Calcium Alginate Foams Prepared by a Microfluidic T-Junction System: Stability and Food Applications

Highly porous alginate foams were prepared via a novel route in which highly viscous alginate solutions were bubbled using a microfluidic T-junction device. The relationship between bubble size and bubbling conditions such as air pressure and solution flow rate was studied, and the ability of the T-junction setup to generate monodisperse microbubbles (mean diameter, ～154 μm) and produce porous foams was systematically investigated. The foams were characterised by optical and scanning electron microscopy. Foams of varying lengths (12–45 mm) were successfully prepared using this technique, with an average density of ～235 kg/m³. The pore diameter within the foams was determined by microscopy to be in the range of 600 nm–200 μm with a mean diameter of ～31 μm. It was concluded that porosity in the foam (>90%) can be varied depending on the initial bubble size. Thus, a possible production method of stable highly porous solid foams for exploitation in food and bioprocess technologies is presented by which products can be made to different sizes.     

Foams generated from viscous non-Newtonian shear-thinning liquids in a continuous multi rotor-stator device

Whilst aeration is ubiquitous in the food industry, little work has been done on foams generated from viscous non-Newtonian liquids. We study the production of foams from viscous shear-thinning liquids containing a non-ionic food grade surfactant (PGE 55), Xanthan gum and caster sugar, using a continuous pilot-scale device having twelve rotor-stator pairs. The effects of process parameters (rotor speed, gas-liquid volumetric flowrate ratio (G/L)) and liquid composition (surfactant concentration, Xanthan gum concentration) on foam gas volume fraction and bubble size distribution are elucidated. X-ray micro-Computed Tomography is employed to characterise the 3D microstructure of the foams. Rotor speed and G/L ratio are the dominant factors in determining the gas volume fraction and bubble size distribution. The foams produced exhibit a rich fine texture with high static stability. For a given energy input in turbulent flow, a higher G/L ratio results in a higher gas fraction and a smaller bubble size.Industrial relevanceAeration is ubiquitous in the food industry and innovative ways to generate stable foams with fine texture from viscous non-Newtonian media are needed to satisfy the increasing demand for better quality, healthier and cheaper products. The use of continuous multi rotor-stator devices operating in turbulent flow and under atmospheric pressure achieves optimum aeration efficiency and prevents foam expansion. The use of an effective surfactant such as PGE 55 and a thickener such as Xanthan gum help provide the desired fine texture and stability for longer shelf-life. Operating at high gas-liquid ratios in turbulent flow achieves the production of finer more uniform foams with less energy input.     

A novel technique for rapid extraction of volatile organohalogen compounds from low permeability media

A new method for rapid extraction of Volatile Organic Compounds (VOC) from low permeability, unconsolidated geologic media such as clayey soil has been developed and tested using trichloroethylene (TCE) as the model compound. The technique is based on a combination of sonication and mechanical agitation of the samples. The sample vials, mounted in a special holder attached to an orbital shaker, were immersed in an ultrasonic bath during extraction. The extracts were analyzed by gas chromatography with electron capture detection (GC-ECD). The method was validated using clay samples from a TCE-contaminated industrial site by comparing TCE recoveries to those obtained by the standard methanol extraction. In all cases, the recoveries obtained with the new method were the same or better than the recoveries obtained with the reference method. The extraction time was shortened from 5 days with the standard method to less than 2 h with the new method. The new technique makes it possible to analyze a large number of samples in a short time, without the need for sample preservation and prolonged storage. It has good potential for on-site analysis to facilitate decisions while field investigations are in progress.     

Preparation and characterization of niosomes containing resveratrol

Resveratrol (RSV) is an antioxidant present in red wine that may be used in functional foods. Niosomes capable on entrapping and retaining RSV were prepared in Span 80 and Span 60-cholesterol (weight ratio 1:1) systems by a two-stage technique: mechanical agitation and sonication. The niosomal formulations were evaluated for morphology and particle size, stability, entrapment efficiency and in vitro RSV release. Niosomes made of Span 80 were very stable but had low entrapment efficiency, while niosomes made of Span 60-cholesterol had better entrapment efficiency but a less monodisperse size distribution. Higher entrapment efficiencies were obtained when low agitation was used in the first stage of the preparation procedure.     

Inactivation kinetics of pectin methylesterase and cloud retention in sonicated orange juice

The effect of sonication on pectin methylesterase (PME) activity and cloud stability of orange juice was studied. Ultrasonic acoustic energy density (AED) levels of 0.42, 0.47, 0.61, 0.79 and 1.05 W/mL and treatment times of 0 (Control), 2, 4, 6, 8 and 10 min were investigated. The highest PME inactivation level observed was 62% for sonication at the highest AED level and treatment time. A fraction conversion model adequately described the PME inactivation compared to first order or polynomial models. A significant change in particle size distribution was observed in sonicated samples due to cavitational effects. These results indicate that the cloud stability of sonicated orange juice depends not only on PME inactivation but also on particle size reduction.Industrial relevancePower ultrasound is a non thermal pasteurisation method that has been identified to meet the US FDA requirement for a 5 log reduction in E. coli pertinent to fruit juices. Apart from microbial inactivation, cloud stability is a critical orange juice quality parameter influencing product shelf life and consumer acceptance. This work demonstrates that sonication at low AED levels and temperatures can be employed to achieve the desired cloud stability.     

Corneal shape changes induced by first and second generation silicone hydrogel contact lenses in daily wear

Purpose

To compare the corneal topographical changes induced by two first and second generation silicone-hydrogel (SiH) contact lenses after 3 months of daily wear (DW).

Methods

Prospective, consecutive case-series in which patients wore one of 3 different contact lenses (either the first generation SiH Focus Night & Day, the second generation SiH Acuvue Oasys or the monthly disposable Soflens 38 hydrogel lens as control group) on a DW basis for 3 months. Over-refraction, visual acuity, mean keratometry, corneal astigmatism, corneal eccentricity, superficial regularity and superficial asymmetry indices were monitored over the 3-month period.

Results

Nineteen eyes of 10 patients completed the study. Seven Focus Night & Day, 7 Acuvue Oasys and 5 Soflens 38 contact lenses were fitted. There were no significant changes between any of the parameters measured at the 3-month visit in any of the SiH groups (non-parametric Wilcoxon test, p > 0.05). However, the control group (Soflens 38) showed statistically significant changes regarding mean keratometry, corneal astigmatism and corneal eccentricity (p < 0.05). Three patients wearing the first generation SiH showed adverse events of different degree related to their high modulus of elasticity.

Conclusions

After 3 months of DW, wearers of first and second generation SiH lenses showed greater corneal stability than hydrogel monthly disposable contact lenses users regarding commonly used topographic corneal shape indices. However, complications related to the mechanical properties of first generation SiH were seen in three patients in the follow-up time.     

Effects of enzymatically modified starch on the encapsulation efficiency and stability of water-in-oil-in-water emulsions

The present study was performed to investigate the possibility of using 4-α-glucanotransferase (4αGTase)-treated starch in W/O/W emulsions to increase their encapsulation efficiency (EE) and stability. Emulsions were prepared using soybean oil, polyglycerol polyricinoleate (PGPR), 4αGTase-treated starch and Tween 20. The mean diameter of W/O/W droplets ranged from 4 to 10 μm depending on the sonication time. When the dye was loaded in the internal water phase, the emulsion prepared by sonication for 1 and 2 min showed a high EE of the dye (>90%). The W/O/W emulsion prepared by sonication for 3 min showed an EE of <90%, but this EE was improved by adding 4αGTase-treated starch to the internal water phase. 4αGTase-treated starch was added to the internal water phase of W/O/W emulsions prepared with a low concentration of PGPR, and the PGPR concentration required to maintain an EE >90% was reduced. W/O/W emulsions containing 4αGTase-treated starch also showed better stability against heating and shearing stresses. These results indicated that 4αGTase-treated starch could be used in the preparation of W/O/W emulsions, which would allow the formulation of W/O/W emulsions with a reduced surfactant concentration.     

Nucleation of lactose using continuous orifice flow

This paper describes two methods used to produce a constant supply of super-saturated lactose solution with nuclei already present, required as the feed stream for a new design of a continuous crystalliser. Both methods involve cooling a hot saturated lactose solution to super-saturation and then passing it through an orifice or applying mechanical agitation to initiate nucleation. Orifice Reynolds number (Re) of 500 and 1000 and wait times subsequent to cooling of 0 and 1 h were used. Wait time and Re had no effect on nuclei numbers, but a wait time at an orifice Re of 1000 increased crystal size and decreased the span of the crystal size distribution, suggesting that these conditions produced faster growing crystals. In experiments with nucleation by mechanical agitation followed by dilution, crystal numbers were several orders of magnitude lower than for orifice nucleation, and resulted in a small span.     

Enhancement of retinal production by supplementing the surfactant Span 80 using metabolically engineered Escherichia coli

The optimal temperature and pH for retinal production using metabolically engineered Escherichia coli in a 7-l fermentor were found to be 30°C and 7.0, respectively. The agitation speed was a critical factor for retinal production. The optimal agitation speed was 400 rpm (oxygen transfer coefficient, k(L)a, = 92 1/h) in batch culture and 600 rpm (k(L)a=148 1/h) in a fed-batch culture of glycerol. Span 80 was selected as a surfactant for retinal production in metabolically engineered E. coli because Span 80 had proven the most effective for increased retinal production among the tested surfactants. Under the optimal conditions in the fed-batch culture with 5 g/l Span 80, the cell mass and the concentration, content, and productivity of retinal were 24.7 g/l, 600 mg/l, 24.3mg/g-cells, and 18 mg l(-1)h(-1) after 33 h, respectively. They were 1.2-, 2.7-, 2.3-, and 2.7-fold higher than those in the fed-batch culture without Span 80, respectively. The concentration and productivity of retinal in this study were the highest ever reported. The hydrophilic portion of Span 80 (sorbitan) did not affect cell growth and retinal production, but the hydrophobic portion (oleic acid) stimulated cell growth. However, oleic acid plus sorbitan did not stimulate retinal production. Thus, Span 80, as a linked compound of oleic acid and sorbitan produced by esterification, proved to be an effective surfactant for the enhancement of retinal production.     

机械搅拌生物反应器的CFD 模拟及其在发酵生产乳酸中的应用

用计算流体力学(CFD)方法中的Mixsim 模拟3L 机械搅拌生物反应器中不同搅拌转速对搅拌流场的影响,结果显示Mixsim 软件可以很好的模拟机械搅拌生物反应器工作过程中的流场变化。在高转速下,剪切速率较大,菌丝体98% 以上为菌丝体小球,直径在0.1～0.3mm,菌体生长速度慢,产乳酸质量浓度较低;低转速下产生的剪切速率较小,菌体大部分为菌丝形态,产乳酸质量浓度较高,但是大量菌丝不利于后期发酵的进行。在400r/min下米根霉发酵产乳酸质量浓度最高,为106.7g/L,菌体80% 以上为1.0～1.5mm 左右的菌丝球,通过CFD 模拟得到该条件下的剪切速率最大值为1.58m/s。     

漏斗式喷气静电纺聚乙烯吡咯烷酮纳米纤维膜的制备及其表征

为克服传统静电纺丝生产效率低、纺丝过程难以控制、针头易堵塞等问题,实现高效制备高质量纳米纤维膜,在气泡静电纺的基础上,提出了漏斗式喷气静电纺丝技术。以聚乙烯吡咯烷酮（PVP）溶液为纺丝液,通过漏斗式喷气静电纺技术成功地制备了高质量的PVP 纳米纤维膜,并运用控制变量法分析了溶液质量分数、表面活性剂质量分数和施加电压等对纤维膜形貌和质量的影响。结果表明：当纺丝溶液中PVP 质量分数为32%,纺丝电压为60 kV,表面活性剂质量分数为0.1%时,获得的PVP 纳米纤维膜综合性能最佳,其表面形貌良好,纤维直径较细且直径分布较均匀。     

Probing the interaction between 3 flavonoids and pancreatic lipase by methods of fluorescence spectroscopy and enzymatic kinetics

The aim of this study was to evaluate the effects of the addition of surfactants sodium stearoyl lactate (SSL) and sucrose ester (SE) on the functional properties of films produced with polysaccharides mixtures (methylcellulose/glucomannan/pectin in 1/4/1 ratio, respectively) and gelatin. The films were produced by the casting method and characterized for their water vapor permeability (WVP), mechanical (tensile strength and elongation to break point), morphological and optical properties. Films with low WVP were obtained with surfactants. Addition of SE to the films with polysaccharide/gelatin ratio of 90/10 showed improved mechanical properties. Films presented smooth surfaces with micro voids and lumpiness, depending on the surfactant tested. Surfactants increased the opacity of the films by a factor of 1–3%. All film properties were dependent on the surfactant affinity for the biopolymer matrix. SE presented more affinity for biopolymer matrix containing high polysaccharide proportion, and SSL presented more affinity for polymer matrix containing high gelatin proportion. The addition of surfactants decreased the water vapor permeability of the films, increasing their hydrophobic character.     

Effect of key process variables on mechanical properties of blended vortex spun yarns

A study of significant factors and their interaction during vortex yarn spinning has been carried out to achieve desired mechanical properties of the polyethylene terephthalate/cotton blended yarns which can offer process and performance advantages. The key significant factors, i.e. feed ratio, air pressure and spindle size were varied in a mixed-level factorial design. The mechanical properties (count lea strength product, tenacity and elongation at break) were studied and feed ratio was found to significantly affect the tenacity and elongation at break of spun yarns. A significant effect of these parameters was observed on the diameter and hairiness of the Muratec vortex spun yarn.     

Proposed Method for Determining Cross-Sectional Area of Guadua angustifolia Bamboo Fibers

This paper summarizes a research aimed to develop a methodology for determining the cross-sectional area of Guadua angustifolia bamboo fibers. The method includes the immersion of fibers into a resin, surface preparation, acquisition, and analysis of optical micrographs using commercial software. Measured areas were compared with other values obtained for thereof, from a standard gravimetric methodology commonly used on natural fibers, which showed substantial differences among calculated areas. Random samples were subjected to both methods using data distribution functions, and the analysis was carried out to determine their statistical goodness. Analysis of fibers diameter distributions reveals they are very well described by a lognormal distribution function. Furthermore, standard gravimetric methods tend to overestimate the fibers’ cross-sectional area in an average value of 15%, which could result in similar magnitude differences on the determination of some mechanical properties such as the tensile strength and the modulus of elasticity.     

均质法和超声法制备NFC及其纳米纸性能研究

以漂白硫酸盐桉木浆纤维为原料,进行TEMPO氧化预处理,再采用均质法和超声法及二者结合法分别制备出纳米纤丝纤维素(Nanofibrillated Cellulose,NFC),再经溶液浇铸法制备纳米纸。重点探讨了不同制备方法对NFC特性及其纳米纸性能的影响。结果表明,不同能耗下,超声2 h、4 h比均质2次、5次制备的NFC的透明性更好,长径比更大,直径更小,最小宽度可达19 nm。工艺能耗低于20 k Wh时,与均质处理相比,超声处理强度(能耗)的增加更有利于纳米纸拉伸强度和透湿率的提高,同时超声2 h、4 h比均质2次、5次制备的NFC纳米纸的光学性能更好,其中超声4h制备的NFC得到的纳米纸拉伸强度与透光率最高,分别为155.8 MPa、89.45%,优于一般的聚合物薄膜,有望应用于柔性显示电子器件的基材。     

Borassus and Tamarind Fruit Fibers as Reinforcement in Cashew Nut Shell Liquid-Epoxy Composites

In this study borassus and tamarind fruit fibers were extracted and their physical and mechanical properties such as diameter, density, tensile strength and interfacial adhesion strength (IAS) were experimentally determined. To study the effect of alkali treatment, both the fruit fibers were treated with 5% vol. sodium hydroxide solution for 0.5 h, 1 h, 2 h, and 4 h durations. Morphological studies of untreated and alkali treated fibers by using scanning electron microscope (SEM) revealed the presence of the surface impurities on the untreated fiber whereas the same were absent on the treated fibers. Fourier transform infrared spectrometry (FTIR) and X-ray diffraction (XRD) analysis also confirmed the elimination of amorphous hemicellulose of the fibers on treatment. Borassus fruit fine fibers and tamarind fruit fibers treated for 2 h exhibited better mechanical properties and improved IAS with Cashew Nut Shell Liquid (CNSL) -Epoxy matrix.     

Preparation and characterization of whey protein isolate films reinforced with porous silica coated titania nanoparticles

Whey protein isolate (WPI) films embedded with TiO₂@@SiO₂ (porous silica (SiO₂) coated titania (TiO₂)) nanoparticles for improved mechanical properties were prepared by solution casting. A WPI solution of 1.5 wt% TiO₂@@SiO₂ nanoparticles was subjected to sonication at amplitudes of 0, 16, 80 and 160 μm prior to casting in order to improve the film forming properties of protein and to obtain a uniform distribution of nanoparticles in the WPI films. The physical and mechanical properties of the films were determined by dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and tensile testing. Water vapor permeability (WVP) measurements revealed that the water vapor transmission rates are slightly influenced by sonication conditions and nanoparticle loading. The DMA results showed that, at high sonication levels, addition of nanoparticles prevented protein agglomeration. The thermal stability of the materials revealed the presence of 3–4 degradation stages in oxidizing the protein films. The addition of nanoparticles strengthens the WPI film, as evidenced by tensile stress analysis. Sonication improved nanoparticle distribution in film matrix; such films can potentially become effective packaging materials to enhance food quality and safety.     

Pilot‐scale Protamex™‐catalysed production of round scad protein hydrolysates:effects of agitation alone and combined with aeration

A pilot‐scale production of round scad protein hydrolysates via Protamex?‐catalysed proteolysis was firstly established. Process optimisation then focused on the use of mechanical agitation (MA) alone or combined with aeration (MAA). Comparative examinations revealed that proteolysis involving either MA or MAA was feasible with a hydrolysis degree up to 55%, and individual and total biogenic amine (BA) contents much lower than the commonly recognised limits (including the dominant BA, cadaverine). MAA is more advantageous in suppressing bacterial counts and activities associated with protein decomposition, enabling reduced volatile basic nitrogen and BAs. Thus, additional aeration to mechanical agitation is recommended for industrial proteolysis of raw materials unavoidably containing micro‐organisms (especially anaerobic bacteria) in common handling practice.     

A new method of ensuring even distribution of a fumigant in flexible fumigation chambers using external fans

A series of commercial fumigations to control narcissus fly larvae in bulbs for export was carried out to determine the effectiveness of a gas distribution method that utilizes external fans positioned outside the chamber. The principle is to generate air motion using the flexibility of the PVC liner. This is done by directing an air-flow along the walls of the liner, thus creating a ripple motion that generates an internal turbulence which mixes the air with the fumigant inside the chamber. With fans placed opposite the corners of the bubble it was possible to divide the airflow along all sides of the bubble wall. Methyl bromide concentrations recorded over the 4-h fumigation period, were compared with previous results obtained when the fumigant was mixed by recirculation. The use of external fans in combination with flexible PVC chambers enabled an even gas distribution to be achieved within the chambers in 1-1.5 h whereas under recirculation, even distribution was not reached during the entire 4-h fumigation period. Post-fumigation mortality data on narcissus fly larvae revealed 100% kill.     

Inactivation of microbes using ultrasound: a review

Alternative methods for pasteurization and sterilization are gaining importance, due to increased consumer demand for new methods of food processing that have a reduced impact on nutritional content and overall food quality. Ultrasound processing or sonication is one of the alternative technologies that has shown promise in the food industry. Sonication alone is not very effective in killing bacteria in food; however, the use of ultrasound coupled with pressure and/or heat is promising. Thermosonic (heat plus sonication), manosonic (pressure plus sonication), and manothermosonic (heat and pressure plus sonication) treatments are likely the best methods to inactivate microbes, as they are more energy-efficient and effective in killing microorganisms. Ultrasonic processing is still in its infancy and requires a great deal of future research in order to develop the technology on an industrial scale, and to more fully elucidate the effect of ultrasound on the properties of foods.