Effects of combined high-pressure and heat treatment on the textural properties of soya gels

SPI, 7S, and 11S globulin at 12% (w/v) protein concentration, at neutral pH, did not form gels when heat-treated (90 °C, 15 min) or when high pressure-treated (300–700 MPa), except for the 11S, which formed a gel when heat-treated. The combination of heat and pressure (that is heating the solutions in a water bath and then pressure-treating at room temperature or the reverse sequence), led to differences: when heat-treatment was before high-pressure treatment, only the 11S fraction formed a self-standing gel; however, when the solutions were pressurised before heat treatment, all the proteins formed self-standing gels. The textural and water-holding properties were measured on the gels formed with the three different soy proteins.     

不同精炼工艺及条件对油脂中3-MCPD含量的影响

为了探究不同精炼工艺及其条件对油脂中3-MCPD含量的影响规律,本文较系统地探讨了溶剂和水相萃取、吸附剂吸附以及高温加热等条件对油脂中3-MCPD含量的影响。结果表明：甲醇、乙醇和异丙醇萃取对降低油脂中3-MCPD的含量效果显著,且萃取次数越多油脂中3-MCPD含量越低,可将其降至11μg/kg;3-MCPD的含量随着水洗次数与加水量的增加会逐渐降低;NaCl溶液水洗也能降低3-MCPD含量,但与NaCl浓度有关;活性炭和活性白土等吸附剂对3-MCPD均有一定吸附效果,但活性炭效果较佳,并且吸附效果与加入量和温度有关;温度高于100℃时,随着温度的增加油脂中3-MCPD含量会逐渐增加,但温度达到240℃以上时能将油脂中3-MCPD降至一定程度。     

中小包装食用油自动化立体库与平面仓库的对比分析

旨在为仓储物流行业及油脂加工厂中仓库设计提供借鉴,以库容量10万箱中小包装食用油(5 L小包装、10 L中包装成品油各5万箱)仓库为研究案例,系统分析了两种仓库(平面仓库和自动化立体库)的主要特点,从占地面积、生产成本、建设投资、运营费用等方面对两种仓库的技术方案进行了比较,并对两种仓库进行了经济分析。结果表明：自动化立体库相较于平面仓库能减少66.4%的占地面积,每年能够节约运营成本近50万元;自动化立体库的增量投资收益率为19.01%,增量投资回收期为5.26年,费用现值相比平面仓库低114万元。针对多品种、多拣选、年吞吐量大、产品可追溯性高、衔接工厂MES/ERP系统且持续运营在6年以上的仓库,使用自动化立体库能够显著降低项目总持有成本,降低工人劳动强度,提高发货效率,改进客户体验。     

高可靠双三相永磁同步电机的转矩优化设计

针对双三相永磁同步电机(PMSM)的输出转矩提升问题,分析了3次谐波电流注入电机相电流和反电动势的控制原理,对驱动系统进行优化,调节3次谐波电流,解决2套绕组间的电流干扰问题。在最优相电流的基础上,提出了永磁体塑形方法,综合考虑定子齿槽效应、铁心饱和以及齿尖、极间漏磁,并得到最优的类正弦反电动势。类正弦电流与类正弦反电动势相互作用,电机的输出转矩提升了18.1%。通过有限元分析和样机试验验证了理论分析的正确性,为高可靠双三相PMSM的规模化应用提供了技术支撑。     

Buckling behaviour of imperfect ring-stiffened cone–cylinder intersections under internal pressure

Cone–cylinder intersections are used commonly in pressure vessels and piping. In the case of a cone large end-to-cylinder intersection under internal pressure, the intersection is subject to a large circumferential compressive force. While both the cone and the cylinder may be locally thickened to strengthen the intersection, it is often desirable and convenient to provide an annular plate ring at the cone-to-cylinder joint to supplement local thickening or as an alternative strengthening measure, leading to a ring-stiffened cone–cylinder intersection. Only limited work has been carried out specifically on ring-stiffened cone–cylinder intersections under internal pressure. This paper presents the first experimental study on such intersections. In addition to the presentation of test results including geometric imperfections, failure behaviour and the determination of buckling mode and load based on displacement measurements, results from nonlinear bifurcation analysis using the perfect shape and nonlinear analysis using the measured imperfect shape are presented and compared with the experimental results.     

Working fluids comparison and thermodynamic analysis of a transcritical power and ejector refrigeration cycle (TPERC)

The combined power and cooling cycles driven by waste heat and renewable energy can provide different kinds of energy forms and achieve a higher thermodynamic efficiency. However, only a few researchers have focused on the improvement of temperature matching between the heat source and working fluid. This paper proposes a transcritical power and ejector refrigeration cycle (TPERC) to improve temperature matching between the heat source and working fluid. Based on the modelling of the TPERC system, a comparison of working fluids and the effects of system parameters on the cooling capacity, work output, thermal efficiency and exergy efficiency are discussed. The results show that of the seven working fluids selected, R1234ze has the largest thermal efficiency and exergy efficiency, principally due to having the highest critical temperature. At the identical turbine back pressure, condensing temperature and evaporation temperature, the turbine inlet temperature and its corresponding generation pressure have little impact on thermal efficiency.     

转速对高速斜盘分级机分级效率的影响

重点介绍高速斜盘分级机在中国黄金集团中原矿业有限公司进行的分级试验,并对高速斜盘分级机的分级原理进行阐述,试验过程中通过调节转速,考察了高速斜盘分级机各产品的产率及粒度变化,分析了转速对高速斜盘分级机内部离心力场以及分级效果的影响,测定不同转速下底流产品及溢流产品的品位变化。试验结果表明,转速对高速斜盘分级机分级效率有显著影响,提高转速,分级效率升高,但转速过高,分级效率会降低;高速斜盘分级机的分级粒径低至10μm以下,细粒级矿物10μm分级具有可行性;高速斜盘分级机在分级过程中兼具有脱泥的特点,可以实现连续作业,解决了当前泥质矿物影响浮选指标的技术难题。     

浸出车间汽提预冷凝器设计及节能效果分析北大核心CSCD

节能降耗对提升浸出车间生产线竞争力具有重要的意义。汽提塔气相温度可达95℃,其中含有49%的水蒸气和51%的正己烷。研究汽提塔气相冷凝特性发现,在操作压力为35 kPa下,温度从95℃下降至40℃的过程中,正己烷不会发生冷凝,水蒸气从70℃开始冷凝,温度降至54℃时,冷凝率可达88%。据此,通过增加汽提预冷凝器可对冷凝产生的热量进行回收,以日处理1000 t大豆浸出车间为例,通过换热器设计软件EDR对汽提预冷凝器进行设计、选型、校核,同时对节能效果进行评价。结果表明,通过设计、选型,换热面积为55 m^(2)、型号为BEM 500×4500 mm的列管换热器可以将新鲜溶剂温度从48℃加热至58℃。分析节能效果发现,浸出车间增加汽提预冷凝器,吨大豆可节约蒸汽8.2 kg、节约电量0.1 kW·h,具有很高的投资价值。     

Phenolic antioxidants in alder smoke during industrial meat curing

Alder wood smoke in a large sausage-curing chamber was analysed with regard to its content of methoxyphenol antioxidants. The use of Tenax adsorbent cartridges permitted simultaneous quantitative sampling of phenols condensed on smoke particles as well as gaseous compounds. The analytical determinations were performed by thermal desorption combined with gas chromatography and mass spectrometry. In addition to methoxyphenols, several other key components were assessed, including 1,6-anhydroglucose, 2-furaldehyde, furans and hydrocarbons. Benzene was the most prominent hydrocarbon. The concentrations of polycyclic aromatic compounds were low, due to a low smoke generation temperature. Predominant smoke components were the 2,6-dimethoxyphenols, which are characteristic thermal degradation products from hardwood. The 2,6-dimethoxyphenols are stronger antioxidants than the 2-methoxyphenols present in lower amounts. The particularly active antioxidants with a 4-alkenyl side-chain constituted 20–30% of total methoxyphenols, which is much more than normally reported for liquid smoke. The phenolic antioxidants may be important not only for the preservation of foods, but also for health as dietary components.     

Volatile compounds of dry-fermented sausages as affected by solid-phase microextraction (SPME)

The analysis of volatile compounds from the headspace of dry-fermented sausages was done by solid-phase microextraction (SPME). The effects of exposure time and fibre coating were investigated. A total of 90 different compounds were extracted by the two fibre coatings and these were identified. Sixty-six compounds were extracted by divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) coating and were identified, while 24 more were found with the carboxen/polydimethylsiloxane (CAR/PDMS) fibre. These 24 volatile compounds were mainly of low molecular weight. Four of the major compounds extracted: acetic acid, ethanol, hexanal and butanoic acid, were in high proportions in the two fibre coatings. However, the main differences were a higher affinity of DVB/CAR/PDMS for aldehydes while, for CAR/PDMS fibre, the higher affinity was for ester compounds. The extraction yields of dry fermented sausages volatile compounds varied according to the fibre coating used and the time of exposure, although competition effects were detected due to the high generation of lipid oxidation products, such as hexanal.