Improved aqueous solubility,bioaccessibility and cellular uptake of quercetin following pH-driven encapsulation in whey protein isolate

The purpose of this study was to increase the water solubility and potential bioavailability of quercetin by encapsulation in whey protein isolate (WPI) based on a green, efficient pH-driven method. According to the results, the water solubility of quercetin increased by 346.9: times after loading into WPI nanoparticles. When the initial quercetin concentration was 0.25 mg mL⁻¹ and WPI was 2% w/v, the encapsulation efficiency reached 94.1%, the Z-average diameter was 36.63 nm, and the zeta potential was −36.4 mV at pH 7.0. The fluorescence spectroscopy assay suggested the molecular complexation of quercetin and WPI at pH 12.0. X-ray diffraction assay indicated the enclosure of amorphous quercetin in WPI. Correspondingly, the bioaccessibility increased from 2.76% to 31.23% and the Caco-2 cell monolayer uptake increased from 0% to 2.12% after nanoencapsulation. This work confirmed that the pH-driven method is an effective approach to prepare WPI–quercetin nanocapsules to improve physical and potentially biological properties of quercetin.     

The effect of Acetobacter sp. and a sulfate-reducing bacterial consortium from ethanol fuel environments on fatigue crack propagation in pipeline and storage tank steels

This paper evaluates the effects of microbiologically influenced corrosion (MIC) on fatigue-crack growth of candidate materials useful in expanding bio-ethanol usage, including a storage-tank steel (ASTM A36) and two pipeline steels (API 5L X52 and X70). The microbiological species sampled and cultivated from an ethanol fuel production stream are responsible for both acetic acid and hydrogen sulfide production that lead to significant increases in fatigue-crack growth rate across a wide range of stress-intensity-factor amplitudes (ΔK). The mechanism for increased fatigue damage is hydrogen uptake through adsorption into the steel, which embrittles material ahead of the growing fatigue crack.     

Selected Saccharomyces cerevisiae yeast strains and accurate separation of distillate fractions reduce the ethyl carbamate levels in alembic cachaças

Ethyl carbamate (EC) is a potentially toxic compound that may be present at concentrations above maximum limits established in alcoholic beverages, such as cachaça. Most traditional alembic cachaça is produced on a small scale using empirical knowledge. The fermentation step is conducted using yeasts that are endogenous to the sugar cane, and the distillation process is relatively uncontrolled. In this study, gas chromatography coupled with mass spectrometry was used to determine the EC levels in distillate musts and fractions produced by spontaneous or selected Saccharomyces cerevisiae strains. The aim was to verify the influence of selected strains as starters for fermentation compared with spontaneous fermentation on EC formation. The distillate fractions from these two production processes were also analysed. Our results demonstrated higher levels of EC (which surpass the limits defined by Brazilian law) in cachaças produced by spontaneous fermentation (50%) compared with the selected strains (30%); and the distillation step showed great contribution for the reduction of the compound. From must to distillate fractions we found an average decrease on EC levels of 62% using selected strains and 44% for the spontaneous fermentation. In addition, careful separation of the distillation fractions was crucial for producing high-quality and safe beverages.     

Effect of electron beam irradiation on the functional properties and antioxidant activity of wheat germ protein hydrolysates

In this paper, the effects of electron beam irradiation (EBI) on wheat germ protein hydrolysates (WGPHs) were investigated. The functional properties of WGPHs were enhanced by EBI, with the emulsifying capacity reaching its maximum value at 10 kGy. Moreover, foaming capacity reached its maximum value at 25 kGy. Additionally, EBI can enhance the antioxidant activity of WGPHs, and a dose-dependent effect was observed. Hydrolysates irradiated at 50 kGy had the greatest antioxidant activity; the DPPH and ABTS⁺ radical scavenging activities increased by 45.77% and 52.52%, respectively, compared to the non-irradiated sample. Additionally, surface hydrophobicity reached its minimum value at 10 kGy. After 10 kGy of irradiation, the fraction of hydrolysates with a molecular weight <1 kDa increased from 88.34% to 90.23%. Irradiation caused the surface morphology to become uneven, and it produced smaller peptides.     

Synthesis and characterization of a triple enzyme-inorganic hybrid nanoflower (TrpE@ihNF) as a combination of three pancreatic digestive enzymes amylase,protease and lipase

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江苏单二啤酒大麦麦芽麦汁中混浊物质的研究

对江苏单二啤酒大麦麦芽麦汁中混浊物质成分进行了研究,结果表明多糖是麦汁混浊的主要成分,含量为82.57%,其次为蛋白质和多酚。采用离子交换色谱技术对混浊物质中的糖类进行了研究,结果表明糖类物质的单糖组成以葡萄糖为主,其次为半乳糖、阿拉伯糖、木糖。采用SDS-PAGE电泳结合基质辅助激光解析飞行时间串联质谱(MALDI-TOF/TOF)对麦汁混浊物质中蛋白质组分进行了鉴定,结果表明蛋白质分子量主要分布于25~45ku及小于18.4ku的两个部分,且主要来自于麦芽水溶蛋白及醇溶蛋白,质谱分析表明混浊蛋白主要为AMY2/BASI复合体A链,此外还有少量的Z4蛋白、大麦醇溶蛋白γ3、油体钙蛋白2及BTI-CMe2.1。本研究结果对于改良江苏啤酒大麦及其麦芽品质具有指导借鉴意义。     

高效疏水电荷诱导色谱介质的基团修饰及其色谱行为的初步研究

以粒径10μm、孔径300球形硅胶为载体,以γ-缩水甘油醚氧丙基三甲氧基硅烷(KH-560)为中间偶联剂,将4-巯基吡啶键合至硅胶上,制备了高效疏水电荷诱导色谱介质。通过单因素实验,探讨了反应温度、反应时间、KH-560的浓度对活化密度的影响,结果表明,在反应温度为75℃,反应时间为10 h条件下,KH-560的利用率大,可获得较宽范围的活化密度,此外还考察了缓冲液pH、反应温度、反应时间、4-巯基吡啶浓度对偶联密度的影响。结果表明,在pH=7.5的缓冲液,反应温度40℃,反应时间6 h下,4-巯基吡啶利用率高,通过控制4-巯基吡啶的浓度,可获得较宽范围的配基密度。最后,于高效液相色谱条件下,通过等度洗脱,考察了流动相pH对牛血清蛋白和溶菌酶保留因子的影响。并通过梯度洗脱,分离了不同等电点的牛血清蛋白和溶菌酶,验证了该介质的高效疏水电荷诱导色谱行为。     

Preparation of Docosahexaenoic Acid-Rich Diacylglycerol-Rich Oil by Lipase-Catalyzed Glycerolysis of Microbial Oil from Schizochytrium sp. in a Solvent-Free System

Docosahexaenoic acid (DHA)-rich diacylglycerol (DAG)-rich oil was prepared by lipase-catalyzed glycerolysis of microbial oil from Schizochytrium sp. in a solvent-free system. The reaction parameters including lipase type, substrate molar ratio, temperature, lipase concentration, and reaction time were screened. The selected conditions were determined as follows: Novozym® 435 (Novozymes A/S, Bagsvaerd, Denmark) as biocatalyst at 8 wt%, substrate ratio (DHA-rich microbial TAG/glycerol) of 1:1 mol/mol, temperature of 50 °C, and reaction time of 12 hours. Under these conditions, the triacylglycerol (TAG), DAG, and monoacylglycerol (MAG) contents in the product were 36.4%, 48.2%, and 15.4%, respectively. The lipase was reused successively for 18 cycles without significant loss of activity under the conditions given above. Fatty acid composition analysis of the final product showed that the contents of DHA in TAG, DAG, and MAG were 53.9%, 44.9%, and 34.8%, respectively. DHA-rich DAG has the potential to be used as an ingredient in infant formula to increase the bioavailability of DHA.     

木脂素的生物合成及其微生物法生产的研究进展

木脂素是一类分布于植物中的次级代谢产物,由两分子苯丙素衍生物聚合而成。木脂素具有抗细菌、抗病毒和抗真菌活性,被广泛用于药物和食品中。目前,木脂素的生产主要依赖于植物提取。植物生长周期长、木脂素含量低等问题,限制了木脂素的商业应用。随着木脂素合成路径和关键酶的不断解析,木脂素的生物催化合成过程受到了越来越多的关注。本文总结了典型木脂素的生物活性、生物合成路径和微生物法生产的研究进展,可以为深入研究木脂素的微生物合成提供参考。