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Antimicrobial Activity of Repurposed Citrus Peels Against Foodborne Bacteria and Sensor-Based Detection of Food Spoilage

CSEF · 2026 Microbiology (Senior Division)

Nandakishore Sukesh

Overview

Microbial spoilage drives food waste and landfill accumulation. In the US, one-third of food is wasted, with fruit peels comprising a substantial portion. Studies suggest that fruit peels contain polyphenols with bactericidal properties, highlighting their potential to inhibit foodborne bacteria and reduce spoilage. This study evaluated the antibacterial activity of orange (Citrus sinensis) and lemon (Citrus limon) peel extracts against Escherichia coli and Bacillus cereus and assessed whether these effects translate to delayed microbial spoilage in grapes and strawberries using sensor-based monitoring of headspace gases. Antibacterial activity was assessed using the Kirby–Bauer disk diffusion method on Mueller–Hinton agar inoculated with E. coli and B. cereus. Zones of inhibition (ZOI) were measured after 24 hours at 37 °C. Fruit spoilage was monitored over seven days using an Arduino-based BME680 sensor to measure headspace total volatile organic compound–related gas resistance (TVOC-GR) as an indicator of microbial metabolic activity. Peel extracts produced a clear ZOI against E. coli and B. cereus. Lemon peel extract demonstrated a larger ZOI than orange (p < 0.05). Mean ZOI for extracts exceeded 50% of gentamicin. In fruit trials, slower declines in TVOC-GR and lower spoilage indices were noted in extract-treated fruits. Lemon and orange peel extracts delayed spoilage by two days and one day, respectively, compared with untreated fruits. This study demonstrates that repurposed citrus peel extracts, particularly lemon, exhibit antimicrobial activity against foodborne bacteria and delay microbial spoilage in fruits, supporting their application as plant-derived antimicrobial agents for food preservation.

Competition history

  • CSEF 2026 Microbiology (Senior Division) · Entry S-16-04

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