The Chemistry of Food Science Created by Katie Foster LGHS Nutrition & Food Science Revised October 2014 HUM-FS-4: Explore the chemistry concepts in Food Science.

Chemical Bonds Chemical Bonds - The force that holds two atoms together. The subatomic particle that forms the bond is the electron. Whether two elements will combine, and in what ratio, depends on their electrons. Two types of chemical bonds

Chemical Bonds Cont. Electrons move in orbitals about the nucleus of atoms in predictable patterns of space Shells – An area of space surrounding the nucleus that has one or more orbitals. Atoms can have up to 7 shells The number of shells in the atoms of a element determines the element’s period, or row in the periodic table.

Shells

Chemical Bonds Cont. Ionic Bonds - The electrons are transferred from one atom to another Causes both atoms to have a charge. Atom that receiving an electron are negatively charged. Atoms that loose an electron become positively charged. Ionic bonds are results of the attraction between positive and negative charges.

Chemical Bonds Cont. Ion – an atom or group of atoms that has a positive or negative charge. Like charges repel each other Opposite charges attract Substances with ionic bonds will tend to dissolve in water. One end of the water molecule is slightly positive, whereas the other end is slightly negative.

Chemical Bonds Cont. Covalent Bonds - are formed when atoms share one or more pairs of electrons. Example: Water molecules are formed by covalent bonds between 2 hydrogen atoms and 1 oxygen atom. Double Bond – More than one pair of electrons can be shared when two atoms share two pairs of electrons.

Organic vs. Inorganic Compounds o Scientist group compounds in two main categories, Organic VS Inorganic o Organic Compounds contain chains or rings of carbon. Most also contain hydrogen and oxygen Most also contain hydrogen and oxygen All the sources of energy in your diet are organic Compounds. (carbohydrates, fats, vitamins & protein) All the sources of energy in your diet are organic Compounds. (carbohydrates, fats, vitamins & protein) All of these are the main components of your diet. All of these are the main components of your diet.

Organic vs. Inorganic Compounds Inorganic compounds either contain no carbon or have only single carbon atoms. Examples of inorganic compounds in your diet… Table Salt, Water, minerals and potassium chloride (no salt)

Classes of Organic Compounds Important in Food Hydrocarbons Alcohols Aldehydes Ketones Acids Amines

Mixtures Mixtures - substances that are put together but not chemically combined. Ex: Calcium an element, Salt is a compound. Both are pure substances. Milk contains both calcium and salt. Milk is a mixture of these two substances plus many others.

Categorizing Mixtures Two categories: Homogeneous and Heterogeneous. Homogeneous – has a uniform distribution of particles throughout the sample. Visually you can’t tell one from another. Examples: Tea and soft drinks.

Categorizing Mixtures Heterogeneous – has a non-uniform distribution of particles. Example: A bowl of vegetable soup. Because when you look at the soup you see the corn, okra, potatoes etc. If you puree the soup in the blender it would then be a homogeneous mixture.

Determining Mixtures Sometime what you see isn’t what it seems when classifying a mixture. Example: Hot Cocoa looks homogeneous but when it sits a while the heavier cocoa molecules will settle to the bottom and the smaller ones will stay at the top. This makes it a heterogeneous mixture.

Understanding Mixtures Most homogeneous mixture are solutions. Solution – homogeneous mixture of one material dissolved in another. The material that dissolves is a called the Solute. The material that doesn’t dissolve is the Solvent. Ex: Sweetened drinks, water is the solvent & sugar is the solute. Ex: Sweetened drinks, water is the solvent & sugar is the solute.

The substances in heterogeneous mixtures can be separated by mechanical means Ex: you can strain vegetable soup and then hand sort the vegetables. Separating homogeneous heterogeneous is more difficult but not impossible. Ex: Salt water is a homogeneous mixture. You cannot separate the salt from water by hand. You can heat saltwater and the water will turn to steam and evaporate, Leaving salt crystals behind. Understanding Mixtures

Resources Ward, Janet. Principles of Food Science. Third ed. Goodheart-WIllcox.