一种水果保鲜乳化蜡的研制

研究了用58#全炼蜡、改性高分子聚合物制备水果保鲜光乳化蜡的方法.考查了石蜡、改性高分子聚合物二者的比例、复合乳化剂对乳液性能的影响.实验结果表明,当乳化剂用量为乳液质量的5％,乳化温度为90～95℃,乳化时间为30 ～40 min时,可以制取一种水果保鲜乳化蜡.     

水性聚氨酯自乳化过程中相反转及影响因素

概述了水性聚氨酯自乳化时的相反转过程,讨论了影响相反转的一些重要因素。     

Effects of Extraction Temperature and Preservation Method on Functionality of Soy Protein

The effects of extraction temperature and preservation method on the functional properties of soy protein isolate (SPI) were determined. Four extraction temperatures (25, 40, 60, and 80 °C) were used to produce SPI and yields of solids and protein contents were determined. Three preservation methods were also tested (spray-drying, freeze-drying, and freezing–thawing) and compared to fresh (undried) samples for each extraction temperature. No differences in yields of solids and protein were observed among SPIs extracted at 25, 40, and 60 °C; however, SPI extracted at 80 °C yielded significantly less solids and protein. Extraction temperature significantly affected SPI functionality. As extraction temperature increased, solubility and emulsification capacity decreased; surface hydrophobicities, emulsification activities and stabilities, and dynamic viscosities increased; and foaming properties improved. Preservation method also significantly affected SPI functionality. Drying method did not affect the denaturation enthalpies of SPIs, but spray-dried SPIs had higher solubilities, surface hydrophobicities, and emulsification stabilities, and lower viscosities, emulsification activities and rates of foaming than freeze-dried SPI exhibited. Emulsification and foaming capacities and foaming stabilities were similar for both methods of drying. There was significant interaction between extraction temperature and preservation method for all functional properties except emulsification capacity.     

焙烤食品中蛋黄夹心料的研制

对焙烤膨化食品中蛋黄夹心混合料主要成分之间的相互作用进行研究,采用正交试验对影响其产品品质的因素进行分析,并通过考察夹心混合料的黏度,得出结论：大豆蛋白用量为9%,麦芽糊精选用DE值10,用量为18%,单甘酯用量为0.4%时,产品口感细腻,质地柔软,风味最佳.     

VELOCITY MEASUREMENTS OF TURBULENT TWO-PHASE FLOW IN A HIGH-PRESSURE HOMOGENIZER MODEL

The effect of disperse phase volume fraction on the turbulence in a scale model of a high-pressure homogenizer was studied experimentally. Velocity fields of the continuous phase were measured using particle image velocimetry. Refractive index matching combined with digital filtering enabled measurement with disperse phase present. Geometry and physical properties were carefully scaled in order to ensure turbulent flow and disperse phase modulation comparable to that of a technical high-pressure homogenizer. The results show a widening of the jet downstream of the gap and increased Reynolds stresses in the region of high turbulence intensity. This is consistent with previous experiments under similar conditions. Furthermore, the spectra of turbulent kinetic energy were investigated, indicating that the increase in turbulent kinetic energy is mainly due to an increase in energy of eddies of large length scales.     

Water-in-diesel fuel nanoemulsions: Preparation,stability and physical properties

In this work, water-in-diesel fuel nanoemulsions were prepared with mixed nonionic surfactants. Several mixtures of sorbitan monooleate and polyoxyethylene (20) sorbitan monooleate, with different Hydrophilic–Lipophilic Balance (HLB) values (9.6, 9.8, 10, 10.2 and 10.4) were prepared to achieve the optimal HLB value. Three mixed surfactant concentrations were prepared at 6%, 8% and 10% to identify the optimum concentration. Five emulsions with different water contents: 5%, 6%, 7%, 8% and 9% (wt./wt.) were prepared using high energy method at the optimum conditions (HLB = 10 and mixed surfactant concentration = 10%). The effect of HLB value, mixed surfactant concentration and water content on the droplet size has been studied. The interfacial tension and thermodynamic properties of the individual and the blended emulsifiers were investigated. Droplet size of the prepared nanoemulsions was determined by dynamic light scattering and the nanoemulsion stability was assessed by measuring the variation of the droplet size as a function of time. From the obtained results, it was found that the mean droplet sizes were formed between 49.55 and 104.4 nm depending on HLB value, surfactant concentration and water content of the blended emulsifiers. The physical properties, kinematic viscosity and density, of the prepared nanoemulsions and the effect of different temperatures on these properties were measured.     

Biosurfactants Production Using Permeate from Whey Ultrafiltration and Bioproduct Recovery by Membrane Separation Process

The management of whey is a challenge for dairy products where the volume produced is remarkable. This problem is minimized through membrane separation processes (MSP) to obtain whey protein concentrate, which has high added value. However, a permeate effluent stream is still generated that is composed of lactose, vitamins, and minerals, which can serve as raw material for the production of biotechnological compounds. Thus, this study aimed to produce biosurfactants using the permeate from whey ultrafiltration as part of the culture media of the bioprocess, to recover the biosurfactant produced using MSP, and to identify the biocompound. The production was carried out using Bacillus methylotrophicus and Bacillus pumilus. The variables nitrogen source (urea or ammonium sulfate), nitrogen source concentration (0.5% or 1.0%), inducer (soybean oil or biodiesel), inducer concentration (1% or 2%), and the addition of micronutrients (with our without) were studied using a fractional factorial experimental design 2^5-1_IV. In the fermentation processes, it was possible to verify the biosurfactant production through the reduction of surface tension, obtaining a minimum value of 35.07 mN/m for B. methylotrophicus and 26.02 mN/m for B. pumilus. Recovery via MSP was an efficient strategy for biosurfactant purification, which was concentrated in the fraction of the retentate. We produced a high-value-added biocompound identified as surfactin, valuing the permeate residue from whey ultrafiltration.     

CO2/N2 Triggered Switchable Surfactants with Imidazole Group

In order to overcome the hydrolysis of 2-alkyl-1-hydroxyethyl imidazoline and its unsatisfactory emulsification–demulsification switchability to water-alkane, the long-chain N-alkylimidazole compounds were synthesized by n-octyl bromide, n-decyl bromide, n-dodecyl bromide, n-tetradecyl bromide and n-hexadecyl bromide with imidazole, respectively and characterized by MS, ¹H NMR and FTIR. The long-chain N-alkylimidazole compounds can be reversibly transformed into charged surfactants by exposure to CO₂. Surface tension values indicated that N-alkylimidazolium bicarbonates had excellent surface activity compared with corresponding conventional surfactants with a lower γ _CMC. The surface behaviors of the five surfactants can be illustrated by A _min. Five conductivity cycles by bubbling CO₂ and N₂ alternately indicated that these surfactants could be switched by CO₂ reversibly and repeatedly. Emulsions were repeatedly stabilized for five cycles by N-alkylimidazolium bicarbonate and broken by bubbling N₂ through the solutions to reverses the reaction, releasing CO₂.     

电喷汽油机燃用微乳化E10含水乙醇汽油的试验研究

应用微乳化理论研制E10含水乙醇汽油乳化剂,在电喷发动机上进行燃用E10含水乙醇汽油对发动机动力性、经济性和排放性的影响试验研究.试验结果表明:基于HLB值理论配制的SPY乳化剂能较好地解决E10含水乙醇汽油的稳定性问题;发动机燃用E10含水乙醇汽油后,动力性略有降低,有效燃油消耗率略有升高,能源消耗率降低;怠速排放的CO、HC、NOx均下降,NOx下降幅度达到65％;多工况排放的CO、HC在低负荷略有降低,中高负荷时明显降低,CO降低9％ ～ 17％,HC降低4％～9％;NOx在中小负荷时降低12％左右,大负荷时改变不明显.     

Development of a new reflectance technique to investigate the mechanism of emulsification

A new reflectance technique has been developed to measure the droplet size evolution during the process of emulsification in real-time. This has been used to investigate the dynamic behaviour of 50% oil-in-water emulsions. The performed experiments were designed in order to investigate the occurring droplet break-up and droplet coalescence phenomena individually, by carefully creating processing conditions where each of those events is dominant. The effect of emulsifier (Tween 20) concentration and different hydrodynamic conditions on the droplet break-up and coalescence phenomena and the emulsion droplet size evolution during processing were all investigated. The concentration of Tween 20 was shown to be a key parameter affecting the droplet size of the emulsion at the early stages of processing (within the first 3 min). However, during the later stages of processing, hydrodynamic conditions have a more pronounced effect on determining the final droplet size. Unlike droplet break-up, droplet coalescence rate decreases by intensifying the hydrodynamic conditions of the process as a consequence of the high capillary pressure of the smaller droplets being produced.