Understanding Food Science Disciplines - What is Food Chemistry?
Food chemistry is one of the fields involved in the multi-disciplinary field of food science. It is the study of food components, such as proteins, carbohydrates, fats, and water. In addition, food chemistry assesses the reactions these components go through during food processing and preservation.
Scientists use statistical quality control methods to assess food components and determine the safety and quality aspects of food products. Food chemistry covers a variety of concepts from biochemicals to enzymes to types of food processing techniques that provide the knowledge to develop better quality, safer, and nutritious products for consumers.
What Are the Main Components of Food Chemistry?
Water and Ice
Water is abundant in almost all foods and affects food texture. Think about the crunchiness and juiciness of freshly picked grapes and the chewy texture of raisins. Water gives the crisp and turgor texture of fruits and vegetables. It's also responsible for the "tenderness" of meat products.
For some products, such as chips, salt, or sugar, the lack of water is important to their quality. This property comes from the nature of water's hydrogen bonds, which allows water molecules to bond to each other as well as with sugar, pectin, proteins, and starches.
Water also affects food safety and stability, as water activity affects the growth of microorganisms, including bacteria, molds, and yeasts. As the Food and Drug Administration (FDA) explains, moisture or water activity above 0.95 provides a suitable environment for the growth of microorganisms. However, food and supplement companies can take steps to reduce water activity below 0.85 to ensure safety. Adding salts or sugars is one approach to lowering water activity.
Additionally, water also affects the sensory quality of food, with one way being the formation of ice crystals. For example, texture, mouthfeel, and appearance change with the size of ice crystals in ice cream. More grainy ice cream results from the formation of large ice crystals, while creamier ones have smaller ice crystals in the emulsion.
Carbohydrates
The type and content of carbohydrates affect the quality and nutritional value of food. Foods with high-quality carbohydrate content are important to complete a healthy diet. The healthiest sources of high-quality carbohydrates are the minimally processed grains, vegetables, fruits, and beans.
Carbohydrates are the most abundant organic substances in nature, and depending on the source and way of processing, can be a healthy or unhealthy diet component. There are many concepts to know related to the presence of carbohydrates in food, but it's valuable to gain a foundational understanding of the four major carbohydrate groups:
- Monosaccharides are the building blocks of all carbohydrates. Three of the most important monosaccharides are glucose, fructose, and galactose.
- Disaccharides are made up of two monosaccharide constituents linked together. Some examples are sucrose (table sugar), maltose, and lactose.
- Oligosaccharides are made up of three to six monosaccharides. Only a few plant derivatives of these sugars have been identified in nature.
- Polysaccharides are usually made up of more than ten monosaccharide units. As they form strong polymers, they make the structural and energy reserve carbohydrates in nature. Some examples are cellulose, the principal component of plants, and glycogen, a form of stored carbohydrates in animals and humans.
Polysaccharides are also categorized into starch-based and non-starch polysaccharides (NSP). NSPs include maize, wheat, and rice, which are insoluble and have a laxative effect. On the other hand, barley, beans, oats, and rye are soluble and can lower cholesterol levels.
Lipids
Lipids are essential food components that contribute to texture, structure, flavor, color, and other desirable qualities of food. In addition, they also play a role in the degradability of food, leading to a loss of quality. As such, it's important to study the effect of lipids on food quality (Montesano et al., 2018).
Oxidative processes of lipids in food contribute to its degradation processes. Unsaturated fatty acids and oxygen are the components that react during the lipid oxidation process. The three mechanisms involved are:
- Lipid autoxidation - A continuous free-radical chain reaction resulting in oxidative deterioration of meat and other meat products starts with the production of free radicals, followed by the propagation of reactive compounds, and finally, the degradation and further reactions of reactive compounds to produce non-reactive ones.
- Enzymatic-catalyzed oxidation - This type of oxidation is characterized by the production of hydroperoxides and the fact that enzymatic-catalyzed oxidation has an initial lag phase, attributed to the concentration of the rate-limiting enzyme, lipoxygenase.
- Lipid photo-oxidation - Photo-oxidation is a faster oxidation process than autoxidation, characterized by the exposure to light and production of hydroperoxides.
However, not all processes involving lipids in food are bad. Depending on the context, chemical processes involving fats can improve the quality of food products. For instance, fat crystallization controls the spreadability, grittiness, and smoothness of food products. As you can imagine, this can be very helpful in baking and pastry making. Fat crystals in food contribute to the mouthfeel and detectability of chocolates, butter, margarine, and ice cream.
Lipids such as fats and oils are made up of glycerol and three molecules of fatty acids. Fatty acids are made up of a straight alkyl chain and a carboxyl group. There are different types of fatty acids depending on the presence of double bonds and the number of carbons in the chain.
- Saturated fatty acids have no double bonds.
- Unsaturated fatty acids have one or more double bonds.
- Monounsaturated fatty acids (MFAs) have one double bond per molecule
- Polyunsaturated fatty acids (PUFAs) have more than one double bond per molecule.
Unsaturated fatty acids are less stable than saturated ones due to their structure. The double bonds allow more reactive species to access the fatty acid molecules resulting in rancidity or the oxidation of fats. This creates an unusual odor and taste in food (Marcus, 2013). The quality and acceptability of meats and other meat products are highly affected by oxidative damage to lipids as it creates an imbalance between the production of reactive oxygen species (ROS) and the animal's defense mechanisms.
- Short- and medium-chain saturated fatty acids (SFAs) have four to 12 carbons in their chain. They are commonly found in coconut oil and milk fats.
- Longer-chain fatty acids have more than 14 carbons in their chain and are commonly found in animal and vegetable fats.
Other lipids are characterized depending on the presence of other molecules in their structure. For instance, phospholipids have phosphates aside from glycerol and fatty acids in their structure. In eggs, meats, and fish, phospholipids make up the larger part of the lipids.
In general, phospholipids are more unsaturated and more prone to oxidation than triacylglycerol (TAG). As such, they are a factor in the limited shelf life of some food as lipid oxidation produces free radicals and reactive aldehydes.
On the other hand, the presence of unsaturated SFAs in food can be a good thing. For instance, in response to heat treatment, lipids in food undergo reactions that contribute to the food's flavor, safety, and nutrition. Heated saturated oil, for example, releases unsaturated, shorter fatty acid chains that contribute more to the flavor of foods.
Amino Acids, Peptides, and Proteins
Amino acids are the building blocks of proteins. They form bonds with other amino acids to form peptides, and eventually, proteins.
Several amino acids are essential diet components as they cannot be metabolically synthesized by the human body. These include phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, leucine, and lysine. As such, people consume proteins as a source of these essential amino acids. However, not all protein sources are the same. For instance, peanuts have higher weight content than fish or eggs, but the latter two have more essential amino acids than peanuts.
Specific amino acids are required for growth or nitrogen balance, and a complete protein includes all of the essential amino acids. However, some people can't consume certain types of proteins as it stimulates an immune response, primarily the production of allergen-specific IgE. These are stable molecules that remain unchanged even with cooking, food processing, and digestion.
Minor Components
Other components like vitamins and minerals are also present in food. They keep the body healthy, functional, and resistant to diseases to an extent. Vitamins are synthesized by other organic substances, and humans need to consume them for their health benefits. Minerals, on the other hand, are inorganic elements that humans absorb from the environment or the animal that has eaten a particular plant.
To adopt a healthier diet with vitamins and minerals, people must eat proper amounts of fruits, vegetables, whole grains, beans, legumes, dairy products, and low-fat proteins.
In some cases, food producers use food additives to maintain or improve the freshness, appearance, texture, and safety of food products. However, these food additives must be checked for their potentially harmful effects first before use.
Final Thoughts
Major and minor components of food affect not just the quality and acceptability but also the safety of food products. The field of food chemistry allows food producers to improve the sensory characteristics, nutritional value, and overall quality of food products. As such, it is important science to consider during product design.
To ensure the quality and safety of your food products, you should partner with a reputable testing laboratory. Eurofins Network of Laboratories will ensure the quality and safety of your food products by scrutinizing every ingredient and component of your food products through more than 200,000 analytical methods. Contact us today to learn more.