专业英语讲义.doc

Lesson 1 Food IndusturyThe food industry is the complex, global collective of diverse businesses that together supply much of the food energy consumed by the world population. Only subsistence farmers, those who survive on what they grow, can be considered outside of the scope of the modern food industry.1.1 ProductionFood is traditionally obtained through farming, ranching and fishing with hunting, foraging and other methods of subsistence locally important. More recently, there has been a growing trend towards more sustainable agricultural practices. This approach, which is partly fueled by consumer demand, encourages biodiversity, local self-reliance and organic farming methods. Major influences on food production are international organizations (e.g. the World Trade Organization and Common Agricultural Policy),national government policy (or law) and war. 1.2 PreparationWhile some food can be eaten raw, many foods undergo some form of preparation for reasons of safety, palatability, or flavor. At the simplest level this may involve washing, cutting, heating or cooling, pressure cooking, fermentation, or combination with other food. In a home, most food preparation takes place in a kitchen. Some preparation is done to enhance the taste or aesthetic appeal; other preparation may help to preserve the food; and others may be involved in cultural identity. A meal is made up of food which is prepared to be eaten at a specific time and place.1.3 Food processingFood processing is the methods and techniques used to transform raw ingredients into food for human consumption. Food processing takes clean, harvested or slaughtered and butchered components and used them to produce marketable food products. There are several different ways in which food can be produced.All food processing involves a combination of procedures to achieve the intended changes to the raw materials. There are conveniently categorized as unit operation, each of which has a specific, identifiable and predictable effect on a food. Unit operations are grouped together to form a process. The combination and sequence of operations determines the nature of the final product. 1.4 Food manufacturePackaged food are manufactured outside the home for purchase. This can be as simple as a butcher preparing meat, or as complex as a modern international food industry. Early food processing techniques were limited by available food preservation, packaging and transportation. This mainly involved salting, curing, curdling, drying, pickling, fermentation and smoking. Food manufacturing arose during the industrial revolution in the 19th century. This development took advantage of new mass markets and emerging new technology, such as milling, preservation, packaging and labeling and transportation. It brought the advantages of pro-prepared time saving food to the bulk of ordinary people who did not employ domestic servants.At the start of the 21 st century, a two-tier structure has arisen, with a few international food processing giants controlling a wide range of well-known food brands. There also exists a wide array of small local or national food processing companies. Advanced technologies have also come to change food manufacture. Computer-based control systems, sophisticated processing and packaging methods, and logistics and distribution advances, can enhance product quality, improve food safety, and reduce costs.1.5 Marketing and retailingFood marketing brings together the producer and the consumer. It is the chain of activities that brings food from “farm gate to plate”.1 The marketing of even a single food product can be a complicated process involving many producers and companies. For example, fifty-six companies are involved in making one can of chicken noodle soup.2 These businesses include not only chicken and vegetable processors but also the companies that transport the ingredients and those who print labels and manufacture cans. The food marketing system is the largest direct and indirect non-government employer in the United States.In the pre-modern era, the sale of surplus food took place once a week when farmers took their wares on market day, into the local village marketplace. Here food was sold to grocers for sale in their local shops for purchase by local consumers.3 With the onset of industrialization, and the development of the food processing industry, a wider range of food could be sold and distributed in distant locations. Typically early grocery shops would be counter-based shops, in which purchasers told the shop-keeper what they wanted, so that the shop-keeper could get it for them. In the 20th century supermarkets were born. Supermarkets brought with them a self service approach to shopping using shopping carts, and were able to offer quality food at lower cost through economies of scale and reduced staffing cost. In the latter part of the 20th century, this has been further revolutionized by the development of vast warehouse-sized, out-of-town supermarkets, selling a wide range of food from around the world.Unlike food processors, food retailing is a two-tier market in which a small number of very large companies control a large proportion of supermarkets. The supermarket giants wield great purchasing power over farmers and processors, and strong influence over consumers. Nevertheless, less than ten percent of consumer spending on food goes to farmers, with larger percentages going to advertising, transportation, and intermediate corporations.41.6 Wholesale and distributionA vast global transportation network is required by the food industry in order to connect its numerous parts. These include suppliers, manufacturers, warehousing, retailers and the end consumers. There are also those companies that, during the food processing process, add vitamins, minerals, and other necessary requirements usually lost during preparation. Wholesale markets for fresh food products have tended to decline in importance in OECD countries as well as in Latin America and some Asian countries as a result of the growth of supermarkets, which procure directly from farmers or through preferred suppliers, rather than going through markets.5The constant and uninterrupted flow of product from distribution centers to store locations is a critical link in food industry operations. Distribution centers run more efficiently, throughput can be increased, costs can be lowered, and manpower better utilized if the proper steps are taken when setting up a material handling system in a warehouse.1.7 Food industry technologiesSophisticated technologies define modern food production. They include many areas. Agricultural machinery, originally led by the tractor, has practically eliminated human labor in many areas of production. Biotechnology is driving much change, in areas as diverse as agrochemicals, plant breeding and food processing. Many other areas of technology are also involved, to the point where it is hard to find an area that does not have a direct impact on the food industry. Computer technology is also a central force, with computer networks and specialized software providing the support infrastructure to allow global movement of the myriad components involved.6Notes1 It is the chain of activities that brings food from “farm gate to plate”.本句的主语It 指的是上面中的 food marketing, 翻译时也可以用汉语代词“这”表示。activities 直译是活动的意思，gate是大门的意思，而plate是餐盘的意思。因此，将这句看起来意思明了的英语句子译成汉语，需要意译处理，例如，可将farm gate处理成“农场”，而不必将gate译出来。2 For example, fifty-six companies are involved in making one can of chicken noodle soup.原文作者强调的是制造one can of chicken noodle soup牵涉的不同行业公司数量之多（56家不同公司），所以把fifty-six companies放在了句子前面，翻译时也要体现这种强调语气，但中文的强调句中词序要作调整。3 Here food was sold to grocers for sale in their local shops for purchase by local consumers.Here 是地点状语，指的是上文中提到的 the local village marketplace.。for purchase by local consumers 是主语 food 的补足语。4 Nevertheless, less than ten percent of consumer spending on food goes to farmers, with larger percentages going to advertising, transportation, and intermediate corporations.本句为简单句，主语是less than ten percent of consumer spending on food ，谓语是goes to farmers ，而with larger 是分词短语，对consumer spending on food 补充说明。5 Wholesale markets for fresh food products have tended to decline in importance in OECD countries as well as in Latin America and some Asian countries as a result of the growth of supermarkets, which procure directly from farmers or through preferred suppliers, rather than going through markets.本句的主语是Wholesale markets，谓语是have tended to decline，in importance是方式状语，in DECD.countries 是地点状语，as a result of是原因状语。这种因果关系桔子翻译时，一般要按照汉语表达习惯，先陈述原因，再给出结果。6 Computer technology is also a central force, with computer networks and specialized software providing the support infrastructure to allow global movement of the myriad components involved.本句从语法上看也是主系表结构简单句，而后面的介词短语 with computerinvolved 是主语的补足语。食品工业食品工业是一个为人们提供大量食物能量、包括各行各业的全球性复合行业。只有自产自用的农民可以认为不包含在现代食品工业范围之内。1.1 生产食物通常由耕作、饲养和捕捞获取，而狩猎、觅食和其他自产自用方法的重要性有限。近来，可持续农业规范势头正在增长。这种趋势部分是由消费者需求，生物多样性、地方自力更生以及有机耕作方式所引起的。食品生产的主要影响来自国际组织（例如，世界贸易组织和共同农业政策）、国内政府政策（或法律）以及战争。1.2 制备尽管某些食物可以生食，但许多食物由于安全、可食性或风味方面的原因，均经过某种程度制备。最简单的制备可以包括清洗、切割、修整或加入其他食品或配料，例如香料。食品制备也可以包括混合、加热或冷却、加压蒸煮、发酵或者与其他食品联合。在家里，大多数食品制备在厨房完成。有些制备是为了增加滋味或美观效果；其他的制备有的是为了保藏食物，还有一些可能是出于文化认同性需要。餐具是在特定时间和地点制备的食品。1.3 食品加工食品加工是将原料转化成供人类消费食品的方法和技术。食品加工利用清洁的、收获或屠宰和分割得到的食品无聊生产上市食品。食品可由若干不同途径生产。为了实现原料的转变，所有食品加工都会联合多种加工方法。这些加工方法可以方便地分类为各种单元操作，每种单元操作对一类食品都会产生特殊的、可辨认和预测的效应。一个加工过程由若干单元结合而成。单元操作的联合和顺序决定了最终产品的特性。1.4 食品制造包装食品是非家庭制造的供人购买的食品。食品制造简单的可如肉店制备肉，复杂的可如现代国际食品工业。早期的食品加工技术仅限于对已有食品的保藏、包装和运输。这主要涉及盐腌、腌制、凝结、干燥、湿腌、发酵和烟熏。食品制造起源于19世纪工业革命时期。这一发展利用了新兴大市场及磨粉、保藏、包装、标签及运输方面的新技术。其省时的制备食品为那些没有雇佣家庭佣人的普通大众带来了好处。21世纪初，食品制造业出现了双重结构，其中若干国际食品加工巨头控制了一大批著名的食品品牌。也有一大批小型区域性或国内食品加工公司。一些先进技术也给食品制造业带来了改变。计算机控制系统、精细的加工和包装方法，以及物流和配送进展，可用来提高产品品质、改善食品安全性和降低各种成本。1.5 市场和零售食品市场将生产商和消费者联系在一起。这是一条使食品“从农场到餐盘”的供应链。即使是单独一种食品的市场活动，也是一个涉及许多生产商和公司的复杂过程。例如，一种鸡肉面汤罐头的制造会牵涉到56家公司。涉及的业务不仅与鸡肉和蔬菜加工商有关，也与运输配料、印刷标签和制造罐头的公司有关。美国的食品市场系统是最大的直接和间接的非政府雇主。在现代化出现之前，农民们将多余的农产品每周一次在集市日拿到当地乡村市场出售。农民在乡村市场将食品出售给零售商，零售商再通过商店将食品卖给当地消费者。随着工业化的出现和食品加工业的发展，许多食品可以长距离配送销售。早期杂货铺通常是柜台型商店，购买者先告诉店主要买什么，然后由店主为其取出需要的货物。20世纪出现了超市。超市为购买者提供了一种利用购物小车的自助购物方式，并通过规模经济和减少用工，可以较低价格出售品质优良的食品。20世纪后期，通过发展大规模仓贮、城外超市和销售世界各地食品，超市食品销售得到进一步改进。食品零售商与加工企业不同，是一个两级分化的市场，其中少数大公司控制着很大的市场份额。超市巨头对农民和加工者有极大的购买力，对消费者影响极大。尽管如此，消费者花费在食品方面的开销只有不到10%到了农民手中，而食品花销的大部分到了广告运输和中间公司手中。1.6 批发和配送食品工业为了将其无数部分联结起来，需要广泛的全球运输网络。这些部分包括供应商、制造商、仓贮、零售商和终端消费者。一些公司在食品加工过程中还会加入各种维生素、矿物质和其他在制造时通常会损失掉的必要成分。超市直接从农民或选择性供货商（而非通过市场）采购食品方式的发展，已经使经合组织国家、拉丁美洲和一些亚洲国家的新鲜产品批发市场的重要性有所降低。从配送中心到商店之间的连续不断的产品物流，是食品工业活动的一个关键环节。配送中心运行效率高，可增加运送量和降低成本，并且，如在仓贮中适当采用搬运系统，还可以使劳动力得到更好的利用。1.7 食品工业技术现代食品生产由多种精细技术构成。这些技术包括许多方面。最早由拖拉机牵引的农业机械实际上已经免除了食品生产许多领域的人工劳动。生物技术正使诸多领域发生变化，如农用化学品、植物育种和食品加工。许多其他技术领域也对食品工业产生影响，很难找到对食品工业不产生影响的某个领域。计算机技术也是一股中心力量，计算机网络及专用软件为食品工业无数相关要素在全球范围活动提供了支持框架。Lesson 2 Water2.1 OccurrenceWater is one of the smallest and simplest molecules found in foods. Yet water and water content are considered to be some of the most influential forces in food chemistry. Water has many roles in food processing and , while the chemistry is simple, the impact on food reactions and food quality is greater than other chemical component.When the chemical composition of food is considered in the aggregate, there is more water than any other component. Fruits, vegetables, beverages, sauces, puddings, frozen desserts, meats and prepared foods all have high water contents. Beside the obvious quality parameters of being too dry or too wet, the amount of water has a tremendous economic impact because most foods are sold on the basis of weight.Even apparently “dry” foods have water and the moisture content is usually critical to quality characteristics. Dry breakfast cereals, crackers, and powdered ingredients such as flour and salt, all have measurable moisture of a few percent. Edible oil is one of the few food ingredients that have no significant or measurable water. Table 2.1 lists the typical water content of selected foods.2.2 Water as an IngredientWater is an ingredient in many processed foods. Ironically, water is often added at some early stage in the processing and then later removed by drying. This suggests a temporary function for water at some intermediate point in the processing scheme. Otherwise , the bother of adding and the expense of drying could be eliminated. When water is used as an ingredient, it comes with much more than just the H2O molecules associated with water. Depending on the source, water will contain various minerals which can influence functionality and interactions with the food components. Processing plants in different locations sometimes seem to produce subtly different products when the only apparent differences are the local water.1 Water can also contain chlorine, fluoride, microorganisms, parasites, off-flavors, color, acidity or alkalinity, environmental contaminants, and particulates. In-plant water filtration and other treatments may be needed to take the variability out of the local water supply.2.3 Water properties and ReactionsWater is a polar molecule and therefore serves as a dissolving solvent for many different polar compounds in food. Water is a dipolar molecule with a negative area near the oxygen atom and positive areas near the hydrogen atoms. This is part of the reason why water heats so well in a microwave field. When exposed to microwaves, water molecules vibrate and flip, creating frictional heat. This dipole nature also allows water molecules to form hydrogen bonds with each other and with other polar molecules in food, such as carbohydrates and proteins. One of the effects of heat, especially mild heat, on foods is the disruption of the hydrogen bonds.Ice, liquid water, water vapor , and steam are prevalent in food processing. The chemical reactivity and physical properties differ greatly from one form of water to anther .Liquid water is fairly inert in foods. It is not typically degraded but more likely, will simply change state and evaporate during processing.One reaction that causes the water molecule to break apart is hydrolysis. The more significant part of hydrolysis is that other molecules in foods such as protein, starch, or lipids will break apart as well. These hydrolysis reactions usually bring about changes in functional properties because polymers may be shortened in length or flavor compounds may be produced.2.4 Water ActivityWhile the actual content of water in a food can be used to estimate whether certain water controlled chemical reactions will occur, the multiple chemical components in food make the system too complex to use percent composition of water as an accurate predictor of reactions.2 Water activity (aw) is considered a more powerful tool in looking at how water will influence chemical reactions in food. aw in foods can be represented by the following equationsaw=P/Powhere P= vapor pressure of water in the food, and Po=vapor pressure of pure water under the same conditions oraw= relative humidity of a food/100oraw= moles of water/ (moles of water + moles of solute)aw varies between the theoretical values of 0 and 1.0. In principle, a food will move to equilibrium with the relative humidity of its surroundings. This explains why, if left in a room of 50% relative humidity, a slice of bread (aw about 0.96) will lose moisture and cracker (aw about 0.10) will gain moisture. The quality of both products would be lost because of the equilibration with the surrounding humidity. This also means that in a packaged food, mixed components such as dried fruit and breakfast cereal flakes will move toward equilibration of aw with each other. Moisture uptake or loss due to relative humidity differences of the food and its environment will often result in quality changes. Packaging that is impermeable to water vapor is used to protect the food from the humidity of its environment.In certain breakfast cereals, the moisture content and aw must be in a narrow range. Physical fracturing of the structure and undesirable chemical reactions will occur if the product is too dry. Loss of crispness will become obvious if the product is too moist.The relationship of aw to water content in a given food system is illustrated by a sorption isotherm in Fig 2.1. At low aw and low water content, water molecules are thought to be spread out in a monolayer referred to by chemists as the BET layer. Water in this state is tightly bound by food components and not easily removed by drying. These water molecules have a low vapor pressure, do not form ice at freezing temperatures, and do not dissolve food components that would otherwise be water soluble.As a dry food is exposed to higher relative humidities it adds more moisture and the additional water molecules are called multilayer water. At even higher moisture and aw , the water becomes more reactive and is called free water. Its chemical reactivity and properties would be similar to pure water. In frozen foods, the proportion of ice vs. liquid water is temperature dependent. Since liquid water is responsible for the vapor pressure aw is controlled primarily by temperature.Not only are chemical reactions controlled by aw , the growth of microorganisms for spoilage or fermentations is influenced by aw . To illustrate how aw can influence the reaction in food, some key chemical reactions and general growth of microorganisms has been summarized as shown in Fig.2.2.2.5 Glass TransitionAnother way of explaining how water affects the texture of food components is glass transition. Proteins and starch are polymers that have glass transition temperatures (Tg). Below the Tg , the polymers will be in the