Modelling the kinetics of peroxidase inactivation, colour and texture changes of pumpkin (Cucurbita maxima L.) during blanching

Abstract

The effects of blanching treatment on peroxidase inactivation, colour and texture of pumpkin (Cucurbita maxima L.) were studied in the temperature range of 75-95°C.Peroxidase inactivation followed a first-order Arrhenius model, where the activation energy and rate of the reaction at a reference temperature of 85°C were 86.20 ± 5.57 kJ mol À1 and 0.27 ± 0.01 min À1 , respectively.During blanching, pumpkin became darker and softer with processing time. The degradation of colour (evaluated throughout CIE L * a * b * colour system, with chroma index and total colour difference) and texture parameters (firmness and energy) showed a fractional conversion model kinetics, being the temperature effect on kinetic parameters well described by the Arrhenius law.The results of this work are a good tool to further optimise pumpkin blanching conditions.

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

“…According to obtained activation energy (Table 3), the observed rate reflects the loss of some functional group or the dissociation of the heme group in the case of peroxidase that need lower activation energy among other proposed processes such as protein unfolding, with a high activation energy Fortea et al 2009). Comparing the inactivation data measured and modeled in this work with relevant reported data, concerning inactivation of peroxidase of different sources, seedless guava peroxidase appears to be more resistant compared to peroxidase obtained from pumpkin (E a were found equal to 96.39 and 86.20 kJ mol −1 , respectively) but more sensitive compared to butternut squash peroxidase (E a were found equal to 96.39 and 149.9 kJ mol −1 , respectively) (Gonçalves et al 2007;Agüero et al 2008).…”

“…Hence, the observed kinetics would correspond to the Table 3 Reaction rate constants and decimal reduction times of peroxidase inactivation in seedless guava by thermal inactivation All measurements were replicated at least three times k rate constants for thermal inactivation of seedless guava peroxidase, E a activation energy of seedless guava peroxidase inactivation inactivation of the heat-resistant fraction of peroxidase Soysal and Soylemez 2005). This result is in accordance with those obtained for peroxidase from pepper (Serrano-Martínez et al 2008), potato or carrot , carrots, potatoes, tomato, green beans, green asparagus, and pumpkin (Soysal and Soylemez 2005;Ganthavorn et al 1991;Gonçalves et al 2007). From the slopes of these lines, the inactivation rate constants (k) were calculated.…”

“…(Williams et al 1986). The presence of residual peroxidase in processed products cause quality changes such as in texture, color, flavor, and nutritional components (Gonçalves et al 2007;Martins and Silva 2002).…”

Effect of different cooking methods on structure and quality of industrially frozen carrots

“…The other 5 kg were washed, peeled, sliced and processed in an industrial plant within 24 h from harvesting. Then, they were blanched by immersion in a hot water bath (100°C) for 2 min 30 s to reach the peroxidase inactivation (Goncąlves et al 2007) and frozen in an ammonia forced air cooling tunnel at − 40°C for 6 min. Frozen samples were then maintained for two months at −18°C in a thermostat to mimic the common storage conditions prior to the commercialization.…”

Kinetics of tomato peroxidase inactivation by atmospheric pressure cold plasma based on dielectric barrier discharge

“…POD being one of the most heat stable enzymes is conventionally used as a marker to monitor and evaluate the extent of heat treatment (Gonçalves, Pinheiro, Abreu, Brandão, & Silva, 2007;Williams, Lim, Chen, Pangborn, & Whitaker, 1986). The specific aims of this work were (i) to evaluate the effects of atmospheric pressure DBD based cold plasma process variables upon activity of tomato peroxidase and (ii) model the kinetics of enzyme activity.…”