scholarly journals Inactivation Kinetics and Thermodynamics Parameters of Polyphenol Oxidase and Peroxidase Activities in an Extract from of Violet Eggplant (Solanum melongena L.)

2021 ◽  
pp. 83-92
Author(s):  
Jocelyn Constant Yapi ◽  
Gbocho Serge Elvis Ekissi ◽  
Kouame Claude Ya ◽  
Patrice Lucien Kouamé
Keyword(s):  
Polyphenol Oxidase ◽  
Thermal Inactivation ◽  
Solanum Melongena ◽  
Inactivation Kinetics ◽  
Kinetic Properties ◽  
Thermostable Enzymes ◽  
Polyphenol Oxidases ◽  
Thermodynamics Parameters ◽  
Z Value ◽  
Increasing Temperature

Enzymatic browning is associated with the action of polyphenol oxidases (PPO) and peroxidases (POD). The products of these enzymes cause undesirable changes of color and flavor of processed eggplant products. The present study aimed to evaluate kinetic properties and thermodynamics parameters of PPO and POD activities for controlling this undesirable process in extract from of violet eggplant. The effect of heat treatment on polyphenol oxidase and peroxidase activities in violet eggplant were studied over a range of 30 to 80 °C. T1/2-values of enzymatic activities are between 6.15 ± 0.03 and 13,27 ± 0,04 min at 80 °C, they decreased with increasing temperature, indicating a difference thermostability of each enzyme. D- and k-values decreased and increased, respectively, with increasing temperature, indicating faster of these enzymes inactivation at higher temperatures. Results suggested that polyphenol oxydase and peroxidase were relatively thermostable enzymes with a Z-value which from 50.25 and from 88.33 °C and Ea of 41.21 and of 27.78 kJmol-1. Thermodynamic parameters were also calculated. The Gibbs free energy ΔG values range from 43.24 ± 0,03 to 91.45 ± 0,01 kJ/mol. These kinetic data can be used to predict prevention of browning in the violet eggplant (Solanum melongena L.) by thermal inactivation of enzymes.

scholarly journals EFFECT OF CHEMICAL AND THERMAL TREATMENTS ON INHIBITION OF PEROXIDASE ACTIVITIE OF PURPLE SKIN EGGPLANT (SOLANUMMELONGENA L.)

2021 ◽  
Vol 9 (04) ◽  
pp. 304-313
Author(s):  
Jocelyn Constant Yapi ◽  
◽  
Jean Bedel Fagbohoun ◽  
Zranseu Ange Benedicte Deffan ◽  
Elvis Gbocho Serge Ekissi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Inactivation ◽  
Solanum Melongena ◽  
Thermal Treatments ◽  
Optimal Temperature ◽  
Spectrophotometric Methods ◽  
Acid Effect ◽  
Fresh Cut ◽  
D Values ◽  
Increasing Temperature

Peroxidase (POD) associated with the browning of fresh-cut fruits and vegetableswas extracted from purple skin eggplant(Solanum melongena L.) and characterised using reliable spectrophotometric methods. Maximal POD activity was found at 35 °C and pH 6.0 with guaiacol as the substrate. The enzyme was stable at his optimal temperature (35 °C) and hisat pH stability was in the range of 5.6 - 6.6.Peroxidase retained its full activity in the presence of ion K+, Cu2+, Na+, Pb2+ and Ba2+ but were inhibited strongly by the ion Fe2+ and Mg2+ and the reducing agents as sodium thiosulfateand ascorbic acid. Effect of heattreatment on eggplant peroxidase showed that D-values decreased with increasing temperature, indicating faster peroxidase inactivation at higher temperatures.At 60 °C, the D-values ranged from 20.42 to 54.24 min. Hence, heat treatment at 60 °C for 30 min reduced browning of eggplant fruit.These data can be used to predict prevention of browning in the purple skin eggplantby thermal inactivation and the use of chimical agents onthe enzyme.

scholarly journals Thermal Inactivation Kinetics of Kudzu (Pueraria lobata) Polyphenol Oxidase and the Influence of Food Constituents

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1320
Author(s):  
Junping Liu ◽  
Jiayan Zhang ◽  
Tao Liao ◽  
Lei Zhou ◽  
Liqiang Zou ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Polyphenol Oxidase ◽  
Thermal Inactivation ◽  
Food System ◽  
Fluorescence Emission ◽  
Inactivation Kinetics ◽  
Pueraria Lobata ◽  
Stable Conformation ◽  
K Value ◽  
Kinetics Of

The thermal inactivation kinetics of kudzu (Pueraria lobata) polyphenol oxidase (PPO) were investigated in model and food systems. PPO in kudzu tissue (tPPO) showed a higher thermostability than that of PPO in crude extract (cPPO) and purification fractions (pPPO). The PPO inactivation rate constant (k) increased with an increase in temperature, and tPPO showed the lowest k value, followed by that of cPPO and pPPO at the same temperature, indicating that PPO in the food system was more resistant to thermal treatment. Food constituents (pectin, starch, sucrose, and bovine serum albumin) in the food system decreased the activity of PPO but increased the thermostability of PPO, among which pectin exhibited the strongest protective effect against thermal inactivation, and the influence of sucrose was much slighter than that of other macromolecules. Fluorescence emission spectra indicated that pPPO exhibited stronger interactions with pectin than sucrose, and pPPO with pectin showed a more stable conformation under thermal treatment.

scholarly journals Effects of Extraction Conditions on Banana Peel Polyphenol Oxidase Activity and Insights into Inactivation Kinetics Using Thermal and Cold Plasma Treatment

Foods ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1022
Author(s):  
Daria Wohlt ◽  
Elena Schwarz ◽  
Andreas Schieber ◽  
Stephanie Bader-Mittermaier
Keyword(s):  
Thermal Stability ◽  
Plasma Treatment ◽  
Polyphenol Oxidase ◽  
Cold Plasma ◽  
Thermal Inactivation ◽  
Atmospheric Pressure Plasma ◽  
Banana Peel ◽  
Inactivation Kinetics ◽  
Food Ingredients ◽  
Banana Variety

The objective of this work was to characterize banana peel polyphenol oxidase (PPO) and to study the inactivation kinetics during thermal and cold atmospheric pressure plasma treatment. Since varietal differences in enzyme characteristics are a well-known phenomenon, ‘Prata’ banana peel PPO was characterized, and PPO activity and thermal stability of the peel PPO of the two dessert banana cultivars ‘Cavendish’ and ‘Prata’ were compared to identify the cultivar better suited for industrial food applications. A crude extract obtained from the peels of the Brazilian banana variety ‘Prata’ revealed highest PPO activities (46.0–55.2 nkat/mL) at 30–40 °C in a range of pH 6.0–6.5 after addition of 0.5 g/gsample polyvinylpyrrolidone and 0.5% (v/v) Triton X-100 during extraction. ‘Cavendish’ PPO activity was four times higher. Banana peel PPO exhibited the highest affinity towards dopamine (KM = 0.94 mM). Thermal inactivation of ‘Prata’ and ‘Cavendish’ PPO was achieved at 90 °C after 5 and 15 min, respectively, whereas cold plasma treatment did not decrease PPO activity below 46% of the initial enzyme activity. The inactivation behavior of PPO could successfully be described by a two-fraction model indicating at least two types of isoenzymes with different thermal stability. The overall high thermal stability was mainly attributed to membrane-bound PPO. The results may help to prevent enzymatic browning of banana peels and thereby facilitate their valorization as food ingredients.

Thermal Inactivation Kinetics of Bacillus coagulans Spores in Tomato Juice

2012 ◽  
Vol 75 (7) ◽  
pp. 1236-1242 ◽  
Author(s):  
JING PENG ◽  
JAE-HYUNG MAH ◽  
ROMEL SOMAVAT ◽  
HUSSEIN MOHAMED ◽  
SUDHIR SASTRY ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Thermal Inactivation ◽  
Storage Temperature ◽  
Thermal Characteristics ◽  
Bacillus Coagulans ◽  
Tomato Juice ◽  
Inactivation Kinetics ◽  
Log Reduction ◽  
Z Value ◽  
Kinetics Of

The thermal characteristics of the spores and vegetative cells of three strains of Bacillus coagulans (ATCC 8038, ATCC 7050, and 185A) in tomato juice were evaluated. B. coagulans ATCC 8038 was chosen as the target microorganism for thermal processing of tomato products due to its spores having the highest thermal resistance among the three strains. The thermal inactivation kinetics of B. coagulans ATCC 8038 spores in tomato juice between 95 and 115°C were determined independently in two different laboratories using two different heating setups. The results obtained from both laboratories were in general agreement, with z-values (z-value is defined as the change in temperature required for a 10-fold reduction of the D-value, which is defined as the time required at a certain temperature for a 1-log reduction of the target microorganisms) of 8.3 and 8.7°C, respectively. The z-value of B. coagulans 185A spores in tomato juice (pH 4.3) was found to be 10.2°C. The influence of environmental factors, including cold storage time, pH, and preconditioning, upon the thermal resistance of these bacterial spores is discussed. The results obtained showed that a storage temperature of 4°C was appropriate for maintaining the viability and thermal resistance of B. coagulans ATCC 8038 spores. Acidifying the pH of tomato juice decreased the thermal resistance of these spores. A 1-h exposure at room temperature was considered optimal for preconditioning B. coagulans ATCC 8038 spores in tomato juice.

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