UV-activated diacetyl for bacterial inactivation and browning inhibition in apple juice

Microbial contamination and enzymatic browning remain key challenges in apple juice processing. This study introduces ultraviolet-activated diacetyl (UV/BD) as a non-thermal intervention that simultaneously ensures microbial safety and quality retention. Treatment with 0.5 mM BD and 1.5 kJ/m² UV reduced native bacterial counts below detection limits and suppressed browning by 32.9% through two synergistic mechanisms: photolytically generated peroxyacetyl radicals selectively oxidize polyphenol oxidase, while oxygen-deprivation resulting from BD photooxidation halts quinone formation and starves peroxidase by inhibiting H₂O₂ generation. The primary BD photolysis product, acetic acid, ensures no harmful residues and no off-flavors detected at the applied concentration. Comprehensive acute and subacute murine toxicity studies confirmed clinical safety, with no mortality, hematological deviations, or histopathological alterations observed. This technology offers immediate scalability via existing UV infrastructure, bridging the critical gap between safety, quality, and sustainability in juice processing.