Effect of Ultra High Pressure Processing on the Particle Characteristics of Lotus-seed Starch

In this paper, the time dependent effects of various pressure treatments on the characteristics of lotus-seed starch which was modified by ultra-high pressure （UHP） were investigated. The results showed that the polarization cross of lotus-seed starch granules was weakening gradually with increasing the treatment time, which indicated the termination of their ordered crystallite structures. The morphologies of granules were collapsed once the UHP was kept at 500 MPa for 60 minutes. The particle size analysis demonstrated that the granule size and distribution of lotus-seed starches increased as the treatment time was prolonged. X-ray diffraction studies showed that the intensity of the feature diffraction peaks of starch decreased and eventually disappeared with increasing the treatment time, and B-type transformation pattern was observed. The Fourier transform infrared spectra （FTIR） analysis of starch showed that the UHP is a physical modification processing because no new groups formed. The research showed that UHP processing at certain degree is capable to achieve the modification of lotus-seed starch. It is of significance for the deep processing of lotus-seed products.

Measuring the antioxidative activities of Queso Fresco after post-packaging high-pressure processing

Some milk-associated proteins are known to be nutritionally valuable and form bioactive peptides that exhibit activity against hypertension and oxidative stress. Consumption of cheeses, such as the popular Hispanic-style cheese Queso Fresco (QF), may be a vehicle for delivery of these milk-associated peptides. This paper describes the effects of high-pressure processing (HPP) on the antioxidative activity (ORAC- FL value) of water-soluble proteins extracted from QF samples. QFs were manufactured according to a commercial-make procedure using pasteurized, homogenized milk, without added starter cultures. The cheese was cut into 45 × 45 × 150 mm3 blocks, double packaged in vacuum bags, and received the following HPP treatments: 200, 400, or 600 MPa for either 0, 5, 10, or 20 min, with warming to an internal temperature of either 22℃ or 40℃ prior to HPP treatment. Results show that the core temperature of the cheese during HPP directly affects the ORAC-FL value. The activities of the lower temperature cheeses are independent of time and pressure, and have a median ORAC-FL value of 27 trolox equivalents (TE). The higher temperature cheeses have higher ORAC-FL values ranging from 21.5 to 96.0 TE;the highest activity corresponded to the cheese held at 400 MPa for the longest time under pressure (20 min). The 600 MPa cheeses increase in activity with increasing time under pressure, but are less active than the control cheese. These results indicate that processing temperature and pressure are important factors in the antioxidative activity of these QF samples and further understanding of the roles of these variables may lead to the manufacture of healthier and more nutritious cheeses and dairy products.

Applications of Microfluidization and High Pressure Processing in Food Industry and the Effect of Them on Food Products

With the development of technology, several new processing techniques are being introduced for the food industry. By applying those novel techniques to food systems, it has been found that the structural and functional properties of food could be altered. Microfluidization which is also known as high pressure homogenization is one of the novel technologies that could be applied in food industry to obtain many beneficial outcomes. High pressure processing is another novel technique that is mainly playing the microbicidal effect. This work is concerned on the possibility of using microfluidization and high pressure processing in food industry based on the experimental findings. These techniques could be used as useful tools in the field of food science and technology.

Changes in Texture, Structure and Pectin of Peach during Pressurization, Heating or Processing of High-pressure-induced and Heat-induced Jam

The objectives of this study are to research the relationship between pectin and the softening of peach by soaking in citric acid solutions for 24 h at 35 ℃, pressurizing for 30 rain at 500 MPa or heating for 10 min. Also, comparing high-pressure-induced jam （HP-jam） and heat-induced jam （H-jam） were evaluated. It was found that firmness of the peach decreased greatly when soaked at pH 2.0 〉 heated 〉 soaked at pH 2.2 or 2.5 〉 pressurized, respectively. About 88% of the peach pectin was water-soluble-pectin and high-methoxyl pectin, while low-methoxyl pectin was slight. During pressurization, the pectin did not change. However, pectin degraded through hydrolysis during heating; consequently, the middle lamella separated. Also, eight kinds of peach jam （65% sugar, pH 2.0 or pH 2.2, and 50% or 60% sugar, pH 2.5） were compared. Both color and flavor of HP-jam were better than H-jam. As the pH values were lower, L-, a-, b-values of jam became higher, and the jam became pinker. Raw peach contained about 0.3%-0.4% pectin, therefore, an addition of 0.6% pectin was needed for both HP- and H-jams. However, there was no great difference in rheology or sensory evaluation between HP- and H-jams.

Surface-Driven High-Pressure Processing

The application of high pressure favors many chemical processes, providing higher yields or improved rates in chemical reactions and improved solvent power in separation processes, and allowing activation barriers to be overcome through the increase in molecular energy and molecular collision rates. High pressures-up to millions of bars using diamond anvil cells-can be achieved in the laboratory, and lead to many new routes for chemical synthesis and the synthesis of new materials with desirable thermody- namic, transport, and electronic properties. On the industrial scale, however, high-pressure processing is currently limited by the cost of compression and by materials limitations, so that few industrial processes are carried out at pressures above 25 MPa. An alternative approach to high-pressure processing is pro- posed here, in which very high local pressures are generated using the surface-driven interactions from a solid substrate. Recent experiments and molecular simulations show that such interactions can lead to local pressures as high as tens of thousands of bars （1 bar=1×10^5 Pa）, and even millions of bars in some cases. Since the active high-pressure processing zone is inhomogeneous, the pressure is different in dif- ferent directions. In many cases, it is the pressure in the direction parallel to the surface of the substrate （the tangential pressure） that is most greatly enhanced. This pressure is exerted on the molecules to be processed, but not on the solid substrate or the containing vessel. Current knowledge of such pressure enhancement is reviewed, and the possibility of an alternative route to high-pressure processing based on surface-driven forces is discussed. Such surface-driven high-pressure processing would have the advantage of achieving much higher pressures than are possible with traditional bulk-phase processing, since it eliminates the need for mechanical compression. Moreover, no increased pressure is exerted on the containing vessel for the process, thus eliminating concerns about materials failure.

Mechanical Analysis of a Multi-Test String in High-Temperature and High-Pressure Deep Wells

The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even lead to string failure.Traditional computational methods for the analysis of these behaviors are often inaccurate.For this reason,here a more accurate mechanical model of the test string is introduced by considering variables such as temperature,pressure,wellbore trajectory,and buckling,as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,setting,and test operations.The model is validated by applying it to a specific high-pressure gas well(located in Northeast Sichuan).

Heat Transfer between Casting and Die during High Pressure Die Casting Process of AM50 Alloy-Modeling and Experimental Results

A method based on die casting experiments and mathematic modeling is presented for the determination of the heat flow density （HFD） and interfacial heat transfer coefficient （IHTC） during the high pressure die casting （HPDC） process.Experiments were carried out using step shape casting and a commercial magnesium alloy,AM50.Temperature profiles were measured and recorded using thermocouples embedded inside the die. Based on these temperature readings,the HFD and IHTC were successfully determined and the calculation results show that the HFD and IHTC at the metal-die interface increases sharply right after the fast phase injection process until approaching their maximum values,after which their values decrease to a much lower level until the dies are opened.Different patterns of heat transfer behavior were found between the die and the casting at different thicknesses.The thinner the casting was,the more quickly the HFD and IHTC reached their steady states.Also,the values for both the HFD and IHTC values were different between die and casting at different thicknesses.

High Pressure Metamorphism of Garnet-Amphibole Rocks from Songshugou Area,Eastern Qinling Mountain and Its Tectonic Implication

Eclogitic garnet-amphibole rocks are scattered around me Songshugou ultramafic bodies in Qinling Mountains . Three metamorphic stages are recognized in terms of petrography, mineral chemistry and geothermobarometry . The first alhite-amphibole stage was of greenschist facies metamorphism with typical mineral assemblage of actinolite+epidote+chlorite+albite ; the pressure and temperature conditions were equal to or lower than 500MPa and about 400 ℃ .The second prograde eclogitic garnet-amphibole stage was of amphibole-eclogite fades metamorphism with typical mineral assemblage of garnet+hornblende± clinopyroxene+ruffle without ptagioclase ,the pressure condition was at least 1000- 1200MPa and the temperature about 600 ℃ .The third retrograde epidote-amphibole stage was of epidote-amphibolite fecies with assemblage of plagioclase+hornblende+epidote+ilmenite/titanite , the temperature was 500-600 ℃ and the pressure from 800MPa down to 500MPa .All three stages took place in one single tectonothermal event called Jinningian movement at about 1000Ma .The p-T path shows a hairpin shape and thus indicates a metamorphism in the sobduction environment. The metamorphk processes of the garnet- amphibole rocks thus provides a significant evidence for the pbte tectonic movement prevailing in the late Middle Proterozoic period.

High Pressure Treatment Changes Spoilage Characteristics and Shelf Life of Pacific Oysters(Crassostrea gigas)During Refrigerated Storage

The effects of high pressure(HP) treatment on spoilage characteristic and shelf life extension of Pacific oysters(Crassostrea gigas) during refrigerated storage were studied.Results showed that HP treatment of 275 MPa for 3 min or 300 MPa for 2 min could achieve 100% full release of oyster adductor muscle,pressures higher than 350 MPa caused excessive release as the shells of oysters were broken,thus use of higher pressures should be cautious in oyster processing industry because of its adverse impact on the appearance of shells.HP treatment(300 MPa,2 min) was proper for the shucking of Pacific oyster(Crassostrea gigas) in China.This treatment caused no organoleptic disadvantage.Moreover,HP treatment resulted in obvious differences in biochemical spoilage indicators(p H,TVB-N and TBARS) changes and volatile compounds profile determined by electronic nose during storage.HP treatment(300 MPa,2 min) also led to a reduction of aerobic bacterial count(APC) by 1.27 log cycles.Furthermore,the APC values of oysters treated by HP were always lower than those of the control samples during storage.Based on the organoleptic,biochemical and microbiological indicators,shelf life of 6-8 d for control and 12 d for HP-treated oysters could be expected.HP treatment showed great potential in oyster processing and preservation.

Optimization of Inactivation Conditions of High Hydrostatic Pressure Using Response Surface Methodology

Response surface methodology (RSM) was employed in the present work and a second orderquadratic equation for high hydrostatic pressure (HHP) inactivation was built. Theadequacy of the model equation for predicting the optimum response values was verifiedeffectively by the validation data. Effects of temperature, pressure, and pressureholding time on HHP inactivation of Escherichia coli ATCC 8739 were explored. Byanalyzing the response surface plots and their corresponding contour plots as well assolving the quadratic equation, the optimum process parameters for inactivation E. coliof six log cycles were obtained as: temperature 32.2℃, pressure 346.4 MPa, and pressureholding time 12.6min.

Effects of Combined Instantaneous High-Pressure and Medium Temperature on Peroxidase Activity in Wax Gourd Juices

Based on the instantaneous pressurization and depressurization produced by high pressure single pole cylinder pump and valve, the effects of the continuous processing on the peroxidase (POD) activity in wax gourd juices were investigated. Results showed that the processing factors such as pressure, temperature, pH and processing time are important to the POD activity. POD in crude juices could be inactivated apparently above 50 MPa(pH 4.6, 35℃, 4 min), and activated at 20 MPa ( P < 0.01). Its remarkable inactivation could also be observed at 45 and 55℃ (20 MPa, pH 4.6, 4 min), and the evident activation appears at the material temperature 35℃ ( P < 0.01). The pH 3.0 could destroy POD almost completely (20 MPa, 35℃, 4 min), while pH 6.0 could not influence apparently the POD activity in crude juices( P > 0.05). In addition, the rules of POD activity along with the treatment time are variational under different processing pressures. The higher the treating pressure is, the shorter the processing time is needed to inactivate POD.

Effects of Combined Instantaneous High-Pressure and MediumTemperature on the Retention of Total Vitamin Cin Wax Gourd Juices

Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juices were investigated under 20 - 80 MPa, 35 - 58℃, pH 3. 0 - 6. 0 and processing time 0-8 min. Results showed that the loss of Vc increased with elevated processing temperatures(50 MPa, 4 min). When the temperature of raw juices was 35℃, the retention of total Vc was higher under 40 - 60 MPa than that under the pressure < 40 MPa or > 60 MPa, and it was up to 94%(4 min). The retention of total Vc decreases slowly within 6 min, but rapidly after 6 min. The pH can also influence the retention of total Vc, and this retention can come to a highest point at pH 6.0.

Thoughts on the Development of High-pressure Hydrocracking Technology in China

The author makes a brief review of the history and the status quo of high pressure hydrocracking catalysts/processes development in China and gives out some thoughts and suggestions on the prospect of the said technology.

Effects of Mg on diamond growth and properties in Fe–C system under high pressure and high temperature condition

Diamond crystal crystallized in Fe–Mg–C system with Archimedes buoyancy as a driving force is established under high pressure and high temperature conditions. The experimental results indicate that the addition of the Mg element results in the nitrogen concentration increasing from 87 ppm to 271 ppm in the diamond structure. The occurrence of the {100}plane reveals that the surface character is remarkably changed due to the addition of Mg. Micro-Raman spectra indicate that the half width of full maximum is in a range of 3.01 cm^-1–3.26 cm^-1, implying an extremely good quality of diamond specimens in crystallization.

The Quality of High Pressure-Induced and Heat-Induced Hyuganatsu Marmalade

Hyuganatsu is a typical Japanese citrus with desirous smell and edible albedo. The objectives of this study are to establish a method for softening hyuganatsu peel without heating and a process for making a high pressure-induced （HP-） marmalade and to compare with heat-induced （H-） marmalade and citrus shaddock family marmalade. Firmness of peel was （greatest to least） pressurized at 500 MPa for 30 min, soaked in citric acid solution at pH 2.7 for 24 h, and boiled for 10 min, respectively. The cell walls of flavedo and albedo did not loosen after pressurization. However, after soaking or heating, the middle lamella of albedo separated. When flavedo was soaked at pH 2.7, 9.3% of pectin was extracted. The amount of naringin was the least in hyuganatsu 〈 pummelo 〈 grapefruit）, and juice sacs 〈 flavedo 〈 segment walls 〈 albedo, respectively. Thus, marmalade was processed. Albedo, segment walls and juice sacs of hyuganatsu were homogenized with citric acid solution （pH 2.7） and mixed with sliced flavedo. Then it was soaked for 24 h at pH 2.7. Sucrose was then added （final sugar 50%）, vacuum packed, then pressurized for 30 min at 500 MPa or boiled for 10 min, respectively. There was no significant difference in sensory evaluation between HP- and H-marmalade. However, the color, transparency and total evaluation of HP-marmalade were better than H-marmalade. Consequently, total evaluation of hyuganatsu-HP-marmalade was rated highly. So, hyuganatsu was considered to be more suitable for marmalade because it was more palatable than the others.

超高压预处理紫苏蛋白与大豆蛋白复配蛋白肉的工艺条件优化

利用超高压(ultra-high pressure,UHP)技术预处理紫苏蛋白与大豆蛋白复配蛋白肉,并利用正交实验探究其最佳工艺条件。采用UHP预处理技术,以紫苏蛋白和大豆蛋白等质量比复配为主要原料,谷朊粉、淀粉、牛肉香精和魔芋胶等为辅料制备新型复合植物蛋白肉。采用单因素实验和正交实验考察水分添加量、魔芋胶添加量和UHP压力对蛋白肉产品的咀嚼性、硬度、弹性、黏弹性、蒸煮和解冻特性的影响。复配蛋白肉的最佳工艺条件(以干基计)为水分添加量40%、魔芋胶添加量0.3%、UHP压力500 MPa。在此工艺条件下所得的紫苏蛋白复合肉与纯大豆蛋白肉相比质构性能最佳,其咀嚼性高达46.993 J,比纯大豆蛋白肉高近10倍,并且蒸煮和解冻损失率较低。该研究可为UHP的利用和紫苏蛋白肉的工艺开发提供初步的科学思路,为植物蛋白肉的机制与工艺研究提供一定理论和技术支持。

海上高压气田无人井口平台集输工艺流程方案比选设计

针对某海上高压气田井口压力高、井口温度低、油品凝点高、节流后易出现水合物和出油管线容易冻堵的问题,结合不同生产井节流后的压力,设置不同压力体系井口加热器以满足流体输送要求。文章研究了两种不同高压气田无人平台工艺流程方案:加热器部分降压设计方案和全部降压设计方案,比较了两种方案的技术特点及经济性,最终推荐高压气田无人井口平台采用加热器部分降压设计的工艺流程方案。

基于超高压技术的响应面优化猕猴桃果肉饮料

研究超高压处理条件下的猕猴桃果肉饮料配比,以强化分层率为指标,通过单因素试验和响应面法对配比进行优化,结果表明:猕猴桃原浆添加量47%,蔗糖添加量12%,增稠剂添加量0.14%。在超高压技术处理后,产品的强化分层率达到47%。对优化后的产品测定色泽和粒径,结果显示L为38,产品色泽明亮;ΔE均小于2,产品色泽均一;颗粒的体积平均粒径D[4,3]为214μm,稳定性好。

动态高压微射流辅助提取石榴皮多糖工艺优化及其抗氧化活性

以石榴皮为原料,优化动态高压微射流辅助提取石榴皮多糖工艺并探究其抗氧化活性。通过单因素试验分析料液比、微射流压力、提取时间以及提取温度对石榴皮多糖得率的影响。进一步通过响应面试验优化提取工艺,试验结果确定最佳工艺条件为料液比1∶34(g/mL)、微射流压力106 MPa、提取时间2.6 h,在该工艺条件下石榴皮多糖得率为(29.07±0.42)%,与预测值接近,表明模型拟合良好,该优化工艺准确可行。同时提取的石榴皮多糖对DPPH·、·OH及ABTS^(+)·具有较好的清除活性。

超高压辅助酶解对汉麻分离蛋白结构和抗氧化活性的影响

本研究以汉麻分离蛋白(Hemp Protein Isolate,HPI)为原料,通过超高压辅助酶解反应对HPI进行改性,测定不同压力下汉麻蛋白酶解产物(hydrolysate of hemp protein isolate,HPIH)的聚丙烯酰胺凝胶电泳(SDS polyacrylamide gelelectrophoresis,SDS-PAGE)电泳特性、表面疏水性、巯基含量、傅立叶红外光谱和内源荧光光谱分析改性前后汉麻分离蛋白的结构变化。结果表明,超高压(ultra-high pressure,UHP)(0.1、100、200、300 MPa)处理对HPI酶解反应具有一定的辅助作用,且随压力的升高酶解反应程度逐渐增大,分子量逐渐降低;HPI经改性后,疏水性基团逐渐暴露,表面疏水性随压力的增大先上升后下降,且变化差异性显著(P<0.05),在200 MPa时表面疏水性达到最大;酶解反应后,HPIH游离巯基含量显著降低(P<0.05),而表面巯基含量随压力增大呈先上升后下降的趋势;通过测定改性前后蛋白质氨基酸组成及含量可知,改性前后HPI氨基酸组成不变,但各氨基酸含量存在不同程度下降;由傅立叶红外光谱图可以看出,与HPI相比,HPIH的吸收峰强度、峰型及峰面积等均发生不同程度变化,说明超高压辅助酶解反应使蛋白质二级结构发生改变;内源荧光光谱显示,HPIH荧光强度增大且最大发射波长发生红移,说明酶解反应改变了HPI的三级结构;抗氧化活性结果表明,适当的压力处理可有效提升酶解产物的抗氧化能力,当压力为200 MPa时,HPIH的DPPH、ABTS^(+)自由基清除能力及还原能力达到最高。综上所述,超高压辅助酶解改性处理能显著改变汉麻分离蛋白的二、三级结构,暴露出疏水基团等活性基团,从而提高其抗氧化性。