High sensitivity in quantitative analysis of mixed-size polystyrene micro/nanoplastics in one step.

As emerging environmental pollutants, microplastics (MPs) and nanoplastics (NPs) pose a serious threat to human health. Owing to the lack of feasible and reliable analytical methods, the separation and identification of MPs and NPs of different sizes remains a challenge. In this study, a hyphenated method involving filtration and surface-enhanced Raman spectroscopy (SERS) for the separation and identification of MPs and NPs is reported. This method not only avoids the loss of MPs and NPs during the transfer process but also provides an excellent SERS substrate. The SERS substrate was fabricated by electrochemically depositing silver particles onto the reduced graphene oxide layer coated on stainless steel mesh. Results show that polystyrene (PS) MPs and NPs are efficiently separated on the SERS substrate via vacuum filtration, resulting in high retention rates (74.26 % ± 1.58 % for 100 nm, 81.06 % ± 1.49 % for 500 nm, and 97.73 % ±0.11 % for 5 µm) and low limit of detection (LOD). The LOD values of 100 nm, 500 nm, and 5 µm PS are 8.89 × 10-5, 3.39 × 10-5, and 1.57 × 10-4 µg/mL, respectively. More importantly, a linear relationship for uniform quantification of 100 nm, 500 nm, 3 µm and 5 µm PS was established, and the relationship is Y = 225.61 lgX + 1076.36 with R2 = 0.980. The method was validated for the quantitative analysis of a mixture of 100 nm, 500 nm PS NPs, 3 µm and 5 µm PS MPs in a ratio of 1:1:1:1, which successfully approaches the evaluation of evaluated PS NPs in the range of 10-4-10 µg/mL with an LOD value of approximately 7.82 × 10-5 µg/mL. Moreover, this method successfully detected (3.87 ± 0.06) × 10-5 µg MPs and NPs per gram of oyster tissue.

Tilapia-soybean protein co-precipitates: Focus on physicochemical properties, nutritional quality, and proteomics profile.

The development of binary protein systems featuring superior nutritional properties and applied range is an interesting and challenging task in the food industry. In this study, the tilapia-soybean protein co-precipitates (TSPCs) with different mass ratios of tilapia meat and soybean meal were constructed. Results of physicochemical properties showed that the highest solubility and thermal stability values of TSPCs were 81.90 % and 90.30 °C, respectively. TSPCs have the full complement of amino acids and enhanced nutritional quality compared to tilapia protein isolate (TPI) and soybean protein isolate (SPI). TSPC2:1 and TSPC1:1 contained the highest levels of tryptophan, aspartic acid, glycine, histidine, and arginine relative to TPI and SPI. The in vitro protein digestibility and protein digestibility corrected amino acid scores of TSPCs were also higher than that of SPI. SDS-PAGE revealed that TSPCs contained protein subunits from TPI and SPI. Moreover, the lysine-to-arginine ratio and ß subunit were greatly correlated with protein digestibility with correlation coefficients of -0.962 (P < 0.01) and -0.971 (P < 0.01), respectively. Compared to SPI, TSPCs displayed a lower lysine-to-arginine ratio and ß-conglycinin content, which improved its digestibility. Proteomic analysis indicated that TSPC1:1 had 989 unique proteins, which gives TSPCs enhanced biological properties compared to TPI and SPI, allowing them to participate in a broad range of biochemical metabolic and signal transduction pathways. The study would advance the utilization of mixed proteins toward exceptional food industry applications.

Compare with different vegetable oils on the quality of the Nemipterus virgatus surimi gel.

To enhance the quality and flavor of surimi-based products, we investigated the effects of vegetable oils (peanut, soybean, corn, coconut, olive, and safflower seed oils) on the texture, water-holding capacity (WHC), microstructure, and flavor of the Nemipterus virgatus surimi gel. The results showed that 6 kinds of vegetable oils could improve the whiteness and flavor of gels. However, peanut, olive, and coconut oils enriching oleic acid or lauric acid were easy to accumulate with an average diameter of more than 0.15 µm. Thus, the gel with the oil showed a loose network structures with large cavities, and the texture was deteriorated, accompanied by decreased WHC (p < .05). Compared with other vegetable oils, soybean, corn and safflower seed oils enriching linoleic acid were emulsified with protein forming a stable interfacial protein film. The gel with the oil showed an increase in the WHC and bound water content. Furthermore, the oil droplets with an average diameter of less than 0.15 µm were evenly distributed in the gel matrix, and the gel exhibited dense network structures with small cavities and smooth surface. In general, soybean and safflower seed oils can be used as a potential additive to improve the quality and flavor of surimi-based products.

Unraveling the microbial community and succession during zha-chili fermentation and their relationships with flavor formation.

Zha-chili is a popular traditional fermented food among people in central and southwest China for its nice flavor. It is produced from grain and fresh chili undergoing spontaneously anaerobic fermentation. In this study, the high-throughput sequencing (HTS), high-performance liquid chromatography (HPLC), and head-space solid-phase microextraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS) were applied to systematically study the dynamic of microbial community and flavor substances during zha-chili fermentation. Simultaneously, the physicochemical factors were investigated to decode the core factors affecting the microbial succession. Results showed that Lactobacillus and Kazachstania were the most dominant bacterium and fungus, respectively, and lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeasts dominated the whole fermentation. Besides, acidity, ethanol, and temperature were the core factors that shifted the microbial succession. Herein, the acidity and ethanol drove the bacterial succession from Weissella to Lactobacillus, then temperature affected the succession that Lactobacillus was partially replaced by Acetobacter. Meanwhile, acidity and ethanol actuated the fungal succession that Gibberella was superseded by Kazachstania. Moreover, Lactobacillus, Acetobacter, Kazachstania, Wickerhamomyces, Kluyveromyces, and Cyberlindnera were the core microbes associated with the formation of flavor substances including lactic acid, acetic acid, ethanol, ethyl lactate, ethyl acetate, and umami free amino acids. These findings will be helpful to unravel the formation of flavor substances based on microbial community and succession during zha-chili fermentation, providing a solid foundation for the process optimization and quality control of zha-chili.

Low-Content Pre-Emulsified Safflower Seed Oil Enhances the Quality and Flavor of the Nemipterus Virgatus Surimi Gel.

Surimi-based products occupy an important position in the aquatic product processing industry. To enhance the quality and flavor of surimi-based products, the effects of pre-emulsified safflower seed oil on the texture, water-holding capacity (WHC), microstructure, and flavor of Nemipterus virgatus surimi gel was evaluated. The texture and whiteness of the gel were improved, and the WHC increased (p < 0.05) as the content of safflower seed oil increased up to 2 mL per 100 g surimi. Furthermore, the drops of pre-emulsified safflower seed oils with an average diameter of less than 0.10 µm were evenly distributed in gel matrix. Microstructure and infrared spectroscopy analyses indicated that low-content pre-emulsified safflower seed oil acted as filler particles to occupy void spaces, resulting in gel exhibiting a dense network structure. Volatile analysis showed the gel containing pre-emulsified oil enriched volatile compounds, mainly resulting from the oxidation and decomposition of oils by the activation of lipoxygenase, which synergistically contributes to unique flavors of gel. Consequently, low-content pre-emulsified safflower seed oil can used to enhance the quality and flavor of N. virgatus surimi-based products. These findings are especially relevant to the current growing interest in low-fat and high-protein diets.

Analysis of changes in the microbial community structure and physicochemical properties during the fermentation of sand crab juice.

The structure of the microbial community during sand crab juice fermentation was analyzed using culture-based methods and high-throughput 16S rRNA gene sequencing. Additionally, the changes in amino acid nitrogen (AAN) and total volatile basic nitrogen (TVB-N) were evaluated. Staphylococcus equorum, Staphylococcus arlettae, Staphylococcus saprophyticus, Salinicoccus amylolyticus and Bacillus cereus were isolated by traditional culture isolation technique. The Good's coverage obtained by high-throughput sequencing was over 99.5%, and the Chao1 and Simpson indices showed small fluctuations, indicating that the species abundance and diversity did not change significantly during the fermentation process, although the abundance decreased. Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria were the dominant bacterial phyla observed during fermentation, whereas Aquabacterium, Roseovarius, Muribaculaceae, and Silicimonas were the dominant bacterial genera. The AAN content increased from 0.15 to 0.43 g/100 mL during the 15-day fermentation, indicating the production of small peptides and amino acids during fermentation. The TVB-N content (25.2 mg/100 mL) on day 15 indicated slight spoilage of sand crab juice, although the freshness conformed to the production standard. These results provide a theoretical basis for improving the quality and optimizing the production process of sand crab juice.

Detection of viable and total fungal community in zaopei of Chinese strong-flavor baijiu using PMA combined with qPCR and HTS based on ITS2 region.

BACKGROUND: Chinese strong-flavor baijiu (CSFB), one of the three major baijiu types, is the most popular baijiu type among consumers in China. A variety of microbes are involved in metabolizing raw materials to produce ethanol and flavor substances during fermentation, which fundamentally determined the quality of baijiu. It is of great importance to study microbial community of fermented grains (zaopei) during baijiu brewing process for improving its quality. In this study, we firstly used propidium monoazide (PMA) to treat zaopei samples from 5-year pit and 20-year pit for removing the interference of non-viable fungi, and analyzed the diversity of total fungi and viable fungi by quantitative PCR (qPCR) and high-throughput sequencing (HTS) based on ITS2 gene. RESULTS: The results showed that total fungi and viable fungi displayed no significant differences at OTU, phylum, or genus levels during fermentation within two kinds of pits. A total of 6 phyla, 19 classes, and 118 genera in fungi were found based on OTUs annotation in zaopei samples from 5-year pit and 20-year pit. Besides, non-viable fungi had little effect on the fungal community diversity during the fermentation cycle. It was found that the most dominant viable fungi belonged to Saccharomyces, Kazachstania, Naumovozyma, and Trichosporon, and Naumovozyma was firstly detected in zaopei samples of CSFB. Moreover, based on the variation of flavor substances in zaopei samples, the quality of CSFB produced from older pit was better than that produced from younger pit. CONCLUSION: The non-viable fungi had little effect on the fungal diversity, structure, and relative abundance in zaopei samples of CSFB, and Naumovozyma was firstly detected in zaopei samples of CSFB. Our findings can be applied as guidance for improving the quality and stability of CSFB.

Characterization and comparison of collagen extracted from the skin of the Nile tilapia by fermentation and chemical pretreatment.

Chemical pretreatment of collagen raw materials is time-consuming and environmentally hazardous. Collagen extraction after fermentation pretreatment has not been reported. We extracted and characterized acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) from Nile tilapia (Oreochromis niloticus) skin following fermentation and chemical treatments and comparatively evaluated the feasibility of fermentation. Fermentation-ASC (FASC) and fermentation-PSC (FPSC) yields (4.76 and 8.14 wt%, respectively) were slightly but not significantly higher than chemical-ASC (CASC) and chemical-PSC (CPSC) yields (4.27 and 7.60 wt%, respectively). All extracts were identified as type I collagens by SDS-PAGE and retained their triple helical structure well, as confirmed through Fourier transform infrared spectroscopy. All collagen microstructures under scanning electron microscopy were multi-layered aggregates. These collagens also had similar biochemical properties (i.e. denatured between 36.5 and 37.1 °C, high soluble at pH 1-4 and at <3% [w/v] NaCl). Therefore, fermentation method is a viable alternative for pretreating collagen extraction materials.

Pathogenicity of Vibrio parahaemolyticus in Different Food Matrices.

The pathogenicity and virulence factors of Vibrio parahaemolyticus in four food matrices--shrimp, freshwater fish, pork, and egg-fried rice--were compared by measuring the thermostable direct hemolysin activity and total hemolytic titer. Significantly high thermostable direct hemolysin and also hemolytic titers (P < 0.05) were produced by V. parahaemolyticus in egg-fried rice > shrimp > freshwater fish > pork. Filtrates of V. parahaemolyticus in shrimp given intraperitoneally induced marked liver and kidney damage and were highly lethal to adult mice compared with filtrates of V. parahaemolyticus in freshwater fish > egg-fried rice > pork. From in vitro and in vivo pathogenicity tests, it seems the type of food matrix has a significant impact on the virulence of V. parahaemolyticus. These results suggest that hemolysin may not necessarily be the only virulence factor for pathogenicity of V. parahaemolyticus. This is the first report that shows that virulence factors produced by V. parahaemolyticus in seafood such as shrimp are more toxic in vivo than in nonseafood.

Modeling antimicrobial activity of lipopeptides from Bacillus amyloliquefaciens ES-2 against Shewanella putrefaciens in shrimp meat using a response surface method.

Bacillus amyloliquefaciens ES-2 can produce antimicrobial lipopeptides, including surfactin and fengycin. In this study, the model of antimicrobial activity against Shewanella putrefaciens in shrimp meat by antimicrobial lipopeptides from B. amyloliquefaciens ES-2 was researched by response surface methodology. The results showed that S. putrefaciens had high sensitivity to antimicrobial lipopeptides, which had a MIC of 0.6 mg/ml. A quadratic mathematical model representative of the action of antimicrobial lipopeptides on S. putrefaciens in shrimp meat was developed as a function of concentration, time, and temperature. A reduction of S. putrefaciens cells of over 2 log cycles could be realized when the temperature was below 5.4°C, the time was over 6 h, and the concentration of the lipopeptides was over 0.3 mg/g.

Isoliquiritigenin from licorice root suppressed neovascularisation in experimental ocular angiogenesis models.

AIM: To explore the antiangiogenic property of isoliquiritigenin (ISL) on in vivo and in vitro models. DESIGN: Laboratory investigation. METHODS: The effect of ISL on angiogenesis development was investigated using ex ovo chick chorioallantoic membrane model. Its effect on pathological angiogenesis was examined by (1) silver nitrate cauterisation-induced corneal neovascularisation in BALB/c mice, followed by topical ISL (0.2-50 µM) and CD31 immunofluorescence of corneal blood vessels; (2) argon laser photocoagulation-induced choroidal neovascularisation in C57BL/6 mice, followed by intravitreal ISL (10-200 µM) and fundus fluorescein angiography and immunofluorescence with Griffonia simplicifolia isolectin-B4 (GSA I-B4); and (3) oxygen-induced retinopathy in C57BL/6J mice pups, followed by intravitreal ISL (1-100 µM) and GSA I-B4 immunofluorescence. The vascular area was quantified and analysed by one-way analysis of variance and Student t test. Expression of vascular endothelial growth factor (VEGF) and pigment-epithelium-derived factor in human umbilical vein endothelial cells was analysed by western blotting. RESULTS: Ex ovo chick chorioallantoic membrane assay showed that ISL dose-dependently suppressed VEGF-induced vessel growth. In vivo experiments illustrated that topical ISL alleviated corneal neovascularisation (IC(50)=7.14 µM, day 7) and intravitreal ISL reduced vessel leakage and GSA I-B4-positive vascular area in choroidal and retinal neovascularisation. ISL was found to dose-dependently suppress VEGF and induce pigment epithelium derived factor expression in cultured endothelial cells. CONCLUSION: Using various experimental models of ocular neovascularisation, the authors have demonstrated that ISL from licorice extract has an antiangiogenic effect. The authors' findings suggest that ISL may be a potential antiangiogenic molecule in the development of therapy for neovascularisation diseases.

In vitro screening for angiostatic potential of herbal chemicals.

PURPOSE: Herbal medicine has long been used in traditional medicinal systems. The authors carried out a first-line screening of four herbal chemicals with reported antioxidative properties and capabilities to suppress endothelial cell growth and migration. These herbal chemicals were isoliquiritigenin (ISL) from licorice, epigallocatechin gallate (EGCG) from green tea, resveratrol (Rst) from grapes, and gambogic acid (GA) from the resin of Garcinia hanburyi. METHODS: Cytotoxicity was studied by MTT cell viability/proliferation assay on human retinal pigment epithelial cells (ARPE19). Effects on vascular endothelial growth factor (VEGF)-induced endothelial cell proliferation and migration were investigated by a scratch-wound model using human umbilical vein endothelial cells (HUVECs). The effects on VEGF signaling in HUVECs were analyzed by Western blotting. RESULTS: At sub-cytotoxic levels, ISL (10 µM), EGCG (50 µM), and Rst (10 µM) suppressed HUVEC proliferation and migration under VEGF (20 ng/mL) stimulation in our scratch-wound model. HUVEC migration was reduced more by ISL and EGCG than bevacizumab, a humanized monoclonal antibody against VEGF. The efficiency of Rst was similar to that of bevacizumab. GA, however, was toxic to cells even at nanomolar concentrations. Western blot analysis showed that these chemicals affected focal adhesion kinase activation and expression of pigment epithelial growth factor. CONCLUSIONS: ISL, EGCG, and Rst are highly effective and efficient in suppressing endothelial cell proliferation and migration, with low cytotoxicity on ARPE19 and HUVEC lines. They are potentially useful for further investigation to develop antiangiogenic therapies by virtue of their small molecular sizes for easy penetration through tissue cells and their low effective dosages.