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In order to improve the stability and bacteriostasis of patchouli essential oil, high-energy emulsification method was used to prepare patchouli essential oil nanoemulsion by using a mixture of tween 80, thiamine pyrophosphate and chitosan, its structure, particle size, ζ potential and polymer dispersity index were analysed. The results showed that the particle size of the newly prepared patchouli essential oil nanoemulsion was about 89.5 nm. The encapsulation rate of patchouli essential oil was 95.85%, and the retention rate remained above 85% for up to 7 days at room temperature. Furthermore, fluorescence microscopy and scanning electron microscopy demonstrated that the droplets of the emulsion were spherical and the dispersion of oil droplets was relatively uniform. It was also showed that the patchouli essential oil was encapsulated in nanoemulsion based on the Fourier transform infrared spectroscopy and X-ray diffraction experiments. The results of the antioxidation and antibacterial experiments showed that the patchouli essential oil nanoemulsion exhibited a better oxidation stability, it had a good inhibitory effect on Staphylococcus aureus and Escherichia coli within a period of 7 days. Altogether, patchouli essential oil nanoemulsion showed a better stability and bacteriostatic activity compared to pure essential oil, and had a broad application prospect in the fields of food preservation.

The ultrasonic-assisted extraction process of polysaccharides from Stropharia rugosoannulata in Bo'ai County and the antibacterial and antioxidant activities were analyzed. On the basis of single factor experiments, with the polysaccharide yield as response value, the ultrasonic-assisted extraction process of polysaccharides from Stropharia rugosoannulata in Bo'ai County was optimized using Box-Behnken experimental design with three factors and three levels. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the polysaccharides extracted from Stropharia rugosoannulata in Bo'ai County were determined using the double dilution method and the plate coating method, respectively. The antioxidant activity was determined using ABTS method and FRAP methods. The results showed that the optimal ultrasonic-assisted extraction conditions were 62 ℃ (ultrasonic temperature), 1:30 g/mL (solid-liquid ratio) and 62 min (ultrasonic time). Under these conditions, the average yield of polysaccharide was 13.25%, which agreed well with the predicted value of 13.35%, the relative error was 0.75%. Among the five common pathogenic bacteria tested, the polysaccharide extract showed the strongest inhibitory effect on Salmonella typhimurium with the minimum inhibitory concentration of 6.25 mg/mL and the minimum bactericidal concentration of 12.5 mg/mL. Meanwhile, the polysaccharide extract showed strong ability to scavenge ABTS+ free radicals and reduce Fe3+, and showed dose-effect relationship within a certain concentration range, although weaker than the positive control (VC) at the same concentration. The results suggested that the regression models were stable and feasible for polysaccharide extraction from Stropharia rugosoannulata in Bo'ai County and the extract had strong antioxidant and antibacterial activities, but its antibacterial effect was selective.

Hydrogel is a polymer material composed of a hydrophilic three-dimensional network structure, which can quickly absorb water, swell, and maintain the swollen state to avoid significant water loss. It can provide sufficient capacity to accommodate a variety of materials, including small molecules, polymers and particles, among which, those that exhibit antibacterial properties are called antibacterial hydrogels. Antibacterial hydrogels have been widely used in many fields, such as biomedicine, textile, chemical industry, agriculture, and tissue engineering. They have great application potential in food packaging, food quality indication, and food preservation, but have not attracted enough attention. According to the type of active ingredients, antibacterial hydrogels can be divided into three categories: Natural polymer antibacterial hydrogel, hydrogels loaded with inorganic/organic antibacterial substances, and antibacterial hydrogels containing light-activated or light-responsive materials. This review expounds on the antibacterial mechanism and application status of these three types of antibacterial hydrogels, in order to provide a broader idea for the application of hydrogels in the field of food to exert its antibacterial effect.

Objective: To isolate and identify Lactobacillus gasseri from 125 fecal samples of healthy infants, and to evaluate its safety and antimicrobial activity. Methods: In this study, fecal samples of 1-month-old healthy infants were taken, and the strains were separated by MRS medium, Gram staining, biochemical identification and 16S rRNA sequencing technology were used to strain identification. Subsequently, the hemolysis of the isolated L. gasseri was evaluated by blood agar. The drug sensitivity of antibiotics was determined by micro broth dilution method, and the safety of the isolated strains were evaluated. Finally, the inhibitory effects of the 15 isolated L. gasseri strains on E. coli ATCC 25922 and S. aureus ATCC 25923 were detected by Oxford cup method. Results: Fifteen strains of L. gasseri were successfully isolated from 125 fecal samples of healthy infants. Hemolysis test results showed that 14 strains of them was hemolytic negative. The 15 tested strains were highly sensitive to tetracycline, vancomycin, linezolid and rifampicin, completely sensitive to imipenem and completely resistant to trimethoprim. The results of antibacterial activity test showed that 6 strains could effectively in inhibiting both E. coli and S. aureus. Conclusion: In this study, three strains of L. gasseri were successfully isolated from healthy infant’s fecal samples, which could not only inhibit E. coli and S. aureus, but also passed the safety test (LGI 6-1, LGI 6-2 and LGI 6-3). As potential probiotic resources, they could provide a research target for further research on function exploring.

Pea polyphenols are secondary metabolites widely existing in peas, mainly including flavonoids (populin, kaempferol, quercetin), phenolic acids (p-coumaric acid, erucic acid, ferulic acid) and tannins (catechins). The content, species and distribution of pea polyphenols depend on pea varieties, but they are affected by environment and inducing factors in the process of their growth. The extraction method of pea polyphenols has gradually changed from inefficient solvent extraction to microwave extraction technology with high efficiency and high extraction rate. The research on its physiological activity has gradually developed to the molecular and cellular level, and its application scope has gradually expanded to meat products, aquatic products, flour products and other industries. In order to further understand the chemical properties and potential utilization value of pea polyphenols, this paper expounds in detail the distribution of pea polyphenols, the factors affecting the types and content of pea polyphenols, the separation and extraction, physiological activity and its application in food industry, in order to provide a theoretical basis for the development and research of pea polyphenols.

In this study, antibacterial PVA-SS-LJ-AgNPs composite films were made by using polyvinyl alcohol (PVA) and soluble starch (SS) as ingredients, glycerol as plasticizer, and lemon juice (LJ) as reducing agent to in situ reduced AgNPs from AgNO3. After single factor and orthogonal experiments, the optimum films preparation process was PVA 3 g, SS 0.5 g, glycerol 3 g, LJ 7 mL, AgNO3 130 mmol/L. Under the optimal process, the tensile strength, elongation at break, water vapor permeability coefficient, moisture absorption rate, and light transmittance of the membrane were 12.16 MPa, 1111.59%, 0.09 g/0.01 h·m2, 12.56%, 48.05%, respectively. Through the analysis of physical properties and structure of the films, lemon juice could successfully restore AgNPs in situ to films. Compared with the PVA-SS films, the tensile strength and elongation at break of the composite films were improved up to 11.51 MPa and 1470.20%, respectively. Compared with PVA-SS-LJ films, the water vapor penetration and moisture absorption were effectively balanced, AgNPs evenly dispersed in the composite films, the compound films had good inhibition effect for E. coli, Salmonella, Bacillus subtilis, S. aureus, P. aeruginosa. In summary, PVA-SS-LJ-AgNPs composite films met the current new requirements of food packaging materials, and had its potential application prospects.

In this study, based on the traditional hot water extraction-ethanol precipitation method for fucoidan, the ethanol-free extraction process of kelp fucoidan was studied in accordance with the difference in the fucose contents and sulfate groups of fucoidans and their beneficial biological activities. Three extraction methods including hot water extraction-ethanol precipitation method, hot water extraction-acid precipitation method, and hot water extraction-acid precipitation-enzymatic hydrolysis assisted extraction method, were applied to prepare fucoidans, and three fucoidan samples (sample 1, sample 2 and sample 3) were obtained, respectively. Fucose and sulfuric acid group-contents and biological activities (antioxidant, antibacterial activities) analysis results showed that the contents of fucose and sulfate groups in fucoidan (sample 3) prepared by hot water extraction-acid precipitation-enzymatic assisted hydrolysis method were 41.10%±0.87% and 24.90%±0.15%, respectively, which were significantly higher than the Trade Standard requirements of fucoidan (SC/T 3404-2012), samples 1 and sample 2. Meanwhile, the sample 3 also had the best antioxidant and antibacterial activities in three fucoidan samples. The Response surface methodology (RSM) was used to optimize the key process conditions of hot water extraction-acid precipitation-enzymatic hydrolysis assisted extraction of fucoidan. The best extraction process parameters were obtained as follows: Extraction temperature was 90℃, extraction time was 2.0 h, liquid material ratio was 40:1 mL/g, and the extraction yield reached 9.65%±0.11%. In this study, raction rate of fucoidan and the biological activity of fucoidan prepared by hot water extraction-acid precipitation-enzymatic assisted hydrolysis method were significantly higher than those prepared by hot water extraction-ethanol precipitation method and hot water extraction-acid precipitation method, therefore, the hot water extraction-acid precipitation-enzymatic assisted hydrolysis method digestion would be a good process to effectively replace the hot water extraction-ethanol precipitation method for fucoidan extraction.

Fermentation is an important means of fish preservation and processing. Fermentation gives fish unique flavor and texture, and microorganisms play an important role in the process of fermentation. This paper introduces the composition of microorganisms in fermented fish and its role in inhibiting miscellaneous bacteria, substance degradation, flavor formation and biogenic amine accumulation, in order to help understand the dominant microorganisms and their fermentation characteristics, prepare industrial starter and improve the yield and quality of fermented fish. In addition, the further study of fermented fish is prospected.

The purpose of this experiment was to study the antibacterial effect of saponins from different sources on common food-borne pathogens, and to develop the application of saponins in the field of food. The size of inhibition zone, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of saponins from three different sources (Gleditsia sinensis shell, green tea and Camellia oleifera seed) were determined by Oxford cup method and double dilution method, respectively. The results showed that the three saponins from different sources all had antibacterial effect on four common food-borne pathogenic bacteria, namely Bacillus subtilis, Staphylococcus aureus, Salmonella sp. and Escherichia coli. Among them, the saponins derived from Gleditsia sinensis shell had the best antibacterial effect. The double dilution method showed that their MICs for the two Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus were both 4 mg/mL, and the MBCs were 16 mg/mL and 8 mg/mL respectively; The MIC of Salmonella and E.coli of two Gram-negative bacteria were 4 mg/mL and 8 mg/mL, and MBC were 8 mg/mL and 16 mg/mL respectively. The results provide devidence for the research and development of safe, high effective and natural plant food preservatives.

The objective of the study was preliminarily explore the antibacterial activity and stability of Thamnolia subuliformis in vitro, the plate drilling method was used to determine the antibacterial activity of methanol extract of Thamnolia subuliformis against common pathogenic bacteria in vitro. The indicator bacteria of Staphylococcus aureus was used to determine the effects of factors such as different temperature, pH and UV irradiation time on antibacterial stability. Petroleum ether, ethyl acetate and n-butanol were used to extract the methanol extract, determine the polarity of its antibacterial active substances, and determine the content of usnic acid. The results showed that the methanol extract of Thamnolia subuliformis had good antibacterial effect on Gram-positive bacteria such as Staphylococcus aureus, Bacillus subtilis, Listeria stephensi, Staphylococcus surface, Listeria evansi, Salmonella paratyphi A, Salmonella paratyphi B of Gram-negative bacteria and Candida albicans. The minimum inhibitory concentration and minimum bactericidal concentration against Staphylococcus aureus were 0.625 and 10 mg/mL respectively; The results of antibacterial stability test showed that temperature had no significant effect on the antibacterial activity of methanol extract of Thamnolia subuliformis (P>0.05), and it still had high antibacterial activity after treatment at 100 ℃ for 30 min; The antibacterial activity of UV irradiation for 40 min and 50 min decreased significantly (P0.05）, showing high antibacterial activity. When the pH was high (8.0, 10.0) or low (2.0, 4.0), the antibacterial activity of the treatment group decreased significantly (P