When the nanoparticles (NPs) in food contact materials are exposed, they may be ingested with the food matrix, resulting in unknown impacts. Here, the biological response of the nanocomposites of nano zinc oxide (nZnO) and walnut protein‐derived peptides (i.e., PW5, WN5, AE6, and WE7) on the Lactobacillus rhamnosus LRa05 growth and adhesion was studied. In an in vitro mouse intestinal adhesion model, we first spotted that the probiotics LRa05 primarily adhered to and colonized the colonic segment. nZnO effectively inhibited the growth and adhesion properties of LRa05 at high concentrations (≥ 1000 μg/mL). Fortunately, when compared to the individual nZnO, the nZnO‐walnut‐derived peptides nanocomposites significantly increased the growth of LRa05. It was found that the alterations in the adhesion ability of LRa05 after treatment with various substances (nZnO and nanocomposites of nZnO‐walnut peptides) were related to the auto‐aggregating property on the LRa05 surface. These results shed light on the effect of food matrices on the safety of nanomaterials in food, and they may have far‐reaching implications for the use of nanomaterials in the food industry.

The interaction between zinc oxide nanoparticles (ZnO NPs) and whey protein (WP) was studied. The gastric epithelial cell line (GES‐1) was used to evaluate the toxicity intensity of ZnO NPs. The interaction mechanism of ZnO NPs and WP was studied by spectroscopic techniques. The results showed that the inhibitory effect of ZnO NPs on cells activity could be reduced when added to ZnO NPs at a concentration of 50 µg/ml. The fluorescence quenching mechanism of ZnO NPs on WP is a combination of dynamic and static quenching. The interaction force between ZnO NPs and WP can be considered as H‐bond and VdW force, and they have two binding sites. The interaction between WP and ZnO NPs leads to the loosening of the structural skeleton of WP and the extension of peptide chain, which exposes the tyrosine (Tyr) and tryptophan (Trp) hydrophobic groups in the hydrophobic region of protein molecules and reduces the hydrophobicity of the microenvironment. The ZnO NPs might form a complex with WP through H‐bond, hydrophobic interactions, and so on, leading to peptide chain rearrangement, and finally causing changes in the secondary structure of α‐helix. Practical ApplicationThis study provides a theoretical basis for future research on the interaction between food ingredients and nanomaterials, the evaluation of toxicity of nanomaterials and the application scope of nanomaterials in food field.

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