I’ve included some definitions that are relevant and useful to know. Most of these are adapted from the textbook Understanding Food: Principles and Preparation (2nd Edition) by Amy Brown.
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Alkaline. Basic; a pH of greater than 7.
Anthocyanin. A blue, violet, or red flavonoid pigment found in plants.
Antioxidant. A compound that inhibits oxidation, which can cause deterioration and rancidity.
Astringency. A sensory phenomenon characterized by a dry, puckery feeling in the mouth. Often present in tea and red wine.
Baking Powder. A chemical leavener consisting of a mixture of baking soda, acid(s) and an inert filler such as cornstarch.
Baking Soda. A white chemical leavening powder consisting of sodium bicarbonate.
Blanch. To dip a food briefly into boiling water.
Calorie (kcal). The amount of energy required to raise 1 gram of water 1°C (measured between 14.5° and 15.5°C at normal atmospheric pressure).
Casein. The primary protein (80 percent) found in milk; it can be precipitated (solidified out of solution) with acid or certain enzymes.
Chemical. A substance obtained through chemistry or that produces a chemical effect. The term “chemical” is used here in its scientific sense. Chemicals and chemical processes can be natural or artificial.
Chlorophyll. A green pigment, present in all green plants and in cyanobacteria, responsible for the absorption of light to provide energy for photosynthesis. Its molecule contains a magnesium atom held in a porphyrin ring.
Chlorophyllins. Bright green water-soluble salts that are derivatives of chlorophyll. They differ from chlorophyll in that their phytyl and methyl groups have been removed due to exposure to alkaline conditions.
Coagulate. To clot or become semisolid. In milk, denatured proteins often separate from the liquid by coagulation.
Colloidal dispersion. A solvent containing particles that are too large to go into solution (dissolve), but not large enough to precipitate out.
Complete protein. A protein, usually from animal sources, that contains all the essential amino acids in sufficient amounts for the body’s maintenance and growth.
Conduction. The direct transfer of heat from one substance to another with which it is in contact. For example, a hot skillet transferring heat to a steak that has been placed on its surface.
Convection. The transfer of heat by moving hot air or liquid (usually water or fat) through or around food. For example, a convection oven transfers heat by moving hot air around food using a fan. Deep fried and boiled foods are also heated by convection via the heated liquid around them.
Crumb. The cell structure appearing when a baked product is sliced. Evaluation is based on cell size (medium to large cells are described as open, while small cells are described as closed), cell shape and cell thickness (thin walls are described as a fine crumb, while thick walls are described as a coarse crumb).
Curd. The coagulated or thickened part of milk that is formed in the initial stages of cheese-making. This is the non-whey portion of milk and is comprised mainly of the milk’s protein (casein) and fat.
Denaturation. The irreversible process in which the structure of a protein is disrupted, resulting in a partial or complete loss of function. This can be caused by a number of things, the most common of which are heating and exposure to acid. When exposed to heat, egg whites will change from clear and goopy to white and hard as their proteins denature. In ceviche, acidic lime juice will denature proteins in seafood and give it the opaque appearance of having been cooked, although it never was exposed to heat. Different proteins will have varying sensitivities to disruptors.
Dietary Fiber. Food material, particularly plant material, that is not hydrolyzed by enzymes secreted by the human digestive tract but that may be digested by microflora in the gut. Plant components that fall within this definition include non-starch polysaccharides (NSP) such as celluloses, some hemi-celluloses, gums and pectins, as well as lignin, resistant dextrins and resistant starches. Sources of dietary fiber include vegetables, wheat and most other grains. Foods rich in soluble fiber include fruits, oats, barley and beans.
Emulsifier. A compound that possesses both water-loving (hydrophilic) and water-fearing (hydrophobic) properties and so is able to disperse in either water or oil.
Emulsion. A liquid dispersed in another liquid with which it is usually immiscible (incapable of being mixed, such as oil and water).
Enriched. Foods that have had certain nutrients, which were lost through processing, added back to levels established by federal standards. For example, enriched wheat flour has had vitamins and minerals added to it that were present in the original grain, but lost during processing.
Enzymatic browning. A reaction in which an enzyme acts on a phenolic compound in the presence of oxygen to produce brown –colored products. The browning of raw apple and potato slices is caused by enzymatic browning.
Enzyme. A protein the catalyzes (facilitates) a chemical reaction without itself being altered in the process. That means that enzymes can continue to facilitate that same reaction without restraint until either they are denatured or the chemicals used in the reaction run out. For example, sliced raw apples brown due to enzymatic browning, but this reaction can be stopped by the addition of lemon juice, an acid which denatures the enzymes and renders them non-functional.
Essential amino acids. (See essential nutrients.) The essential amino acids for humans are: phenylalanine, valine, threonine, methionine, arginine (required for the young, but not for adults), tryptophan, histidine, isoleucine, leucine and lysine. Acronym often used for remembering the essential amino acids: PVT. MAT HILL. Yes, Private Mat spells his name with only one T.
Essential nutrients. Nutrients that the body cannot synthesize at all or in necessary amounts to meet the body’s needs. These nutrients must be acquired through the diet.
Fat bloom (chocolate). A layer of fat particles that have migrated to the surface of a piece of chocolate and crystallized there, creating a light brown or whitish appearance. Usually occurs due to the fluctuations in temperature during storage (melting and re-solidifying) or because the chocolate was not properly tempered during manufacture. For the less common cause of whitish looking chocolate, see sugar bloom (chocolate).
Fermentation. The conversion of carbohydrates to carbon dioxide and alcohol by yeast or bacteria.
Flavonoid. A plant pigment having a structure based on or similar to that of flavone. Found in citrus, tea, wine and dark chocolate. A subject of interest in the scientific community for their in vitro antioxidant properties and potential health benefits. So far, research has not shown conclusive evidence that a diet high in flavonoid compounds is beneficial.
Foam. A colloidal dispersion of a gas in a liquid.
Fortified. Foods that have had nutrients added that were not present in the original food. For example, orange juice is often fortified with calcium, and milk is often fortified with vitamin D.
Freeze-dry. To remove water from food when it is in a frozen state, usually under a vacuum.
Freezer burn. White or grayish patches on frozen food caused by water evaporation. Vacuum packing or otherwise preventing the exposure of frozen food to air will help prevent freezer burn.
Fructose. A simple sugar (or monosaccharide) that cannot be broken down into any smaller carbohydrate. Most commonly found in fruits and honey. It is the sweetest of the natural sugars at 150-170 percent of the sweetness of sucrose (table sugar). It is also known as fruit sugar or levulose.
Functional food. A food or beverage that imparts a physiological benefit that enhances overall health, helps prevent or treat a disease or condition, or improves physical/mental performance. For example, drinking orange juice (rich in vitamin C) to prevent, or help speed recovery from, a cold.
Galactose. A simple sugar (or monosaccharide) that cannot be broken down into any smaller carbohydrate. It possesses only 30 percent of the sweetness of sucrose (table sugar).
Gelatinization. The increase in volume, viscosity, and translucency of starch granules when they are heated in a liquid. For example, adding flour or starch to cold chicken broth would produce a cloudy thin liquid, but with heat, the starch granules would gelatinize, resulting in a thicker and more translucent liquid. This is one of the principles behind gravy making.
Genetically modified organisms (GMOs). Plants, animals, or microorganisms that have had their genes altered through genetic engineering using the application of recombinant deoxyribonucleic acid (rDNA) technology.
Glucose. A simple sugar (or monosaccharide) that cannot be broken down into any smaller carbohydrate. It is commonly found throughout nature, and is necessary for many biological functions. It has only 70-80 percent of the sweetness of sucrose (table sugar), but is still sweet. It is also known as dextrose.
Gluten. A group of proteins (most commonly found in wheat) which bond to form an elastic network that gives necessary structure and function to doughs, batters and baked goods.
GRAS list. A list of compounds that are exempt from the “food additive” definition because they are “generally recognized as safe” based on “a reasonable certainty of no harm from a product under the intended conditions of use.” Many food items on this list are those that have been in use for so long with no adverse effects that the government does not see a need to prove their safety through testing. Salt is an example of a GRAS food. However, some newer additions to the GRAS list have been more controversial.
Hemicellulose. Any of a class of substances that occur as constituents of the cell walls of plants and are polysaccharides of simpler structure than cellulose.
Homogenization. A mechanical process that breaks up the fat globules in milk into much smaller globules that do not clump together and are permanently dispersed in a fine emulsion. This process allows milk to be a uniform liquid, without the cream (fat) portion rising to the top.
Hydrogenation. A commercial process in which hydrogen atoms are added to the double bonds in unsaturated fatty acids to make them more saturated. Hydrogenation can change liquid fats into solid fats. Commercial shortenings are made from vegetable oil that has been partially hydrogenated.
Fun fact: Partial hydrogenation can lead to the artificial formation of trans fats, but complete hydrogenation (fully saturating every bond) cannot yield trans fats. Commercial shortenings (historically very high in trans fats) have decreased their levels of trans fat by using a combination of almost completely hydrogenated fat and completely unhydrogenated oil. Mixing the two creates a shortening with similar properties to the partially hydrogenated, but minimizes the formation of trans fats.
Hydrolysis. The chemical breakdown of a compound due to a reaction with water.
Hydrophilic. A term describing “water-loving” or water-soluble substances.
Hydrophobic. A term describing “water-fearing” or non-water-soluble substances.
Incomplete protein. A protein, usually from plant sources, that does not provide all the essential amino acids.
Induction. The transfer of heat energy to a neighboring material without contact. For example, an induction cooktop works by creating an electromagnetic field in its immediate vicinity. Any ferrous (magnetic) cookware within that field will begin to heat up and cook the food. The source of the energy (induction coil) and the cookware never touch.
Invert sugar. An equal mixture of glucose and fructose, created by hydrolyzing sucrose (table sugar). For example, many candy recipes call for adding cream of tartar (an acid) to a sugar solution. The purpose of adding the acid is to hydrolyze the sucrose molecule so it will break down into its two more basic sugar components—one glucose and one fructose.
Julienne. To cut food lengthwise into thin strips.
Knead. To work a dough by pushing, stretching and folding it. Important in the formation of gluten in baked goods.
Kosher. Food that is prepared and eaten according to Jewish dietary laws.
Lactose. A disaccharide comprised of glucose and galactose. It is commonly found in milk and dairy products and is the least sweet of the common natural sugars with only 15 percent of the sweetness of sucrose (table sugar). It is also known as milk sugar.
Maillard reaction. The reaction between a reducing sugar (most commonly glucose, fructose, lactose and maltose) and a protein in the presence of heat, resulting in the formation of brown complexes. For example, the browning of meat and toast are the result of the Maillard reaction, which introduces important flavors and aromas as well as an attractive appearance to cooked foods.
Maltose. A disaccharide comprised of two glucose molecules. It is found in barley and is often produced when amylase (an digestive enzyme found in saliva) breaks down starch. It is approximately 40 percent as sweet as sucrose (table sugar). It is also known as malt sugar and plays an important role in the brewing of beer and adds flavor to malted milkshakes and malted milk ball candy.
Marbling. In meat, this is fat deposited in the muscle that can be seen as white streaks or spots.
Melanin. A class of back or brown pigments naturally occurring in many plant and animal tissues.
Meniscus. Vital to accurate and precise measurement of liquids, this is the bottom of the concave arc at the water’s surface. Liquids should be measured at eye level in a liquid measuring cup, and the meniscus should line up with the desired measurement.
Modified starch. A starch that has been chemically or physically modified to create unique functional characteristics. Can be made from a variety of grains such as wheat, rice, tapioca, or, most commonly, corn. Industrially, modified starches are available for use in natural, organic or gluten free foods in addition to conventional foods, so you may see it on the labels of all sorts of pre-packaged goods.
Monounsaturated fat. A fatty acid that has one double bond along its chain; the remaining bonds are single.
Muffin Method. A method of combining ingredients where the liquids are added to the dry ingredients and then stirred only enough to hydrate the dry ingredients. The batter should remain lumpy. Continued stirring beyond what is needed to wet the dry ingredients will result in the overproduction of gluten, which will yield a less tender product with large tunnels (tunneling) or air cells. The muffin method is used in the preparation of muffins, pancakes, coffee cakes, waffles, and cake-like cookies. It is also sometimes called the quick-bread method, blending method or stirring method.
Nitrate. A salt or ester of nitric acid, containing the anion NO3− or the group –NO3. Historically, nitrates were often added to sausages and cured meats in the form of potassium nitrate (KNO3), which was discovered in the Middle Ages and named saltpeter, for its salt-like appearance. It serves to brighten meat color and improve its flavor, safety and shelf life. Scientists have since discovered that these benefits are actually imbued by nitrites produced by small amounts of salt-tolerant bacteria that break down the nitrates that were originally added to the meat. Although added nitrites are more common in today’s rapidly produced cured meats, long-cured and aged cured meats (like prosciutto) still uses nitrates, usually in the form of saltpeter or those naturally occurring in sea salts. In the US, residual nitrate and nitrite content is limited to 200 parts per million (0.02%) due to the small risk of the formation of nitrosamine in food, a carcinogen.
Nitrite. A salt or ester of nitrous acid, containing the anion NO2− or the group -NO2. Today, very small amounts of nitrites are often added to sausages and cured meats. It serves to brighten meat color and improve its flavor, safety, shelf life and prevent the growth of Clostridium botulinum, a bacteria that could otherwise produce a lethal botulism-causing toxin when present in an oxygen-free environment (like the inside of a sausage). In the US, residual nitrate and nitrite content is limited to 200 parts per million (0.02%) due to the small risk of the formation of nitrosamine in food, a carcinogen.
Nutraceutical. A bioactive compound (nutritive or non-nutritive) that has health benefits.
Nutrients. Food components that nourish the body to provide growth, maintenance and/or repair. Foods components that do not meet this definition are often referred to as non-nutritive, as in artificial sweeteners and Calorie-free natural sweeteners like stevia. Non-nutritive components are still considered food, but do not provide any nutritional value.
Olfactory. Relating to the sense of smell.
Osmosis. The movement of a solvent through a semi-permeable membrane to the side with the higher solute concentration, equalizing the solute concentration on both sides of the membrane.
Overrun (ice cream). The volume over and above the volume of the original frozen dessert mix, caused by the incorporation of air during freezing.
Oxidation. The addition of an oxygen molecule to a given compound. Alternately defined as the loss of electrons. Oxidation has many implications in chemistry, but with regards to food, it is often responsible for off-flavors and rancidity in fats. Antioxidants are chemical compounds, such as vitamin E, (aka tocopherols) that prevent harmful oxidation reactions, usually by attracting the oxygen (or losing electrons) themselves.
Parboil. To partially boil, but not fully cook, a food.
Pasteurization. A food preservation process that heats liquids to 160°F (71°C) for 15 seconds, or 143°F (62°C) for 30 minutes, in order to kill bacteria, yeasts and molds. Commercially available milk, juices and liquid egg products are pasteurized. Raw milk is not pasteurized, is not commercially available, and is generally considered to be a health risk by the scientific community.
pH scale. Measures the degree of acidity or alkalinity of a substance, with 1 the most acidic, 7 neutral, and 14 the most alkaline (basic).
Phenolic compounds. Also called phenols or phenolics, are a class of chemicals which are comprised of an aromatic (circular) ring attached to one or more hydroxyl (-OH) groups.
Pheophytin. A chlorophyll molecule lacking a central Mg2+ ion. It can be produced from chlorophyll by treatment with a weak acid, producing a drab brown pigment.
Photosynthesis. The process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct.
Pith. The spongy white inner rind of citrus fruits. Also known as the albedo, it is most known for its uncommonly powerful bitterness. Its flavor is generally considered undesirable, with the notable exceptions of candied citrus peel and certain cocktails where the addition of bitterness improves the overall flavor profile.
Plasticity. The ability of a substance to be shaped or molded. Solid fat is an example of a food with plastic characteristics. (Think butter sculpture!)
Polymers. A molecule, compound or mixture of compounds whose structure is composed of multiple repeating units.
Polyunsaturated fat. A fatty acid that has two or more double bonds along its chain; the remaining bonds are single.
Prebiotics. Non-digestible food ingredients (generally fibers such as fructooligosaccharides (FOS) and inulin) that support the growth of probiotics.
Probiotics. Live microbial food ingredients (i.e., bacteria) that have a beneficial effect on human health.
Protein. A large molecule composed of one or more chains of amino acids. An essential component of the human diet. In addition to providing amino acids needed for the assembly of proteins in our bodies, a gram of protein also yields approximately 4 Calories.
Protein complementation. Two incomplete-protein foods, each of which supplies the essential amino acids missing in the other, combined to yield a complete protein profile. Some foods historically eaten together have been found to complement each other, such as rice and beans. This technique of combining incomplete-protein foods is very important in meat- or animal-protein-free diets.
Quickbread. Bread leavened with air, steam, carbon dioxide from baking soda or baking powder or other non-yeast source. Muffins, pancakes, coffee cakes, waffles, banana bread, and cake-like cookies are all examples of quickbreads.
Rancid. The breakdown of the polyunsaturated fatty acids in fats that results in disagreeable odors and flavors.
Reducing sugar. Sugars such as glucose, fructose, lactose, maltose and others that have a reactive aldehyde or ketone group. These sugars play a crucial role in the Maillard browning reaction. Sucrose is not a reducing sugar.
Rennin. An enzyme originally obtained from the lining of a calf’s stomach and sold commercially as rennet. A non-animal origin alternative is now also available. This enzyme is key in cheese-making.
Retrogradation. The seepage of water out of an aging gel due to the contraction of the gel (bonds tighten between the amylase molecules). Also known as syneresis or weeping.
Roux. A thickener made by cooking equal parts or flour and fat (usually butter). Short cooking times lead to a blonde or light-colored roux with powerful thickening properties that is historically used in sauce-making in French cuisine. It is also useful in thickening gravy, stews and soups. In Creole cuisine, roux is traditionally cooked for much longer until it develops dark, complex flavor and color. However, most of a roux’s thickening power is lost with longer cooking.
Saturated fat. A fatty acid that has only single bonds along its chain; there are no double bonds along its structure.
Saturated solution. A solution holding the maximum amount of dissolved solute at room temperature.
Sear. To brown the surface of meat by brief exposure to high heat.
Simple syrup. A basic mixture of boiled sugar and water. Usually a 1:1 ratio.
Smoke point. The temperature at which a fat or oil begins to smoke.
Solubility. The ability of one substance to blend uniformly with another. For example, salt is soluble in water. Salt has greater solubility in hot water than in cold water.
Solute. Solid, liquid or gas compounds dissolved in another substance. For example, in saltwater salt is the solute and water is the solvent. In chocolate milk, chocolate syrup is the solute and milk is the solvent. In seltzer water, carbon dioxide is the solute and water is the solvent.
Solution. A completely homogeneous mixture of a solute (usually a solid) dissolved in a solvent (usually a liquid). For example, in saltwater salt is the solute and water is the solvent. In chocolate milk, chocolate syrup is the solute and milk is the solvent. In seltzer water, carbon dioxide is the solute and water is the solvent.
Solvent. A substance, usually a liquid, in which another substance is dissolved. For example, in saltwater salt is the solute and water is the solvent. In chocolate milk, chocolate syrup is the solute and milk is the solvent. In seltzer water, carbon dioxide is the solute and water is the solvent.
Standards of Identity. Requirements for the type and amount of ingredients a food should contain in order to be labeled as that food. For example, for something to be labeled as “orange juice” it must contain a certain percentage of juice from oranges; if it falls below the requirement in any way, it must be labeled something other than “orange juice”, usually orange drink or something similar. Not every type of food has a Standard of Identity.
Structure/function claims. Statements identifying relationships between nutrients or dietary ingredients and body function. These health claims are held to the standard of “significant scientific agreement.” Cheerios’ claim to be a heart healthy food is an example of a structure/function claim. Note that the FDA does not typically evaluate claims made by supplement manufacturers, so use caution!
Sublimation. The process in which a solid changes directly to a vapor without passing through the liquid phase. Dry ice is an example of this phenomenon.
Sucrose. A disaccharide comprised of glucose and fructose. It is commonly known as table sugar or saccharose and is plays an important role in many foods. Sucrose is one of the only sugars that will not contribute to the Maillard browning reaction, as it is non-reducing.
Sugar bloom (chocolate). A layer of sugar particles that have migrated to the surface of a piece of chocolate and dried there, creating a dusty white appearance. Usually occurs due to the presence of moisture or humidity. For the more common cause of whitish looking chocolate, see fat bloom (chocolate).
Supersaturated solution. An unstable solution created when more than the maximum solute is dissolved in solution. This is usually made possible by raising the temperature of the solution, thereby increasing solubility, then allowing the mixture to cool slowly. Without agitation, the extra solute can remain in solution for a time; during that time, the solution is considered supersaturated. This technique is often used in candy-making.
Suspension. A mixture in which particles too large to go into solution remain suspended in the solvent.
Tannins. Polymers of various flavonoid compounds, some of which yield reddish and brown pigments. Present in tea and red wine.
Tempering (chocolate). To heat and cool chocolate to specific temperatures, making it more resistant to melting and resulting in a smooth, glossy, hard finish.
Trans fat. An unsaturated fat molecule with a trans-isomer fatty acid. “Trans” describes the molecular formation in which a double bond on an unsaturated fatty acid has carbons attached on opposite sides of the molecule, as opposed to “cis” formation, where carbons are attached on the same side. Trans formation yields a linear structure, much like a saturated fatty acid, unlike a cis fatty acid, which is bent. Trans fats can be mono- or polyunsaturated, but never saturated. They do occur rarely in nature, but are more commonly introduced in the diet via foods that contain partially hydrogenated fats. There are ways to reduce trans fats in partially hydrogenated products, such as vegetable shortening, by increasing the level of hydrogenation (thereby reducing the remaining unsaturated fats) and then adding back in pure unsaturated fats in the form of vegetable oil. Trans fats have been implicated in various health problems, including an increased risk for heart disease.
Ultrahigh-temperature (UHT) milk. Milk that has been pasteurized using very high temperatures, is aseptically sealed, and is capable of being safely stored unrefrigerated for up to three months.
Unsaturated fat. A fatty acid that has one or more double bonds along its chain.
Viscosity. The resistance of a fluid to flowing freely, caused by the friction of its molecules against a surface. In simplified terms, viscosity is used to describe the thickness a food, usually a sauce or other fluid. Something with a high viscosity (like sour cream) will move slowly and is considered “thick”, something with a low viscosity (like water) will move rapidly and is considered “thin”. Viscosity measurements must be taken at a constant temperature. After all, everyone knows molasses moves slower in winter, right?
Water activity (aw). Measures the amount of available (free) water in foods. Water activity ranges from 0 to 1.00, which is pure water. Water activity is one of the single most important concepts in food safety today. Limiting the amount of available water prevents the growth of microbes, which need water to survive and thrive. In addition to keeping food safe, a low water activity is one way to allow for extended shelf life without refrigeration for many foods.
Whey. The liquid portion of milk, consisting primarily of water, lactose and whey proteins. It is the watery component removed from the curd in cheese manufacture. Leftover whey from cheesemaking is often dried and used as filler in many pre-packaged dry goods and seasonings, especially those with a dairy flavor element. Check the label on dry mac and cheese or Doritos next time you pick some up. You might be surprised at how many places you find whey.
Xanthan gum. A water-soluble natural gum produced by bacterial fermentation and used as a thickener, gelling agent, binder, or stabilizer in food.
Yeast (active). A fungus (a plant that lacks chlorophyll) that is able to ferment sugars and that is used for producing food products such as bread and alcohol.
Zest. Shavings from the colorful, outermost layer of a citrus fruit. Also known as the flavedo, it contains a high concentration of flavorful essential oils and can imbue powerful citrus flavors without adding unwanted acidity or moisture to recipes.