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.
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.
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:
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 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:
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.
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.
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 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.
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.
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.
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