教学课程资源库 更多>>

关键词： Oxidation  

摘要： Various physical, chemical, and biological practices have been adopted in the meat industry to enhance the tenderness of aged chicken meat. Among these, electrical field stimulation is used as an innovative tool in enhancing meat quality. Purposely, the present study was designed to evaluate the effectiveness of electrical stimulation (ES) on different quality attributes (chemical, physical, & sensory) of laying aged chicken (Gallus domesticus) carcasses. To assess the effect of ES on meat quality of aged chicken (1.5 years), a total of 54 birds were slaughtered and their respective carcasses were subjected to electric field strengths (EFSs) of 3.67 and 7.33 V/cm. Physicochemical and sensorial characteristics of the ES-treated groups (3.67 and 7.33 V/cm) and control group (without ES) meat were compared during the storage periods 0, 30, and 60 days. The results revealed that the electrical conductivity and specific energy consumption increased significantly with an increase in the EFS. ES significantly (p < .05) decreased peroxide number (by 12.62%), free fatty acids (FFA;by 13.46%), drip loss (by 4.25%), and cooking loss (by 50.85%), and increased pH (by 5.90%). Besides, ES-treated samples showed significant superiorities in terms of sensory characteristics in comparison with control samples. An artificial neural network (ANN) gave a good fitting to predict the development of peroxide value and FFA during storage. Practical applications Electrical stimulation (ES) has been studied as a means to reduce the time required for aging to prevent meat hardness. ES improves the tenderness of meat by reducing cut values, increasing the sarcomere length, and reducing the diameter of muscle fibers. The application of ES helps in reducing the storage time, storage cost, de-feathering force, and microbial load on a chicken carcass. Aged chicken meat carcass can be treated by ES before storage to help meat processing industries for storing meat safely. This study aimed to invest

关键词： 1   2   3   4-tetrazine 1   3-dioxides   atom-atom potentials method   crystal structure prediction   DFT   density functional theory   explosive parameters   high-energy-density materials   molecular structure   thermochemistry  

摘要： Simulation of crystal structures of series 1(2)-R-1(2)H-[1,2,3]triazolo[4,5-e][1,2,3,4]tetrazine 5,7-dioxides, 1,5,7-trioxides, 4,6-dioxides and 3,4,6-trioxides was carried out using an original technique based on the method of atom-atom potentials and quantum chemistry. The effect of the position of the substituent in the triazole ring on the change in the crystal structures of these compounds and their thermochemical characteristics was studied for the first time. For some of synthesized compounds, thermochemical characteristics were investigated and differential scanning calorimetry curves were obtained. Detonation parameters were calculated, on the basis of which the prospects for the use of the considered compounds were assessed.

关键词： Chemical modification   Coating   Films   Polyethylene glycol   Starch  

摘要： This study proposes a simple route to obtain starch grafted copolymers from cassava and banana starches chemically modified with amphiphilic maleic anhydride-poly (ethylene glycol) methyl ether (Ma-mPEG). The starches were extracted from cassava (StC) and banana (StB) pulp and characterized by FTIR spectroscopy, amylose content, scanning electron microscope (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and average molecular weight. Starches were chemically modified with amphiphilic Ma-mPEG in three mass ratios 1:1, 1:2 and 1:3. Thermal behavior and interactions of Ma-mPEG/starch in the Stg-(Ma-mPEG) copolymers were studied by DSC and TGA. The T-g values showed a higher plasticizer effect in the copolymers obtained from StC. Films were formed from StC-g-(Ma-mPEG) and StB-g-(Ma-mPEG) copolymers, thermal and morphological properties were studied. An increase in the mass ratios of Ma-mPEG and the absence of the glycerol in the formulations formed homogeneous films. StC-g-(Ma-mPEG) 1:3 with 2% concentration showed a potential use as coating in strawberries, presenting a lower weight loss (15.5 +/-& nbsp;5.7%) than the control sample (18.6 +/-& nbsp;3.3%).

关键词： fused porphyrins   directly linked corroles   metal complexes   electrochemistry   magnetic properties  

摘要： Metal complexes of doubly and triply linked porphyrins and corroles are presented with a particular focus on their electrochemical, electronic and magnetic properties. The potential utility of these compounds as electrocatalysts for energy related research is elucidated with the help of recent examples.

关键词： fused porphyrins   directly linked corroles   metal complexes   electrochemistry   magnetic properties  

摘要： Metal complexes of multi-porphyrins and multi-corroles are unique systems that display a host of extremely interesting properties. Availability of free meso and beta positions allow formation of different types of directly linked bis-porphyrins giving rise to intriguing optical and electronic properties. While the fields of metalloporphyrin and corroles monomer have seen exponential growth in the last decades, the chemistry of metal complexes of bis-porphyrins and bis-corroles remain rather underexplored. Therefore, the impact of covalent linkages on the optical, electronic, (spectro)electrochemical, magnetic and electrocatalytic activities of metal complexes of bis-porphyrins and -corroles has been summarized in this review article. This article shows that despite the (still) somewhat difficult synthetic access to these molecules, their extremely exciting properties do make a strong case for pursuing research on these classes of compounds.

关键词： Ultrasonic treatment   Red bean protein   Lutein   Interactions   Functional properties  

摘要： The complexation of red bean protein (RBP) and lutein (LU) enhances the functional properties of proteins and increases their applicability as nutraceuticals for LU. The effects of ultrasonic treatment on the interactions between RBP and LU, physicochemical properties, antioxidant activities, and digestion behaviors of RBP-LU complexes were investigated. Ultrasonic treatment promoted the non-covalent binding of RBP with LU through hydrophobic interactions, causing the binding site to be closer to tryptophan than tyrosine. This process resulted in a more flexible secondary structure and less compact tertiary conformation of complexes with higher binding ratios, surface hydrophobicity, surface charge, and smaller particle size. The enhanced RBP-LU interactions and structural modifications of complexes induced by ultrasound possibly enhanced the functional properties. Ultrasonic treatment maximized the emulsifying and antioxidant activities of these complexes, and also enhanced the release of LU in the intestine by altering the digestion behavior of the complex, thereby improving its bioaccessibility. An appropriate ultrasonic treatment could facilitate RBP-LU interactions and modify the structure of complexes to improve their functional properties.

关键词： Cow ghee   Microfluidization   Rheology   Particle size   Thermal analysis   Fourier transform infrared  

摘要： Application of microfluidization can influence physicochemical, structural, rheological and functional properties of the food matrix, significantly. In the present research, effect of high pressure microfluidization treatment (50-200 MPa, single pass) on pH, refractive index (RI), free fatty acid (FFA) values, colour measurements, rheology, particle size, structural properties and thermal properties of cow ghee (CG) were investigated. Upon microfluidization, the pH values of CG significantly increased from 4.5 to 4.9. The shear-thinning nature of microfluidized CG was demonstrated by a Rheogram between apparent viscosity and shear rate. At 50 MPa, the apparent viscosity of the sample increased but then decreased as the microfluidization pressure was increased. Thermal analysis revealed an increase in glass transition temperature (Tg) at 50 MPa from 32 to 37 C and a significant effect was observed on it as the pressure was increased. GC-MS analysis revealed that micro fluidization at 150 MPa reduced the cholesterol level in CG by 39.37%. The current research is the first one on microfluidization of CG and can open new channels on the research end.

关键词： Chemical structure   Hydrocarbons   Liquids   Physical chemistry   Surfactants  

关键词： Hydroxyapatite  

摘要： Ductal carcinoma in situ (DCIS) is frequently associated with breast calcification. This study combines multiple analytical techniques to investigate the heterogeneity of these calcifications at the micrometre scale. X-ray diffraction, scanning electron microscopy and Raman and Fourier-transform infrared spectroscopy were used to determine the physicochemical and crystallographic properties of type II breast calcifications located in formalin fixed paraffin embedded DCIS breast tissue samples. Multiple calcium phosphate phases were identified across the calcifications, distributed in different patterns. Hydroxyapatite was the dominant mineral, with magnesium whitlockite found at the calcification edge. Amorphous calcium phosphate and octacalcium phosphate were also identified close to the calcification edge at the apparent mineral/matrix barrier. Crystallographic features of hydroxyapatite also varied across the calcifications, with higher crystallinity centrally, and highest carbonate substitution at the calcification edge. Protein was also differentially distributed across the calcification and the surrounding soft tissue, with collagen and beta-pleated protein features present to differing extents. Combination of analytical techniques in this study was essential to understand the heterogeneity of breast calcifications and how this may link crystallographic and physicochemical properties of calcifications to the surrounding tissue microenvironment.