Ultrasound is a green processing technology which causes no harmful residues, and therefore it has attracted wide research interest in the field of non-thermal processing, especially sterilization. However, research has shown that ultrasonic treatment alone has limited effect on microorganisms, which can be improved by hurdle technology, namely combined treatment with other sterilization technologies. Bactericides have several advantages such as a wide scope of application, low price, easy availability, and convenient storage. The combined use of ultrasound with bactericides can not only improve the bactericidal effect, but also reduce the residue of harmful by-products, and enhance the poor permeability of bactericides. This article reviews three effects induced by ultrasonic cavitation including sonoporation, sonochemistry and sonoluminescence, and it focuses on the mechanism and influential factors of microbial killing by combined treatment of ultrasound with bactericides and its application in the food field. Finally, some future research directions are discussed. We anticipate that this review will provide a reference for the development of food sterilization technologies based on combined use of ultrasound and bactericides.

As a green non-thermal physical sterilization technology, ultrasonic can kill microorganisms in a short period of time while causing little damage to functional components in foods and maintaining food quality, making it a promising candidate for application in the food industry. Spores, a dormant form of vegetative cells with strong resistance to various processing techniques and sanitizers, are difficult to inactivate, attributable to its dense structure. As ultrasonic has only a limited killing effect on spores, many studies have applied a combination of ultrasonic and other sterilization technologies to kill spores. This review focuses on the killing effect and mechanism of ultrasonic alone and in combination with other sterilization technologies on bacterial spores. This review is expected to provide a theoretical reference for the non-thermal inactivation of bacterial spores.

As a new non-thermal food sterilization technology, pulsed light has gradually become a research focus for its advantages of high efficiency, convenience and environmental friendliness. Pulsed light has a strong penetration ability and a wide sterilization spectrum, which has found wide application. Pulsed light can maintain food texture, flavor and taste, making it highly promising for research. However, there is currently a lack of systematic research on the mechanism of pulsed light sterilization; although a wide range of methods have been applied, the synergistic mechanisms between different effects are still not clear. In this context, this paper reviews the mechanism of pulsed light sterilization and its application in the field of foods. First, using VOS viewer software and bibliometric, the current status of research on pulsed light sterilization is analyzed to provide accurate information and clues for understanding the research trends and development directions in the field of pulsed light sterilization technology. Secondly, from the perspectives of its biophysical, photothermal and photochemical effects the process of multi-target, multi-core and multi-system action of pulsed light on bacteria is elucidated to enhance our understanding of the mechanism of pulsed light sterilization. Finally, the application of pulsed light sterilization to different food categories is summarized. In the future, further understanding of the mechanism of pulsed light sterilization and its combination with other sterilization technologies will expand the application scope of food sterilization.

Bitterness, one of the 5 “basic tastes”, is usually undesired by humans. However, abundant literature reported that bitter fruits and vegetables have beneficial health effects due to their bitter contributors. This review provided an updated overview of the main bitter contributors of typical bitter fruits and vegetables and their health benefits. The main bitter contributors, including phenolics, terpenoids, alkaloids, amino acids, nucleosides and purines, were summarized. The bioactivities and wide range of beneficial effects of them on anti-cancers, anti-inflammations, anti-microbes, neuroprotection, inhibiting chronic and acute injury in organs, as well as regulating behavior performance and metabolism were reported. Furthermore, not only did the bitter taste receptors (taste receptor type 2 family, T2Rs) show taste effects, but extra-oral T2Rs could also be activated by binding with bitter components, regulating physiological activities via modulating hormone secretion, immunity, metabolism, and cell proliferation. This review provided a new perspective on exploring and explaining the nutrition of bitter foods, revealing the relationship between the functions of bitter contributors from food and T2Rs. Future trends may focus on revealing the possibility of T2Rs being targets for the treatment of diseases, exploring the mechanism of T2Rs mediating the bioactivities, and making bitter foods more acceptable without getting rid of bitter contributors.

Biofilms are a constant concern in the food industry; understanding the effect of environmental conditions on biofilm formation is essential to develop effective control strategies. Therefore, this study was conducted to investigate biofilms formation by Staphylococcus epidermidis under various conditions. Biofilms were cultured in nutrient broth containing different carbon source concentrations (0–10 mg/mL) on polystyrene surfaces for 32 h of incubation at 37 ℃ or 55 ℃, with quantification and enumeration at 8, 16, 24 and 32 h. S. epidermidis developed biofilms under all tested conditions; achieved the highest yield of biofilm biomass at 2.5 mg/mL for all carbon sources at 37 ℃. The highest efficiency of extracellular polymeric substance (EPS) molecule production occurred under glucose availability in the growth environment, with a higher yield of biomass and a significantly smaller number of metabolically active cells than under other tested conditions. A condensed ball-shaped structure was observed under the lactose condition. Meanwhile, biofilms in the presence of maltose showed mainly opaque thick rich colonies, while a compact multilayered-shaped structure was exhibited under both glucose and sucrose conditions. These results contribute to a better understanding of the biofilm formation by S. epidermidis in order to reduce contamination and recontamination in the food industry.