An overview of tea saponin as a surfactant in food applications.

The residue of Camellia seeds after oil extraction contains many bioactive ingredients, including tea saponin. Tea saponin has many pharmacological effects and is an excellent nonionic surfactant. The development of natural surfactants has become a hot topic in food research. This review gathers the applications of tea saponin as a surfactant in food. It focuses on the application of tea saponin in emulsions, delivery systems, extraction and fermentation, as well as the challenges and development prospects in food applications. Tea saponin shows great potential as a surfactant in food applications, which can replace some synthetic surfactants. The full utilization of tea saponin improves the comprehensive utilization value of Camellia seed residue, contributes to the sustainable development of Camellia industry and avoids resource waste.

Inhibition of Staphylococcus aureus biofilms by poly-L-aspartic acid nanoparticles loaded with Litsea cubeba essential oil.

Staphylococcus aureus (S. aureus) biofilms contamination on various food-contacting surfaces is considered a significant threat in the field of food. Poly-L-aspartic acid (PASP) was proven to damage biofilm by affecting bacterial adhesion, metabolic activity, and extracellular polymeric substances in this study. Especially for eDNA, its generation was reduced by 49.4 %. After treatment with 5 mg/mL of PASP, the number of S. aureus in the biofilm at different growth stages decreased by 1.20-1.68 log CFU/mL. The nanoparticles prepared by PASP and hydroxypropyl trimethyl ammonium chloride chitosan were used to embed LC-EO (EO@PASP/HACCNPs). The results indicated that the particle size of the optimized nanoparticles was 209.84 nm with an encapsulation rate of 70.28 %. Compared to LC-EO alone, EO@PASP/HACCNPs had more significant permeation and dispersion effects on biofilms and possessed long-lasting anti-biofilm activity. For the biofilm grown for 72 h, the population of S. aureus in the EO@PASP/HACCNPs-treated biofilm was additionally reduced by 0.63 log CFU/mL compared with the LC-EO-treated group. EO@PASP/HACCNPs were also applied to different food-contacting materials. The lowest inhibition rate of EO@PASP/HACCNPs on S. aureus biofilm still reached 97.35 %. The sensory properties of the chicken breast were not affected by EO@PASP/HACCNPs.

Effect of soy protein isolate nanoparticles loaded with litsea cubeba essential oil on performance of lentinan edible films.

Environmental issues caused by plastic packaging materials have gotten increasingly severe, and substantial research has been conducted on environmentally friendly active packaging materials. In this study, the Litsea cubeba essential oil loaded soy protein isolate nanoparticles (LSNPs) with appropriate particle size, high storage stability and salt solution stability were fabricated. The LSNPs with the highest encapsulation efficiency of 81.76 % were added into the lentinan edible film. The microstructures of the films were observed by scanning electron microscopy. The physical properties of the films were measured. The results show that the lentinan film with LSNPs in the volume ratio of 4:1 (LF-4) had the highest elongation at break of 196 %, the lowest oxygen permeability of 12 meq/kg, and good tensile strength, water vapor barrier property, antibacterial property, oxidation resistance and thermal stability. The study suggested that LF-4 film could inhibit the growth of bacteria and delay the oxidation of lipid and protein on beef surface for 7 d.

Cold nitrogen plasma modified cuminaldehyde/ß-cyclodextrin inclusion complex and its application in vegetable juices preservation.

E. coli O157:H7 is one of the most common food-borne pathogens and usually related to contaminated vegetables. This study was to prepare an effective antibacterial agent and applied in vegetable juices. In this study, ß-cyclodextrin inclusion complexof CUM (CUM /ßCD-IC) was prepared using ultrasonication technique and then treated with cold nitrogen plasma (CNP) to observe its effect in the physicochemical and antibacterial properties of CUM/ßCD-IC. Various characterization techniques such as fluorescence, fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) confirmed the formation of IC between CUM and ßCD. Phase solubility and double reciprocal profiles studies proved the enhanced solubility of CUM with increasing amount of ßCD and the guest/host stoichiometry of 1:1. Computational modeling and FT-IR indicated that the phenyl ring with isopropyl chain of CUM is inserted in the hydrophobic ßCD. Investigations of thermal properties proved that the ßCD-IC formation improved the stability of CUM. Antibacterial test results indicated that CNP-CUM/ßCD-IC exhibited better antibacterial activity than CUM/ßCD-IC. After CNP-CUM/ßCD-IC treatment, it was observed by TEM that the cell membrane of E. coli O157:H7 was broken. In addition, the antibacterial activity of CNP-CUM/ßCD-IC in vegetable juices was carried out and the findings revealed that CNP-CUM/ßCD-IC has an excellent antibacterial effect on vegetable juices.

Controlled-release casein/cinnamon essential oil nanospheres for the inactivation of Campylobacter jejuni in duck.

Campylobacter jejuni (C. jejuni) is one of the most common foodborne pathogens that cause human sickness mostly through the poultry food chain. Cinnamon essential oil (CEO) has excellent antibacterial ability against C. jejuni growth. This study investigated the antibacterial mechanism of CEO against C. jejuni primarily through metabolism, energy metabolism of essential enzymes (AKPase, ß-galactosidase, and ATPase), and respiration metabolism. Results showed that the hexose monophosphate pathway (HMP) was inhibited, and that the enzyme activity of G6DPH substantially decreased upon treatment with CEO. Analysis of the effect of CEO on the expression of toxic genes was performed by the real-time PCR (RT-PCR). The expression levels of the toxic genes cadF, ciaB, fliA, and racR under CEO treatment were determined. Casein/CEO nanospheres were further prepared for the effective inhibition of C. jejuni and characterized by particle-size distribution, zeta-potential distribution, fluorescence, TEM, and GC-MS methods. Finally, the efficiency of CEO and casein/CEO nanospheres in terms of antibacterial activity against C. jejuni was verified. The casein/CEO nanospheres displayed high antibacterial activity on duck samples. The population of the test group decreased from 4.30 logCFU/g to 0.86 logCFU/g and 4.30 logCFU/g to 2.46 logCFU/g at 4 °C and at 25 °C for C. jejuni, respectively. Sensory evaluation and texture analysis were also conducted on various duck samples.

Cold plasma treated phlorotannin/Momordica charantia polysaccharide nanofiber for active food packaging.

Momordica charantia polysaccharide (MCP) has been repeatedly reported due to its anti-diabetic properties. Up to our knowledge, no research has discussed the use of MCP as a nanofiber matrix in an active food packaging. As an antibacterial and anti-oxidant agent, phlorotannin (PT) was encapsulated in MCP nanofibers to promote these activities. Nanofiber membranes were treated with cold plasma to increase their application performance. Antioxidant and antibacterial activities of PT and MCP against Escherichia coli O157:H7 were individually evaluated. The prepared nanofibers were assessed for their physical and mechanical properties in order to select the better-characterized ones. The successfulness of PT loading into MCP nanofibers was confirmed using SEM, AFM, TGA and DSC. After cold plasma treatment, the release efficiency of PT from the nanofibers was enhanced by 23.5 % (4 °C) and 25 % (25 °C), respectively. Correspondingly, both antibacterial and anti-oxidant activities of PT/MCP nanofibers were markedly improved.

Improving the stability of thyme essential oil solid liposome by using ß-cyclodextrin as a cryoprotectant.

The objective of this study was to investigate the preparation of the freeze-dried ε-polylysine (ε-PLY)-coated thyme essential oil (TEO) liposome, and its application in vegetable juices to control the Escherichia coli O157:H7 growth. Firstly, the solid liposomes (SLP) were obtained via freeze-drying in the presence of ß-cyclodextrins as cryoprotectant under different ratios of ß-cyclodextrin: lipid (w/w) (2:1, 4:1, 6:1 and 8:1). The ultraviolet visible and fourier transformed infrared spectrograms results indicated the presence of TEO and ε-PLY in SLPs. Subsequently, the morphology, antioxidant activity, digestibility, release rate and phase inversion temperature of SLPs were measured respectively. The SLP powders and re-hydrated SLP solutions exhibited the optimal physical and chemical properties when the ratio of ß-cyclodextrin: lipid was 6:1. In addition, SLPs stored at 4 °C and 12 °C possessed favorable particle size, PDI and zeta potential. Finally, the desired antibacterial effects of SLPs on Escherichia coli O157:H7 in 4 vegetable juices were achieved at a concentration of 5 mg/mL.