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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.

Aims The apoptosis and autophagy play an important role in the pathogenesis of sepsis-induced cardiac dysfunction. Previous studies have demonstrated that melatonin protects against cardiac dysfunction during sepsis. In addition, silent information regulator 1 (SIRT1) is a therapeutic target for sepsis-induced myocardial dysfunction. The aims of this study were to investigate whether SIRT1 was involved in melatonin's cardioprotection during sepsis and the mechanisms. Materials and methods In this study, twenty-four male C57BL/6 mice were randomly assigned to four groups: Control group, LPS group, LPS + Melatonin group and LPS + Melatonin + EX527 group. Mice were treated with lipopolysaccharide for 8 h with or without melatonin or EX527. The cardiac function, myocardial injury biomarkers, cardiac histopathology, cardiomyocyte apoptosis, autophagosome as well as the protein expressions of SIRT1, cleaved caspase-3, LC3-II/LC3-I ratio and p62 in the myocardium were assayed. Key findings The results demonstrated that melatonin significantly improved cardiac function, decreased creatine kinase (CK) and creatine kinase-MB (CK-MB) levels, attenuated myocardial architecture destruction, inhibited cardiomyocyte apoptosis and increased cardiac autophagy as compared with the LPS group. In addition, melatonin significantly increased SIRT1 protein expression in the myocardium of mice with sepsis, while inhibition of SIRT1 by EX527 abolished melatonin's cardioprotection during sepsis. Significance In this study, we found that melatonin protected against sepsis-induced cardiac dysfunction by regulating apoptosis and autophagy via activation of SIRT1 in mice.

Aromatic alcohols (including β-phenylethanol, tyrosol and tryptophol) could contribute positively to the aroma flavor of huangjiu at an appropriate amount. In this study, it was found that the aromatic alcohols in huangjiu were predominantly synthesized by Saccharomyces cerevisiae HJ01. The Ehrlich pathway and shikimate pathway, including 31 genes, are responsible for aromatic alcohol biosynthesis in S. cerevisiae. During the first 120 h of huangjiu fermentation, the genes GAP1HJ01 (permease), BAT2HJ01 (transaminase), PDC1HJ01 and PDC5HJ01 (pyruvate decarboxylase), and ADH1HJ01 (alcohol dehydrogenase) formed integrated Ehrlich pathway are responsible for aromatic alcohol biosynthesis. In S. cerevisiae HJ01, the mutations in the promoter region of genes GAP1HJ01, BAT2HJ01, PDC1HJ01, and PDC5HJ01 involved in the Ehrlich pathway increased the promoter strength and transcriptional levels of related genes. The addition of 20 U/g acid protease could substantially increase the expression levels of genes involved in the Ehrlich pathway, and therefore there were 34.7% increasing for the concentration of total aromatic alcohols.

Salmonella is a kind of common pathogenic bacteria and most of them were associated with serovars, enteritidis and typhimurium. This study was aimed at evaluating the antibacterial activity of tea tree oil (TTO) liposomes-loaded chitosan electrospun nanofilms against Salmonella (S. typhimurium and S. enteritidis) on chicken meat. Liposomes were prepared using TTO at a concentration of 6.0 mg/mL. The particle size, polydispersity index (PDI), zeta potential and entrapment efficiency of prepared liposomes were 144.3 ± 1.08 nm, 0.230 ± 0.012, −54.7 ± 2.01 mV and 39.20 ± 1.45% respectively. The physical properties of TTO liposomes/chitosan nanofibers were also determined. The nanofiber membranes embedded with liposome-encapsulated TTO exhibited high antibacterial activity against Salmonella, which had almost no impact on the sensory properties of chicken meat. Results showed that around 5 log10 reductions of Salmonella were observed in chicken meat by TTO liposomes/chitosan nanofibers treatment for 4 days at 12 °C and 25 °C. The investigation thus showed that the prepared TTO liposomes/chitosan nanofibers can prevent the microbial contamination by Salmonella to extend the shelf life of chicken meat.

Escherichia coli O157:H7 (E. coli O157:H7) is one of the most common pathogens in fresh vegetables and fruits, and most of the diseases produced by E. coli O157:H7 are associated with biofilms. Cold nitrogen plasma (CNP) is a cold sterilization technique which has no residue. However to completely eliminate the biofilm on the surface of vegetables the processing power and time of CNP have to be enhanced, which will impact on the quality of fruits and vegetables. Thus the sequential treatment of CNP and phage techniques was engineered in this study. Compared to treatment performed separately, sequential treatment not only had more mild treatment conditions as 400W CNP treatment for 2min and 5% phage treatment for 30min, but also exhibited more remarkable effect on eradicating E. coli O157:H7 biofilms in vitro and on vegetables. The population of E. coli O157:H7 was approximately reduced by 2logCFU/cm2 after individual treatment of 5% phages for 30min or 500W CNP for 3min. While the sequential treatment of CNP (400W, 2min) and phages (5%, 30min) reduced the E. coli O157:H7 viable count in biofilm by 5.71logCFU/cm2. Therefore, the sequential treatment holds a great promise to improve the current treatment systems of bacterial contamination on different vegetable surfaces.

This work describes the effect of cold nitrogen plasma to enhance the antibacterial activity of poly(ethylene oxide) (PEO) nanofibers containing antibacterial agent. Beta-cyclodextrin (β-CD) and tea tree oil (TTO) were used as a host-guest to form water-soluble inclusion complex. The encapsulation efficiency of TTO in inclusion complex could reach 73.23% at 60°C. As antibacterial agent, the inclusion complex was encapsulated into PEO matrix by electrospun. After plasma treatment, the release efficiency of antibacterial agent from PEO nanofibers was improved. As a result, the antibacterial activity of PEO nanofibers was enhanced accordingly. The plasma-treated nanofiber membranes achieved the highest antibacterial activity against Escherichia coli O157:H7, which was tested on the beef for 7d, with inhibition efficiently of 99.99% whether at 4°C or 12°C. The plasma-treated PEO nanofiber membranes containing TTO/β-CD inclusion complex (TTO/β-CD-IC) can prolong the shelf-life of beef, suggesting it has potential application in active food packaging.