Antimicrobial activity of orange juice processing waste in powder form and its suitability to produce antimicrobial packaging

Abstract

Orange peel essential oil is a common value-added product from orange juice processing waste. It is antimicrobial and used to produce antimicrobial films and coatings. This study reports the first development of antimicrobial films using orange peel as powder (OPP) instead of the extracted essential oil. The OPP amount needed for antimicrobial films was determined by studying the OPP effects on conidia germination inhibition (minimum inhibitory concentration (MIC)) and mycelial growth reduction for Botrytis cinerea, Aspergillus niger, and Penicillium sp. This amount was incorporated into linear low-density polyethylene using plastic processing machinery. The resulting LLDPE/OPP composite film was characterized for antimicrobial activity against Botrytis cinerea, antimicrobial compound release, and mechanical, barrier, and optical properties. We found the same OPP MIC (8.4 mg OPP/mL air) for the three fungi although their mycelial growth kinetics and conidia germination inhibition periods varied with OPP amount differently. 21.1 mg OPP/mL air completely inhibited the germination of Penicillium sp., B. cinerea, and A. niger conidia for 3, 2, and 1 days. The antimicrobial film was a LLDPE/OPP composite with 46% plastic replacement that reduced B. cinerea growth by 30% over a 7-day storage period at 23 °C, less than OPP due to limonene/citral reduction during processing. Plastic replacement resulted in films with the barrier and mechanical properties of plastics commonly used in food packaging. This study demonstrates the OPP antimicrobial capacity against food spoilage microorganisms and its suitability to produce antimicrobial packaging for food applications and presents a novel approach to utilizing orange juice processing waste.