There is a need for effective postharvest controls capable of inactivating bacterial foodborne pathogens, which can be applied to the organic and conventional apple industries. This study evaluated the efficacy of natural antimicrobials (essential oils or cultured dextrose) when incorporated into carnauba wax and applied to apples. Organic Gala apples were spot inoculated with a five strains/serovars cocktail (∼9 Log CFU/mL) of Listeria monocytogenes, Shiga-toxigenic E. coli O157:H7, or Salmonella. Inoculated apples were coated with organic carnauba wax containing a 1% and 2% (v/v) mixture of essential oils (EOs) in equal proportions (oregano, clove bud, cinnamon bark, and coriander seed) or commercially cultured dextrose at 0.5% (w/v). Apples coated with carnauba wax only and uncoated apples were used as control treatments. Apples were stored at 20 °C and sampled for up to 40 days. Five treatments with three biological replicates and three samples per replicate were used for each treatment (n = 9). A sensory discrimination test was used to identify differences between waxed apples for treatments with the greatest efficacy. Carnauba wax containing 2% EOs was the most effective treatment for inactivating target foodborne pathogens inoculated on apples for 40 days. This treatment showed 4.05, 1.38 and 2.81 Log CFU/apple reduction in L. monocytogenes, E. coli O157:H7, and Salmonella, respectively, compared to uncoated apples. Carnauba wax containing 2% EOs showed significantly (P ≤ 0.001) lower populations of L. monocytogenes and Salmonella compared with 1% EOs, 0.5% cultured dextrose, or wax-only control. In contrast, there were no significant differences (P > 0.05) for E. coli O157:H7. Sensory evaluation showed that panelists could detect differences for apples treated with wax containing 2% EOs, but not for 1% EOs compared to wax-only control. This study provides information to the organic and conventional apple industry about the efficacy of antimicrobial waxes to inactivate bacterial foodborne pathogens.

Biofouling presents significant challenges to the crop production industry, notably reducing irrigation efficiency and potentially dispersing pathogens to irrigated crops. This study evaluated the efficacy of peracetic acid (PAA) and chlorine (Cl) against Salmonella biofilms in irrigation lines with or without fertilizers. Pond water (PW) with 2-4-1 fish emulsion (O), PW with 4-0-8 synthetic liquid fertilizer (S), or PW with no fertilizer (NoFert) was inoculated with 2 log CFU/mL of a rifampicin-resistant Salmonella cocktail. Inoculated water was then circulated through polyethylene loop irrigation system for a month. Salmonella populations both in the water and attached to the tubing were determined. Data showed that a single point of contamination from the water resulted in a biofilm formation with O and NoFert, but not the S treatments, after 3 days. Both PAA and Cl effectively reduced Salmonella populations for all fertilizer treatments in water samples. However, when no sanitizer was introduced to the line, bacterial dispersion resulted in the contamination of a subsequent irrigation event for the O treatments but not the S and NoFert treatments, which presented no microbial proliferation. Our findings suggest that O treatments resulted in persistent biofilm formation that could lead to contamination of irrigation water when no sanitizers are introduced. These studies provide insight into the behavior of foodborne pathogens in irrigation distribution systems. IMPORTANCE: The accumulation of bacteria in water distribution systems due to biofouling can lead to contamination, making it crucial to evaluate and implement effective mitigation measures to prevent these issues and ensure safe and efficient irrigation practices. The use of the 2-4-1 fish emulsion in-line may support the establishment of Salmonella biofilms and subsequent cross-contamination of irrigation water if not fully flushed from the system. This study demonstrates that PAA and Cl effectively reduce Salmonella contamination in water but will not eliminate populations in-line once biofilms are established.

D’Anjou pears are routinely stored for up to nine months under controlled-atmosphere (CA) conditions to meet market demands. While this practice maintains fruit quality, limited information exists on pears’ natural microbiota throughout storage. The objective of this study was to describe fungal and bacterial composition on marketable and unmarketable conventional, whole, intact pears under two storage practices (bulk vs wrapped) at 3, 6, and 9 months in long-term CA cold storage. Storage practices had a significant effect on the composition and succession of both fungal and bacterial communities. No significant differences in Chao1 index were found between the bacterial and fungal communities on marketable or unmarketable pears. Trends in Chao1 indices of fungal and bacterial communities peaked at mid-storage and declined by 9 months, with wrapped pears showing parallel trends, and bulk pears exhibiting a sharper late-stage reduction. No distinct clusters could be found for 3- and 6-month fungal communities, irrespective of marketability, or whether bulk or wrapped. The principal coordinate analysis of the bacterial communities showed tight clustering by time point for the individually wrapped pears, irrespective of their marketability. Bacterial communities included genera common in food-processing and plant environments, such as Pseudomonas (19.2% relative abundance [RA]) and Acinetobacter (3.31% RA). Fungal communities shifted over time, with spoilage-associated genera like Aureobasidium (23.3% RA), Penicillium (9.28% RA), Botrytis (0.33% RA), and Mucor (0.14% RA) present at different storage stages. IMPORTANCE: This study highlights the influence of storage duration and packaging on microbial succession, establishing initial benchmarks of pear surface microbiomes. The observed lack of significant differences in microbial diversity between marketable and unmarketable pears suggests that these baseline community profiles can serve as critical reference points for identifying other influential factors. Variables such as handling practices may exert a more direct effect on microbial dynamics and, consequently, product quality. Establishing these baselines is essential because they provide a foundation for detecting deviations linked to spoilage or safety risks. Moreover, understanding these patterns can guide the development of targeted microbial control strategies in postharvest systems, enabling interventions that maintain fruit quality, reduce losses, and possibly improve food safety throughout the supply chain.

D’Anjou pears are routinely stored for up to nine months under controlled atmosphere (CA) conditions to meet market demands. While this practice maintains fruit quality, limited information exists on pears’ natural microbiota throughout storage. The objective of this study was to describe fungal and bacterial composition on marketable and unmarketable conventional, whole, intact pears under two storage practices (bulk vs wrapped) at 3, 6, and 9 months in long-term CA cold storage. Storage practices had a significant effect on the composition and succession of both fungal and bacterial communities. Overall, fungal communities exhibited lower estimated Chao1 alpha diversity (mean 18.3) compared to bacterial communities (mean 166.4). No significant differences in Chao1 index were found between the bacterial and fungal communities on marketable or unmarketable pears. Trends in Chao1 indices of fungal and bacterial communities peaked at mid-storage and declined by 9 months, with wrapped pears showing parallel trends and bulk pears exhibiting a sharper late-stage reduction. No distinct clusters could be found for 3- and 6-month fungal communities, irrespective of marketability or being bulk or wrapped. The principal coordinate analysis of the bacterial communities showed tight clustering by time point for the individually wrapped pears, irrespective of their marketability. Bacterial communities included genera common in food-processing and plant environments, such as Pseudomonas and Acinetobacter . Fungal communities shifted over time, with spoilage-associated genera like Aureobasidium , Penicillium , Botrytis , and Mucor present at different storage stages. Significance: This study highlights the influence of storage duration and packaging on microbial succession, establishing initial benchmarks of pear surface microbiomes. The observed lack of significant differences in microbial diversity between marketable and unmarketable pears suggests that these baseline community profiles can serve as critical reference points for identifying other influential factors. Variables such as handling practices may exert a more direct effect on microbial dynamics and, consequently, product quality. Establishing these baselines is essential because they provide a foundation for detecting deviations linked to spoilage or safety risks. Moreover, understanding these patterns can guide the development of targeted microbial control strategies in postharvest systems, enabling interventions that maintain fruit quality, reduce losses, and improve food safety throughout the supply chain.