Inactivation of Peach Polyphenoloxidase by Exposure to Pulsed Electric Fields

Abstract

The effect of exponential decay pulsed electric fields on peach (var. Miraflores) polyphenoloxidase (PPO) was evaluated. Electric field intensities ranged from 2.18 to 24.30 kV/cm. Pulses of 0.02 and 0.08 ms width were applied in mono-and bipolar mode. A 70% maximum reduction in enzymatic activity was achieved after 5 ms using 0.02 ms width pulses in bipolar mode at 24.30 kV/cm. Peach PPO activity decreased following an exponential decay kinetic model. Rate constants ranged from 9.0 to 138 ms -1 in monopolar mode, and from 8.7 to 235 ms -1 in bipolar mode. An exponential decay model may describe the relationship between residual PPO and input electric energy.

Effect of pulsed electrical fields on the structural properties that affect french fry texture during processing

“…While some researchers found a high level of inactivation (88%) on orange juice with E = 35 kV cm -1 for 5 µs (Yeom, Streaker, Zhang, & Min, 2000) and 93.8% on tomato at 24 kV cm -1 (Giner et al, 2002), others found very low levels of inactivation of 10% (1000 pulses of 1 µs at 1 or 2 Hz and field strength up to 35 kV cm -1 ) on PME extracted from fresh juice and dissolved in buffer solution; even an increase level of PME was found in the freshly squeezed juice (Van Loey, Verachtert, & Hendrickx, 2001). …”

Thermal inactivation of polyphenoloxidase and peroxidase in Jubileu clingstone peach and yeast isolated from its spoiled puree

“…In peaches, the activity of PPO and POD has long been known and has still been widely studied (Reyes & Luh, 1960;Flurkey & Jen, 1978;Alba et al, 1996;Girner et al, 2002). For Brazilian cultivars, although thermal inactivation of PPO and POD in Granada clingstone peaches (Toralles et al, 2005) and even the potential for enzymatic browning of some Brazilian peach cultivars (Toralles et al, 2004) are known, there is very little literature pertaining to the thermal inactivation of other peach cultivars.…”

Controle do escurecimento enzimático e da firmeza de polpa em pêssegos minimamente processados

“…Ciência Rural, v.41, n.6, jun, 2011. ao escurecimento enzimático, seja pela elevada concentração de compostos fenólicos e/ou atividade de enzimas oxidativas, com destaque para polifenoloxidases (PPO) e peroxidases (POD) (GIRNER et al, 2002).…”