scholarly journals Role of Ascorbic Acid in the Extraction and Quantification of Potato Polyphenol Oxidase Activity

Foods ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2486
Author(s):  
Shu Jiang ◽  
Michael H. Penner
Keyword(s):  
Ascorbic Acid ◽  
Polyphenol Oxidase ◽  
Model Systems ◽  
Ascorbate Oxidase ◽  
Polyphenol Oxidase Activity ◽  
Spectrophotometric Methods ◽  
Enzyme Extraction ◽  
Dependent Inactivation ◽  
Primary Substrate

The ability to accurately measure the activity of polyphenol oxidase (PPO) in complex matrices is essential. A problem encountered when using spectrophotometric methods is interference due to ascorbic acid (AA), often used as an enzyme “protecting agent” during PPO extraction. This study focuses on the nature of AA’s effect on spectrophotometric determinations of PPO activity as well as enzyme extraction. Potato extracts and semi-purified PPO were used as enzyme sources. The inactivation of PPO attributed to AA is substrate-mediated. The extent of AA-dependent inactivation of PPO in model systems varied between substrates. AA only slows mechanism-based inactivation of PPO induced by catechol, possibly owing to the prevention of quinone formation. AA minimally protects PPO activity during enzyme extraction. The problem associated with AA in PPO assay could be circumvented by using ascorbate oxidase to remove AA when catechol is the primary substrate or by using chlorogenic acid as the primary substrate.

scholarly journals Erythrocyte catalase inactivation (H2O2 production) by ascorbic acid and glucose in the presence of aminotriazole: role of transition metals and relevance to diabetes

1994 ◽  
Vol 303 (3) ◽  
pp. 935-939 ◽  
Author(s):  
P Ou ◽  
S P Wolff
Keyword(s):  
Ascorbic Acid ◽  
Transition Metal ◽  
Copper Ions ◽  
Acid Oxidation ◽  
H2o2 Production ◽  
Erythrocyte Catalase ◽  
Catalysed Oxidation ◽  
Dependent Inactivation ◽  
A Minor

Erythrocytes exposed to ascorbic acid in the presence of aminotriazole undergo a dose- and time-dependent inactivation of endogenous catalase which is proportional to environmental hydrogen peroxide (H2O2) concentrations. The production of H2O2 seems to be dependent upon the availability of transition metal chelatable by o-phenanthroline (OPT), although the kinetics of catalase inactivation and H2O2 production by externally added copper ions in the presence of OPT is complex. Furthermore, although glucose is also able to undergo a transition-metal-catalysed oxidation yielding H2O2, the production of H2O2 by glucose seems to be a minor process by comparison with ascorbic acid oxidation. Indeed, on the basis of these data, transition-metal-catalysed ascorbic acid oxidation is likely to be a more important source of oxidative stress in the diabetic state than hyperglycaemia.

scholarly journals EFFECT OF PRE-TREATMENT ON QUALITATIVE INDICES OF WHITE ROOTS

2018 ◽  
Vol 12 (1) ◽  
Author(s):  
I. Bilenka ◽  
Ya. Golinskaya ◽  
N. Dzyuba ◽  
H. Martirosian
Keyword(s):  
Ascorbic Acid ◽  
Polyphenol Oxidase ◽  
Raw Materials ◽  
Microwave Processing ◽  
Raw Material ◽  
Oxidative Enzymes ◽  
Ascorbate Oxidase ◽  
Root Crops ◽  
Pre Treatment ◽  
Technological Methods

In the work, various technological methods are presented of preliminary processing of celery and parsnip roots to prevent their darkening during cooking in restaurants. These methods are: immersing in a citric acid solution (c = 0.05 %, 0.1 %, 0.15 %), in solution NaCl (c = 0. 5%, 1 %, 2 %), and microwave processing in various modes. The activity of peroxidase, polyphenol oxidase, and ascorbate oxidase enzymes of root crops in the varietal section is also determined. Fresh white roots were selected as research objects: celery of the varieties Yablucnyy and Diamant, and parsnip of the varieties Student and Kruhlyy. It was revealed that polyphenol oxidase shows the highest activity. In order to inactivate the above-stated oxidoreductase, different methods of treating white roots were compared, too. The lowest oxidative enzymes activity was characteristic of the roots of the Diamant varieties and the parsnip roots of the Student variety, which were selected for further work. Studies have been carried out on changes in the mass fraction of L-ascorbic acid during steam blasting and microwave processing in different modes. It is proved that the treatment of white roots with ultra high frequency irradiation at 650 W for 1 minute is optimal. Such treatment allowes preventing the darkening of the raw material after its peeling due to the action of oxidation-reducing enzymes. It also allows preserving L-ascorbic acid by 64.6 % and 65.0 % in the roots of celery and parsnip, respectively. The distribution of polyphenol oxidase activity in the celery and parsnip root crop is analyzed. The results of the work can be used in preparation of dishes with the use of white roots in restaurants in order to improve technological techniques during processing of raw materials into finished products, improve its quality, and preserve L-ascorbic acid, as well as expand the range of culinary products based on spicy aromatic raw materials.

scholarly journals MEKANISME INHIBISI ENZIM POLIFENOL OKSIDASE PADA SARI BUAH MARKISA DENGAN SISTEIN DAN ASAM ASKORBAT1

2015 ◽  
Vol 4 (2) ◽  
pp. 32
Author(s):  
Elida Mardiah
Keyword(s):  
Ascorbic Acid ◽  
Enzyme Inhibition ◽  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Polyphenol Oxidase Activity ◽  
Optimum Activity ◽  
Oxidase Enzyme

 ABSTRACT The mechanism of polyphenol oxidase enzyme inhibition was studied by isolation of enzyme from the passion fruite juice (Passiflora Sp). The extracted enzyme polyphenol oxidase has an optimum activity at pH 5,6 and temperature of 300 C using a pirogalol substrate. The pattern of inhibition of the enzyme polifenol oxsidase studied using cysteine and ascorbic acid. Cystein of 10 mM consentration can inhibit the enzyme polyphenol oxidase activity as 97.25%, ascorbic acid with the same concentration can inhibit the enzyme polyphenol oxsidace 96.5%. The pattern of inhibition of cysteine is more likely to be competitive, while non-competitive with ascorbic acid. Keyword: polyphenol oxsidase, inhibition, cysteine, ascorbic acid

scholarly journals Features of the enzyme composition of Jerusalem artichoke tubers

2019 ◽  
Vol 21 (91) ◽  
pp. 14-19
Author(s):  
I. Bilenka ◽  
N. Lazarenko ◽  
O. Zolovska ◽  
Ya. Golinskaya
Keyword(s):  
Ascorbic Acid ◽  
Polyphenol Oxidase ◽  
Raw Materials ◽  
Enzyme System ◽  
Jerusalem Artichoke ◽  
Microwave Processing ◽  
Biologically Active ◽  
Ascorbate Oxidase ◽  
Activity Of Enzymes ◽  
Active Substances

The article deals with different methods of preparing Jerusalem artichoke tubers to stabilize the color of semi-finished products and finished products. The varieties Interés and Violet de Rennes were chosen as objects of study. The purpose of this work is to study the activity of the enzyme system of Jerusalem artichoke tubers, followed by the use of raw materials as an ingredient in the preparation of culinary dishes with high nutritional and biological value. In accordance with the objective, the characteristics of the enzymatic composition of the material under study were researched. It was found that of the oxidoreductases present, the most active enzyme is polyphenol oxidase. It has been established that in the tubers of Jerusalem artichoke, the activity of polyphenol oxidase is in 1.8 times lower, peroxidase – in 1.34 times higher; ascorbate oxidase is in 2.79 times higher than that of Violet de Rennes tubers. A comparative analysis was performed on the reduction of the activity of enzymes and the preservation of the mass fraction of L-ascorbic acid in heat treatment and microwave processing. It has been established that the most successful method of treating Jerusalem artichoke tubers in order to inactivate the enzyme system and to preserve L-ascorbic acid is a microwave processing of 600 W in 1 minute. Studies have shown that with such preparation, the semi-finished product does not change color, the activity of the enzyme polyphenol oxidase decreases by 20 times, and the maintenance of the content of L-ascorbic acid is 68.4%. In further studies, it is important to study the technologies for preparing culinary dishes based on Jerusalem artichoke tubers using the results obtained to stabilize the color and preserve the biologically active substances of the raw materials.

scholarly journals Effect of antioxidants and pH on browning and firmness of minimally processed eggplant

2020 ◽  
Vol 48 (1) ◽  
pp. 79-89
Author(s):  
Diana P. USCANGA-SOSA ◽  
María B. PÉREZ-GAGO ◽  
Fernando C. GÓMEZ-MERINO ◽  
José A. HERRERA-CORREDOR ◽  
Aleida S. HERNÁNDEZ-CÁZARES ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Polyphenol Oxidase ◽  
Oxidase Activity ◽  
Storage Period ◽  
Visual Quality ◽  
Minimally Processed ◽  
Polyphenol Oxidase Activity ◽  
Minimal Processing ◽  
Visual Evaluation

Minimal processing of eggplant (Solanum melongena L.) generates loss of firmness and polyphenol oxidase catalyzes the oxidation of phenolic compounds producing enzymatic browning. The aim of this study was to evaluate the effect of 1% ascorbic acid and 2% calcium ascorbate in aqueous solution at natural pH of the antioxidant (pH 2.6 and 7.8, respectively), or adjusted to pH 5 with generally recognized as safe substances, mantaining the quality of minimally processed eggplant stored at 5 °C for 6 d. Water was used as a control. The color, firmness, polyphenol oxidase activity, and visual quality was evaluated in the freshly cut fruit at 3 and 6 d of storage. No effect of the treatments on firmness or polyphenol oxidase activity was observed. At 3 d of storage, a correlation was observed between polyphenol oxidase activity and the visual evaluation of the cut product. Samples treated with 2% calcium ascorbate and the rest of the treatments at pH 5 had a lower browning index than those treated with 1% ascorbic acid and the control. At the end of the storage period, the visual quality of the eggplant samples treated with 1% ascorbic acid at pH 5 was evaluated above the marketing limit, whereas those treated with 1% ascorbic acid at pH 2.6 had the lowest quality indicators. An adjustment to pH 5 helps to preserve the luminosity and visual quality of the eggplant, however firmness was not affected by calcium ascorbate or the pH of the medium.

Pectin-based edible coating preserves antioxidative capacity of plum fruit during shelf life

2020 ◽  
Vol 26 (7) ◽  
pp. 583-592 ◽  
Author(s):  
Sima Panahirad ◽  
Rahim Naghshiband-Hassani ◽  
Nasser Mahna
Keyword(s):  
Ascorbic Acid ◽  
Shelf Life ◽  
Polyphenol Oxidase ◽  
Peroxidase Activity ◽  
Oxidase Activity ◽  
Edible Coating ◽  
Total Phenolic ◽  
Antioxidative Capacity ◽  
Three Solutions ◽  
Polyphenol Oxidase Activity

Exploiting safer methods for fruit preservation such as application of edible coatings can improve shelf life, valuable characteristics, and antioxidative capacity. The current study aimed to investigate the effect of a pectin-based edible coating on antioxidative capacity of plum fruit during shelf life (19 ± 2 ℃ and 65% relative humidity for eight days). To do this, three solutions (0.5, 1, and 1.5%) of pectin, plasticized by glycerol (0.3% w/v), were applied on plum fruit and compared to a control treated with only distilled water. Ascorbic acid, total phenolics, anthocyanin and flavonoid contents, total antioxidative capacity based on 1,1-diphenyl-2-picryl-hydrazyl hydrate method, peroxidase (as an antioxidant enzyme), and polyphenol oxidase (as an oxidant enzyme) activities were recorded during this period. The results demonstrated that pectin-based edible coating was significantly effective on maintaining ascorbic acid, anthocyanin and flavonoid contents, and antioxidative capacity in plum fruits (P ≤ 0.01). The activities of enzymes were significantly affected by the coatings; peroxidase activity increased and polyphenol oxidase activity decreased (P ≤ 0.01). All pectin concentrations significantly caused higher ascorbic acid and anthocyanin contents, antioxidative capacity, and peroxidase activity but a lower polyphenol oxidase activity than the control; however, just 1 and 1.5% concentrations were effective in terms of total phenolic compounds and flavonoid content, respectively, and the other concentrations acted the same as the control. In general, the coating constituted from 1.5% pectin showed the best results for most measured parameters. Considering the influences of pectin-based edible coating on antioxidative characteristics of plum fruits, its application can be potentially regarded as a favorable method to enhance nutritional value of fruits.

Sign in / Sign up

Export Citation Format

Share Document