Inactivation kinetics of peroxidase and polyphenoloxidase in peach juice treated with ozone

JARAMILLO-SANCHEZ, GABRIELA; GARCIA-LOREDO, ANALÍA; GÓMEZ, PAULA; ALZAMORA, STELLA M.

New Orleans

Congreso; Institute of Food Technologists 2014 annual meeting; 2014

Institute of Food Technologists

Thermal treatments, traditionally used to inactive microorganisms and deteriorative enzymes in fruit juices, provoke a negative impact on nutritional, functional and sensory properties. Therefore, the exploration of new preservation factors that cause minimal changes in food quality attributes is needed. Ozone is an emerging agent that is being studied as an alternative to conventional processes. The aims of this work were to evaluate the efficacy of ozone on the inactivation of endogenous peroxidase (POD) and polyphenoloxidase (PPO) in peach juice and analyze the suitability of different models to characterize the enzymes inactivation kinetics. Peach juice samples (pH = 3.7; 11.7 ºBrix) were treated with gaseous ozone (oxygen flow rate: 5 L/min; 20 ºC) at different concentrations (10 and 18 ppm) and treatment times (0-12 min). Experiments were performed in triplicate. Inactivation curves were modeled by first-order, first-order fractional conversion and Weibull models. POD and PPO activities in juice samples were reduced due to ozonation, and the magnitude of the inactivation depended markedly on ozone concentration and treatment time. Higher inactivation rates were attained when samples were exposed to the highest ozone concentration (18 ppm). Maximum activity reductions 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. In general, the inactivation curves obtained from experimental data showed a slight downward concavity, except for PPO inactivation curve of samples treated with the highest ozone concentration, which presented upward concavity. Among the models assessed to describe inactivation kinetics, Weibull model allowed the best fit and more accurate estimation of parameters. This study provides useful information on the applicability of ozone to inactivate deteriorative enzymes in peach juice.