超声波辅助SDS反胶束前萃花生蛋白研究

采用SDS(十二烷基磺酸钠)/异辛烷―正辛醇反胶束体系萃取花生蛋白,并采用超声波辅助萃取,主要研究全脂花生粉加入量、缓冲溶液pH值、萃取时间、萃取温度、超声波功率、KCl浓度、SDS浓度、Wo对蛋白萃取率影响。设计正交实验优化萃取工艺,结果表明,最优前萃工艺条件为:花生粉加入量0.015 g/mL、缓冲溶液pH值9、萃取时间40 min、萃取温度35℃、超声波功率270 W、KCl浓度0.25 mol/L、SDS浓度0.07 g/mL、Wo为24;在此条件下,花生蛋白萃取率为89.62%±1.15%。     

Possibilities of using near infrared reflectance/transmittance spectroscopy for determination of polymeric protein in wheat

Possibilities of using near‐infrared reflectance and near‐infrared transmittance (NIR/NIT) spectroscopic techniques for detecting differences in amount and size distribution of polymeric proteins in wheat were investigated. To evaluate whether differences in polymeric protein due to genetic or environmental variations were detectable by NIR/NIT techniques, wheat materials of different background were used. Size‐exclusion high‐performance liquid chromatography was applied to detect variation in polymeric protein. Partial least squares regression gave high R² values between many protein parameters and NIR/NIT spectra (particularly second‐derivative spectra of NIR 1100–2500 nm region) of flours, while no such relationship was found for whole wheat grains. Most and highest correlations were found for total amount of extractable and unextractable proteins and monomer/polymer protein ratio. Some positive relationships were found between percentage of total unextractable polymeric protein in the total polymeric protein and percentage of large unextractable polymeric protein in the total large polymeric protein and NIR/NIT spectra. Thus, it was possible to detect differences in polymeric proteins with NIR/NIT techniques. The highest amount of positive correlations between NIR/NIT spectra and protein parameters was found to be due to environmental influences. Some correlations were found for breeding lines with a broad variation in gluten strength and polymeric protein composition, while a more homogeneous sample showed less correlation. Thereby, detection of variation in amount and size distribution of polymeric protein due to cultivar differences with NIR/NIT methods might be difficult. Copyright © 2007 Society of Chemical Industry     

The Formation of Natural Gas Hydrate From SDS-Solutions and Decomposition By Microwave Heating in a Static Reactor

Gas mixture hydrates were quiescently produced from sodium dodecyl sulfate solutions of 20 ppm, 50 ppm, and 300 ppm to examine the potential for natural gas storage. Owing to the presence of C₂H₆ and C₃H₈, the concentration of 20 ppm is sufficient to promote the hydrate formation, although higher concentrations are better. The porous hydrate trapping more free water shows better microwave absorption and a higher decomposition rate. While conducting the work, pre-depressurization may weaken the water activity by forming ice.     

The Effect of Multi-walled Carbon Nanotubes on Solubility of Methane in Water

In this research, the effects of multi-walled carbon nanotubes (NTs) on dissolution of methane in water have been investigated. The tests were performed in a 370 CC vessel at pressures 3 and 5 bar and temperatures of 1–5°C. The solution volume was 300 CC. For any solution data of vessel pressure versus time and the total absorption capacity were collected. NTs were dispersed in water by using the sodium dodecyl sulfate (SDS) solution with a concentration of 1 wt% and applying ultrasonic agitation for 25 min. Utilization of 0.1 wt% SDS at a pressure of 3 bar reduced the dissolution capacity, while at the pressure of 5 bar a negligible increase was observed. Dissolution capacity increased up to 5.26% by using of NT along with SDS at the pressure of 5 bar and low temperatures. Utilization of SDS, NT, and their mixtures improved the pressure reduction slope of methane at low temperatures.     

Solubility of Methane in Water at the Presence of β-Cyclodextrin,SDS, and Multi Wall Carbon Nanotubes at Low Temperatures

In this research, the solubility of methane in water at presence of β-cyclodextrin (CD), sodium dodecyl sulfate (SDS), and multiwall carbon nanotubes (NTs) have been investigated. The tests were performed at the pressures 3 and 5 bars and temperatures of 1–3°C. For any solution, data of vessel pressure versus time and the total absorption capacity were collected. NTs were dispersed in water by using SDS solution with a concentration of 1 wt% and applying ultrasonic agitation for 25 min. Addition of 0.5 wt% cyclodextrin increased the capacity of methane absorption as much as 14.63% at temperature 1°C and primary pressure of 3 bar. Dissolution capacity increased up to 5.26% by using NT along with SDS at the pressure of 5 bar and low temperatures. Simultaneous usage of CD, SDS, and NT (the solution containing 1 wt% CD, 0.1 wt% SDS, and 1 wt% NT) had the highest effect on the increase of amount and rate of dissolution. The amount of dissolution increases for this solution was 14.63% at temperature 1°C and the primary pressure 3 bar. Utilization of CD, SDS, and NT and their mixture improved the initial dissolution rate of methane at low temperatures.     

Metabolic profile and biological activities of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco: Studies on the essential oil and polar extracts

We investigated the metabolic profile and biological activities of the essential oil and polar extracts of Lavandula pedunculata subsp. lusitanica (Chaytor) Franco collected in south Portugal. Gas chromatography–mass spectrometry (GC–MS) analysis revealed that oxygen-containing monoterpenes was the principal group of compounds identified in the essential oil. Camphor (40.6%) and fenchone (38.0%) were found as the major constituents. High-performance liquid chromatography with diode array detection (HPLC–DAD) analysis allowed the identification of hydroxycinnamic acids (3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and rosmarinic acids) and flavones (luteolin and apigenin) in the polar extracts, with rosmarinic acid being the main compound in most of them. The bioactive compounds from L. pedunculata polar extracts were the most efficient free-radical scavengers, Fe²⁺ chelators and inhibitors of malondialdehyde production, while the essential oil was the most active against acetylcholinesterase. Our results reveal that the subspecies of L. pedunculata studied is a potential source of active metabolites with a positive effect on human health.     

从啤酒酿造酵母中提取蔗糖酶及酶的性质研究

采用SDS抽提法从啤酒酵母中提取蔗糖酶,通过正交实验对SDS浓度、提取时间、pH、提取温度等条件进行优化,确定了最佳提取工艺条件是：SDS浓度0.6mmol/L,温度50℃,时间10h,pH5.0。制得的粗酶经醇沉后,采用Q-琼脂糖凝胶FF阴离子交换层析方法得到纯化的酵母蔗糖酶,纯化倍数为16.8倍,并对蔗糖酶的酶性质进行了研究。     

Application of high density steam flash-explosion in protein extraction of soybean meal

The high density steam flash-explosion (HDSFE) was used to extract protein from soybean meal. Soybean meal samples were treated at 1.3 MPa and 1.8 MPa for 60 s, 120 s and 180 s, respectively. After HDSFE treatment at 1.8 MPa for 180 s, the extraction yield of protein was increased from 50.50% to 65.66% compared with untreated soybean meal. The emulsification properties and fat-binding capacity of soy protein isolate (SPI) extracted from soybean meal treated by HDSFE were all improved compared with SPI extracted from untreated soybean meal and white flakes. Molecular weight distribution analysis of SPI showed that after HDSFE treatment the peak with molecular weight about 504 kDa and 43.3 kDa disappeared and the peak with molecular weight about 669 kDa increased indicating protein aggregation. Gel electrophoresis showed that high molecular weight aggregates of protein have been formed by covalent bond.