摘要：
Without slight doubt synthesis of carboxylic acids and their derivatives through the carboxylation reactions of organometallic compounds using CO2 as the raw material are one of the most attractive and hot research topics in the field of CO2 utilization. Therefore, broadening the scope of nucleophilic reagents for this appealing page of carboxylic acids synthesis is always interesting. Over the past few decades, organoboron compounds have aroused great interest in the organic chemistry community as promising organometallic reagents owing to their high stability, reactivity, safety, and easy accessibility. Not surprisingly, these compounds have recently found application in the area of CO2-fixation reactions. This review describes the achievements that have been reported on this fast-growing research arena.
摘要：
Synthesis of carboxylic acids and derivatives using CO2 as a sustainable and renewable source of carboxyl is most probably the area that has experienced the most growth in the field of CO2 conversion reactions. Over the years, an enormous effort has been put forth by scientists toward exploration of the utility of various nucleophilic partners in the coupling with electrophilic CO2. Organosilicon compounds are one of the latest nucleophilic reagents that was joined to the story of carboxylation reactions with CO2 and has been the subject of a number of studies in recent years. The aim of this review is to present an overview of the recent advances and achievements of the desilylative carboxylation of organosilicon compounds, with particular emphasis on the mechanistic aspects of the reactions.
关键词：
Maillard reaction;Pickering emulsion;curcumin;thermal stability;whey protein
摘要：
In this study, whey protein isolates (WPI), lactose (Lac) Maillard-reacted products, and epigallocatechin gallate (EGCG) complex were used to enhance the thermal stability of the Pickering emulsion delivery of curcumin. Atomic force microscopy combined with Fourier transform infrared spectroscopy were employed to study the morphological characteristics and structural changes of WPI-Lac/EGCG nanoparticles. Results proved that WPI-Lac and EGCG were combined by hydrogen bonding and hydrophobic interaction. The mechanism underlying WPI-Lac/EGCG-stabilized Pickering emulsion was further characterized by confocal laser scanning microscopy. The optimal binding ratio of WPI-Lac to EGCG was 1:1 (w/w) at pH 3.0. The particle size and zeta potential of the WPI-Lac/EGCG nanoparticles were about 110 nm and 27 mV, respectively. Analysis of microstructure and droplet size distribution revealed that the glycated WPI-Lac/EGCG-stabilized emulsions exhibited more uniform droplet distribution, stronger thermal stability, and higher curcumin percentage retention than WPI. These results indicate that the WPI-Lac/EGCG nanoparticles are potential stabilizers for Pickering emulsion requirements. This study provides a basis for the construction of Pickering emulsion systems while carrying pro-/hydrophobic bioactive components.
摘要：
Purple sweet potato anthocyanins are common natural pigments widely used in food industry, while they are often thermally processed in application. Degradation of anthocyanins, formation of polymers and color changes of purple sweet potato extract (PSPE) were investigated at 90 degrees C in the range of pH 3.0-pH 7.0. Data analysis indicated a first-order reaction for anthocyanins degradation in solutions with pH 3.0, 5.0 and 7.0 have half-lives of 10.27, 12.42 and 4.66h, respectively. The polymeric color formation followed zero-order kinetics, progressively increasing with pH values. The color of PSPE were changed with heating time and pH value through visual observation and colorimetric characterization. Analysis by UV-Vis spectrophotometry and HPLC indicated that anthocyanins in solution with pH 3.0 changed from monomeric anthocyanin into new polymers during heat treatment. Degradation of anthocyanins was accompanied by an increase in polymeric color index, due to the formation of melanoidin pigments and condensation reactions.
摘要：
In this study, pectin was applied as a carbohydrate-based coating to improve physicochemical stability of sodium caseinate/zein (CZ) complex protein nanoparticles. Pectin coating was achieved via a pH- and heating-induced facile electrostatic adsorption process. The effect of pectin coating was tested on two different nanoparticle structures, i.e. solid and hollow CZ nanoparticles. The inter- and intra-molecular interactions between proteins and pectin were characterized by Fourier transform infrared and fluorescence spectroscopy. Pectin coating significantly improved the stability of nanoparticles under gastrointestinal conditions, showing minimal change in particle size and polydispersity. Our results showed that pectin coating not only significantly increased the capability of protein nanoparticles to encapsulate curcumin and but also provided sustained release under gastrointestinal conditions. Pectin coated CZ nanoparticles demonstrated exceptional stability by maintaining their morphology before and after freeze-drying. Therefore, pectin coating is an effective strategy to potentially realize practical applications of protein nanoparticles as oral delivery vehicles. (C) 2017 Elsevier Ltd. All rights reserved.
摘要：
Kafirin, the prolamin protein from sorghum, was fabricated into spherical nanoparticles and then introduced as a fully natural interfacial stabilizer for Pickering emulsions. Kafirin nanoparticles produced via anti-solvent precipitation method exhibited water over oil wetting preference. The resultant oil-in-water emulsions exhibited resistance against coalescence with internal oil phase fraction ranging from 58.8% to 78.6%. Emulsion droplet size distribution and rheological properties of emulsions stabilized by kafirin particles were influenced by the applied particle concentration, oil fraction and ionic strength in aqueous phase. Basic trends included: increasing particle concentration in aqueous phase led to increase in emulsified phase volume, decrease in oil droplet sizes and increase in storage moduli for the visco-elastic responses; As oil phase fraction increased, the emulsified phase volume fraction and droplet size increased, and the rheological properties shifted from fluid dominant to elastic dominant. The addition of salt in aqueous phase promoted the migration process and lifted the stiffness of gel-like emulsions. Cryo-scanning electron microscopy (cryo-SEM) and optical microscopy under fluorescence field evidenced the attachment of kafirin particles on oil-water interface. Overall, kafirin nanoparticles offer promising prospects in fulfilling the demands of "surfactant-free" emulsions with tunable characteristics. (C) 2015 Elsevier Ltd. All rights reserved.
