Microbial inactivation kinetics in orange juice processed by novel technologies

GARCIA-CARRERA, N.; PALOU, E.; GUERRERO, S N; ALZAMORA, STELLA MARIS; LOPEZ-MALO, A.

Orlando, USA

Congreso; 2006 IFT Annual Meeting; 2006

IFT

The application of emerging technologies for food preservation has increased as an alternative to traditional thermal processing to supply safe food with high quality. Evaluate and model the survival of native flora (standard plate and yeast and mold counts) in orange juice (pH 3.6; 12 brix) processed by two non-thermal techniques: short wave ultraviolet radiation (UV-C) and high intensity ultrasound (US) applied individually or combined. U.S. treatments (20 kHz, 108 µm -wave amplitude) were performed by introducing a 25 mm probe in a jacketed 600mL-vessel at 35ºC containing juice. The UV-C device consisted of a 90 cm long glass tube fixed vertically with a 70 cm long UV-C-lamp (30 W, 254nm, low pressure) inside the tube. Orange juice was pumped through the UV-C chamber using a peristaltic pump adjusted to 6mL/s flow rate. Treated liquid was recirculated from a 500mL-vessel at 35ºC. The juice microbial populations were monitored by plate counting and spiral plate techniques during the treatments. UV-C treatment was effective in suppressing microbial native flora in orange juice reaching 2-log reduction in about 5-10 minutes. US was less effective, and its action was highly dependent on the considered microorganism. The use of UV-C light combined with high intensity ultrasound was effective for enhancing individual microbial inactivation effects in orange juice. Weibull type distribution model was useful explaining observed differences between treatments and/or microorganisms. The use of the combined treatment led to a great inactivation with the majority of the population done in the first minutes of treatment. Extensive further work on applications of these techniques in food would be required before making them more generally accepted.