Inactivation Kinetics Of Peroxidase Research Articles

Thermosonication for peroxidase inactivation in sugarcane juice

To allow a widespread commercialization of sugarcane juice it is necessary to develop an effective preservation method. For that, thermosonication was evaluated as an alternative processing technology. Therefore, ultrasound (US) and conventional (CH) treatments were compared regarding peroxidase (POD) inactivation. Both treatments were performed for 25 min at 50–80 °C, with matched temperature profiles. POD inactivation kinetics were evaluated under different US parameters: pulse regime, US application time and power intensity. After treatments, sugarcane juice was monitored for 32 days under refrigerated storage to verify juice quality. Results showed that POD inactivation followed Weibull model for US and CH treatments at 70, 75 and 80 °C. At 70 and 75 °C, US lead to faster POD inactivation when compared to CH. The use of 20s on/10s off pulse regime, US application for 25 min and 75% power intensity were the best conditions for enzyme inactivation (77.3%). During refrigerated storage, POD regeneration, phenolic compounds degradation nor sedimentation were observed in the juice treated by US. For CH, on the other hand, sedimentation and lower phenolic compounds were observed. Overall, US is a potential technology for sugarcane juice enzymatic inactivation with reduced processing times and/or temperatures, leading to a better quality juice.

Effect of microwave-assisted processing on polyphenol oxidase and peroxidase inactivation kinetics of açai-berry (Euterpe oleracea) pulp

Microwave heating has been considered a promising technology for continuous flow thermal processing of fluid foods due to better retention of quality. Considering the importance of açai-berry pulp and its perishability, the inactivation kinetics of peroxidase (POD) and polyphenol oxidase (PPO) were investigated under conventional and microwave heating. First-order two-component model was well fitted to the data, indicating the presence of at least two fractions with different resistances. POD was more thermally resistant (90% inactivation for 40 s at 89 °C) and could be considered as a processing target. Inactivation curves dependency on heating technology suggests specific effects of microwaves on the protein structure. Additionally, the dielectric properties of açai-berry pulp were evaluated at 915 and 2,450 MHz for temperatures up to 120 °C. Power penetration depth dropped with temperature at 915 MHz (from 29 to 11 mm), but was less affected at 2,450 MHz (between 8 and 11 mm).

Application of infrared-assisted steam blanching to improve enzymatic inactivation and quality retention of Chrysanthemum indicum L. flower.

The effects of innovative infrared-steam blanching (ISB) on the peroxidase (POD) inactivation, POD inactivation kinetics, characteristic component (phenolics, carotenoids and flavonoids) content, colour and regeneration of POD activity during storage of Chrysanthemum indicum L. flowers were comparatively studied following steam blanching (SB) and infrared blanching (IB). ISB and SB allowed a stable surface temperature of the flowers at approximately 100°C, and IB caused the temperature rose up to a high value of 129.2°C. POD was inactivated to 5.7% of its residual activity after ISB for 90s, 5.8% after SB for 180s and 5.3% after IB for 270s. In all processes, the POD inactivation kinetics followed a first-order model (R 2 varied from 0.932 to 0.957) and ISB achieved lower T 1/2, E a and D values and a higher k value than SB and IB. The sample blanched with ISB maintained more characteristic components and colour retention than those blanched with SB and IB. Moreover, ISB allowed the brightest colour and prevented the regeneration of POD activity in dried C. indicum flowers during storage. Therefore, ISB for 90s at 100°C is recommended as a more suitable method for blanching C. indicum flowers. The findings in the current work provide a new blanching method for natural plant products.

Ohmic blanching of Tetsukabuto pumpkin: Effects on peroxidase inactivation kinetics and color changes

The present work aimed to evaluate the application of an alternative technology for food blanching, the ohmic heating process, and compare it to conventional blanching of hybrid Tetsukabuto pumpkin. The influence of both treatments on the inactivation kinetics of peroxidase and on color changes of pumpkins was investigated. Different kinetic models were evaluated, and the Weibull distribution model showed the best fit to the experimental data. It was verified that ohmic heating accelerated the enzymatic inactivation process; for a reduction higher than 90% in peroxidase initial activity it took 2 min of ohmic blanching, while conventional blanching took 4 min to achieve the same degree of inactivation. Also, no significant differences (p > 0.05) between ohmic and conventional treatments were observed on the color of the samples. The overall results indicated that ohmic technology was efficient to promote the inactivation of undesirable enzymes and to maintain the food color.

Kinetics of peroxidase inactivation, color and temperature changes during pumpkin (Cucurbita moschata) blanching using infrared heating

Fresh Pumpkin is sensitive to microbial or enzymatic spoilage even in refrigeration temperatures, thus; blanching before freezing or canning is a proper way for preservation and commercialization of this product. In this study infrared irradiation was chosen as heating source and peroxidase as an indicator of enzyme inactivation adequacy for pumpkin blanching. Pumpkin purée was treated under 5 levels of temperature and 2 levels of sample thickness. Effect of thermal processing on the kinetic parameters of peroxidase inactivation (k, Ea, D and Z values) and color changes (ΔE) was investigated. Peroxidase inactivation of pumpkin samples followed a first order kinetics model. Calculated activation energies and Z values of enzyme inactivation process for 4 and 8 mm thickness levels were 130.63, 119.46 kJ mol−1 and 18.18, 17.85 °C, respectively. No significant difference was observed between activation energies and Z values of two thickness levels. But, the effect of temperature and thickness on inactivation rate constants (k) and D values was significant (P < 0.05). Investigation on the kinetics of color change was carried out by the calculation of ΔE changes during l log enzyme inactivation period. In this study, sample thickness showed a more significant effect on ΔE variations than temperature.

Peroxidase inactivation kinetics is affected by the addition of calcium chloride in fruit beverages

The effect of calcium chloride addition on the peroxidase (POD) thermal inactivation was evaluated in a fruit juice model solution and coconut water. The evaluation was conducted over the temperature range from 63 to 85 °C, considering the non-isothermal profile of processing. The accumulated lethality was calculated and the obtained data were well described by the first order kinetic model. The presence of calcium chloride resulted in an increase of POD thermal stabilities in both fruit juice model solution and green coconut water, being the inactivation kinetics also affected. Although all enzyme kinetics data of fruit juice solution can be described by the first order kinetic model, their response to thermal processing were different depending on the concentration of calcium chloride. The obtained results highlight the importance of evaluating engineering aspects of food formulation, as ingredients applied for nutritional or sensorial aspects can also impact the process performance.

Inactivation kinetics of peroxidase and polyphenol oxidase in peach juice treated with gaseous ozone

AbstractThe effectiveness of gaseous ozone for inactivating peroxidase (POD) and polyphenoloxidase (PPO) in peach juice was investigated. The suitability of first‐order and Weibull models to describe inactivation kinetics was also analysed. Peach juice was exposed to ozone (0.11 and 0.20 mg O3 min−1 mL−1) in a bubble column up to 12 min at 20 ± 1 °C. Enzyme activities were reduced due to treatments. The magnitude of the inactivation increased with ozone level and exposure time. Reductions in activity after 12 min of treatment ranged between 99.5% and 99.8% for POD and between 93.9% and 97.3% for PPO, depending on ozone concentration. Inactivation curves were successfully fitted with the first‐order and Weibull models; although, based on the root‐mean‐square error, the corrected Akaike and the Bayesian Schwarz criterion, the Weibull model showed stronger capability in all cases.

Kinetics of Peroxidase Inactivation in Carrot Juice Treated with Pulsed Electric Fields

Peroxidase activity accounts for quality losses in many plant-based foods. The paper provides insight into the inactivation kinetics of peroxidase (POD) in carrot juice treated with pulsed electric fields (PEF). Juice samples were subjected to electric field intensities of 20 to 35 kV/cm for 300 to 2000 μs. Up to 93% of the initial activity was inactivated after treating at 35 kV/cm for 1500 μs. POD activity inactivation correlated well with the increase in energy density input. A first-order fractional conversion model best fitted the experimental results. Other kinetic approaches such as the Fermi's model can be used to estimate residual POD activity values in treated juices as a function of electric field strength. Pulsed electric fields (PEF) are a processing technology that can be used for the pasteurization of liquid food products. Peroxidase activity inhibition is required in carrot juices to prevent undesirable quality losses, such as discoloration, flavor changes, and loss of nutrients. The most significant processing parameters ruling POD inactivation in PEF-treated carrot juice are identified and mathematical modeling of experimental data is conducted.

Thermal inactivation kinetics of Rabdosia serra (Maxim.) Hara leaf peroxidase and polyphenol oxidase and comparative evaluation of drying methods on leaf phenolic profile and bioactivities

Inactivation kinetics of peroxidase and polyphenol oxidase in fresh Rabdosia serra leaf were determined by hot water and steam blanching. Activation energy (52.30 kJ mol(-1)) of polyphenol oxidase inactivation was higher than that (20.15 kJ mol(-1)) of peroxidase. Water blanching at 90 °C or steam blanching at 100 °C for 90 s was recommended as the preliminary treatment for the retention of phenolics. Moreover, comparative evaluation of drying methods on the phenolics profiles and bioactivities of R. serra leaf were conducted. The results indicated that only intact leaf after freeze drying retained the initial quality. The sun- and air-dried leaves possessed identical phenolic profiles. The homogenised leaf (after freeze-drying) possessed a lower level of phenolics due to enzymatic degradation. Good antioxidant activities were detected for the sun- and air-dried leaves. There was insignificant difference in anti-tyrosinase and anti-α-glucosidase activities among sun-, air-, and freeze-dried leaves.

Inactivation kinetics of peroxidase in zucchini (Cucurbita pepo L.) by heat and UV-C radiation

The effect of traditional thermal water blanching, or its combination with a UV-C radiation pre-treatment (11 J/m 2 ), on the inactivation kinetics of peroxidase in zucchini ( Cucurbita pepo L.) was carried out in the temperature range of 80 to 98 °C, and up to 3 min of processing time. Peroxidase inactivation started being noticed only at temperatures around 85 °C. For both treatments, the inactivation kinetics followed a first order reaction with the Arrhenius model describing the temperature dependence of the reaction rate. The obtained kinetic parameters ( k Heat 89.6 °C = 7.37 × 10 − 7 ± 3.47 × 10 − 7 min − 1 and E a Heat = 925 ± 69 kJ mol − 1 ; k Heat 89.6 °C + UV-C = 2.42 × 10 − 5 ± 6.58 × 10 − 6 min − 1 and E a Heat + UV-C = 596 ± 48.8 kJ mol − 1 ) showed that UV-C radiation had a significant contribution to increase the peroxidase degradation rate. These results will help to design new pre-processing conditions for the production of frozen zucchini, using less severe thermal treatments and attempt to minimize quality losses. The use of UV-C radiation in processing creates novel methodologies, which can be complementary to classical techniques, providing reduced processing times and increased efficiency. Having been proved to be particularly useful in sterilization of liquids and surfaces, inhibition of microbial population and in decrease of protein synthesis, its application in combination with the traditional blanching may be in favor of less severe heating treatments. The evaluation of the kinetics of zucchini ( Cucurbita pepo L . ) peroxidase inactivation with the traditional blanching method and combined with ultraviolet radiation suggests that short UV-C treatments may be a useful non-chemical pre-freezing method, allowing the application of shorter blanching times, leading to a product with eventual higher quality retention which is highly relevant to industry. ► Heat blanching + UV-C above 85 °C promoted a synergistic effect on enzyme inactivation. ► Peroxidase heat + UV-C radiation inactivation in zucchini follows first-order kinetics. ► Addition of UV-C radiation to heat blanching favors a less severe blanching treatment. ► A UV-C radiation chamber was conceived by University of Algarve, Portugal.

Kinetics of Crude Peroxidase Inactivation and Color Changes of Thermally Treated Seedless Guava (Psidium guajava L.)

Thermal treatment of seedless guava (Psidium guajava L.) cubes was carried out in the temperature range of 80–95 °C. The kinetics of peroxidase inactivation and color changes due to thermal treatments were determined. Peroxidase inactivation followed a first-order kinetic model, where the activation energy was 96.39 ± 4 kJ mol−1. Color was quantified in terms of L, a, and b values in the Hunter system. The color changes during processing were described by a first-order kinetic model, except total color difference which followed a zero-order kinetic model. The temperature dependence of the degradation followed the Arrhenius relation. The activation energies (Ea) for L, a, b, and total color difference (ΔE) were 122.68 ± 3, 88.47 ± 5, 104.86 ± 5, and 112.65 ± 5 kJ mol−1, respectively. The results of this work are a good tool to further optimize seedless guava thermal treatment conditions.

High pressure and thermal inactivation kinetics of polyphenol oxidase and peroxidase in strawberry puree

The objective of this work was to study the thermal and high pressure inactivation kinetics of polyphenol oxidase (PPO) and peroxidase (POD) in strawberry puree. PPO from two strawberry cultivars (‘Festival’ and ‘Aroma’) was found to be highly thermostable in strawberry puree with no significant inactivation even after 30 min treatment at 100 °C. In contrast, POD from the two cultivars displayed very high thermosensitivity with complete inactivation in less than 5 min at 70 °C. The thermal inactivation kinetics of strawberry POD was described by a biphasic model. The activation energies for the inactivation of the stable and the labile fractions were estimated to be 254.9 and 221.6 kJ/mol respectively. Combined high pressure–thermal treatment at pressures ranging from 100 to 690 MPa, temperatures ranging from 24 to 90 °C and treatment times between 5 and 15 min did not have significant effect on PPO while substantial inactivation of POD was observed. The inactivation kinetics of POD during combined high pressure–thermal processing was well described by first-order kinetics probably due to the inactivation of the labile fraction during the pre-heating and the compression phase. The oxidative enzymes polyphenol oxidase and peroxidase cause the degradation of anthocyanins and other polyphenols in strawberry products, leading to discoloration and loss of antioxidant activity. In this work the thermal and high pressure inactivation of strawberry polyphenol oxidase and peroxidase was investigated so as to assess the suitability of high pressure processing as an alternative to thermal processing. Strawberry polyphenol oxidase was found to be highly resistant to both thermal and high pressure inactivation. Thus in order to maintain the quality of processed strawberry products, high pressure processing should be accompanied by additional measures such as exclusion of oxygen, refrigerated storage and the use of natural enzyme inhibitors.

Modelling the kinetics of Seedless Guava (Psidium guajava L.) Peroxidase Inactivation due to Heat and Thermosonication Treatments

Effect of heat and thermosonication on inactivation kinetics of peroxidase in seedless guava have been studied over a temperature range of 80-95°C. Application of thermosonication was studied at 25, 50 and 75% of radiation intensity at the same temperature range. Ultrasonic wave’s intensity had significant(P<0.05) effect on peroxidase inactivation rate except the 25% intensity radiation. In both treatments, the enzyme kinetics showed a first-order kinetics model with monophasic behaviour. The activation energy, the rate constants were estimated which proving that the enzyme became more heat labile. Therefore, thermosonication can affect a process with reduced processing time and increased efficiency.

Effect of heat and thermosonication treatments on peroxidase inactivation kinetics in watercress ( Nasturtium officinale)

The effect of heat and the combined heat/ultrasound (thermosonication) treatment on the inactivation kinetics of peroxidase in watercress ( Nasturtium officinale) was studied in the temperature range of 40–92.5 °C. In the heat blanching processes, the enzyme kinetics showed a first-order biphasic inactivation model. The activation energies and the rates of the reaction at a reference temperature for both the heat-labile and heat-resistant fractions were, respectively, E a1 = 421 ± 115 kJ mol −1 and E a2 = 352 ± 81 kJ mol −1, k 1 84 . 6 ° C = 18 ± 14 min - 1 and k 2 84 . 6 ° C = 0 . 24 ± 0 . 14 min - 1 . The initial relative specific activity for both isoenzyme fractions were also estimated, being C 01 = 0.5 ± 0.08 μmol min −1 mg protein −1 and C 02 = 0.5 ± 0.06 μmol min −1 mg protein −1, respectively. The application of thermosonication was studied to enable less severe thermal treatments and, therefore, improving the quality of the blanched product. In this treatment the enzyme kinetics showed a first-order model. The activation energy, the rate of reaction at a reference temperature and the initial relative specific activity were, respectively, E a3 = 496 ± 65 kJ mol −1, k 3 87 . 5 ° C = 10 ± 2 min - 1 and C 03 = 1 ± 0.05 μmol min −1 mg protein −1, proving that the enzyme became more heat labile. The present findings will help to design the blanching conditions for the production of a new and healthy frozen product, watercress ( Nasturtium officinale), with minimized colour or flavour changes along its shelf life.

Microwave Blanching of Vegetables

ABSTRACT: Three vegetables, spinach, carrot, and bell peppers were blanched conventionally in water and using pulsed microwave at 95 ± 2 C. The effect of various parameters like mass of the product, mobility of the product in the microwave field, and physical geometry on the temperature attained was evaluated. The study also included the kinetics of peroxidase inactivation, temperature, and power distribution during microwave blanching. The study highlights the potential application of microwave blanching in reducing the loss of valuable nutrients. The kinetics of peroxidase inactivation indicated that microwave blanching was comparable to water blanching with higher reaction rate in the case of water blanching. The temperature and absorbed power levels during microwave blanching was influenced by the vegetable itself, its quantity, shape, location in the oven, and the microwave power applied.

Thermal inactivation kinetics of peroxidase and lipoxygenase from fresh pinto beans ( Phaseolus vulgaris )

Thermal inactivation kinetics of crude peroxidase (POX) and lipoxygenase (LOX) in fresh pinto beans were studied over the temperature range of 55–90°C. The inactivation of both enzymes followed first-order kinetics. The biphasic inactivation curves for POX indicate the existence of several isoenzymes of varying heat stability. In the temperature range of 55–70°C, the activation energies (E a) of POX were 46.5 kcal·mol–1 for the heat-labile portion and 37.6 kcal·mol–1 for the heat-stable portion. On the other hand, the LOX enzyme had an E a value of 42.26 kcal·mol–1 at 55–75°C and 49.1 kcal·mol–1 at 55–90°C.

Regeneration and the kinetics of peroxidase inactivation

The objective of this work was to investigate why non-linear first-order kinetics of inactivation are observed when high-purity horseradish peroxidase (HRP) is heated under mildly acidic conditions. On heating HRP at 70 °C in acetate, pH 5.6, strong activity regeneration was found after short heating times whilst weak regeneration was observed after more extensive heating. This variation in regeneration is proposed as the major cause of the non-linear inactivation behaviour. Support for this proposal was the finding that simple first-order kinetics are followed when no regeneration occurred after heating the enzyme under neutral conditions. Using capillary electrophoresis, the major isoenzyme was shown to reform during activity regeneration. Under neutral conditions, new protein species were formed as a result of heating but these did not revert to the original isoenzyme on cooling.