Inactivation kinetics of food enzymes during ohmic heating

Jakób, Alina; Bryjak, Jolanta; Wójtowicz, Halina; Illeová, Viera; Annus, J.; Polakovič, Milan

doi:10.1016/j.foodchem.2010.04.047

Cited by 97 publications

(37 citation statements)

References 23 publications

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“…The rate of heat generation within the tomato samples depended on voltage gradient and electrical conductivity which varied during the heating and evaporation processes of the sample. This observation of voltage gradient and electrical conductivity effect on the heating rate of tomato samples is in good agreement with the findings of Assiry et al (2010b) and Jakob et al (2010).…”

Section: Resultssupporting

confidence: 93%

The process of producing tomato paste by ohmic heating method

et al. 2014

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In this study, the effect of ohmic heating technique on electrical conductivity, water evaporation rate, heating rate, colour parameters, pH and energy consumption of tomato samples was investigated. Ohmic heating was accomplished till the moisture content of the tomato samples reduced from initial moisture content of as 9.33 (dry basis) to a safer level of 2.2. The results of the nonlinear mathematical model including the effects of voltage gradient level and the temperature on the electrical conductivity changes had good agreement (R≥ 0.955) with the experimental data. Also, it was observed that the electrical conductivity increased along with concentration of tomato samples. The range of electrical conductivity during ohmic heating was 3.19-8.95 (S/m). It was found that processing time decreased from 28.32 to 4.3 min over the voltage gradient range studied (6 to 14 V/cm), which resulted in decreased specific energy consumption from 4.63 to 3.05 (MJ/kg water). Due to increasing of heating rate and water evaporation rate at high voltage gradient, the change of the pH was limited. Samples processed in high voltage gradient had higher L*, b* and hue angle (h), lower a* and Chroma (C) values as compared to low voltage gradient. The optimum value of processing time, pH, colour, specific energy consumption was obtained at 14 V/cm voltage gradient level.

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Section: Resultssupporting

confidence: 93%

The process of producing tomato paste by ohmic heating method

et al. 2014

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“…This variation in the rate of PPO inactivation may be due to different composition of the food materials analysed (Queiroz et al, ). Jakob, Bryjak, Wójtowicz, Illeová, Annus, and Polakovic () and Icier, Yildiz, and Baysal () had also reported ohmic heating as a more efficient method for enzyme inactivation in food materials as compared to hot water or the conventional method of thermal treatment. In the present study the slight increase in PPO activity during OH treatment at 30–45 sec was observed, Icer et al (2008) also reported such findings and explained the reason for such behavior due to the change of conformation of the enzyme due to which higher enzyme–substrate interaction and consequently to an optimal consumption of the substrate occurs.…”

Section: Resultsmentioning

confidence: 99%

Ohmic heating assisted polyphenol oxidase inactivation of watermelon juice: Effects of the treatment on pH, lycopene, total phenolic content, and color of the juice

Makroo

Saxena

Rastogi

et al. 2017

J Food Process Preserv

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Fresh watermelon juice was treated at 90 °C by hot‐water (HW) and ohmic (OH) treatment (with SS:316 electrodes) for 15, 30, 45 and 60 sec. PPO activity was reduced to 36.15 and 8.87% in 60 sec by HW and OH treatment respectively. The PPO inactivation was fitted to the first order model; the reaction constant (k), D90 obtained was 0.02 s−1, 115.1 sec, and 0.062 s−1, 37.1 sec for HW and OH treatment respectively. During both the treatments of watermelon juice total phenols (TPC) showed significant change whereas no significant change was observed in lycopene content. Total change in color (ΔE) during OH treatment was found lesser as compared to HW treatment, hue angle was found to increase at a higher rate in HW than that of OH treatment. Finally it was concluded that PPO of water melon juice can be inactivated rapidly by OH than HW treatment. Practical applications Enzymatic browning and lycopene degradation are the major factors that limit the storage of watermelon juice. High temperatures and processing times employed during thermal processing cause deleterious changes in the color, flavor, and sensory aspects of the product. Therefore, this study was conducted to investigate the comparative effect of ohmic and conventional heating on inactivation of PPO as well as quality changes in watermelon juice so as to suggest a time‐efficient alternative that can be explored further for commercial packaging.

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“…Instant high volume heating occurs and gives a uniform temperature distribution, especially for liquid foods with high electrical conductivity (Demirdoven, et al, 2014;Goullieux & Pain, 2014;Icier, Yildiz, & Baysal, 2008;Jakób, Bryjak, Wójtowicz, Illeová, Annus, & Polakovic, 2010).…”

Section: Accepted M Manuscriptmentioning

confidence: 99%