Suppressing of milk-borne pathogenic using new water-soluble chitosan-azidopropanoic acid conjugate: Targeting milk-preservation quality improvement

Dairy animals are major reservoirs for many milk-borne pathogens (MBPs) such as Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli O157:H7). Thus, dairy industries dedicate most of their processes to eliminate or minimize microbial contamination. Although pasteurization may offer an ideal solution for microbial decontamination; nevertheless, it may negatively impact organoleptic and nutritive values of dairy products. In this context, this work aimed to develop an innovative strategy, to tackle this challenge, based on the chemical preservation of milk. In this endeavor, we have succeeded to design a new safe multifunctional bio-preservative based on natural antimicrobials (water-soluble chitosan (WSC) and 2-azidopropanoic acid (APA), (WSC-APA) conjugate). Interestingly, the minimum inhibitory concentrations (MICs) of WSC-APA have the capacity to completely suppress the proliferation of E. coli O157:H7 and S. aureus cells (100% bacterial reduction) in refrigerated milk samples during 20 and 24 h, respectively. Moreover, no Staphylococci species could be detected in refrigerated milk samples remediated with WSC-APA (0.25 mg/mL) after 6 storage days. Meanwhile, the coliform count has reduced by 99.7% in conjugate-treated milk samples during 10 storage days. Thus, new bio-preservative (WSA-APA) can be safely used to increase the shelf-life of milk without sacrificing its organoleptic and nutritive values.