Food Chemistry

Food Chemistry

What is Food Chemistry?

According to the major classes of According to the major classes of food constituentshttps: proteins and enzymes, lipids, carbohydrates, vitamins, flavours and colourants, minerals the micro components, :proteins and enzymes, lipids, carbohydrates, vitamins, flavours and colourants, minerals and other micro components, additives and pollutants, the information related to the topic of food chemistry is broken down into chapters.

Chemist Working at the Laboratory

Food chemistry, as its name suggests, is the area of chemistry that examines the biochemistry of food, including its characteristics and how they are metabolised by the body. It entails the investigation of several chemical elements, including proteins, carbohydrates, and more. In food chemistry, we discover strategies to improve food quality as well as how various processing methods influence various food types.

History of food chemistry

A focus on agricultural chemistry emerged in the writings of J. G. Wallerius, Humphry Davy, and others, leading to the development of the scientific approach to food and nutrition. For instance, Elements of Agricultural Chemistry, by Davy, was published in the United Kingdom in 1813 as part of a course of lectures for the Board of Agriculture and is now in its sixth edition. Carl Wilhelm Scheele’s 1785 isolation of malic acid from apples was among earlier research.

Eben Horsford of Lowell, Massachusetts, translated and published some of Liebig’s studies on the chemistry of food in 1848.

The Society of Public Analysts was established in 1874 with the intention of using analytical techniques for the general public’s benefit. It was also motivated by worries about the quality of the food supply, particularly difficulties with food adulteration and contamination, which by the 1950s had progressed beyond purposeful contamination to include chemical food additives. Food chemistry would emerge with the growth of schools and institutions across the world, most notably in the United States, along with dietary ingredient research, most notably the Single-grain experiment from 1907 to 1911. The United States Food and Drug Administration was established in 1906 as a result of more study conducted by Harvey W. Wiley at the United States Department of Agriculture in the late 19th century. The Agricultural and Food Chemistry Division of the American Chemical Society was founded in 1908, and the Institute of Food Technologists was founded in 1909.

Food physical chemistry serves as a foundation for food chemistry because it frequently draws from rheology, theories of transport phenomena, physical and chemical thermodynamics, chemical bonds and interaction forces, quantum mechanics, reaction kinetics, biopolymer science, colloidal interactions, nucleation, glass transitions, and freezing/disordered or noncrystalline solids.

Major Food Components:

1) Water Structure

All living creatures include large amounts of water, which is why practically all meals do as well. Despite adding no calories to the diet, it is necessary for life. The texture of food is considerably influenced by water. It impacts the sense of the softness of meat as well as giving fruits and vegetables a crisp texture or turgor. Keep water out of such goods to retain quality. For some food products, such potato chips, salt, or sugar, lack of water is a crucial component of their quality.

Water Structure

Thus, preserving food by freezing, dehydration, or concentration lengthens its shelf life and prevents bacterial development. The ability of water to dissolve tiny molecules into real solutions and disperse bigger molecules into colloidal solutions makes it an essential solvent or dispersing medium.

Water is important for many chemical processes that are catalysed by enzymes, including the hydrolysis of substances like sugars, where acids and bases ionise. In addition, it serves as a heating, cooling, and cleaning agent. It is crucial to understand some of water’s distinctive qualities since it serves so many tasks that are crucial to a food scientist.

2) Protein Structure:

Protein Structure

Since they account for 50% or more of a cell’s dry weight, proteins are the most prevalent molecules in a cell. Each protein performs a specific function in a living cell because of its distinct structure, conformation, or shape. Proteins play a crucial role as blood system carriers and make up the intricate muscle system and connective tissue network.

Enzymes are proteins first and foremost, and they play a crucial role as catalysts in numerous food reactions. Nitrogen, oxygen, hydrogen, and carbon are components of every protein. The majority of proteins contain sulphur, and some of them also include other substances. For instance, milk proteins contain phosphorus, and haemoglobin and myoglobin both contain iron. Some proteins also contain copper and zinc as ingredients. Amino acids comprise proteins.

At least 20 distinct amino acids may be found in nature, and depending on their makeup and structure, they each have unique capabilities. Protein molecules can undergo significant alterations in response to even little modifications, such a change in pH or even heating food. Such alterations can be observed while making cottage cheese from milk that has acid added to it or making scrambled eggs from eggs that have been heated and stirred. Proteins are crucial components of food, both nutritionally and practically speaking. Around 4 kilocalories of energy per gramme may be found in proteins. They have a significant impact on how a food’s texture is determined. They are intricate molecules, thus it’s crucial to comprehend the fundamentals of protein structure in order to comprehend the behaviour of many of them.

For example, strong flour with a high protein content is needed to make bread, therefore the quantity and type of protein in flour impacts its eligibility for usage in various products. Examples of food items that employ the functional characteristics of protein include meringue, cheese, bread, and jelly. Lean meats, fish, and poultry, as well as beans, tofu, lentils, and other legumes, grains, including bread and pasta, nuts, and seeds, are examples of common protein-rich foods.

Protein Requirements:

The amount of protein a child needs depends on their age and weight. For instance, a typical preschooler aged 4-6 years old needs around 22 grammes of protein daily, and a child aged 7 to 10 years old needs about 28 grammes.

Protein Fortified Foods:

In addition to eating a lot of naturally occurring protein-rich meals, we may also purchase protein supplements like drink mixes enriched with protein, such PediaSure or Carnation quick breakfast. There are several foods that can contain multiple sources of protein, such a cheeseburger, which combines meat, cheese, and a bun.

Other examples of meals with added protein are tuna fish sandwiches, cheeseburgers, pizza, grilled cheese sandwiches, peanut butter and jelly sandwiches, macaroni and cheese sandwiches, etc. Fruits, beans, and vegetables all make excellent sources of protein.

Essential Amino Acids in Foods:

The smallest building block of proteins, amino acids are described as organic molecules with amine and carboxylic acid functional groups. Amino acids are made up of molecules of nitrogen, carbon, oxygen, and hydrogen. Essential amino acids, often referred to as limiting amino acids, are those that human bodies are unable to synthesise and must therefore be taken from dietary sources.

There are 8 essential amino acids:

1. Tryptophan,

2. Tyrosine,

3. Valine,

4. Leucine,

5. Isoleucine,

6. Lysine,

7. Methionine, and

8. Phenylalanine.

Functions of Essential Amino Acids:

A number of metabolisms can benefit from the inclusion of amino acids. They are a component of intricate biological systems and processes. An amino acid’s use and function depend on other amino acids, minerals, carbohydrates, and fatty acids, and it has indirect effects that show up in a variety of metabolisms.

Non-Essential Amino Acids in Foods:

Amino acids that are non-essential can be produced by human bodies. Although they serve the same purposes and serve our bodies in a similar manner to limiting amino acids, the difference is that those amino acids may be obtained through our food. The remaining 12 amino acids are classified as non-essential amino acids and include compounds like alanine, cysteine, glutamine, glycine, histidine, threonine, asparagine, and proline.

3) Carbohydrates Structure:

Carbon, hydrogen, and oxygen are the three elements that make up carbohydrates, which can be either simple or complex molecules. Simple sugars, dextrins, starches, cellulose, hemicellulose, pectins, and gums are some of the significant dietary carbohydrates. Due to their practical qualities, they serve as major sources of fibre or energy in the diet and are also vital dietary ingredients.


Our diet contains carbs from plant-based sources. Because they are essentially carbon hydrates, carbohydrates have that name. They are specifically made of carbon and water and have the chemical formula Cn(H2n O). Monosaccharides, sometimes referred to as sugars, are the most basic kind of carbohydrates and contain the general formula CnH2nOt. The majority of them have six carbon atoms. Trisaccharides have three sugar units, oligosaccharides have many units, disaccharides have two units, trisaccharides have three, and polysaccharides are complex polymers with up to thousands of units linked together to create a molecule. Each one of these molecules is a complex carbohydrate polymer with unique characteristics that are influenced by the type of sugar units that make up the molecule, the type of glycosidic connections, and the degree of branching. A plant polymer called starch is kept in the roots and seeds of plants. It gives people energy (4 kcal per gramme) and is hydrolyzed to glucose, which supplies the glucose required for the proper operation of the brain and central nervous system.

Long-chain glucose polymers are present in starch grains, which are insoluble in water. When starch granules are agitated in water, they temporarily suspend rather than forming a real solution like the smaller salt and sugar molecules do. When starch is boiled, the swelling becomes permanent, and the starch starts to seep out. This quality of starch granules makes it possible to employ starch as a thickening.

Carbohydrates perform several functions in food:

  • It can be employed as thickeners, stabilisers, gelling agents, and fat replacements, to name a few .
  • influencing texture (gluten, starch).
  • Water absorption due to hygroscopic nature.
  • Offering a source of food for yeast.
  • regulating the dispersion of protein or starch molecules during pectin gelation.
  • Preventing deterioration.
  • Postponing protein coagulation.
  • Crystals provide structure.
  • Affecting osmosis .
  • Changing the fruit’s colour.
  • viscosity and structure have an impact on texture.
  • Adding flavours outside sweetness.

Sources of Starches:

Cereal grains like wheat, maize, or rice are the most significant sources of starches. While cornflour creates clearer combinations like gravies or sauces, wheat results in a thick, muddy mixture. Potatoes, vegetables, roots, and tubers, such as cassava’s root, are regularly utilised to prepare gluten-free dishes. Legumes like soy beans are another source of starch. In tropical Asia, the stems and trunks of the sago palm are used to make sago, a powdered starch. Starch may also be found in fruits. The banana is one illustration.


Thousands of monosaccharide units make up the complex hydrophilic carbohydrates that make up gums. The most prevalent monosaccharide in gums is galactose; glucose is typically missing. Due to their size and affinity for water, gums are frequently referred to as hydrocolloids; when combined with water, they produce stable aqueous colloidal dispersions or sols. Due to the extremely branched nature of the molecules, most gums are unable to gel. As a result, they are able to bind or trap vast volumes of water within of their branches. Gums are categorised as soluble fibre since the body does not fully digest and absorb them. Therefore, compared to digestible carbs like starch, they contribute comparatively few calories to the diet.

Main Characteristics of Gums:

The two most crucial features of gum are its size and galactose content. Gum is a huge, highly branching hydrophilic polymer. It produces viscous liquids and is frequently referred to as hydrocolloids. The majority of gums don’t gel.

Sources of Gum:

Salad dressings, sauces, soups, yoghurt, canned evaporated milk, ice cream, and other dairy items, as well as baked goods, meat products, and fried dishes, all frequently include gums. They replace starch as thickening agents in food goods.

Additionally, they help stabilise emulsions and preserve the creamy texture of ice cream and other frozen sweets. They are frequently included in goods with decreased fat because they can boost viscosity and take the place of the fat’s contribution to texture and mouth feel.

Classification of Gums:

Gums are sourced from plants and fall into five categories: microbial exudates, seaweed extracts, synthetic gums made from cellulose, and seed gums and plant exudates.

  • Guar gum and locust bean gum, which are seed gums
  • Plant exudates, including gum tragacanth and gum arabic
  • Xanthan, gellan, and dextran, microbial exudates
  • Seaweed polysaccharides, including agar, alginates, and carrageenan

Functional Roles of Gums in Food Technology:

Gums can serve a variety of purposes in food items.

They are listed below:

  • Thickeners: condiments, soups, sauces, and salad dressings
  • Ice cream, frosting, and emulsified product stabilisers
  • Candy: Control crystal size
  • Salad dressings as suspending agents
  • Fruit bits and cheese analogues as gelling agents
  • Coating agents and deep-fried food batters
  • Fat substitutes, including low-fat ice cream, sweets, and salad dressings
  • Starch substitutes for baked goods, sauces, and soups
  • Fillers: low-fat meals, and
  • Beverages, soups, and baked items are sources of fibre.


Another soluble fibre found in some foods is mucilage. It is an exopolysaccharide, a kind of polymer found in several plant-based diets. It is a naturally occurring, organic plant product with a large molecular weight (200,000 and higher), but its precise structure is unclear. Galactose, mannose, and other monosaccharides are found in mucilages, while galactose, glucuronic acid, and other monosaccharides are found in gums.

Mucilage shares many chemical similarities with gums and pectins but has certain unique physical characteristics. It is found in diverse locations in almost all plant types, often in negligible amounts, and is commonly combined with other compounds like tannins and alkaloids.

Uses of Mucilages:

Although edible, mucilage has a somewhat bland flavour. Due to its demulcent qualities, it is utilised in medicine. Since the mucilaginous root of the marshmallow plant has a demulcent quality, the extract used to make traditional marshmallows also served as a cough suppressant. It serves as a kind of paper adhesive.

In Sweden, a dairy product called filmjolk is traditionally produced using some carnivorous plants that include mucilage. Specific enzymes interact with soybean sugars during the fermentation of natto soyabean to create mucilage. The volume and viscosity of the mucilage are significant natto properties that help to create the distinct flavour and aroma of natto.

4. Lipids Structure:

“The framework for the construction and operation of living cells is made up of lipids, which are organic molecules with hydrogen, carbon, and oxygen atoms.”

What are Lipids?

Since water is a polar molecule, these organic compounds are nonpolar molecules that can only dissolve in nonpolar solvents. These molecules, which are present in meals like oil, butter, whole milk, cheese, fried dishes, as well as some red meats, can be produced by the liver in the human body.

Properties of Lipids

Fats and oils make up the family of organic substances known as lipids. These molecules produce a lot of energy and are in charge of several bodily processes. The following list includes some crucial properties of lipids.

  • Lipids are fatty or oily nonpolar molecules that are kept in the body’s adipose tissue.
  • A diverse class of substances known as lipids is mostly made up of hydrocarbon chains.
  • Lipids are organic compounds that are high in energy and supply that energy for several living activities.
  • A family of chemicals known as lipids is distinguished by its solubility in nonpolar solvents and insolubility in water.
  • Lipids play an important role in biological systems because they create the cell membrane, a mechanical barrier that separates a cell from its surroundings.

Lipid Structure

Lipid Structure

Classification of Lipids

There are two major categories into which lipids fall:

  • Unsaponifiable lipids
  • Saponificable lipids
Nonsaponifiable Lipids

Hydrolysis cannot break down a nonsaponifiable lipid into smaller molecules. Lipids that cannot be saponified include prostaglandins, cholesterol, etc.

Saponifiable Lipids

Wax, triglycerides, sphingolipids, and phospholipids are examples of saponifiable lipids, which may be hydrolyzed in the presence of a base, acid, or enzymes because they contain one or more ester groups.

These groups can also be separated into polar and non-polar lipids.

Triglycerides, a kind of nonpolar lipid, are used as fuel for energy storage.

Membranes use polar lipids that might create a barrier with an external aqueous environment. Sphingolipids and glycerophospholipids are two types of polar lipids.

The key building blocks of all these lipids are fatty acids.

Examples of Lipids

Lipids come in a variety of varieties. Butter, ghee, vegetable oil, cheese, cholesterol and other steroids, waxes, phospholipids, and fat-soluble vitamins are a few examples of lipids. These chemicals all share characteristics in common, such as being insoluble in water and soluble in organic solvents.


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