一种食品成形机设计方案反求

成形机是淡水鱼方便食品加工的关键设备之一 ,目前国内还没有十分成功的设计先例 ,本文应用反求设计的思想 ,对淡水鱼方便食品成形机的设计进行讨论 ,得出了恰当的设计方案 ,实践证明所得的结论有效、可行。     

β-O-4型木素模型化合物的合成及其在GIF型仿酶降解体系中的变化(

研究了一种β-O4型木素模型化合物--4-(α-(2-甲氧基苯氧基)-乙酰基)-愈创木酚的合成方法,并利用薄层色谱(TLC)、红外光谱和核磁共振谱(1H-NMR)等手段对它们的化学结构进行了分析与确认.采用由Cu2+/吡啶/过氧化氢组成的GIF型仿酶系统对这一木素模型物进行仿酶降解,结合高效液相色谱(HPLC)及GC-MS等分析方法,分析了该β-O4型木素模型化合物在降解过程中的结构变化,并对这种仿酶降解的机理进行了探讨.研究结果表明通过利用过量愈创木酚和4-乙酰基愈创木酚的溴化物的反应并结合羟甲基化可以得到含α-羰基的酚型β-O4木素模型化合物.GIF仿酶降解体系对β-O4型木素模型物有较强的碎解能力,降解后产生较多的脂肪族小分子化合物,一部分成为香草醛、香草酸等低分子芳香族化合物,该结果可以说明此降解体系能有效导致β-O-4型木素模型化合物的各种类型的裂解反应.     

Determination of vitamin a in foods ‐ a review

Formerly, few foods were routinely analyzed for vitamin A, but recent emphasis on nutrient requirements, nutrient labeling, and use of dietary convenience foods has created need for determining vitamin A in a variety of foods. There are many vitamin A methods — some suitable for certain products only. For regulatory purposes, the FDA specifies the AOAC method where it is applicable. However, some food analysts and organizations continue with their own vitamin A methods. If possible, a single, widely applicable general method should be used for vitamin A in foods. Vitamin A may be determined by spectrophotometric, colorimetric, and fluorometric procedures. Sometimes chromatography is required as an important part of the method. Colorimetric procedures with SbCl₃ are now most widely used to measure vitamin A (retinol) in foods. If vitamin A content is high enough and extracts sufficiently free of interfering substances, spectrophotometric or flurometric methods are satisfactory. Methods in various stages of development for determining vitamin A in foods are based on flurospectrophotometry, gas‐liquid chromatography, high‐performance liquid chromatography, and automation. To estimate total vitamin A nutritional value of certain foods may also require determination of vitamin A isomerization and contents of carotenes, cryptoxanthin, reinaldehyde, and apo‐carotenal.     

Colour evaluation of freeze-dried roselle extract as a natural food colorant in a model system of a drink

The roselle extract, using acidified water-95% ethanol (1:1) as a solvent, was subjected to freeze-drying. Maltodextrin and trehalose, 2 and 3 g/100 ml extract, were used as stabilisers. Addition of the stabiliser retarded anthocyanin degradation. Colour changes of the freeze-dried roselle powder during storage were monitored using the CIELAB system. It was found that pigment concentration markedly changed with a minor change in lightness and hue. However, the changes in chroma mainly came from anthocyanin degradation. The freeze-dried roselle powder with maltodextrin (3 g/100 ml) proved to have superior colour stability. A model system of a drink adding this powder was carried out and the colour evaluation was compared to drinks containing commercial colorants: SAN RED RC^® and carmoesin. During a 12-week storage period at 30 °C, the change in hue of all three groups was within the same shade suggesting any change in pigment concentration had insignificant effect on hue shift. By contrast, the degradation of pigments highly correlated to changes in lightness and chroma. Even though a drink with roselle anthocyanin powder was the least stable in colour, the overall appearance of the drink was rated close to ‘like slightly’ throughout 56 days.     

基于VB的PC机与单片机串行通信的米厂控制系统设计

主要介绍在大米加工厂，如何实现对各设备的监控。在分析大米加工工艺流程和硬件接口连接的基础上，探讨了如何利用VB语言和单片机汇编来编程实现串行通信以及系统是如何抗干扰的。     

巴拿赫空间中不放大映射的不动点

证明了以下结论：若T是巴拿赫空间X中的闭凸子集D到紧致子集D中的不放大映射，且x1是D中任一点，那么由xn 1=2^-1(xn Txn)所表示的序列{xn}收敛于T的不动点，并由此得到了两个推论。     

Banach代数上映射的方向导数

设A为一有单位元的复Banach代数，D包含A为非空开集。西方中引入并研究了映射F：D→A的一阶方向导数DF（a）和高阶方向导数D^(n)f(a)。利用Riesz函数演算，证明了它们的一些性质，讨论了它们与内导子δa的关系。特别地，当f∈H（Ω），a∈A且δ(a)包含Ω时，得到了算子δ^(n)F(a)的一个表示。     

圆网纸机改造为长网纸机的技术创新

介绍了国内某企业4600 mm圆网纸机改造为长网纸机的情况。纸机车速由改造前的120～150 m/min提高到350～500 m/min;纸机产品由原来的挂面箱纸板改为52～150 g/m2铜版原纸,产品档次提高,生产的铜版原纸质量达到用户要求;单台日产量由改造前的50～70 t提高到200～250 t;改造后电耗、煤耗、浆耗、水耗均有下降;改造后企业的经济效益明显提高。     

啤酒酵母和糖化酵母的杂交

本文进行了生产用啤酒酵母07和糖化酵母Saccharomyoes diastat(?)cus 1752的种间杂交,试图通过杂交的方法将糖化酵母的DEX基因重组入杂交子中并得以表达。实验表明,杂交子不仅能够水解和发酵糊精即获得并表达了DEX基因,而且在细胞形态、巨大菌落形态、DNA含量以及产孢能力等方面均不同于单倍体双亲株1303 a his dex和2002 a ade DEX。遗传分析表明,杂交种N3204的51个减数分裂产物其糊精发酵特性以及遗传标记均出现了双亲类型的分离或重组现象。这些结果都证明,通过传统的杂交方法可以获得啤酒酵母和糖化酵母的杂交种。与生产用啤酒酵母亲株07比较,杂交种N3204和N3216在IL啤酒发酵过程中显示酒精产生速率快,发酵度高等较优良的发酵特性。     

啤酒发酵罐的清洗和灭菌技术

发酵罐的微生物状况对啤酒质量影响很大,清洁无菌是啤酒生产中卫生管理的基本要求。良好的CIP系统可以对发酵罐进行有效的清洗。本文对发酵罐的清洗机理、清洗方法、清洗程序、清洗剂和灭菌剂的选择以及CIP系统的运行质量等问题进行了探讨。     

Economic effect of a smoke-free law in a tobacco-growing community

Objective

To determine whether Lexington, Kentucky''s smoke‐free law affected employment and business closures in restaurants and bars. On 27 April 2004, Lexington‐Fayette County implemented a comprehensive ordinance prohibiting smoking in all public buildings, including bars and restaurants. Lexington is located in a major tobacco‐growing state that has the highest smoking rate in the US and was the first Kentucky community to become smoke‐free.

Design

A fixed‐effects time series design to estimate the effect of the smoke‐free law on employment and ordinary least squares to estimate the effect on business openings and closings.

Subjects and settings

All restaurants and bars in Lexington‐Fayette County, Kentucky and the six contiguous counties.

Main outcome measures

ES‐202 employment data from the Kentucky Workforce Cabinet; Business opening/closings data from the Lexington‐Fayette County Health Department, Environmental Division.

Results

A positive and significant relationship was observed between the smoke‐free legislation and restaurant employment, but no significant relationship was observed with bar employment. No relationship was observed between the law''s implementation and employment in contiguous counties nor between the smoke‐free law and business openings or closures in alcohol‐serving and or non‐alcohol‐serving businesses.

Conclusions

No important economic harm stemmed from the smoke‐free legislation over the period studied, despite the fact that Lexington is located in a tobacco‐producing state with higher‐than‐average smoking rates.Many studies have shown that smoke‐free laws implemented in US cities are not harmful to business activity. For example, one paper shows that New York City''s 1995 Smoke‐Free Air Act had no adverse effects on restaurant employment growth, which instead was three times higher than the rest of the state from 1993 to 1997.¹ Another study examined sales tax receipts in 15 cities with and without ordinances banning smoking in restaurants from 1986 to 1993, and found that smoke‐free ordinances did not negatively affect restaurant sales.² Similarly, Sciacca and Eckrem³ found that gross restaurant sales in Flagstaff, Arizona, increased between 16% and 25.8% per business 1 year after a smoke‐free ordinance was implemented. Other studies focused on bar and tourism receipts have shown no adverse effects of smoking ordinances on revenues.^4,5,6 A recent study of the El Paso, Texas, US smoke‐free ordinance, the strongest smoke‐free law in that state, found no changes in restaurant or bar revenues on the basis of a comparison of sales tax and mixed‐beverage tax data over the 12 years preceding and 1 year after the law was implemented.⁷ Scollo and Lal⁸ and Scollo et al,⁹ provide a comprehensive review of this literature.On 27 April, 2004, after an unsuccessful legal challenge, Lexington‐Fayette County, Kentucky, implemented a 100% smoke‐free ordinance, prohibiting smoking in all public buildings, including restaurants, bars, bowling alleys and other businesses. Currently, about 37% of the US population is protected by local or state‐wide smoke‐free laws.¹⁰ However, tobacco‐growing states typically have weak tobacco control laws and provide less public protection from secondhand smoke.¹¹ Lexington‐Fayette County was the first community in Kentucky, a national leader in burley tobacco production¹² and cigarette smoking,¹³ to enact such legislation. The purpose of our study is to determine whether the smoke‐free law affected: (1) employment in restaurants and bars in either Lexington‐Fayette or its contiguous counties or (2) the rate of business closures in food and drinking establishments in Lexington‐Fayette County.     

硫酸盐法制浆过程中热电联产机组的集成应用

对加拿大某硫酸盐法制浆工厂将热电联产与其他一些能够影响发电能力的措施相结合进行生产的集成应用进行了研究。这些能够影响发电能力的方法包括减压阀的去除,蒸汽压力水平和生物质锅炉生产能力的调节,以及生产过程中能耗的降低。采用CADSIM Plus软件来模拟热电联产车间的工作情况,同时考虑到了车间启动阶段的动态特性和对发电量的影响。研究表明,用涡轮机代替减压阀,可以产生14.4MW的电量。通过应用热电联产机组和相应的工艺措施,在回收利用了23%的内部能量的同时,还可以停用现存的燃油锅炉,并产生44.5MW的电量。因此,在制浆造纸工业中实施热电联产,不仅技术上可行,而且能够带来显著的经济效益。研究中还对此项目进行了成本分析,结果表明,其投资回收期不足1年。     

Optimization of a Wall Material Formulation to Microencapsulate a Grape Seed Extract Using a Mixture Design of Experiments

The microencapsulation by spray drying of a commercial grape seed extract (GSE) using maltodextrin (MD), mesquite gum (MG), and zein (Z) as wall materials was investigated. A mixture design of experiments (MDOE) with the three wall material components was used to find optimal wall material formulations. The parameters used to evaluate the microcapsules obtained were encapsulation efficiency (EE), encapsulation productivity (EP), release of the core material in water (RE Water), hygroscopicity (MH), and degree of caking (CD). Four optimal formulations were then selected and evaluated including antioxidant activity (AA), release of the core material at pH 1, 4, 7, and 10, and in simulated gastric (GF) and intestinal fluid (IF), morphology and glass transition temperature (Tg). Microcapsules had a smooth surface with sizes ranging from 4 to 16 μm, a Tg of 160?±?1 °C, and an AA of 1.90?±?0.05 mmoles Trolox/g. The two formulations with the most optimal results were T3 (44 % MG-56 % Z) and T4 (34 % MD-66 % Z), with an EE of 85 % and 82 % and an EP of 98 % and 99 %, respectively. The release was between 50 % to 52 % for T3 and 52 % to 55 % for T4 at the different pHs. The RE in GF and IF were 70 % and 63 %, respectively, for T3, and 71 % and 63 % for T4; most of the release happened during the first hour. Both formulations protected the GSE from thermal degradation at temperatures up to 180 °C.     

Dryspec2: a computer model of a two-stage dryer

Dryspec2 (DRYer System for Property and Energy Control) is an interactive computer program for use in making calculations relative to a two-stage dryer for dairy products. The program indicates the relationship between the energy consumed by the drying process, the process parameters and the properties of the raw material and of the powder produced. To develop Dryspec2, simple model representations of both drying stages were made. Moreover, known physical relations were used to the maximum possible extent. Sorption isotherms form an essential part of the total drying model. The model can be attuned to the situation prevailing in actual practice by taking two model parameters of the first drying stage and one parameter of the second drying stage from data associated with the drying installation concerned. This gives the model a high degree of flexibility. Dryspec2 can be applied for such purposes as finding the optimum process conditions needed to produce a powder that must satisfy specific quality requirements at the lowest possible energy consumption. Dryspec2 is also suitable for use in designing or modifying a spray drying plant. Incorporation of the drying model underlying Dry spec2 into on-line process control is currently under development.     

Phase Behavior of a Meat-Starch Extrudate Illustrated on a State Diagram

ABSTRACT: The phase behavior of a meat-starch extruded system was illustrated on a state diagram. A mixture of meat and potato granules (1.48:1) was extruded with a twin-screw extruder. The extrudates were equilibrated at relative humidities between 0 to 88% and their glass transitions were determined.
Starch and proteins were phase separated at macromolecular level and retained their own phase transitions. The state diagram of the system showed that proteins dictated the texture of the mixed system, with starch contributing to the high value of the mechanical properties. Water had a plasticizing effect on both biopolymers. At room temperature, the extrudates with aw < 0.32 were glassy, while those with aw > 0.57 were rubbery.