Relationship between optical properties of beverages and microbial inactivation by intense pulsed light

• We observed the efficacy of IPL as a sterilization treatment for various liquids.
• Transmittance and extinction coefficient decisively affected on the sterilization effect.
• Microbial reduction increased exponentially as the extinction coefficient gets lower.

This study determined the inactivation effects of the intense pulsed light (IPL) on Pseudomonas aeruginosa in various liquid foods and elucidated the relationship between microbial reduction and the optical properties of twelve liquid foods. In mineral water and isotonic beverage, 7.0 log reductions of P. aeruginosa were obtained with the IPL treatment at total fluence of 0.97 J/cm2. At 12.17–24.35 J/cm2, 7.0 log reductions were shown in five liquid samples (apple juice, carbonated beverages and plum juice), while only 0.5- to 2.0-log reductions were shown in the rest samples even after 29.21 J/cm2 total fluence of the IPL treatment. High value of transmittance and low value of extinction coefficient have a decisive effect on the microbial inactivation because it allows the intensity of the IPL to be preserved as it penetrates into the sample. The best-fit regression kinetic which can explain the relationship between extinction coefficient and bactericidal effect was an exponential function.Industrial relevanceIntense pulsed light (IPL) is one of the nonthermal processing technologies for ensuring safe foods with satisfactory qualities. Through this study, transparent liquids showed a high microbial reduction level after IPL treatment in a short time. So it can be concluded that IPL has a potential as an excellent alternative or complement to conventional thermal processing of transparent liquids. Also, inactivation kinetic equation deducted from this study can be used to predict the microbial reduction level of specific liquid before IPL treatment by using its extinction coefficient.