UV-C treatment of soymilk in coiled tube UV reactors for inactivation of Escherichia coli W1485 and Bacillus cereus endospores

Abstract

Coiled tube UV reactors were used to investigate the influence of tube diameter (1.6 mm ID, and 3.2 mm ID) and Reynolds number (Re) to inactivate Escherichia coli W1485 and Bacillus cereus spores in raw soymilk (RSM). Four levels of Re (343, 686, 1029 and 1372) were tested in RSM inoculated separately with each bacterium and treated in the UV reactors at a constant residence time of 11.3 s with UV-C dose of 11.187 mJ/cm 2 at 253.7 nm. Inactivation efficiency of both microorganisms increased with Re. Maximum reductions of 5.6 log10 CFU/ml of E. coli and 3.29 log10 CFU/ml of B. cereus spores were achieved in the 1.6 mm ID UV reactor. Inactivation efficiency was higher in the 1.6 mm ID UV reactor than the 3.2 mm ID UV reactor for both the organisms. Effect of UV-C light on lipid oxidation of untreated RSM, measured as malondialdehyde and other reactive substances (MORS) content, was much higher (95 nmol/ml) than the UV-treated (58 nmol/ml) and thermally pasteurized (55 nmol/ml) RSM during the storage period of 7 days. The UV-C treatment can be effectively used for reducing E. coli cells and B. cereus spores in soymilk without compromising its quality.

Bacillus cereus un patógeno importante en el control microbiológico de los alimentos

“…Entre los métodos físicos utilizados para la inactivación de esporas de B. cereus, se ha reportado el tratamiento de leche de soya con radiación UV-C [90]. Además, se comparó el tratamiento térmico con la radiación con un haz de electrones, observándose que este último fue más efectivo para inactivar células vegetativas y esporas de B. cereus [91].…”

Efficacy of Ultraviolet Radiation as Non-thermal Treatment for the Inactivation of Salmonella Typhimurium TISTR 292 in Pineapple Fruit Juice

“…This process would create the mixing effect and extra resident time in order for the pineapple juice to pasteurize (Muller, et al, 2011). The UV reactor was wrapped with aluminum foil for safety measured (Bandla et al, 2012). The frequency of the pump was set to 30, 35 and 40 Hz to adjust the flow rate of the juice.…”

“…The UV-C dose was calculated using Eq. (3) (Chia et al, 2012;Bandla et al, 2012) by multiplying the residence time with the irradiance intensity at pineapple juice surface, that was measured using UV radiometer (UVX Radiometer, UVP Company, US).…”

“…Fluid turbulence is one of the factors influencing the efficiency of UV light disinfection (Koutchma et al, 2004;Bandla et al, 2012). The turbulent flow of the juice will increase the inactivation of microorganisms in fruit juices.…”

Effects of Physicochemical Characteristics of Pummelo Fruit Juice towards UV Inactivation of Salmonella Typhimurium

“…Several literatures have been published on Dean flow UV reactor (Feng et al, 2013;Bandla et al, 2012;Choudhary et al, 2011;Muller et al, 2011;Franz et al, 2009;Ghaly and Singh, 2007) with various configurations and samples. However, only Muller et al (2011) reported the effect of absorptive and physicochemical properties of naturally cloudy apple juice, blood orange juice and elderberry nectar on the inactivation of pertinent microorganisms utilizing a UVivatec Lab System (Bayer Technology Services GmbH, Germany).…”