Digestive protection of probiotic Lacticaseibacillus rhamnosus in Ricotta cheese by monoglyceride structured emulsions

This research aimed at studying the potential use of monoglyceride (MG) structured emulsions (MSEs) as delivery and protective systems for probiotic bacteria in Ricotta cheese. To this purpose, a low-fat commercial Ricotta cheese was added with MSEs formulated with milk, as water phase, and sunflower oil (MSE-SO) or anhydrous milk fat (MSE-AMF), as lipid phase. A commercial whole milk Ricotta cheese (W-RC) was considered as reference. A probiotic Lacticaseibacillus rhamnosus strain was inoculated as free cells in W-RC or embedded into the MSEs and added to the low-fat Ricotta at the same reference fat content. After physico-chemical characterisation, L. rhamnosus viability and sample destructuring behaviour upon in vitro digestion were evaluated. At the end of in vitro digestion, both W-RC and sample containing MSE-SO were unable to protect cells. By contrast, sample with AMF ensured a sufficient probiotic viability, even after 14 days of storage at 4 °C. This result was attributed to system composition and structure. During the gastric phase, the presence of caseins and MG-AMF mixed structures induced the formation of clots, entrapping and protecting cells against the acidic pH of the stomach, as confirmed by confocal micrographs and particle size. During the intestinal phase, cell viability was guaranteed by the formation of mixed micelles promoted by MG. It was demonstrated that microbial cells located near MG structures where they found protection.     

微流控法可控构建微尺度功能材料

微尺度功能材料的功能取决于材料结构和组分的精确协同匹配，但如何实现微尺度空间上多样化材料结构的精确调控和功能组分的精确协同定位仍是一大挑战。本文综述了微流控法可控构建新型微尺度功能材料的研究新进展，重点介绍了基于微流控制备的微尺度相界面体系中材料结构和组分的精确协同匹配来设计构建具有独特结构和功能的微尺度功能材料的新策略。首先介绍了以液滴状和液流状微尺度相界面体系为模板，分别可控构建具有多样化结构的功能微颗粒和微纤维的进展；然后介绍了以微通道受限空间内微尺度相界面体系为模板、原位可控构建微通道膜和功能微阀的进展。今后研究应关注于微尺度相界面体系的结构扩展创新及其规模化制备技术。     

Double emulsions (W/O/W): physical characteristics and perceived intensity of salty taste

This study addressed the correlation between physical characteristics of double emulsions and sensory perception, as the microstructure of these systems may provide the mechanism to understanding the initial cause of the altered salty taste. Thus, double emulsions (W/O/W) were prepared using different volumes of the internal aqueous phase while maintaining the same fat and sodium contents in the evaluated systems. Polyglycerol polyricinoleate (PGPR) and tween 80 were used as hydrophobic and hydrophilic emulsifiers, respectively. After preparation, the samples were stored at 25 °C for 4 days and submitted to analysis of optical microscopy, distribution and polydispersity of the oil droplets size, electrical conductivity, rheological behaviour and sensorial analysis. It was found that the use of different emulsifier concentrations (PGPR) did not influence the physical characteristics of the emulsions with the same formulation, but emulsions with different internal aqueous phase concentrations presented different results. These distinct characteristics may have influenced sensorial perception, as the emulsion with higher internal phase concentration was considered saltier. Thus, it can be concluded that structural differences of the double emulsions can be used to decrease the sodium contents without perceivable changes in salty taste.     

纳米SiO2防气窜乳液制备及分散稳定性研究

针对高温高压超深油气井防气窜固井技术难题,以纳米SiO2作为原材料制备的防气窜乳液具有良好的抗温性和防气窜效果,但超细纳米材料颗粒表面存在非常多的硅羟基,极易团聚在一起,乳液里的固相材料会沉淀、结块,造成产品失效。本文以搅拌分散为实验手段,研制了纳米SiO2防气窜乳液,通过Zeta电位、表观黏度、粒径分析、稳定性分析等表征方法,研究了影响乳液分散稳定性的化学因素。结果表明:纳米SiO2乳液的pH值应在11~12,颗粒间的静电斥力强,乳液的平均粒径小、表观黏度低,分散效果好;电解质存在压缩双电层效应,可大幅度降低纳米颗粒间的静电斥力,制备纳米SiO2防窜乳液应避免引入电解质;电位阻型分散剂SCNF加量达到5%时就接近饱和吸附量,当分散剂加量过大后,只能对外相水产生增黏作用;加入稳定剂增加了纳米SiO2颗粒的布朗运动阻力,可以大幅度提高纳米SiO2防窜乳液的稳定性,所制得的乳液平均粒径小于200 nm,固含量可达45%,室温下可储存一年以上,底部无析水沉淀现象。     

Liquid‐Filling Polydimethylsiloxane Composites with Enhanced Triboelectric Performance for Flexible Nanogenerators

Material functionalization of triboelectric nanogenerators (TENG) plays an important role in TENG's electric performance for sustainable energy harvesting. In this work, a method for improving polydimethylsiloxane (PDMS) composites triboelectric performance has been proposed, via filling high dielectric constant liquid (instead of solids) into PDMS matrix. The improvement is attributed to the high dielectric constant liquid in PDMS matrix that reduced the effective thickness of PDMS and increased the dielectric constant of PDMS composite synchronously. At 50% filling ratio (PDMS‐HD50), the triboelectric performance exhibits an enhancement of 4.5‐fold in output voltage and 3.9‐fold in output current as compared to pure PDMS. The results, besides higher transparency, are superior to the results from traditional solid dielectric constant doping materials like BaTiO₃ nanoparticle in PDMS. This work has proved potentials of dielectric liquid filling materials in fabricating TENGs and could be a guidance for exploring new liquid filling materials.     

天然大豆分离蛋白稳定高内相乳液的制备及表征

本研究以天然大豆分离蛋白(SPI)为原料,探究了其稳定高内相乳液(HIPEs)的基本性质。对SPI的SDS-PAGE电泳、平均粒径,ζ电位进行表征与测定,探讨了蛋白浓度对稳定HIPEs显微结构、油滴粒径及流变性质的影响。结果表明:实验室制备SPI颗粒性质优良,为天然低变性率SPI。新鲜制备的HIPEs呈凝胶状,将其放置在室温下储藏6个月后仍保持稳定,稳定性优于牛血清白蛋白(BSA)及酪蛋白酸钠(SC)稳定的HIPEs。显微结构图表明其内部存在紧密堆积的网络结构。蛋白浓度为1.0 wt%时,SPI稳定HIPEs的最高油相体积分数为0.87。油相体积分数为0.8时,SPI稳定HIPEs的最低蛋白浓度为0.6 wt%。流变性质表明HIPEs内部存在以弹性为主的凝胶网络结构,随着蛋白浓度的增大,油滴粒径逐渐减小且呈均匀分布,粘弹性能逐渐增大。本研究对于开发新型高脂健康食品提供了新思路。