Inactivation of B. cereus spores in whole milk and almond milk by serpentine path coiled tube UV-C system: Numerical simulation of flow field, lipid peroxidation and volatiles analysis

Abstract

A novel continuous thin-film (1.59 mm) serpentine path coiled tube (SPCT) UV system operating at 254 nm wavelength was designed and compared with flow field distribution of whole milk with helical path coiled tube (HPCT) UV system using computational fluid dynamics. The results revealed efficient velocity magnitude distribution at serpentine bend geometric locations of the SPCT UV system. Further in this study, we evaluatedBacillus cereusSpores inactivation in whole milk (WM) and almond milk (AM) using the developed SPCT UV system. Experimental data showed that > 4 log reduction of spores was achieved after six and ten passes of WM and AM at a flow rate of 70 and 162 mL/min, respectively. The bio-dosimetry method was used to verify the delivered reduction equivalent fluence (REF) and reported as 33 ± 0.73 and 36.5 ± 1.9 mJ/cm2. We noticed no significant effect on lipid oxidation and volatiles profile (p > 0.05) up to delivered REF of 60 mJ/cm2. This study demonstrated that high levels of inactivation ofB. cereusspores could be feasible with minimal impact on product quality by UV-C processing of dairy and non-dairy opaque scattering fluids.