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Background Pathogenic bacteria contamination has been a global health challenge in the food industry. In this context, ultrasound technique is attracting much more attention as an alternative non-thermal processing method to inactivate pathogens. Compared with traditional thermal process, Ultrasonic Sterilization technology can reduce energy consumption, maintain nutritional content and cause less damage to overall foods quality. Despite ultrasonic sterilization (US) has been proved effective both for its individual and synergistic effect with other antibacterial agents and strategies, but still a knowledge gap exits there in the regulation mechanism of ultrasonic treatment on microorganism physiology that contributes to its application. Scope and approach Recently, increasing numbers of efficient sterilization strategies based on ultrasound technique have been presented, and the ultrasound-driven cavitation effect has become a promising research direction of US, which can cause a chain of physical and chemical damage to bacterial cells. Therefore, this review mainly discusses the antibacterial effects of US based on its acoustic cavitation combing with mechanical vibration and acoustic streaming, and summarizes the potential antibacterial mechanisms from three fields: sonoporation, sonochemistry and sonoluminescence. Key findings and conclusions The mechanical stress on bacterial cells, formation of radicals and activation of sonosensitizers induced by acoustic cavitation have been proved as major antibacterial mechanisms in different application strategies of ultrasound to inactivate bacteria, respectively. The information in this review provides the necessary theoretical basis for extending the antibacterial application of ultrasound technique in food processing.

The aim of this study is to develop a flame-retardant viscose fiber using the phosphazene derivative of a natural polymer. Hexachlorocyclotriphosphazene (HCCTP) and keratin were used as the raw materials to synthesize cyclotriphosphazenekeratin (CCTPK). The Fourier transform infrared spectroscopic results indicate that CCTPK was successfully synthesized. The thermal analysis shows that the introduction of phosphazene into keratin lowered the primary decomposition temperature, increased the decomposition rate, and caused less weight loss. CCTPK blended viscose fibers were prepared by the wet spinning method, and the properties of the fiber were investigated. Limiting oxygen index of the flame-retardant fiber containing 10 % flame retardant was 28.6 %, which decreased to 27.5 % after 30 washing cycles. After burning, the scanning electron microscopy image showed an inflated carbonized coat on the fiber surface. The effect of CCTPK on the mechanical properties of the fibers was insignificant. CCTPK was compatible with keratin, and the flame retardancy of the viscose fiber was significantly improved.

Carbon microspheres were prepared using cellulose as a precursor by hydrothermal carbonization and the composites were prepared using carbon microspheres as the filler and poly(lactic acid) as the polymeric matrix. The morphologies and structures of carbon microspheres were characterized by scanning electron microscopy and Fourier-transform infrared spectrometry. The crystallinity, tensile properties and thermal properties of the composites were tested. The results show that the tensile properties and thermal properties of the carbon microsphere/poly(lactic acid) composites were improved by the addition of CMSs.

A crosslinked chitosan (CCTS) coated Ag-loading nano-SiO 2 composite (CCTS–SLS) was prepared. The structures of CCTS–SLS were characterized by field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The antibacterial properties of CCTS–SLS were measured as the minimal inhibitory concentration and the rate of bacterial growth. The experimental results indicate that the antibacterial activity of CCTS–SLS was affected by the mass ratio of SLS to chitosan, acetic acid concentration and crosslinking time. Moreover, CCTS–SLS exhibited high antibacterial activity against Escherichia coli and Staphylococcus aureus as a result of the coordinated action of CCTS and SLS.

Poly(ethylene terephthalate) (PET) had been compounded with antibacterial materials for preparing antibacterial masterbatch using a twin-screw extruder. Composite antibacterial PET fibers were prepared using the antibacterial masterbatch and pure PET resin by high-speed melt-spinning device, with spinning rate 3500 m/min. The antibacterial PET fibers of 5 wt % antibacterial materials were very effective against tested germs, with antibacterial ratios more than 90%, and had well mechanical properties. Scanning electron microscopy micrograph shows that antibacterial materials have been well dispersed in PET matrix. Microstructure of composite antibacterial fibers was studied by X-ray diffraction, and the nucleating effect of antibacterial materials in the cooling crystallization process of PET was confirmed by differential scanning calorimetry (DSC). Result of thermogravimetry (TG) result shows that the addition of antibacterial materials accelerated the degradation of PET. The aged properties of antibacterial fibers were evaluated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009