Salmonella Typhimurium (S. Typhi) and Escherichia coli (E. coli) have been responsible for an increasing number of outbreaks linked to fresh produce, such as baby spinach leaves, in the last two decades. More recently, antimicrobial biodegradable packaging systems have been attracting much attention in the food packaging industry as eco-friendly alternatives to conventional plastic packaging. The objective of this study was to evaluate the effect of antibacterial nanocomposite films on inoculated spinach leaves and on the sensory properties of these leaves during eight days of refrigerated storage. In this study, an antibacterial film comprised of sweet potato starch (SPS), montmorillonite (MMT) nanoclays and thyme essential oil (TEO) as a natural antimicrobial agent was developed. Our results showed that the incorporation of TEO in the film significantly (p < 0.05) reduced the population of E. coli and S. Typhi on fresh baby spinach leaves to below detectable levels within five days, whereas the control samples without essential oil maintained approximately 4.5 Log colony forming unit (CFU)/g. The sensory scores for spinach samples wrapped in films containing TEO were higher than those of the control. This study thus suggests that TEO has the potential to be directly incorporated into a SPS film to prepare antimicrobial nanocomposite films for food packaging applications.

The primary objective of this study is to develop and characterize a novel active biodegradable nanocomposite film using sweet potato starch (SPS) for food packaging. Montmorillonite (MMT) nanoclay at a constant weight of 3% and thyme essential oil (TEO) at three levels (2%, 4%, and 6% v/v) are incorporated into SPS film. The results show that incorporating MMT and TEO into SPS film greatly enhanced (P < 0.05) water resistance by 50%. MMT incorporation also hinders the degradation rate of the film. Furthermore, the combined effect of MMT and TEO (up to 4%) improve tensile strength, elongation, and tristimulus color values (P < 0.05). Fourier transform infrared (FT‐IR) spectroscopy and X‐ray diffraction (XRD) results confirm that the noted improvements are related to MMT exfoliation and good interaction between SPS and MMT in the presence of TEO. These results suggest that SPS may provide a viable solution to the waste disposal of plastic packaging materials used for food products.

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