教学课程资源库 更多>>

关键词： Food change   Irradiated product   Solanum lycopersicum  

摘要： The aim of this study was to evaluate the effect of gamma radiation doses on storage in postharvest conservation of cherry tomatoes in relation to physicochemical characteristics. The samples of cherry tomatoes were submitted to gamma radiation from a source of Cobalt-60 type Gammacell-220 at doses of 0.25, 0.50, and 1.0 kGy and non-irradiated samples, and stored at room temperature during maturation. Analyses of moisture content, ash content, pH, titratable acidity, soluble solids (Brix), ratio (soluble solids/titratable acidity), carotenoids, ascorbic acid - vitamin C, firmness, peel and fleshy mesocarp color - lightness (L*) and Chroma (C*) at 1, 7, 14, 21 and 28 days after irradiation (DAI) were performed. An increase of total carotenoids and weight loss has been observed as the irradiation dose increased over storage time of cherry tomatoes. The firmness of irradiated group of cherry tomatoes was lower than that of control non-irradiated from 7 DAI. Irradiation did not alter the values of ash contents (0.50-0.62%), pH (6.8-7.2), and peel color L* (32-41) of cherry tomatoes compared to non-irradiated tomatoes. The storage periods of cherry tomatoes also were responsible for the differences observed in titratable acidity, total carotenoids, vitamin C, weight loss and firmness;therefore, it was affirmed that the fruits presented behaviors equal to those expected, since during the ripening and senescence period there are changes in the physicochemical characteristics of most fruits. Thus, it was concluded that irradiation up to 1.0 kGy gamma-rays could improve sufficiently the postharvest conservation of cherry tomatoes to satisfy the consumer with acceptable nutritional quality.

关键词： Waxy rice starch   Enzymatic digestion   USANS   SAXS   Porous granules   Acid milk gels  

摘要： Waxy rice starch granules were digested by amyloglucosidase at 50 degrees C for up to 24 h. Granular and lamellar structures of the digested starch granules were studied using particle sizing, scanning electron microscopy (SEM), ultra-small angle neutron scattering (USANS), and small-angle X-ray scattering (SAXS). The appearance of spherical pores on the starch granule surface upon enzymatic digestion is identified by SEM. USANS was able to monitor changes in the pore polydispersity as digestion progressed. The size of the digested starch granules decreased with digestion time up to 8 h owing to enzymatic degradation. Excessive digestion (15 h and 24 h) resulted in a slight increase in apparent starch granule diameter, suggesting that the particles might be swollen or aggregated. Thermal (50 degrees C) and enzymatic treatments of the starch granules induced a destruction of the starch internal lamellar structures, with enzymatic digestion showing a more prominent effect. Incorporation of the digested starch granules into acid milk gels in a pasted form resulted in a decrease in elasticity, while their incorporation in a granular form resulted in a marked (nearly 3-fold) increase in the elasticity of the acid milk gels.

关键词： Hot extrusion   Extruded microparticulated whey proteins   Reduced-fat yogurt   Creaminess   Viscosity  

摘要： This study investigated the influence of various form and sizes of microparticulated whey proteins (MWPs) in powder and liquid extruded microparticulated whey proteins (eMWPs) on the physicochemical and sensory properties of reduced-fat (<0.5 g/100 g), plain-type stirred yogurts (formulations F1, F2, F3, F5, and F6). The full-fat (3.5 g/100 g) yogurt formulation (F4) was used as a reference standard. Subjects included 36 individuals who took part in the sensory test. eMWPs showed significantly (p < 0.01) lower rates of syneresis and higher firmness compared to Simplesse and other market products, whereas the dry matter content and hydration process playing an important role. Viscosities were decreased by increasing the particle size of eMWPs within the range of 0.1-10 mu m, which showed a strong correlation with firmness and creaminess of reduced-fat yogurts. These outcomes indicated the strength of the yogurt gel and the possibilities of controlling the creaminess of reduced-fat yogurts by adjusting the size of the microparticles. Thus, for the sensory test of reduced-fat yogurt, F1 and F2 with eMWPs were highly ranked compared to reference yogurt.

关键词： Nigella sativa seed oil   Physicochemical properties   Al-Qassim, KSA  

摘要： An investigation of physicochemical properties of Nigella sativa seed oil from Al-Qassim, KSA was con-ducted using cold press and Soxhlet extraction methods. The effect of solvent polarity on the oil components and properties were examined using hexane, tetrahydrofuran, ethanol, dichloromethane, methanol and methanol-water binary system. The results demonstrated a high yield of oil with the Soxhlet method using ethanol (40.16%) while the samples extracted with the methanol-water binary system produced the lowest yield (28.28%). Linoleic acid was the major free fatty acid in all samples followed by oleic and palmitic acids. Moreover, the triacylglycerol analysis was carried out using a high-performance liquid chromatography system. The results revealed that the studied oil samples were rich in unsaturated triacylglycerols mostly as 3 Linoleic acid (LLL) but low in saturated triacylglycerols. Thymoquinone, which is known as a powerful antioxidative and antiradical agent was detected in all samples except the sample extracted with the methanol-water binary system. The effect of solvent polarity and the solvent boiling point was observed through the quantity of the main components of each oil sample even though they are from the same source of seed. This study showed that the aforementioned properties were affected by the polarity of the solvent used during the extraction process. (C) 2020 The Authors. Published by Elsevier B.V.

关键词： Carbon-based materials   Oxygen reduction reaction   Hydrogen peroxide electrosynthesis   Structural and electrochemical characterization  

摘要： Carbon-based catalysts are widely used in oxygen reduction reactions (ORR) via 2e- H2O2 electrogeneration. The direct comparability of the structural proprieties of different carbon matrices applied on ORR, however, has never been tested. Here, we evaluate how the electrochemical and structural properties of different carbon-based materials, including carbon Printex XE2B (PXE2BC), Printex L6 (PL6C), carbon derived from lignin (LIGC), graphite (GRA) and glassy carbon (GC), affect on ORR. All the materials were characterized by Raman spectroscopy, X-ray photoelectron spectrometry (XPS), elementary analysis, field emission gun scanning electron microscopy, surface area measurements and electrochemical assays for the evaluation of ORR. Notably, the morphology, the size of the particles and the types of functional groups present in the structure of carbon materials were keys in the efficiency of ORR. The carbon materials PL6C and PXE2BC with high surface area and oxygenated functional groups in their structure displaced the ORR potential, facilitating the reaction. Carbon materials with less surface area, such as GRA, LIGC and GC, and whose main functional groups in their structures were non-oxygenated or nitrogenated, were less active in ORR. The displacement of the potential and the efficiency of H2O2 generation were directly dependent on the electrochemical and structural characteristics of the materials used as catalysts. These results are particularly relevant regarding a proper choice of carbon catalyst can increase the efficiency of ORR. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Powdered infant formula milk   Radio frequency   Cronobacter sakazakii   Color   Protein denaturation  

摘要： Radio frequency (RF) has been proved effective in inactivating Cronobacter sakazakii in powdered infant formula milk (PIFM). For successful industrial application, the quality of PIFM after combined RF and hot air treatment (RF-HA) were further investigated based on 5-log inactivation of Cronobacter sakazakii as compared with hot water treatment (HW). Severer color deterioration was observed on HW treated samples. No significant difference existed on solubility (>99%) and crude protein content (about 13 g/100 g) after both treatments. Protein denaturation temperature obtained from the differential scanning calorimetry curves increased with decreasing moisture content of PIFM and RF-HA resulted in more stable protein structures. Fourier transform infrared spectrum further confirmed the development of Maillard reaction, which was weaker in RF-HA. Microstructure by scanning electron microscopy revealed more obvious particle agglomeration behavior induced by RF. Overall, higher water activity, 0.4 as the upper limit, was not good for maintenance of nutritional attributes, though conducive to sterilization. This study could provide useful information for PIFM quality evaluation and optimization of thermal pasteurization methods.

关键词： Porosity  

摘要： This study aims at evaluating the impact of pumpkin powder (12%) and Basil seed gum (BSG) (0.00%, 0.50%, 1.00%, and 1.50%) on the physicochemical, rheology, textural properties, and sensorial parameters of sangak bread. First, the fresh pumpkin slices (5mm thickness) were dried (hot air, 65 degrees C) and samples were powdered and used in sangak bread formulation. Pumpkin bread dough formulated with basil gum showed pseudoplastic and thixotropic behavior. The bread dough viscosity increased from 10.95 to 21.53 with increasing BSG percent from 0.00% to 1.50% (p < .05). With increasing BSG percent, the density of baked breads was reduced from 880.10 to 692.45 kg/m(3). The control sample had an average bread volume of 65.38 cm(3), increasing to 70.74, 75.41 and 83.95 cm(3) for 0.5%, 1.0% and 1.5%, respectively (p < .05). The surface color of samples was affected by the addition of BSG. The L* index raised from 61.84 to 74.12 with rising BSG levels from 0.0% to 1.5%, while b* index and a* index values reduced from 48.25 to 39.57 and 9.73 to 5.27 with rising BSG concentration from 0.0% to 1.5%, respectively, (p < .05). The pumpkin bread with 1.50% BSG demonstrated a color, with L*, a*, and b* indexes equal to 74.12, 5.27, and 39.57, respectively. The weight, moisture content (MC), and volume values of breads increased from 52.83 to 58.12 g, 30.04% to 37.29%, and 65.38 to 83.95 cm(3), respectively. BSG improved the porosity of the breads and results in reduced baking loss and softer bread product. The sangak bread with 1.5% BSG had the best score of color, porosity, and appearance, and the bread with 1% BSG hd the highest satisfactory in terms of flavor, textural properties, and total acceptance (p < .05). Practical applications In the breads, hydrocolloids (gums) have been utilized to develop dough quality, baked breads properties, textural and sensorial parameters, and extension of product shelf life. This study evaluated the effect of pumpkin powder and Basil seed gum

关键词： drug release   ibuprofen‐   loaded   PLA   IBU electrospun mats   poly(lactic acid)  

摘要： To solve the problems of limited drug solubility and poor biodistribution with polymers in drug delivery system, ibuprofen (IBU) is chosen to prepare IBU-loaded poly(lactic acid) (PLA) micro-fibrous mats via electrospinning. Distinguished from the previous studies, a lower toxic binary solvent dichloromethane/ethanol (DCM/EtOH, v/v = 8/2) is used to successfully fabricate PLA/IBU electrospun mats with outstanding properties. In order to further evaluate the effects of IBU content on PLA, there are characterization methods employed as follows: scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and UV-vis spectrophotometer. The results show that IBU can be physically and uniformly distributed both on the surface and inside of PLA fibers. Compared with pure PLA mats, the crystallinity and mechanical properties of PLA/IBU electrospun mats has significantly improved. Meanwhile, in vitro drug release behavior demonstrates that with the increasing content of IBU, the rate of IBU release has increasingly improved. Particularly, the release behavior of PLA/IBU mats exhibited best with 20% IBU content, and the release amount reached 74.3% at the end of 240 h. Considering all these features, PLA/IBU electrospun mats have the potential to be used in the fields of wound dressing and drug delivery.

关键词： alginate   carbonated water   gelation   hydrogel   wound dressing  

摘要： Hydrogels are highly biocompatible materials, and alginate is utilized for wound dressing. Contrary to traditional beliefs, alkaline conditions (ie, pH of approximately 8.5) are favorable for healing wounds. However, existing wound dressing materials are employed under neutral or weakly acidic (pH 5.5-6.5) conditions. To address this issue, in this study, we successfully prepared alkaline calcium alginate hydrogels using carbonic acid and evaluated their physicochemical properties. Using inversion tube tests, we determined that the gelation time of the hydrogels was less than 5 minutes. Furthermore, the pH measurements demonstrated that the prepared gels were alkaline (pH of 8.38-8.57) due to the volatilization of carbon dioxide from the hydrogel surface. Due to the short gelation time of the hydrogels, they can be prepared immediately before use under medical settings, and the pH of the hydrogels may facilitate the proliferation of fibroblasts and keratinocytes. In addition, the physicochemical properties of the prepared hydrogels were determined to be excellent with respect to transparency, the ability to absorb physiological saline, and possessing a high water content (approximately 99%). The hydrogel prepared in this study may have applications in wound dressings.

关键词： MOF   Cerium   Composite   Carbonaceous material   Electrochemical process  

摘要： Ce/carbonaceous matrices-based composites with potential application in electrochemical processes were successfully produced. Ce-based MOF-76 (Metal Organic-Framework-76 family, formed by lanthanide ions coordinated to 1,3,5-benzenetricarboxylic acid ligand - H3BTC or simply BTC) was prepared with different percentages of graphene oxide (GO) in situ (named Ce-BTC-GO(X%)), then calcined to CeO2-rGO(X%). All obtained materials were characterized by physicochemical techniques. The presence of carbonaceous matrices in the composites improves their thermal stability, alters particles shape, and decreases their size. All materials underwent Cyclic Voltammetry tests and selected composites were evaluated by Electrochemical Impedance Spectroscopy, Hydrogen Evolution Reaction and Oxygen Evolution Reaction. The electron transfer between Ce3+/Ce4+ redox pairs is observed around 1.3 and 1.2 V vs. Ag/AgCl(***) for oxidation and reduction, respectively. Among all produced materials, the Ce-BTC-GO(30%) presented the best electrochemical response, reaching 0.506 A g(-1) of anodic current and 19.92 C g(-1) of charge density. Its capacitance reaches 3340.8 mu F cm(-2), while its resistance to charge transfer decreases (2.4 Omega cm(2)) and Tafel equation slopes are 84.3 mV dec(-1) for HER and 60.5/127.9 mV dec(-1) for OER.