Food Science

Summary

Food science is a field concerned with studying the biological, chemical, and physical properties of food. Food scientists make use of the tools of science, technology, and engineering to develop effective ways of producing and preserving a safe, healthy food supply for communities and nations. Issues addressed by food science include the safe cultivation and harvest of food plants; the healthy and humane breeding and slaughter of livestock; the optimal preservation of food as it is processed, stored, packaged, and distributed; and the manufacture of new food products with maximal nutritional value and appeal. Food science is also the discipline responsible for identifying the inherent nutritional properties of various foods and the ways in which foods interact with human biological systems once they have been consumed. Efforts in this field are critical to addressing global hunger and malnutrition.

Definition and Basic Principles

Food science is a multidisciplinary field in which principles from biology, chemistry, and engineering are applied to the study of the chemical, physical, and microbiological properties of food. Food scientists investigate the elements contained in foods, factors involved in the physical and chemical deterioration of food, and how different foods interact with human physiology. Many experts look to food science as a way to address global hunger and malnutrition in the twenty-first century. The specific application of knowledge from food science to practical issues such as preserving, processing, manufacturing, packaging, and distributing food, as well as questions of food safety and quality, is sometimes called food technology.

The fact that foods are chemical systems is an important fundamental principle of food science. The same basic elements that form the cells and tissues of the human body, including carbon, oxygen, hydrogen, nitrogen, sulfur, and calcium, are the ones that make up the majority of the foods people eat. The chemical composition of foods and the ways in which the atoms and molecules within a food are arranged and bonded to each other determine properties such as a food's flavor, texture, color, and nutritional value.

Food scientists are also concerned with the processes of digestion, or how foods are broken down and absorbed by the body. Digestion occurs through the action of enzymes (biological substances that facilitate chemical reactions) found in saliva, pancreatic juices, and the lining of the small intestine. Nutrition—the study of how the chemical composition of different foods contributes to human health, growth, and disease—is another important subfield of food science. The six basic nutritional components of the human diet are carbohydrates, proteins, fats or lipids, vitamins and minerals, and water. Each of these components serves different vital functions within the human body.

Background and History

Humans have been working to identify the properties of different foods and experimenting with ways of processing and preserving foods since time immemorial. In ancient China, Rome, Greece, Egypt, and India, fermentation was commonly used to produce alcoholic beverages and to preserve food, and archaeological finds suggest that in the Middle East, as long ago as 12,000 BCE, fruits, vegetables, and meats were deliberately laid out in the hot sun to preserve them. Many ancient civilizations also had a rudimentary understanding of the nutritional and medicinal properties of specific foods. The Roman writer Pliny the Elder, for instance, asserted that consuming cabbage was good for vision, could relieve headaches and stomach problems, and could even prevent hangovers.

Food science as a formal scientific discipline has a much more recent history. Beginning about the nineteenth century, researchers working in fields such as biology and chemistry often took an interest in questions of food science. For example, the French bacteriologist Louis Pasteur introduced the technique of pasteurization in 1864, and in 1847, the German chemist Justus von Liebig published his seminal work, Researches on the Chemistry of Food. Liebig was among the first scientists to clearly outline the principle that foods are metabolized, or broken down by the body to produce energy. He also understood the nutritional importance of chemicals such as nitrogen and sulfur.

It was not until the twentieth century that food science and the application of technology to the processing and packaging of food became a recognized field of study in its own right. One of the major achievements of twentieth-century food scientists was the invention of vacuum packaging, which helps preserve perishable foods longer by removing air from the containers in which they are kept, thus preventing the action of bacteria. Other breakthroughs were the development of quick freezing, pioneered by the frozen vegetable manufacturer Clarence Birdseye; the use of thermal processing to improve the safety of canned foods, which had been around since the late eighteenth century; and the use of radiation to kill microorganisms in foods. Dedicated food science departments were created at universities throughout the United States and the world, and professional organizations such as the Institute of Food Technologists and the European Federation of Food Science and Technology gathered practicing food scientists together to share their knowledge.

By the twenty-first century, food science had progressed to a point where researchers were able to tinker with the production of various foods in ways that had never before been thought possible. For example, in the making of cheese, rennet (an enzyme from the stomachs of unweaned animals such as calves) has largely been replaced by a synthetically engineered enzyme called chymosin, which is more chemically consistent and pure. Also, advances in food science allow growers to use genetic engineering rather than breeding to create genetically modified foods with more desirable attributes, such as tomatoes that take longer to ripen and reach supermarket shelves just at the point when they are ready to eat.

How It Works

Three chemical compounds form the building blocks of food: carbohydrates, fats (or lipids), and proteins. Carbohydrate molecules, which are found in fruits, vegetables, grains, starches, and dairy products, consist of atoms of carbon, hydrogen, and oxygen, chemically bonded in a ratio of 1:2:1. Monosaccharides and disaccharides such as glucose, fructose, and sucrose have just one or two molecules of this kind and are known as simple sugars. Polysaccharides such as starch, glycogen, and cellulose (an important component of dietary fiber) contain several carbohydrate molecules and are known as complex carbohydrates. Food science is able to reveal the chemistry behind the behaviors of carbohydrates in different foods. Because sugar molecules tend to crystallize (form solid geometric structures) at low temperatures, for example, ice cream with too much milk in it can be gritty because of the crystallization of lactose, a sugar found in milk whey.

Protein molecules, which are found in meats, nuts, eggs, beans, and dairy, are composed of long chains of amino acids. An amino acid is an organic compound that contains at least one carboxyl group (–COOH) and one amino group (–NH₂). The amino acids in a protein are linked to each other by peptide bonds and folded into particular shapes. By identifying how a protein denatures (how the shape of its folded amino acids changes) when heat or chemicals are applied to it, food science can demonstrate how different methods of cooking affect foods and why. For example, when heat is applied to meat, the tidy folds created by the chains of amino acids it contains collapse, causing the protein molecules to shrink and release water. This is why a steak seared on a pan is smaller after cooking.

Lipids, such as animal fats and vegetable oils, are large molecules that are not soluble in water but are soluble in organic solvents such as acid. There are many different kinds of naturally occurring lipids, but most are largely composed of various fatty acids and glycerol. Glycerol is a type of alcohol, and a fatty acid is a compound that contains carbon and hydrogen atoms linked together in a long line and ending in a carboxyl group. Again, food science is concerned with how the chemical structure of lipids contributes to their physical characteristics. For example, the way in which the fatty acids in a lipid molecule are arranged determines whether a given fat will be solid at room temperature (such as lard) or liquid (such as vegetable oil).

Contemporary food scientists use a variety of sophisticated instruments to analyze the chemical composition and physical properties of foods. For example, a tool known as a spectrophotometer is used to detect how much light is absorbed by the atoms and molecules in a given sample of food and how much passes through it. Another food analysis technique is chromatography, which passes a sample of a food substance, in either liquid or gaseous form, through a medium that allows different components of the sample to travel at various rates. Spectrophotometry, liquid chromatography, and gas chromatography are all methods of analysis that enable food scientists to determine exactly what percentage of a specific food is made up of components such as fatty acids, amino acids, cholesterol, and carbohydrates. They also allow researchers to test for the presence of particular vitamins and minerals.

Digestion and Nutrition. The chemical composition of foods affects how they are broken down, or digested, by the body. The primary chemical reaction involved in digestion is called aerobic respiration, which involves tearing apart the bonds between carbon, oxygen, and hydrogen, the elements found in all three major types of food compounds. When aerobic respiration occurs, the energy contained within these bonds is released, and the individual atoms can be rearranged into different forms.

By analyzing the chemical characteristics of foods and how these properties relate to their digestion, food science can reveal why certain foods affect people the way they do. For example, because aerobic respiration is able to act directly on molecules of simple sugars, commonly found in soft drinks or colas, they are very quickly converted into energy. This results in an intense burst of energy that rapidly fades away—the so-called sugar high that a sweet drink can provide. In contrast, complex carbohydrates, commonly found in whole grains such as oats and brown rice, must first be broken down into simpler forms by enzymes before aerobic respiration can take place. These foods take longer to digest and provide longer-lasting energy, which is why a bowl of oatmeal in the morning can make a person feel full for hours. The structure of proteins is even more complex than that of whole grains, so they provide an even longer-lasting source of energy. Lipid molecules, the hardest of all to digest, provide the body with its most long-lasting source of energy.

Although lipids take the longest time to digest, once they have been broken down, they provide the most energy per weight of food. For this reason, excess energy is stored within the body as fat deposits called adipose tissue. These enable the vital activities of cells to continue even when there is a temporary shortage of food. However, excess fat deposits are also stored inside organs and blood vessels. Here, they can block the normal flow of blood and lead to serious health problems such as heart failure. The question of how people can maximize the positive physiological effects of foods and avoid the harmful effects of an unhealthy diet is one of the primary concerns of food scientists. Among other pieces of knowledge, research has revealed that fiber, a type of carbohydrate found in fruits, vegetables, grains, and legumes, is essential for the proper functioning of the bowels and adheres to fat molecules traveling through the digestive system so they can be more easily disposed of as waste. Food science has also shown that certain kinds of unsaturated fatty acids, including omega-3 fatty acids, are extremely helpful in promoting heart health and preventing the buildup of cholesterol in the blood vessels.

Although it may not satisfy a person's hunger, water is one of the most important nutrients required by the body. Water is the major component of every cell in the body and the environment within which every chemical reaction in the body takes place. It serves as a medium of transport for nutrients and waste, and it helps maintain a steady body temperature.

Other chemical components found in food and important for human nutrition include vitamins and minerals. These nutrients serve a variety of essential functions. For example, vitamin E is an antioxidant, a substance that inhibits oxidizing reactions that can damage cells, and vitamin C helps the body process amino acids and fats. Calcium and magnesium are both minerals that are important in the formation of strong, healthy bones.

Applications and Products

Preservation Techniques. One of the most important applications of food science is the development of preservation techniques that lengthen the time that a food can remain safe to consume and palatable. Among the many factors that cause foods to deteriorate are being exposed to microorganisms such as bacteria, molds, and yeast; experiencing changes in moisture content; being exposed to oxygen or light; undergoing the action of natural enzymes over time; being contaminated by industrial chemicals; and being attacked by insects or animals such as ants or rodents. Any of these factors may cause physical or biochemical reactions in foods that result in changes in texture, color, and taste or make them unsafe to eat.

Heating food is an effective method of preservation because high temperatures destroy both microorganisms and enzymes. However, too much heat can cause detrimental changes in the flavor, texture, and nutritional content of foods. Two commonly used methods of mild heat treatment are pasteurization and blanching. Pasteurization, which is most often applied to milk but also used to preserve fruit juices, beer, and eggs, involves heating the food to a temperature of 161 degrees Fahrenheit for just a few seconds. Blanching, most often used for vegetables destined to be frozen, dried, or canned, involves briefly dipping the food in water of about 212 degrees Fahrenheit. The most common severe heat treatment is canning. First, the food is placed inside a cylindrical steel or aluminum container, and the air is drawn out of it using a vacuum. Then, the lid is sealed in place, and heat of about 240 to 250 degrees Fahrenheit is applied to the can. The process of canning ensures that the food in question reaches the point of commercial sterility and does not contain any live bacterium of the species Clostridium botulinum. This potentially deadly pathogen, if ingested, causes a kind of poisoning known as botulism.

Refrigeration and freezing are the two major types of cold preservation. Refrigeration, which takes place at temperatures ranging from 40 to 45 degrees Fahrenheit, does not destroy microorganisms or enzymes but somewhat inhibits the reactions they cause that result in spoiling. In and of itself, refrigeration is not a long-term method of preservation for most foods. Freezing, which takes place at temperatures below 32 degrees Fahrenheit, is a more effective inhibitor of biochemical reactions than refrigeration and can preserve foods for longer periods. However, extremely cold temperatures can cause undesirable chemical changes, such as crystallization, in foods. If the water molecules in a food crystallize, they will rupture cell walls and cause the food to be softer and more liquid when it is eventually thawed.

Besides thermal processing and the use of cold temperatures, a host of other techniques to combat the deterioration of food have been developed, such as dehydration, radiation, fermentation, and the use of natural and artificial preservative agents such as sugars, salts, acids, and inorganic chemicals such as sodium benzoate and sulfur dioxide. Preservation is also aided by careful control over the characteristics of the atmosphere in which a food is stored.

Genetically Modified Foods.Genetically modified (GM) foods, also known as genetically engineered foods, are those whose existing genetic structure has been changed by the introduction of a new gene from a different organism. The technology that enables scientists to do this is called gene splicing, and the new genetic information is known as recombinant DNA. The purpose of genetic modification is usually to achieve some specific trait that will increase the food's usefulness for either producers or consumers. For example, DNA from bacteria has been incorporated into many strains of plants to enable them to resist attacks from insects and other pests. Some plants, such as soybeans, have been genetically modified so that they no longer produce particular substances, such as certain proteins, that can cause allergic reactions in people. By 2020, over 90 percent of all soybeans, cotton, and corn planted in the United States were genetically modified. Many GM crops in the United States are used as animal feed. However, according to some estimates, more than half of the foods for sale on supermarket shelves in the United States contain some ingredient from a genetically modified, or transgenic, plant.

Only a small number of food products from genetically modified animals have been approved for consumption in the United States, including genetically engineered Atlantic salmon. In 2009, the US Food and Drug Administration (FDA) issued guidelines for its approach to regulating genetically engineered animals, opening the door for food products from such animals. Potential applications of this technology to animals raised for food include pigs with a genetic modification that causes them to produce omega-3 fatty acids, or salmon or chickens that grow much faster than usual. In 2020, the FDA approved the use of a line of pigs for human food and medical use called GalSafe pigs. The intentional genomic alteration (IGA) was developed to remove alpha-gal sugar from the surface of the pigs' cells. Individuals with alpha-gal syndrome are allergic to these sugars, but they can eat GalSafe pigs.

Manufactured Foods. In vitro meat, also known as cultured meat, is animal muscle tissue that is grown outside of a living organism. It represents a relatively new and very specialized application of food science that makes use of tissue engineering techniques borrowed from cell biology and biotechnology. The production of in vitro meat involves harvesting either muscle cells or stem cells (cells that are pluripotent, or able to give rise to any number of different cell types) from a live animal, such as a chicken, cow, or pig. Alternatively, cells from a slaughtered animal can be used. The cells are then cultured within a medium that provides them with a large quantity of the nutrients required for growth. Typically, this includes amino acids, vitamins, minerals, and glucose. In this environment, the cells multiply rapidly. To encourage the cultured cells to fuse and form the three-dimensional structures that make up muscle fibers and tissues, they are placed on a scaffold, usually made of collagen. They may also be stretched or electronically stimulated to help them form the correct structures. At the end of this process, a substance similar to ground meat is produced.

Beverages and Snacks. Food science principles lie behind almost every beverage and snack food found on supermarket shelves. Carbonation, for example, enables the production of nonalcoholic soft drinks such as colas and sparkling water. Carbonation is simply the introduction of carbon dioxide gas into a liquid. It takes place at high pressures and low temperatures because both of these factors increase the solubility of carbon dioxide. Alcoholic beverages such as beer and wine are produced through a process called fermentation. A substance—barley in the case of most beers, grapes in the case of wines—is chemically broken down by the action of microorganisms such as bacteria or yeast. Fermentation takes place under anaerobic conditions (in the absence of oxygen) because this is what causes the microorganisms to react with the carbohydrates in the substance to be fermented. In the process, sugars present in the original substance are converted into ethyl alcohol, the flavor and texture of the beverage is markedly changed, and its shelf life is prolonged.

Candy and other sweet confections are also the products of food science principles. To control the taste and texture of their products, candy manufacturers use a number of clever techniques designed to manipulate the behavior of sugar. For instance, many different candies begin with the same two ingredients: sugar and water. By changing the ratio of sugar to water, changing the boiling temperature of the sugar-water solution, controlling the time it takes for the boiling mixture to cool down, and adding various interfering agents such as butter, gelatin, cocoa, or pectin to the mixture, candy manufacturers can create a host of different textures from the same basic foundation: creamy and smooth, hard and brittle, moist and chewy, or smooth and transparent.

Careers and Course Work

Food science research and related industries such as agriculture, food processing and manufacturing, and food safety and inspection offer various career opportunities. For example, food chemists analyze, create, and modify the biochemical compounds and chemical processes involved in the synthesis or development of food products. They may work for food manufacturing companies, biotechnology corporations, government institutions, environmental consulting companies, and agricultural universities. Food bacteriologists, who often work in similar settings, research food-borne pathogens' microbiological and molecular basis. Their work supports the safe production, packaging, and distribution of food plants and animals. Food safety inspectors work in meat-processing plants, fisheries, large farms, restaurants, and food production facilities. They may also work for federal agencies. Food safety inspectors use their knowledge of biology and chemistry to ensure that food products such as dairy, grains, fish, fruits, vegetables, meats, and poultry properly conform to national or industry-based sanitation standards.

Taking high school courses in biology, chemistry, physics, and mathematics provides a good early foundation for an eventual career in food science. At the undergraduate level, courses in organic and inorganic chemistry, nutrition, cell and molecular biology, biochemistry, genetics, bacteriology, microbiology, and agricultural science are especially relevant. Several colleges and universities offer specialized undergraduate degrees in food science or food technology for students who are especially certain of their ambitions. To acquire a position as a technician, an associate's degree or certification in an area such as chemical or biochemical technology may be all that is required. Positions conducting independent research at an academic or government institution or food science research in private laboratories require completing a bachelor's degree in science and, usually, a master's or doctoral degree in biochemistry, bacteriology, chemical technology, or a related field.

Social Context and Future Prospects

The potential impact of the field of food science is far-reaching and predominantly positive. For example, the advent of in vitro meat has environmental and ethical implications. If widely used, cultured meat could result in huge energy and water savings over traditional methods of bringing meat to market, reduce pollution from farming, and end factory farming. Similarly, the gene-splicing technology used to create GM foods has already been applied to the problem of global poverty. To increase the nutritional content of rice for consumption in developing countries, where rice often makes up a huge portion of the diet, researchers have created strains of genetically modified rice. The new rice contains large amounts of beta-carotene, a precursor for the synthesis of vitamin A, which contributes to the iron content of blood and helps maintain the structure and functioning of the eyes. The product, called Golden Rice, was the subject of much debate. Researchers hoped it would benefit places where malnutrition often causes anemia and blindness and is responsible for high child morbidity. In 2021, the Philippines was the first country to approve commercial Golden Rice cultivation. However, the decision was reversed in April 2024, and all cultivation was halted.

Emerging food technologies continue to be surrounded by skepticism and debate. For example, many food scientists employed by large food conglomerates are engaged in developing foods that are particularly appealing to consumers. Some critics argue these foods contribute to rising obesity rates and other health problems by making foods addictive. Many consumers and advocacy groups argue that the health safety risks and environmental impact of products such as GM foods have not been properly assessed, and these products could have devastating unintended consequences. For example, some worry that plants containing genes from foreign species may be allergenic or toxic to humans. Others posit that genetically modified organisms may interact with the environment unpredictably. One study of monarch butterfly larvae found that feeding them leaves dusted with bioengineered corn pollen stunted their growth and, in some cases, caused death. Nevertheless, many food scientists point out that modifying the genetic information in plants and animals is hardly new. The process of selective breeding, they say, pursues essentially the same goal and has been used for centuries.

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