Durable superhydrophobic coatings for stainless-steel: An effective defense against Escherichia coli and Listeria fouling in the post-harvest environment

• Published in: Food research international 2023-11, Vol.173, p.113227-113227, Article 113227
• Main Authors: DeFlorio, William, Liu, Shuhao, Arcot, Yashwanth, Ulugun, Beril, Wang, Xunhao, Min, Younjin, Cisneros-Zevallos, Luis, Akbulut, Mustafa
• Format: Article
• Language: English
• Subjects: Bacterial contamination; Food safety; Food-contact surfaces; Leafy vegetables; Stainless-steel; Superhydrophobic
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2023.113227

[Display omitted] •Durable superhydrophobic nanodiamond based coating for stainless-steel.•Water contact angle of 156.3 ± 1.9° with 2.3 ± 0.5° contact angle hysteresis.•Surfaces characterized with SEM, AFM, and ATR-FTIR.•2.3 ± 0.6 log10 & 2.0 ± 0.9 log10 reductions in E. coli &L. innocua, respectively.•Resisted fouling from contaminated Romaine lettuce leaves. Increasing concerns revolve around bacterial cross-contamination of leafy green vegetables via food-contact surfaces. Given that stainless-steel is among the commonly used food-contact surfaces, this study reports a coating strategy enhancing its hygiene and microbiological safety through an antifouling approach via superhydrophobicity. The developed method involves growing a nickel-nanodiamond nanocomposite film on 304 stainless-steel via electroplating and sequential functionalization of the outer surface layer with nonpolar organosilane molecules via polydopamine moieties. The resultant superhydrophobic stainless-steel surfaces had a static water contact angle of 156.3 ± 1.9° with only 2.3 ± 0.5° contact angle hysteresis. Application of the coating to stainless-steel was demonstrated to yield 2.3 ± 0.6 log10 and 2.0 ± 0.9 log10 reductions in the number of adherent gram-negative Escherichia coli O157:H7 and gram-positive Listeria innocua cells, respectively. These population reductions were shown to be statistically significant (α = 0.05). Coated stainless-steel also resisted fouling when contacted with contaminated romaine lettuce leaves and maintained significant non-wetting character when abraded with sand or contacted with high concentration surfactant solutions. The incorporation of superhydrophobic stainless-steel surfaces into food processing equipment used for washing and packaging leafy green vegetables has the potential to mitigate the transmission of pathogenic bacteria within food production facilities.