Study of lipoxygenase and peroxidase as blanching indicator enzymes in peas: change of enzyme activity, ascorbic acid and chlorophylls during frozen storage

LWT ◽  
2005 ◽  
Vol 38 (8) ◽  
pp. 903-908 ◽  
Author(s):  
Vural Gökmen ◽  
K. Savaş Bahçeci ◽  
Arda Serpen ◽  
Jale Acar
Keyword(s):  
Ascorbic Acid ◽  
Enzyme Activity ◽  
Frozen Storage

Stability of antioxidant vitamins in whole human blood during overnight storage at 4°C and frozen storage up to 6 months

2018 ◽  
Vol 88 (3-4) ◽  
pp. 151-157 ◽  
Author(s):  
Scott W. Leonard ◽  
Gerd Bobe ◽  
Maret G. Traber
Keyword(s):  
Ascorbic Acid ◽  
Whole Blood ◽  
Healthy Subjects ◽  
Frozen Storage ◽  
Blood Collection ◽  
Plasma Samples ◽  
Optimal Conditions ◽  
Plasma Ascorbic Acid ◽  
Blood Samples ◽  
Sample Handling

Abstract. To determine optimal conditions for blood collection during clinical trials, where sample handling logistics might preclude prompt separation of erythrocytes from plasma, healthy subjects (n=8, 6 M/2F) were recruited and non-fasting blood samples were collected into tubes containing different anticoagulants (ethylenediaminetetra-acetic acid (EDTA), Li-heparin or Na-heparin). We hypothesized that heparin, but not EDTA, would effectively protect plasma tocopherols, ascorbic acid, and vitamin E catabolites (α- and γ-CEHC) from oxidative damage. To test this hypothesis, one set of tubes was processed immediately and plasma samples were stored at −80°C, while the other set was stored at 4°C and processed the following morning (~30 hours) and analyzed, or the samples were analyzed after 6 months of storage. Plasma ascorbic acid, as measured using HPLC with electrochemical detection (LC-ECD) decreased by 75% with overnight storage using EDTA as an anticoagulant, but was unchanged when heparin was used. Neither time prior to processing, nor anticoagulant, had any significant effects upon plasma α- or γ-tocopherols or α- or γ-CEHC concentrations. α- and γ-tocopherol concentrations remained unchanged after 6 months of storage at −80°C, when measured using either LC-ECD or LC/mass spectrometry. Thus, refrigeration of whole blood at 4°C overnight does not change plasma α- or γ-tocopherol concentrations or their catabolites. Ascorbic acid is unstable in whole blood when EDTA is used as an anticoagulant, but when whole blood is collected with heparin, it can be stored overnight and subsequently processed.

scholarly journals Effect of Frozen Storage on Polyphenol Oxidase, Antioxidant Content, and Color of Pawpaw (Asimina Triloba [L.] Dunal) Fruit Pulp

2017 ◽  
Vol 6 (3) ◽  
pp. 93 ◽  
Author(s):  
Robert G Brannan ◽  
Gai Wang
Keyword(s):  
Ascorbic Acid ◽  
Polyphenol Oxidase ◽  
Frozen Storage ◽  
Color Difference ◽  
Browning Index ◽  
Air Samples ◽  
Significant Difference ◽  
Main Effect ◽  
Effect Of Treatment ◽  
Main Effects

Polyphenol oxidase (PPO) activity values for pawpaw pulp during frozen storage were measured for the main effect of month of storage at three levels (0, 4, 8 months) and treatment at four levels (vacuum, air, ascorbic acid or n-acetylcysteine). A significant effect of treatment was observed in PPO activity (p<0.001). Post hoc analysis revealed no significant difference between samples that were vacuum packaged and those for which no attempt to exclude air was made. The addition of the two chemical browning inhibitors significantly lowered PPO activity. Ascorbic acid exhibited a significant 69% reduction in PPO activity compared to vacuum and air samples and n-acetylcysteine was significantly more effective than ascorbic acid and almost completely inhibited PPO activity compared to the vacuum and air samples. CIELAB tristimulous color values (L*, a*, b*) were used to generate the applied color values total color difference (DE), browning index, hue and chroma in pawpaw pulp for the two main effects. Analysis of variance for the main effects showed significance for all seven color attributes at p<0.001. For the main effect of storage time, ANOVA showed significance during storage for all seven color attributes at p<0.001, indicating that there were color changes during storage. Pawpaw pulp samples at 8 months of storage were significantly darker (lower L*), more yellow (higher b*), more vivid (higher chroma), and had a higher browning index than the samples at 0 or 4 months of storage. For the main effect of treatment, ascorbic acid and n-acetylcysteine treatment produced pawpaw pulp that was significantly different than samples to which air was not excluded for all seven dependent color variables. Specifically, n-acetylcysteine and ascorbic acid produced pulp that was lighter (higher L*), less red (lower a*), and more yellow (higher b* and hue), more vivid (higher chroma), and exhibited more color difference (higher DE). A strategy to inhibit enzymatic browning during frozen storage would be useful for the nascent pawpaw industry.

scholarly journals Serum Folate Forms Are Stable during Repeated Analysis in the Presence of Ascorbic Acid and during Frozen Sample Storage

2019 ◽  
Vol 3 (6) ◽  
pp. 993-1002
Author(s):  
Neelima Paladugula ◽  
Zia Fazili ◽  
Maya R Sternberg ◽  
Gwendolyn Gabey ◽  
Christine M Pfeiffer
Keyword(s):  
Ascorbic Acid ◽  
Folic Acid ◽  
Repeated Measures ◽  
Storage Stability ◽  
Frozen Storage ◽  
Serum Folate ◽  
Repeated Measures Design ◽  
Repeat Analysis ◽  
The Mean

Abstract Background Serum folate forms, and particularly tetrahydrofolate, are sensitive to oxidation. Methods Using a repeated measures design, we investigated the stability of folate forms in convenience samples with added ascorbic acid (AA; 5 g/L) analyzed initially and after variable (approximately 1–33 weeks) storage time at −70 °C. We examined the recovery of tetrahydrofolate added at different spiking levels to serum with and without AA (5 g/L). We also assessed the long-term frozen storage stability of folate forms. Results Repeat analysis produced consistent results with the initial analysis; the mean relative change (95% CI; Lin's concordance correlation between initial and repeat result; sample size) was 0.08% (−0.24% to 0.39%; rc = 0.999; n = 301) for 5-methyltetrahydrofolate, 4.23% (2.44%–6.05%; rc = 0.984; n = 211) for pyrazino-s-triazine derivative of 4α-hydroxy-5-methyltetrahydrofolate (MeFox), −0.22% (−1.90% to 1.49%; rc = 0.986; n = 214) for folic acid, and 1.49% (−2.71% to 5.88%; rc = 0.889; n = 81) for tetrahydrofolate. Linear regression testing for a time trend indicated an estimated average percent change of less than ±5% for samples retested after 4 months: 5-methyltetrahydrofolate Ptrend = 0.0007, folic acid Ptrend &lt; 0.0001, MeFox Ptrend = 0.38, and tetrahydrofolate Ptrend = 0.0256. The mean ± SD tetrahydrofolate spiking recovery was 96.7% ± 9.4% for serum with added AA, but &lt;50% for serum without added AA. We observed ≤10% loss for most serum folate forms during 4 years of storage at −70 °C. Conclusions Serum containing added AA showed acceptable stability of folate forms during repeat analysis from the same vial within 4 months, complete spiking recovery of tetrahydrofolate during sample processing, and long-term frozen storage stability of folate forms.

Effects of Antioxidants on the Retail Appearance and Display-Life of Frozen Bacon1

1988 ◽  
Vol 51 (2) ◽  
pp. 105-109 ◽  
Author(s):  
L. E. JEREMIAH
Keyword(s):  
Ascorbic Acid ◽  
Regression Analysis ◽  
Propyl Gallate ◽  
Frozen Storage ◽  
Butylated Hydroxytoluene ◽  
Butylated Hydroxyanisole ◽  
Retail Display

The efficacy of three antioxidants and a reductant for preventing deterioration in factors contributing to the retail acceptability of bacon slices during frozen storage and simulated retail display was examined. The antioxidants butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and propyl gallate (PG) and the reductant [ascorbic acid (AA)] were incorporated into a dry sugar bacon cure alone or in combination. Composite results indicated that incorporation of the formulations evaluated into dry sugar bacon cures did not appear to be practical for either extending the frozen storability or retail display-life of frozen and thawed bacon from an appearance aspect. However, incorporation of BHA and BHT in combination extended the retail display life of fresh bacon slices by approximately 3.5 d, based upon regression analysis.

Stabilization of papain from papaya peels / Estabilización de la papaína de la cáscara de papaya

1998 ◽  
Vol 4 (3) ◽  
pp. 179-187 ◽  
Author(s):  
N. Espin ◽  
M.N. Islam
Keyword(s):  
Ascorbic Acid ◽  
Enzyme Activity ◽  
Protective Effect ◽  
Total Concentration ◽  
Sodium Ascorbate ◽  
Sodium Metabisulfite ◽  
Appreciable Effect ◽  
Original Activity ◽  
Before And After ◽  
Erythorbic Acid

Crude papain in papaya peels was stabilized before drying by the addition of various chemicals (ascorbic acid, sodium ascorbate, erythorbic acid, sodium erythorbate, sodium metabisulfite, sodium tetrathionate, 4-hexylresorcinol, t-butyl hydroquinone [TBHQ], rutin, α-tocopherol, trehalose, and sucrose). Chemicals were added to the ground papaya peels at 0, 0.12, 0.25, 0.5, 0.75, 1, 1.25, and 1.5% (w /w). Drying temperatures were 40, 55 and 60 °C. Enzyme activity was measured before and after drying by the casein digestion method. Percentage of enzyme activity retained (% EAR) was calculated by assigning a value of 100% EAR to fresh peels. Possible synergism between chemicals was also studied for a 1:1 ratio chemical/chemical at 1% total concentration. The highest % EAR was obtained at 55 °C for all chemicals except for sucrose and trehalose which showed their best effect at 40 °C. TBHQ rutin, α-tocopherol and 4-hexylresorcinol showed a destabilizing effect. Maximum protective effect occurred at 1% concentration. At this concentration sodium tetrathionate showed the best protective effect (90% EAR) followed by sodium metabisulfite (85% EAR), while both sodium ascorbate and sodium erythorbate retained 75% of the original activity. Ascorbic acid and erythorbic acid were 10% less effective than their corresponding sodium salts, possibly due to lower pH. Trehalose showed only 57 % EAR while sucrose failed to produce any appreciable effect. No synergistic effect was shown by any combination of chemicals.

Transgenic potato overproducing l-ascorbic acid resisted an increase in methylglyoxal under salinity stress via maintaining higher reduced glutathione level and glyoxalase enzyme activity

2011 ◽  
Vol 33 (11) ◽  
pp. 2297-2307 ◽  
Author(s):  
Chandrama Prakash Upadhyaya ◽  
Jelli Venkatesh ◽  
Mayank Anand Gururani ◽  
Leonid Asnin ◽  
Kavita Sharma ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Enzyme Activity ◽  
Salinity Stress ◽  
Reduced Glutathione ◽  
Transgenic Potato ◽  
Glutathione Level

Effects of Some Vitamins on Lactoperoxidase Enzyme Activity

2009 ◽  
Vol 79 (3) ◽  
pp. 188-194 ◽  
Author(s):  
Melda Sisecioglu ◽  
Murat Cankaya ◽  
Hasan Ozdemir
Keyword(s):  
Ascorbic Acid ◽  
Enzyme Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Bovine Milk ◽  
Exchange Chromatography ◽  
Inhibition Mechanism ◽  
Vitamin K3 ◽  
Vitro Effect

Objective: The present paper investigates the in vitro effect of L-ascorbic acid (vitamin C), menadione sodium bisulfate (vitamin K3), and folic acid on purified lactoperoxidase (LPO). Methods: This enzyme was purified from bovine milk by Amberlite CG 50 resin, CM Sephadex C-50 ion-exchange chromatography, and Sephadex G-100 gel filtration chromatography. Results: Rz (A412/A280) value for the purified LPO was found to be 0.8. Lactoperoxidase was purified 20.45-fold with a yield of 28.8 %. Purity of enzyme was checked by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method and a single band was observed. All tested vitamins caused inhibition of the enzyme activity and displayed a competitive type of inhibition mechanism. IC50 values of these three vitamins were 2.03 µM, 0.025 mM, and 0.0925 mM, and the Ki constants were 0.508±0.257 µM, 0.0107±0.0044 mM, and 0.0218±0.0019 mM respectively. Conclusion: The vitamins discussed here displayed inhibition-type competition with LPO enzyme at varying concentrations. Our study showed that L-ascorbic acid exhibited a much higher inhibitory effect at lower concentrations, so it was evidently a more potent inhibitor than other vitamins tested.

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