## 2 Materials and Methods
### Pilot-Scale Pulsed Light Operation  
A continuous thin-profile pilot-scale PL equipment (Solaris Disinfection Inc., Mississauga, ON, Canada) fitted with a coiled tube (CT) reactor, described earlier by [PERSON] and [PERSON] [17], was set up and used in the laboratory darkroom of the Food Process Engineering Lab at the University of British Columbia for PL treatment (Figure 1a). The PL lamp was 8 mm in diameter and 62 cm in length, supplying polychromatic light from 200 to 1100 nm wavelengths at 2.0 kV. The flash rate was maintained at 3 Hz. The distance between the lamp and the coil chamber was maintained at 5.9 cm, including the filter placed below the coil chamber. The CT reactor was made of quartz due to its high optical transmittivity for a broad range of wavelengths. The CT reactor was 56.3 cm in length, with a 0.95 mm wall thickness, 0.9 cm inner tube diameter, 1.19 cm outer tube diameter, 26.2 mm inner coil diameter, 48.5 mm outer coil diameter, 38 mm helical diameter, and 49 turns. The minimum sample volume required was 300 mL to simulate a controlled, continuous process. The flash rate, treatment time, and treatment initiation were controlled via a wired controller located outside the darkroom supplied by Solaris Disinfection Inc. A Masterflex L/S Economy Variable-Speed Drive (Masterflex, Quebec, QC, Canada) unidirectional peristaltic fluid pump was used to pump samples from the input tank through the coil chamber at different speeds. The intake tube was submerged into a slightly slanted input tank. A customized stainless-steel parabolic metal cover was fabricated (False Creek Fabrication, Vancouver, BC, Canada) and placed over the coil chamber. The cover's interior wall was made shiny to reflect the pulsed light to the top of the coil chamber. The cover had holes on two sides to allow the input and output tubes through. Due to the tubing's transparency outside of the coil chamber, they were all covered with aluminum foil to avoid uncontrolled light exposure as the fluid traveled.  
In this study, 3 mm-thick transparent and bronze-tinted PSS (POLYSHINE, Shanghai Pincheng Plastics Co., Ltd., Shanghai, China) were used as clear and bronze-tinted filters, respectively. The solid sheets were cut to 30 inches in length and 6 inches in width, then placed above the PL frame. The chamber coil was rested on top of the filter. The clear filter allowed approximately 90% light transmission at 400-1100 nm wavelengths while limiting UV transmission at wavelengths below 400 nm (Figure 1b). The bronze-tinted filter allowed visible and NIR wavelength transmissions at lower levels than the clear filter while limiting UV wavelength transmissions similarly to that of the clear filter. Before treatment, the filters were sprayed with 70% ethanol solution and wiped with Kimwipes to remove dust and other debris. The fluence per flash received by the coil chamber with no filter, the clear filter, and the bronze-tinted filter were 18.61 \(\pm\) 0.39, 9.92 \(\pm\) 0.27, and 1.47 \(\pm\) 0.12 mJ/cm\({}^{2}\), respectively. The transmission through the filters, as well as the fluence through the reactors, was measured using a 1 cm\({}^{2}\) aperture polyelectric head sensor (PE80 BF-DIF-C, Ophir-Spiricon LLC, North Logan, UT, USA) with a Nova II display (OphirSpiricon LLC, North Logan, UT, USA) at the proximal end of the reactor, as described by [PERSON] and [PERSON] [17].