教学课程资源库 更多>>

关键词： Liposome   Gum Arabic   Sodium alginate   Curcumin   Physical stability  

摘要： Natural biopolymers such as food gums can be effective in improving the physical stability of colloidal particle dispersions. To improve the loading stability of curcumin in liposomes, liposomes with gum arabic (GA) or sodium alginate (SA) (0-2% w/v) were prepared and their physicochemical properties evaluated. Results showed that GA, which has a high surface activity, interacted more with the liposome surface resulting in smaller liposome size and polydispersity. However GA disrupted the internal lamellar structure of the liposomes at low concentrations, resulting in increased flocculation and was associated with poor retention of encapsulated curcumin. In contrast, SA formed a viscious continuous phase due to the gum network which reduced particle mobility and sedimentation, and increased curcumin retention, although this was associated with an increase in particle size and polydispersity index.

关键词： Fermentation-induced gelation   Soy protein isolate   Characterization  

摘要： Influence of lactic acid bacteria (LAB) on gel characteristics of fermentation-induced soy protein isolate (SPI) gel, including hardness, water holding capacity (WHC), pH, solubility, turbidity, particle size, zeta potential, surface hydrophobicity, free sulfhydryl, microstructure, rheological properties and in vitro gastrointestinal digestion was evaluated. First, fermentation increased the turbidity and average particle size, which was supported by a lower degree of solubility and zeta potential absolute value. The surface hydrophobicity was reduced after lactic acid bacteria fermentation, and a similar phenomenon occurred on the free sulfhydryl groups. It was found that fermentation resulted in SPI denaturation, structural changes, and aggregates formation, which were the foundation of gel formation. Subsequently, fermentation-induced SPI gels depended on the lactic acid bacteria used for fermentation, showing the specificity of gel characteristics. Among them, Lactobacillus acidophilus (L. acidophilus), Lactobacillus plantarum (L. plantarum), Lactobacillus casei (L. casei), and mixed strains of Lactobacillus bulgaricus (L. bulgaricus), and Streptococcus thermophilus (S. thermophilus) (1:1) exhibited the high coagulation ability, which could enhance the hardness and water holding capacity of the gels. L. plantarum-G had the lowest solubility and free sulfhydryl content and the highest turbidity, particle size, and zeta potential. Scanning electron microscope (SEM) results showed that L. casei-G and L. plantarum-G exhibited a dense and uniform three-dimensional network. The rheological properties showed that the earliest gel point and the highest storage modulus (G') and loss modulus (G") were acquired by L. casei-G, whereas the G' curve of L. lactis-G was still in the growth stage, and no platform was found in the growth curve. The ability of L. lactis to form gels was weaker. At the same time, the G' and G" of all LAB fermentation-induced gels showed strong freq

关键词： Achyranthes aspera   CuO nanoparticles   Physicochemical and morphological properties   Renewable application  

摘要： The present study was reported with synthesize of copper oxide nanoparticles by ethno botanical species. Bio convivial and compatible approaches were made to utilize the renewable source of leaves extract of Achyranthes aspera Linn as efficient capping and stabilizing agent as well. Also, natural A. aspera was functioned as reductant in the formation of CuO NPs. The phytosynthesized CuO nanoparticles were extensively characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, Scanning electron microscopy, Energy dispersive X-ray diffraction, High resolution tunnelling electron microscopy and also comprehensively examined their biological applications like antibacterial and antifungal susceptibility against E. lenta, E. aerogenes and C. albicans strains. An XRD result of prepared CuO nanoparticles reveals the monoclinic crystalline structure and average crystallite size of 11-16 nm. The morphology variations for different concentrations of precursor material were noticed by SEM image. Furthermore, the crystalline planes found in SAED pattern of synthesized CuO NPs were coincide to the analysed XRD spectra. In the present study, a novel green approach was used to synthesize of CuO NPs for the antibacterial activity of poorly characterized and emerging pathogens of E. lenta and E. aerogenes. Further, the physicochemical, morphological and biological properties of CuO NPs are discussed.

关键词： Lactococcus   Pediococcus   Volatile compounds   Free amino acids   Biogenic amines   Correlation  

摘要： The quality and flavor formation in fermented fish sausages are based on the complex metabolism of microbial community. In this study, the dynamic changes of physicochemical characteristics, volatile compounds, and microbial communities in the naturally fermented tilapia sausage were studied during the fermentation process. The main physical indexes (gel strength, whiteness, and hardness), dominant flavor free amino acids (glycine, alanine, and glutamic acid) and characteristic volatile flavor compounds (hexanal, heptanal, octanal, benzaldehyde, (E)-2-octenal, 4-ethylbenzaldehyde, (E)-2-heptenal, (E,E)-2,4-decadienal, 1-octen-3-ol, 2-pentylfuran, and 2-ethyl-furan) were significantly enhanced after fermentation, and were positively correlated with Lactococcus, Pediococcus, Enterococcus, and Lactobacillus. The microbial metabolic network showed that Lactococcus, Pediococcus, and Enterococcus played a significant role in the formation of physicochemical and flavor characteristics, while the accumulation of biogenic amines might result from the metabolism of Enterococcus, Enterobacter, and Citrobacter. Isolation of lactic acid bacteria in Lactococcus and Pediococcus might be suitable to improve the fermented tilapia sausage. Microbial metabolic network has revealed the physicochemical and flavor formation of tilapia sausage and can provide guidance for future research on screening of starters.

关键词： Physicochemical properties   Starch digestibility   Estimated glycaemic index   High amylose maize starch   Steamed bun  

摘要： Resistant starch (RS) is a portion of starch that resists enzymatic digestion. It is applied in the production of Chinese steamed bun (CSB) to increase daily fibre intake. In this study, the incorporation of type-2 RS known as high-amylose maize starch (HM) (5%, 10%, 15%, 20%, 25% and 30%) and its effect on the rheological and physicochemical properties, nutritional values, in vitro starch digestibility and estimated glycaemic index (eGI) properties of CSBs were determined. High HM incorporation levels increased RS and dietary fibre contents and reduced the pasting viscosities and calorific values of CSBs. The addition of HM-enriched RS also affected total starch content and eventually resulted in the decreased susceptibility of starch to digestive enzymes in vitro. The decrement in starch hydrolysis rate markedly reduced the eGI of HM-containing CSBs. The incorporation of 25% HM into CSBs (eGI = 68.45) could be applicable in developing a nutritious and medium-eGI CSB without jeopardising desirable physical attributes.

关键词： Geopolymers   Alkali-activated materials   Mine tailings   Industrial waste  

摘要： The mining industry produces a large amount of mine waste rock and tailings, which pose a severe threat to the environment. The most common way for the disposal of these industrial wastes is dumping at sites, which contributes to soil degradation and water pollution, and also covers the useful land. Recycling of mine tailings (MTs) in raw material - intensive applications presents a good alternative to manage the waste generated from mining and mineral processing industries. The geopolymer technology provides a green solution to the utilization of MTs, avoiding its negative environmental impacts. This paper is the first part of the review which summarizes the physicochemical and environmental aspects of different types of MTs, as well as the technological aspects of the preparation of geopolymers (GPs) based on them. The work scrutinizes potential environmental and socio-economic risks of the mining industry associated with the accumulation of tailings. The issues of MTs toxicity that should be taken into account when developing methods for disposal of tailings in geopolymers are touched upon. The features of the chemical and mineral composition of tailings used in geopolymers, as well as their physical properties, are systematized and scrutinized. Methods of utilizing MTs as precursors of GPs or aggregates described in the scientific literature, as well as general patterns of the geopolymerization process are discussed. Finally, the key issues in this area that require additional research are highlighted. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： active films   arthrospira platensis polysaccharide   chitosan   food packaging  

摘要： Active films from chitosan incorporated with Arthrospira platensis polysaccharide (APP) of various ratios (0.0%, 0.5%, and 1.0%, w/v) were developed by solution casting. The effect of APP on the structural, physicochemical, mechanical, antimicrobial, and antioxidant properties of the chitosan-APP films (CA-film) was investigated. Fourier transform infrared spectra (FTIR) confirmed successful incorporation of chitosan and APP. The compact structure of the films was observed clearly in scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. X-ray diffraction (XRD) patterns suggest the semi-crystalline structure was increased upon addition of APP. The composite films showed an improved water resistance and vapor barrier properties, and reduced by at least 27.4% and 32.1% in swelling degree (S-d) and water vapor permeability (WVP) compared with chitosan film (C-film), respectively. However, the transparency decreased slightly, which may be due to the shrinkage of the spacing of the polymer interchain. The composite films also displayed enhanced the mechanical properties. The antimicrobial activity of the CA-film showed an increase of at least of 0.41-fold in inhibition zone diameter for E. coli. At a concentration of 1.2 mg/mL, the antioxidant activity of CA-film was enhanced by more than threefold compared with C-film. Therefore, CA-films have good potential as sources of active packaging material for the food industry.

关键词： ingredient functions   molecular structure   nutritional quality   plant‐   based protein   ultrasonic‐   assisted extraction (UAE)  

摘要： Ultrasonication is a green technology that has recently received an enormous research attention for extraction of plant-based proteins and tailoring the functionalities of these ingredients. Ultrasonication is generally used as a pretreatment method in the conventional protein solubilization protocols because it can break the cell matrix to improve the extractability. The rate of protein extraction and increase in the extraction yields depend on operating conditions such as sonic energy density, time of sonication, the substrate to slurry ratio, agitation, and so on. Ultrasonication is also applied to modify the physical, structural, and functional properties of protein-based ingredients, besides simultaneous extraction and modifications. Significant changes that occur in protein physical properties due to sonication include size reduction, rheology, electrical conductivity, and zeta (zeta) potential. These changes are due to cavitation-induced shear leading to changes in secondary and tertiary structures, including protein aggregation and cross-linking due to oxidation. Physical and structural changes affect the resulting ingredient functionality and nutritional quality of protein. Changes in the functional properties, especially hydrophobicity, solubility, emulsion, and foaming, depend on the extent of ultrasound energy applied to the protein. This study aims to review major ultrasound process parameters and conditions for extraction and modification of plant proteins and their impact on protein structural changes and resulting physicochemical, functional, and nutritional properties.

关键词： Silica  

摘要： Agaricus bernardii was a typical mushroom in Inner Mongolia, China, with high metabolic rate, respiration rate and dehydration. The storage time of A. bernardii was very short. It was necessary to prolong postharvest storage. This study was to determine the physicochemical and selected enzyme activities of A. bernardii packed with different barrier packaging materials. The materials concluded low-density polyethylene (PE), poly(butylene adipate-co-terephthalate)/poly(l-lactic acid) (PBAT/PLLA), PBAT/PLLA/hydrophobic silica (0.5S SiO2) and polyamide/PE, respectively. The performance analysis of the materials, gas composition, sensory quality, physicochemical properties, nutritional quality, and index of senility of the mushrooms were measured. The results indicated that the low O-2 (<1%) and moderate CO2 levels (4-7%) in 0.5S SiO2 film maintained a high level of soluble protein, soluble sugar, ascorbic acid, and phenolic contents, inhibited the increase of malondialdehyde, increased the antioxidant enzymes activities of peroxidase and decreased the enzymes activities of polyphenol oxidase. The quality index of the mushroom packed in the 0.5S SiO2 film remained a good condition and kept the market value after 15 days of storage. Practical applications The biodegradable poly(butylene adipate-co-terephthalate)/poly(l-lactic acid) (PBAT/PLLA/SiO2) film has a suitable water vapor permeability and CO2/O-2 permeability radio, which could establish a suitable steady-state inner atmosphere and maintain quality of mushrooms. Compared with the other films, PBAT/PLLA/SiO2 film kept the market value after 15 days of storage and the application of 0.5S SiO2 film could have potential on maintaining the quality of postharvest of Agaricus bernardii. Moreover, expected to replace the nondegradable food packaging material.

关键词： Solvent treatment   Crystallization   Flowability   Compressibility   Ofloxacin  

摘要： Purpose To investigate the potentials of a simple solvent treatment technique for improving the physicochemical and mechanical properties of ofloxacin. Methods Ofloxacin was treated with 5% aqueous ammonia solution at a solid to solvent ratio of 1:3 and treatment time of 4 h in stoppered flasks, then filtered under vacuum. Changes in ofloxacin powder characteristics were monitored using SEM, particle size analysis, IR, DSC, XRD, hydrophilicity, equilibrium solubility, dissolution rate, flowability, and compressibility tests. The effect of PVP K90 and Tween 80 used in two concentrations (0.2% and 2%) was investigated. Crystals of ofloxacin having particle size < 160 mu m were included whenever appropriate for comparison. Results The treated ofloxacin showed bundles of elongated prisms with a wide particle size range (2 to 39 mu m). Average size was reduced from 9.8 to 6.4 and 4.6 mu m with 2% Tween 80 and PVP, respectively. Different analytical techniques confirmed that neither structure modification nor additive molecule incorporation in crystal lattice occurred during treatment. The treated powder showed repose angle 39 degrees, bulk density 0.282 g/cm(3), tap density 0.319 g/cm(3), Hausner ratio 1.13, Carr's index 11.6%, compact hardness 5-6.45 kg, porosity 13-6.38%, and elastic recovery 4.5-8.8%. The corresponding values for untreated ofloxacin were 59.5 degrees, 0.221 g/cm(3), 0.314 g/cm(3), 1.42, 29.6%, 3.74-5.27 kg, 15.38-7.22%, and 4.57-8.83%, respectively. Values were further improved by PVP addition. Conclusions Treating ofloxacin powder with 5% aqueous ammonia solution in the presence of 2% PVP improves the dissolution, flowability, and compressibility of the drug. The treated powder is suitable for the preparation of tablets with few excipients.