Food chemistry

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Food chemistry is the study of chemical processes and interactions of all biological and non-biological components of foods. [1] [2] The biological substances include such items as meat, poultry, lettuce, beer, milk as examples. It is similar to biochemistry in its main components such as carbohydrates, lipids, and protein, but it also includes areas such as water, vitamins, minerals, enzymes, food additives, flavors, and colors. This discipline also encompasses how products change under certain food processing techniques and ways either to enhance or to prevent them from happening. An example of enhancing a process would be to encourage fermentation of dairy products with microorganisms that convert lactose to lactic acid; an example of preventing a process would be stopping the browning on the surface of freshly cut apples using lemon juice or other acidulated water.


History of food chemistry

The scientific approach to food and nutrition arose with attention to agricultural chemistry in the works of J. G. Wallerius, Humphry Davy, and others. For example, Davy published Elements of Agricultural Chemistry, in a Course of Lectures for the Board of Agriculture (1813) in the United Kingdom which would serve as a foundation for the profession worldwide, going into a fifth edition. Earlier work included that by Carl Wilhelm Scheele who isolated malic acid from apples in 1785.

Some of the findings of Liebig on food chemistry were translated and published by Eben Horsford in Lowell Massachusetts in 1848. [3]

In 1874 the Society of Public Analysts was formed, with the aim of applying analytical methods to the benefit of the public. [4] Its early experiments were based on bread, milk and wine.

It was also out of concern for the quality of the food supply, mainly food adulteration and contamination issues that would first stem from intentional contamination to later with chemical food additives by the 1950s. The development of colleges and universities worldwide, most notably in the United States, would expand food chemistry as well with research of the dietary substances, most notably the Single-grain experiment during 1907-11. Additional research by Harvey W. Wiley at the United States Department of Agriculture during the late 19th century would play a key factor in the creation of the United States Food and Drug Administration in 1906. The American Chemical Society would establish their Agricultural and Food Chemistry Division in 1908 while the Institute of Food Technologists would establish their Food Chemistry Division in 1995.

Food chemistry concepts are often drawn from rheology, theories of transport phenomena, physical and chemical thermodynamics, chemical bonds and interaction forces, quantum mechanics and reaction kinetics, biopolymer science, colloidal interactions, nucleation, glass transitions and freezing/disordered or noncrystalline solids, and thus has Food Physical Chemistry as a foundation area. [5] [6]

Water in food systems

A major component of food is water, which can encompass anywhere from 50% in meat products to 95% in lettuce, cabbage, and tomato products. It is also an excellent place for bacterial growth and food spoilage if it is not properly processed. One way this is measured in food is by water activity which is very important in the shelf life of many foods during processing. One of the keys to food preservation in most instances is reduce the amount of water or alter the water's characteristics to enhance shelf-life. Such methods include dehydration, freezing, and refrigeration [7] [8] [9] [10] This field encompasses the "physiochemical principles of the reactions and conversions that occur during the manufacture, handling, and storage of foods". [11] .


Sucrose: ordinary table sugar and probably the most familiar carbohydrate. Saccharose.svg
Sucrose: ordinary table sugar and probably the most familiar carbohydrate.

Comprising 75% of the biological world and 80% of all food intake for human consumption, the most common known human carbohydrate is Sucrose [ citation needed ]. The simplest version of a carbohydrate is a monosaccharide which contains carbon, hydrogen, and oxygen in a 1:2:1 ratio under a general formula of CnH2nOn where n is a minimum of 3. Glucose is an example of a monosaccharide as is fructose. When combined in the way that the image to the right depicts, sucrose, one of the more common sugar products found in plants, is formed.

A chain of monosaccharides form to make a polysaccharide. Such polysaccharides include pectin, dextran, agar, and xanthan.

Sugar content is commonly measured in degrees brix.


The term lipid comprises a diverse range of molecules and to some extent is a catchall for relatively water-insoluble or nonpolar compounds of biological origin, including waxes, fatty acids (including essential fatty acids), fatty-acid derived phospholipids, sphingolipids, glycolipids and terpenoids, such as retinoids and steroids. Some lipids are linear aliphatic molecules, while others have ring structures. Some are aromatic, while others are not. Some are flexible, while others are rigid.

Most lipids have some polar character in addition to being largely nonpolar. Generally, the bulk of their structure is nonpolar or hydrophobic ("water-fearing"), meaning that it does not interact well with polar solvents like water. Another part of their structure is polar or hydrophilic ("water-loving") and will tend to associate with polar solvents like water. This makes them amphiphilic molecules (having both hydrophobic and hydrophilic portions). In the case of cholesterol, the polar group is a mere -OH (hydroxyl or alcohol).

Lipids in food include the oils of such grains as corn, soybean, from animal fats, and are parts of many foods such as milk, cheese, and meat. They also act as vitamin carriers.

Food proteins

Proteins compose over 50% of the dry weight of an average living cell[ citation needed ][ clarification needed ] and are very complex macromolecules. They also play a fundamental role in the structure and function of cells. [12] Consisting mainly of carbon, nitrogen, hydrogen, oxygen, and some sulfur, they also may contain iron, copper, phosphorus, or zinc.

In food, proteins are essential for growth and survival, and requirements vary depending upon a person's age and physiology (e.g., pregnancy). Protein is commonly obtained from animal sources: eggs, milk, and meat. Nuts, grains and legumes provide vegetable sources of protein, and protein combining of vegetable sources is used to achieve complete protein nutritional quotas from vegetables.

Protein sensitivity as food allergy is detected with the ELISA test.


Enzymes are biochemical catalysts used in converting processes from one substance to another. They are also involved in reducing the amount of time and energy required to complete a chemical process. Many aspects of the food industry use catalysts, including baking, brewing, dairy, and fruit juices, to make cheese, beer, and bread.


Riboflavin (Vitamin B2), water-soluble. Riboflavin.png
Riboflavin (Vitamin B2), water-soluble.

Vitamins are nutrients required in small amounts for essential metabolic reactions in the body. These are broken down in nutrition as either water-soluble (Vitamin C) or fat-soluble (Vitamin E). An adequate supply of vitamins can prevent diseases such as beriberi, anemia, and scurvy while an overdose of vitamins can produce nausea and vomiting or even death.


Dietary minerals in foods are large and diverse with many required to function while other trace elements can be hazardous if consumed in excessive amounts. Bulk minerals with a Reference Daily Intake (RDI, formerly Recommended Daily Allowance (RDA)) of more than 200 mg/day are calcium, magnesium, and potassium while important trace minerals (RDI less than 200 mg/day) are copper, iron, and zinc. These are found in many foods, but can also be taken in dietary supplements.


Food colouring is added to change the colour of any food substance. It is mainly for sensory analysis purposes. It can be used to simulate the natural colour of a product as perceived by the customer, such as red dye (like FD&C Red No.40 Allura Red AC) to ketchup or to add unnatural colours to a product like Kellogg's Froot Loops. Caramel is a natural food dye; the industrial form, caramel colouring, is the most widely used food colouring and is found in foods from soft drinks to soya sauce, bread, and pickles.


Flavour in food is important in how food smells and tastes to the consumer, especially in sensory analysis. Some of these products occur naturally like salt and sugar, but flavour chemists (called a "flavourist") develop many of these flavours for food products. Such artificial flavours include methyl salicylate which creates the wintergreen odor and lactic acid which gives milk a tart taste.

Food additives

Food additives are substances added to food for preserving flavours, or improving taste or appearance. The processes are as old as adding vinegar for pickling or as an emulsifier for emulsion mixtures like mayonnaise. These are generally listed by "E number" in the European Union or GRAS ("generally recognized as safe") by the United States Food and Drug Administration.

See also

Related Research Articles

Antioxidants are compounds that inhibit oxidation. Oxidation is a chemical reaction that can produce free radicals, thereby leading to chain reactions that may damage the cells of organisms. Antioxidants such as thiols or ascorbic acid terminate these chain reactions. To balance the oxidative stress, plants and animals maintain complex systems of overlapping antioxidants, such as glutathione and enzymes, produced internally, or the dietary antioxidants vitamin C and vitamin E.

Biochemistry The study of chemical processes in living organisms

Biochemistry, sometimes called biological chemistry, is the study of chemical processes within and relating to living organisms. Biochemical processes give rise to the complexity of life.

Carbohydrate Organic compound that consists only of carbon, hydrogen, and oxygen

A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula Cm(H2O)n (where m may be different from n). This formula holds true for monosaccharides. Some exceptions exist; for example, deoxyribose, a sugar component of DNA, has the empirical formula C5H10O4. The carbohydrates are technically hydrates of carbon; structurally it is more accurate to view them as aldoses and ketoses.

Lipid A substance of biological origin that is soluble in nonpolar

In biology and biochemistry, a lipid is a macrobiomolecule that is soluble in nonpolar solvents. Non-polar solvents are typically hydrocarbons used to dissolve other naturally occurring hydrocarbon lipid molecules that do not dissolve in water, including fatty acids, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides, and phospholipids.

Polysaccharide long chain of polymeric carbohydrate modules

Polysaccharides are long chains of carbohydrate molecules, specifically polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with water (hydrolysis) using amylase enzymes at catalyst, which produces constituent sugars. They range in structure from linear to highly branched. Examples include storage polysaccharides such as starch and glycogen, and structural polysaccharides such as cellulose and chitin.

Thiamine chemical compound

Thiamine, also known as thiamin or vitamin B1, is a vitamin found in food, and manufactured as a dietary supplement and medication. Food sources of thiamine include whole grains, legumes, and some meats and fish. Grain processing removes much of the thiamine content, so in many countries cereals and flours are enriched with thiamine. Supplements and medications are available to treat and prevent thiamine deficiency and disorders that result from it, including beriberi and Wernicke encephalopathy. Other uses include the treatment of maple syrup urine disease and Leigh syndrome. They are typically taken by mouth, but may also be given by intravenous or intramuscular injection.

Vitamin Nutrients required by organisms in small amounts

A vitamin is an organic molecule (or related set of molecules) that is an essential micronutrient which an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet. Vitamin C can be synthesized by some species but not by others; it is not a vitamin in the first instance but is in the second. The term vitamin does not include the three other groups of essential nutrients: minerals, essential fatty acids, and essential amino acids. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols. Though some sources list fourteen by including choline, major health organizations list thirteen: vitamin A (as all-trans-retinol, all-trans-retinyl-esters, as well as all-trans-beta-carotene and other provitamin A carotenoids), vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin B6 (pyridoxine), vitamin B7 (biotin), vitamin B9 (folic acid or folate), vitamin B12 (cobalamins), vitamin C (ascorbic acid), vitamin D (calciferols), vitamin E (tocopherols and tocotrienols), and vitamin K (quinones).

Pantothenic acid chemical compound

Pantothenic acid, also called vitamin B5 is a water-soluble B vitamin and therefore an essential nutrient. All animals require pantothenic acid in order to synthesize coenzyme A (CoA) - essential for fatty acid metabolism - as well as to in general synthesize and metabolize proteins, carbohydrates, and fats. The anion is called pantothenate.

A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures, such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted to smaller molecules in the process of releasing energy, such as for carbohydrates, lipids, proteins, and fermentation products, leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host.

Human nutrition Provision of essential nutrients necessary to support human life and health

Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and health. Poor nutrition is a chronic problem often linked to poverty, food security or a poor understanding of nutrition and dietary practices. Malnutrition and its consequences are large contributors to deaths and disabilities worldwide. Good nutrition is necessary for children to grow physically, and for normal human biological development.

Food science Applied science devoted to the study of food

Food science is the basic science and applied science of food; its scope starts at overlap with agricultural science and nutrition and leads through the scientific aspects of food safety and food processing, informing the development of food technology. The Institute of Food Technologists defines food science as "the discipline in which the engineering, biological, and physical sciences are used to study the nature of foods, the causes of deterioration, the principles underlying food processing, and the improvement of foods for the consuming public". The textbook Food Science defines food science in simpler terms as "the application of basic sciences and engineering to study the physical, chemical, and biochemical nature of foods and the principles of food processing".

Powdered milk Dehydrated milk product

Powdered milk or dried milk is a manufactured dairy product made by evaporating milk to dryness. One purpose of drying milk is to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated, due to its low moisture content. Another purpose is to reduce its bulk for economy of transportation. Powdered milk and dairy products include such items as dry whole milk, nonfat (skimmed) dry milk, dry buttermilk, dry whey products and dry dairy blends. Many exported dairy products conform to standards laid out in Codex Alimentarius. Many forms of milk powder are traded on exchanges.

Milk substitute non-dairy substitute for milk

A milk substitute can refer to a liquid used as a replacement for the milk from a mammal. Mammalian milk analogues are white or whitish liquids that resemble either dairy or human-breast milk.

Sports nutrition

Sports nutrition is the study and practice of nutrition and diet with regards to improving anyone's athletic performance. Nutrition is an important part of many sports training regimens, being popular in strength sports and endurance sports. Sports nutrition focuses its studies on the type, as well as the quantity of fluids and food taken by an athlete. In addition, it deals with the consumption of nutrients such as vitamins, minerals, supplements and organic substances that include carbohydrates, proteins and fats.

Oat milk is a plant milk derived from whole oat grains by extracting the plant material with water. Oat milk has a creamy texture and oatmeal-like flavor, and is manufactured in various flavors, such as sweetened, unsweetened, vanilla or chocolate.

Animal nutrition focuses on the dietary nutrients needs of animals, primarily those in agriculture and food production, but also in zoo's, aquariums, and wildlife management.

Kefir Fermented milk drink made from kefir grains

Kefir or kephir, is a fermented milk drink similar to a thin yogurt that is made from kefir grains, a specific type of mesophilic symbiotic culture. The drink originated in the North Caucasus, Eastern Europe and Russia, where it is prepared by inoculating cow, goat, or sheep milk with kefir grains.

Thomas Burr Osborne was a biochemist and early discoverer of Vitamin A. He is known for his work isolating and characterizing seed proteins, and for determining protein nutritional requirements. His career was spent at the Connecticut Agricultural Experiment Station.

Food physical chemistry is considered to be a branch of Food chemistry concerned with the study of both physical and chemical interactions in foods in terms of physical and chemical principles applied to food systems, as well as the applications of physical/chemical techniques and instrumentation for the study of foods. This field encompasses the "physiochemical principles of the reactions and conversions that occur during the manufacture, handling, and storage of foods"

Pea milk is a type of plant milk made using pea protein, which is made of yellow peas. Commercial pea milk typically comes in sweetened, unsweetened, vanilla and chocolate flavours, and is usually enriched with vitamins. It is marketed as a more environmentally-friendly alternative to almond milk and a non-GMO alternative to soy milk. The two largest brands of pea milk are Ripple Foods and Bolthouse Farms. Pea Milk is a plant-based alternative to dairy milk. It is available in several countries including the USA, UK and Australia and is vegan, nut – free and lactose free. Pea Milk is a part of plant – milks which are gaining in popularity due to increased lactose intolerance among consumers and demand for environmentally sustainable products. The plant-based milk industry as per 2019 estimates is worth approximately $5 billion USD and will reach a value of $26 billion USD in 5 years. There has been research in the role of pea proteins in preparing infant formula, yoghurt and calf mixtures. The colour is off-white and pea milk is made through crushing yellow split peas and mixing the soluble components with water. Pea Milk may also be prepared at home. It is perceived to be environmentally sustainable and requires less water than the production of dairy milk. There is limited information on the total carbon emissions and water consumption of producing ready to drink pea milk.


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  2. John M. de Man. 2009. Food process engineering and technology, Academic Press, Elsevier: London and New York, 1st edn.
  3. Eben Horsford (editor) (1848) Liebig's Researches on the Chemistry of Food and the Motion of the Juices in the Animal Body, Lowell Massachusetts
  4. Proc. Soc. Analyt. Chem p. 234
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  6. Physical Chemistry Of Food Processes: Fundamental Aspects.1992.van Nostrand-Reinhold vol.1., 1st Edition,
  7. Pieter Walstra. 2003. Physical Chemistry Of Foods. Marcel Dekker, Inc.: New York, 873 pages
  8. Physical Chemistry Of Food Processes: Fundamental Aspects.1992.van Nostrand-Reinhold vol.1., 1st Edition,
  9. Henry G. Schwartzberg, Richard W. Hartel. 1992. Physical Chemistry of Foods. IFT Basic Symposium Series, Marcel Dekker, Inc.:New York, 793 pages
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  11. Pieter Walstra. 2003. Physical Chemistry Of Foods. Marcel Dekker, Inc.: New York, 873 pages
  12. Food and Nutrition Board of Institute of Medicine (2005) Dietary Reference Intakes for Protein and Amino Acids, page 685, from National Academies Press