Impact of combined nano natural antimicrobials and pulsed electric field on pineapple juice preservation

Abstract

This study evaluates the synergistic use of pulsed electric field (PEF) treatment and nano-formulated natural antimicrobials derived from agricultural waste for microbial inactivation in fresh pineapple juice. Subcritical ethanol extraction at 180 °C yielded the highest xanthone content from mangosteen peel, consistent with recent studies showing that subcritical solvents enhance solubility and stability of bioactive compounds under elevated temperature and pressure. Among tested natural antimicrobials, mangosteen peel extract, steam-distilled bergamot oil, and hydrolyzed coconut oil—bergamot oil exhibited the strongest antimicrobial activity, achieving up to 100% inhibition against Escherichia coli, S. aureus, and S. cerevisiae at 5% concentration. PEF treatment at 40 kV/cm with 500 pulses achieved a 2.2-log reduction in S. cerevisiae counts, a parameter set comparable to other reported non-thermal juice preservation studies. When combined with nano-formulated antimicrobials, yeast inactivation improved significantly, reaching up to 4.5-log reduction. Shelf-life studies demonstrated that combined PEF and antimicrobial treatment delayed microbial regrowth in pineapple juice for at least 16 days at +9.5 °C. These outcomes compare favorably with prior PEF–antimicrobial approaches in other fruit juices, highlighting the broader potential of this strategy. Overall, this study demonstrates a promising, non-thermal preservation method that integrates sustainable bioactive compounds with scalable processing technology to improve microbial safety while maintaining product quality.