibitors to be investigated and compared relative to both PM and AG.

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