Search

The aim of this study was to investigate the effect of mixed fermentation of Jiuqu and Saccharomyces cerevisiae on the quality of kiwifruit wine. The results showed that total titratable acidity, methanol and organic acids of kiwi wine fermented by Jiuqu + Saccharomyces cerevisiae EC1118 were significantly lower (p < 0.05) than that in other groups. There was no significant difference in the content of flavor substances in kiwi wines fermented by a mixed group and Saccharomyces cerevisiae EC1118 alone, but the sensory evaluation showed a significantly large difference. On the sensory scale, kiwi wine fermented by mixed fermentation had a unique presentation and typical bouquet, better than those fermented by Jiuqu and Saccharomyces cerevisiae EC1118 alone. In conclusion, mixed fermentation of Jiuqu + Saccharomyces cerevisiae EC1118 could improve the quality of the kiwi wine, which provides a promising application prospection for kiwi wine production.

In this study, we developed a novel liquid fermentation medium of Cordyceps militaris using pupa powder and wheat bran as nitrogen resources instead of the traditionally used peptone. This process ...

In order to establish a high performance liquid chromatography (HPLC) fingerprint of Chinese prickly ash (Zanthoxylum) based on acid amide components, 38 specimen were collected from Western China. Similarity analysis, hierarchical clustering analysis (HCA) and principal component analysis (PCA) were carried out to analyze the obtained fingerprints. Furthermore, uncertainty and reliability values of the established HPLC fingerprints were evaluated. Similarity values ranged between 0.587 and 0.999 for specimen of Zanthoxylum bungeanum Maxim. and between 0.991 and 0.999 for specimen of Zanthoxylum armatum DC. 17 samples from different habitats were classified by HCA into three groups, i.e. Group I (8 samples), Group II (6 samples) and Group III (3 samples) and were divided into three clusters by PCA. The compound of peak 6 was identified as hydroxyl-β-sanshool. The characteristic compounds of peaks 5, 7, 8, 10, 12 and 13 were tentatively identified by LC–MS as other acid amide compounds. As for credibility analysis, the results showed that the values of macroscopic qualitative reliability and macroscopic quantitative reliability of the reference chromatogram fingerprint were more than 0.9772. Statistical analysis indicated that the HPLC fingerprint technology may be applied for quality assessment and classification of Zanthoxylum.

A novel indicator film from carboxymethyl-cellulose (CMC)/starch (S) and purple sweet potato anthocyanins (PSPA) was prepared and characterized. The Fourier transform infrared spectroscopic (FT-IR) analysis indicated that new interaction were generated between the components of the film, and the scanning electron microscopic (SEM) and X-ray diffraction spectra (XRD) showed that PSPA was well dispersed in CMC and starch-based film. The results from differential scanning calorimetric (DSC) analysis revealed that the novel film had increased melting temperature. The addition of PSPA into the film resulted in the increase of tensile strength but the decrease of elongation at break and moisture content. The analysis of color change demonstrated that the film color was changed from red to blue and green when exposed to different pH or ammonia. In their application trial, the SCA film was used as labels to monitor the freshness of fish stored at 20 °C, and the results showed that the color of the film was changed from red to blue when the fish became spoiled. The observation was consistent with the TVB-N value, which was higher than the set limit (20 mg/100 g). Hence, the novel indicator film could be used as intelligent food packaging to monitor fish freshness.

This study investigated the impact of different storage conditions on the qualities of dried Z. armatum, including color, numbness, and aroma, for seven months to identify a suitable storage method. The storage conditions (n = 12) included four kinds of packaging methods, namely vacuum and non-light packaging (VnL), vacuum and light packaging (VL), ventilation and non-light packaging (K), non-vacuum and light packaging (nVL) stored at different temperature, room temperature, 0−4 °C, and −18 °C. The results showed that temperature affected the most of its qualities. There was a significant reduction in the qualities of Z. armatum at room temperature, however, at −18 °C, the contents of chlorophyll, hydroxy-α-sanshool, and linalool in Z. armatum were found to be retained at 1.33–1.37 mg/g, 21.24–23.64 mg/g, and 64.53–67.29 μL/mg at the seventh month, respectively. Light also played an important part in deteriorating the qualities of Z. armatum. At room temperature, the contents of chlorophyll, hydroxy-α-sanshool, and linalool in the VnL were higher than those in the VL. Additionally, oxygen also affected the color and numbness in Z. armatum but had little effect on aroma. At room temperature, the contents of chlorophyll and hydroxy-α-sanshool in the VnL and K were 1.11 mg/g and 1.03 mg/g, 19.10 mg/g and 11.95 mg/g at the seventh month, respectively. However, the trends of linalool loss in the VnL and K were almost the same during storage. Therefore, the optimal way to preserve dried Z. armatum was VnL at −18 °C.

Cathepsin B (CatB) cDNA of 759 bp from Jian carp (Cyprinus carpio var. Jian) with amino acid similarity of 99.6% to common carp was cloned. The mature CatB was expressed in Escherichia coli BL21 transferred with vector CatB-pET-30a. It was purified and identified as a single band (29 kDa) on SDS-PAGE. Optimum CatB activity was observed at 40 °C and pH 5.5. Mouse anti-CatB polyclonal antibody with a high titer of 1:256000 was prepared successfully and shown to specifically recognize the antigen both in prokaryotic cells and in the tissues of Jian carp according to western blotting and immunohistochemistry results. Immunolocation analysis showed that CatB distribution at protein level varied among the tested tissues. The results presented in this study may provide a significant reference for future research on the inherent relationship between CatB and the quality of fish or fish products at both the gene and protein levels.

A novel antimicrobial peptide named NP-6 was identified in our previous work. Here, the mechanisms of the peptide against Escherichia coli (E. coli) were further investigated, as well as the peptide’s resistance to temperature, pH, salinity, and enzymes. The transmission electron microscopy (TEM), confocal laser scanning microcopy (CLSM), and flow cytometric (FCM) analysis, combined with measurement of released K+, were performed to evaluate the effect of NP-6 E. coli cell membrane. The influence of NP-6 on bacterial DNA/RNA and enzyme was also investigated. The leakage of K+ demonstrated that NP-6 could increase the permeability of E. coli cell membrane. The ATP leakage, FCM, and CLSM assays suggested that NP-6 caused the disintegration of bacterial cell membrane. The TEM observation indicated that NP-6 could cause the formation of empty cells and debris. Besides, the DNA-binding assay indicated that NP-6 could bind with bacterial genomic DNA in a way that ethidium bromide (EB) did, and suppress the migration of DNA/RNA in gel retardation. Additionally, NP-6 could also affect the activity of β-galactosidase. Finally, the effect of different surroundings such as heating, pH, ions, and protease on the antimicrobial activity of NP-6 against E. coli was also investigated. Results showed that the peptide was heat stable in the range of 60~100 °C and performed well at pH 6.0~8.0. However, the antimicrobial activity of NP-6 decreased significantly in the presence of Mg2+/Ca2+, and after incubation with trypsin/proteinase K. The results will provide a theoretical support in the further application of NP-6.

We investigated the permselectivity and interfacial electron transfers of an amphiphilic branch-tailed fluorosurfactant self-assembled monolayer (FS-SAM) on a gold electrode by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The FS-SAM was prepared by a self-assembly technique and a &ldquo, click&rdquo, reaction. The barrier property and interfacial electron transfers of the FS-SAM were also evaluated using various probes with different features. The FS-SAM allowed a higher degree of permeation by small hydrophilic (Cl&minus, and F&minus, ) electrolyte ions than large hydrophobic (ClO4&minus, and PF6&minus, ) ones. Meanwhile, the redox reaction of the Fe(CN)63&minus, couple was nearly completely blocked by the FS-SAM, whereas the electron transfer of Ru(NH3)63+ was easier than that of Fe(CN)63&minus, which may be due to the underlying tunneling mechanism. For hydrophobic dopamine, the hydrophobic bonding between the FS-SAM exterior fluoroalkyl moieties and the hydrophobic probes, as well as the hydration resistance from the interior hydration shell around the oligo (ethylene glycol) moieties, hindered the transport of hydrophobic probes into the FS-SAM. These results may have profound implications for understanding the permselectivity and electron transfers of amphiphilic surfaces consisting of molecules containing aromatic groups and branch-tailed fluorosurfactants in their structures.

In this paper, the catalytic performance of non-purified esterase from wheat bran immobilized on glass fibre membrane carrier is established, the immobilization conditions observed were enzyme 1 mL, phosphate buffer 3 mL (pH 7.0), immobilization time 1 h, immobilization temperature 29 °C. After carrier functionalization some characteristics of immobilized enzyme were studied, the results showed that immobilized enzyme presenting improved characteristic than that of free enzyme. The optimum pH for free and immobilized enzymes were found to be 8 and 7, respectively. As for optimum temperature for free and immobilized enzymes were observed to be 30 °C and 40 °C, respectively. When the enzyme was immobilized on glass fibre membranes, its Km increased about 7 times. In addition, storage and thermal stability of the free wheat esterase were increased by as a result of membrane immobilization, after 12 days of storage, the immobilized enzyme still retained about 91.10% of its original activity at 4 °C, indicating a great potential in industrial application.

Antimicrobial peptides (AMPs) have generated growing attention because of the increasing bacterial resistance. However, the discovery and identification of AMPs have proven to be challenging due to the complex purification procedure associated with conventional methods. For the reasons given above, it is necessary to explore more efficient ways to obtain AMPs. We established a new method for discovery and identification of novel AMPs by proteomics and bioinformatics from Zanthoxylum bungeanum Maxim seeds protein hydrolysate directly. This process was initially achieved by employing ultra-performance liquid chromatography-electrospray ionization-mass spectrometry/mass (UPLC-ESI-MS/MS) spectrometry to identify peptides derived from Z. bungeanum Maxim seed protein hydrolysates. Three online servers were introduced to predict potential AMPs. Sixteen potential AMPs ranging from 1.5 to 2.7 kDa were predicted and chemically synthesized, one of which, designated NP-6, inhibited activity against all the tested strains according to antimicrobial assay. Time-killing assay indicated that NP-6 could quickly kill almost all the Escherichia coli within 180 min and Staphylococcus aureus at 360 min. Moreover, the simulation 3D structure of NP-6 was consisted of α-helix and random coil, and this was verified by circular dichroism (CD) spectra. At last, the scanning electron microscope (SEM) images of E. coli and S. aureus treated by NP-6 demonstrated that NP-6 had a significant effect on bacteria cell morphology. Our findings provide an efficient approach for discovery of AMPs, and Z. bungeanum Maxim seeds may be a nature resource to extract antimicrobial agents.

Bacillus spp. are the dominant spoilage organisms in a rehydrated non-fermented soy product, Sichuan yuba in China. In this study, we used two spoilage Bacillus amyloliquefaciens strains DY1a and DY1b to evaluate their destructive capability on rehydrated Sichuan yuba at 25 °C. Compared with the uninoculated soy product, the texture profile of the inoculated samples showed that the hardness, springiness, chewiness, and cohesiveness decreased significantly. Scanning electron microscope (SEM) revealed that the surface of bacteria-inoculated soy product was scattered with deep holes and loose film network structure. The subsequent analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) indicated that the α and α’ subunit of 7S globulin and the acid subunit of 11S glycinin were hydrolyzed by Bacillus during storage. In addition, disulfide bond contents in inoculated samples decreased by 38.7–27.5%. Protein secondary structure characterized using Fourier transform infrared spectroscopy (FTIR) revealed that spoilage Bacillus inoculation reduced the β-sheet by 13.02–14.11%, and increased the β-turn by 15.55–16.00%. Consequently, the texture deterioration of Sichuan yuba was associated with soy protein degradation caused by B. amyloliquefaciens.

In order to evaluate the antioxidant and &alpha, glucosidase activities of polysaccharides from Chrysanthemum morifolium cv. Hangju (CMPs), the response surface methodology was applied to optimize the parameters for extraction progress of CMPs by ultrasound, with heat reflex extraction (HRE) performed as the control. The difference in the physicochemical properties of polysaccharides obtained by the two methods were also investigated. The maximum yields (8.29 &plusmn, 0.18%) of polysaccharides extracted by ultrasonic assisted extraction (UAE) were obtained under the optimized conditions of ultrasonic power 501 W, extraction time 19 min, and ratio of liquid-to-raw material 41 mL/g. Polysaccharides extracted by UAE possessed lower protein contents (2.56%) and higher uronic acids contents (7.08%) and low molecular weight fractions than that by HRE. No significant differences were found in monosaccharide composition and Fourier transform infrared (FT-IR) spectra of polysaccharides extracted by UAE and HRE, while polysaccharides by UAE possessed stronger antioxidant and &alpha, glucosidase inhibitory activities. Therefore, UAE was an efficient way to obtain CMPs.

In order to improve the flavor and stability of purple sweet potato and peanut compound beverage, the orthogonal experiment was used to determine the optimum process of enzymatic hydrolysis and composite stabilizer. The results showed that the ratio of purple sweet potato to peanut was 8: 1 (w / w), and raw to liquid ratio was 1: 8 (w / w). In addition, 0.3% glucoamylase was added to the mixture and incubated at 65°C for 1.5 h. Carrageenan, xanthan gum, sodium alginate and CMC-Na were compound stabilizer at the best concentration of 0.06%, 0.2%, 0.1%, 0.04%.