HNSC 1200: Unit 5

Protein and Diet

- A diet short in any of the essential amino acids limits protein synthesis. - In building a protein, no other amino acid can fill another's spot. - If a cell building a protein cannot find a needed amino acid, protein synthesis stops and the partial protein is released. - These partially completed proteins are not stored until the amino acid is available. - They are instead dismantled and the amino acids are released back into circulation. - They are either picked up by other cells, or are dismantled and used for other purposes.

Winterization of fats

- A process to produce salad oils that do not crystallize (i.e., become cloudy) at refrigerator temperatures. - Oils can become cloudy at lower temperatures because some of the triglyceride molecules crystallize or become solid. - Involves lowering the temperature of oil to a point at which the triglycerides with high melting points crystallize (approximately 2oC - 0oC). - The oil is then filtered to remove the crystals and the remaining oil has a lower melting point and does not crystallize at refrigerator temperatures.

Caramelization

- A series of chemical reactions occur when sugars are heated to temperatures greater than their melting point. - Begins with dehydration and ends with polymerization that yields brown colours. - Dry sugar or a sugar solution are heated until it first melts into a clear liquid and then becomes a smooth, brown mixture. - When the reactions are not too extensive, a desirable caramel flavour and light brown colour results. - When the reactions are too extensive (beyond caramel formation), bitter dark coloured compounds are formed. - The temperature required depends on the sugar being used, but the average temperature required is 200oC. - Caramelized sugar is less sweet then table sugar, but has a stronger flavour. The darker the caramel, the less sweet it is. - is widely used in the food industry both for flavour and colour properties (e.g., dessert toppings, ice cream, pudding, candies like caramels and peanut brittle). - consists of 50% digestible CHO, 25% non-digestible CHO, and 25% polycyclic aromatic hydrocarbons.

How fat becomes part of our food

- Added during food processing - Added during food preparation - Added at the table - Found naturally in foods

Cultured (fermented) milk

- Bacterial cultures are added to ferment the lactose into lactic acid. - This increased acidity results in a thickened consistency. - Examples include yogurt, sour cream, buttermilk and kefir.

Sterols

- large molecules consisting of interconnecting rings of carbon atoms, with side chains of carbon, hydrogen and oxygen. - e.g. cholesterol and phytosterol

Classification of lipids

1. Triacylglycerols (triglycerides) 2. Phospholipids 3. Sterols

Carbohydrate-based fat replacers

- Plant polysaccharides - Include derivatives of cellulose, maltodextrins, gums, modified starches and polydextrose - Some are digested, so provide 4 kcal per gram, however others are not digested, so are virtually non-caloric - They produce a mouthfeel that is similar to that associated with fat but they do not taste like fat and do not function like fat in cooking - Can withstand heat, however cannot be used for frying e.g., Oatrim - made from hydrolyzed oat flour, used in baked goods and salad dressings

Meat

- Broadly defined, meat includes muscle tissue and organs of beef, veal, lamb, pork, poultry and fish. - Red meat has negligible carbohydrate content as the glycogen is used up in the continuing metabolic process after slaughter. - Major components of meat are water, fat and protein, as well as some vitamins and minerals. - Poultry tends to have a lower fat content and slightly higher protein content per weight than red meat. - High water content and neutral ph makes meat susceptible to spoilage- this can be reduced by curing (salt addition) or drying. - Other processing of meat includes grinding, canning and freezing. - usually has some visible fat within the muscle called marbling (seen as white streaks or drops in the muscle). - Presence of fat increases juiciness and gives better eating quality. Due to health concerns some animals are now bred to have leaner meat (less marbling, lower fat content). - The colour of meat is often used to judge freshness and it is usually wrapped in material that is permeable to oxygen to preserve the red colour. Without oxygen, beef is normally bluish-purple. When meat is not fresh it turns brown. - Fish flesh is highly perishable because of the high levels of unsaturated fatty acids which can be readily oxidized. - Fish fat is rich in a chemical called trimethylamine oxide (TMAO).After capture, the TMAO is converted to trimethylamine (TMA), which is responsible for the 'fishy' odour.

Saturated Acids

- Butyric acid: found in butter has 4 carbon atoms, single bonds and is saturated. - Stearic acid: found in beef has 18 carbon atoms, single bonds and is saturated. - Palmitic acid: found in palm oil and cocoa butter has 16 atoms, single bonds and is saturated.

Potential Health Benefits of CLA

- CLA may play potential roles in cancer prevention. - In some animal studies, CLA has been shown to inhibit cancers, lower cholesterol, improve diabetes, improve immune function and potentially lower body fat. - However other studies have shown no effect, or even negative effects (like liver hypertrophy and insulin resistance when CLA isomer supplements are used), so research on humans has been limited. - CLA is available in pills sold as over the counter products in grocery and drug stores.

Nonenzymatic Browning

- Caramelization - Maillard reaction

Plant protein crops

- Cereals - Pulse, Nuts and Oilseed (Legume) Storage Proteins

Varieties of milk

- Cultured (fermented) milk - Evaporated milk - Sweetened condensed milk - Ultra high temperature (UHT) milk - Skim milk powder

Proteins as Enzymes

- Enzymes act as catalysts that speed up chemical reactions without being used in the reaction itself. - do not stop functioning when an animal is slaughtered or when a plant is harvested; therefore, we must consider enzyme activity when dealing with foods. - Names of enzymes often include the substrate or substance on which they act, and have an "ase" ending, e.g., lactase (acts on lactose), protease (acts on proteins), lipase (acts on lipids). - The name of an enzyme may also describe the reaction that is catalyzed, e.g., oxidase (catalyzes oxidation reactions). - Enzymes are used in foods such as meat tenderizers (bromelain, papain), clotting of milk (rennin or chymosin). - Enzymatic browning is an undesirable browning reaction that occurs when some fruits and vegetables such as banana, apple, potato are cut and exposed to oxygen. - The browning reaction can be blocked by denaturing the enzyme using heat or by excluding oxygen by covering the surface of the food or by adding ascorbic acid (vitamin C)

Cereals

- Plant protein crops - Have protein contents not greater than 15-17%. e.g., wheat, corn, rye, rice, oats, barley. - In wheat, the principal proteins are the gliadin and glutelin fractions, which represent about 80% of the endosperm protein. - Gluten is a complex formed from gliadins and glutelins following hydration and mixing of wheat flour. - The hydrated gluten complex forms a 3-dimensional viscoelastic network that gives wheat flour its valued dough and bread-making characteristics.

Conjugated linoleic acid (CLA)

- Fat acting as Functional Foods and Nutraceuticals - In conjugated linoleic acid, the two double bonds are separated by one single bond: --CH=CH-CH=CH- - CLA is an essential fatty acid found mostly in animal products such as milk and meat - Meat of ruminants (cows, sheep) and other animals that chew the cud contains more CLA than non-ruminant meats such as turkey, chicken and pork. - This is because bacteria in the stomach of ruminants convert linoleic acid to CLA, which is absorbed into the animal tissue. - Non-ruminants do not have this type of bacteria, so they cannot produce CLA.

Fat-based replacers

- Fat molecule created with fewer carbon atoms in the structure (a shorter length of fatty acids). - Therefore, fewer calories are provided. - Long chain fatty acids can be combined with sucrose to produce a compound known as sucrose polyester.

Hydrolytic rancidity

- Hydrolytic rancidity is the result of the breaking of triglyceride structure composed of short chain fatty acids. - Results in the production of glycerol and free short chain fatty acids such as butyric acid and caproic acid (found in butter). - The short chain fatty acids are volatile and produce off flavours and odours. - Heat acts as a catalyst for this reaction, which can cause problems when wet foods are deep-fried. - This introduces water to the oil, making the oil prone to hydrolytic rancidity, especially when the oil has not been heated (as heat breaks down the enzymes that also fuel hydrolytic rancidity). - Butter stored at room temperature can be at risk for hydrolytic rancidity, because this temperature is an ideal environment for the enzymes that contribute to the rancidity, and because butter contains water. Therefore, butter should be stored in the fridge or freezer.

Unsaturated fatty acids (CIS)

- In the cis form, the hydrogen atoms on the double bond are on the same side as the double bond. - Trans fatty acids have a higher melting point than the cis fatty acids.

Unsaturated fatty acids (trans)

- In the trans form, the hydrogen atoms are on opposite sides of the double bond from one another. - Trans fatty acids have a higher melting point than the cis fatty acids. - Trans fatty acids can be found naturally in meat, poultry and processed milk products. - However the majority of trans fatty acids in our diet are formed during the process of hydrogenation.

Fat Replacers

- Ingredients that replace some or all of the functions of fat and may or may not provide energy. - difficult to find a fat substitute that will perform well in all food products. - Common food ingredients such as fibre, sugar/carbohydrates, and proteins can take the place of fats. - Even though they still provide calories, they provide far less calories than fat would. - To gain FDA consent to use fat replacers in a product, it must be proven that little energy is contributed, that it is non-toxic, that it does not build up in body tissues, and does not rob the body of essential nutrients.

Polyunsaturated:

- Linoleic acid - Lenolenic - Linoleic and linolenic acids are essential fatty acids which we will look at in greater detail later in this unit.

Emulsification

- Lipoproteins and phospholipids present in the egg yolk help to keep fat dispersed in water. -Used in products such as mayonnaise, salad dressings, sauces (like hollandaise and béarnaise), ice cream and some cakes.

Oxidative rancidity

- Occurs primarily with the unsaturated fatty acid portions of triglycerides. - Reaction begins with the addition of oxygen to carbon atoms next to a double bond in a fatty acid. The reaction results in formation of hydroperoxide. - Oxidative damage can be prevented or slowed down through the use antioxidants such as BHT (butylated hydroxytoluene, an antioxidant and antimicrobial compound) or vitamin E (an antioxidant).

Pulse, Nuts and Oilseed (Legume) Storage Proteins

- Plant protein crops - Pulses are beans (e.g., Navy beans, kidney beans, black beans, etc.), peas (e.g., split peas, chickpeas) and lentils. - Contain higher protein contents, ranging from 18-45%, e.g., peas, lentils, beans, soybean, canola, mustard. - Contain very little amounts of gliadin and glutelin. Majority of the proteins are soluble in water or salt solutions. - Most pulses offer protein of good quality, while being low in fat. - Legumes include pulses, soybeans, seeds and peanuts. - Nuts are grown on various trees and ground plants. - Provide protein, unsaturated fat, fibre, vitamins, minerals and phytochemicals

Protein Structure Classification

- Primary (1°): Linear sequence of amino acids - Secondary (2°): Repeating pattern of linear amino acids; alpha-helix (coiling) or beta sheet - Tertiary (3°): Three dimensional shape, coils fold back on themselves resulting in a more compact, globular shape - Quaternary (4°): Globular proteins combined with each other; more complex structure (e.g. insulin, hemoglobin)

Protein-based fat replacers

- Proteins are blended with gums to form gels, which have similar functions and structure as fat - They provide 1.3 to 4 kcal per gram used - Used to manufacture low-fat frozen and refrigerated products such as ice cream and other dairy products (e.g., can provide texture to cheese), but cannot be used for frying or at high temperatures (the protein coagulated at high temperatures and function is compromised). - e.g., 'Simplesse' is a microparticulated protein, which is produced by reshaping milk and egg white protein into tiny round particles. The process produces protein particles so small that they are perceived as fluid by the mouth.

Flavour Binding

- Proteins bind to flavour molecules. - They can also be used to enhance the flavour of processed food (food system: simulated meats (e.g., textured soy protein, tofu)).

Protein Quality

- Proteins from animal sources are of higher quality than plant based proteins. - Protein quality helps to determine how well a diet supports the growth of children and the health of adults. - It is influenced by the digestibility of the protein and its amino acid composition.

Role of Fats in foods

- Provide essential nutrients (e.g., essential fatty acids, fat soluble vitamins) - Provide concentrated source of energy & raw materials for making needed products - Provide taste, smell and texture to foods - Stimulate appetite and contribute to feelings of fullness - Can be used for heat transfer without burning food during heat transfer

Maillard reaction

- Reaction between the carbonyl group (CO) of carbohydrates and amine group (NH2) of an amino acid or protein at high temperatures. - A series of reactions such as fragmentation and polymerization eventually lead to the formation of brown pigments called melanoidins. - In most cases this is a highly desirable reaction such as in baking and roasting (e.g., baking bread, browning a piece of meat, roasting coffee beans). - It can be undesirable, e.g., browning and off-flavour development of skim milk powder stored over a long period of time. - May result in the formation of acrylamide, which may be a carcinogen. Foods that tend to have higher levels of acrylamide include potato chips, french fries, crackers, bread and cereals.

Amino acid composition

- The balance of amino acids in a protein determines its biological value and nutritional quality. - High biological value proteins are ones with ample amounts of all essential amino acids. - Low quality proteins do not. - Within a single day of restricting essential amino acid intake, the body starts to limit the breakdown of working proteins and reduce amino acid use for fuel to conserve the essential amino acids it currently has.

Rancidity

- The chemical spoilage that commonly occurs with fats and fatty foods is called rancidity. - Causes off-flavours and rancid odours. - The longer a fat is stored, the greater the risk for rancidity. - Fats and oils exposed to heat, oxygen and light are more likely to become rancid (i.e., fats and oils used for cooking). - Highly unsaturated fats/oils such as polyunsaturated fats are much more susceptible than saturated or monounsaturated fats. - Foods that easily go rancid are nuts, wheat germ and whole wheat flour. - Fats that have become rancid should be discarded, as they will transfer their off-flavours to the foods they are used in/with.

Skim milk powder

- The water content of the milk is removed, first through the use of a vacuum and then by spray drying (see unit 2 for more information drying methods). - This form of milk can be used in baked goods and can be added to water to reconstitute fluid milk.

Effects of processing on unsaturated fats

- Unsaturated fatty acids can be found in both cis and trans form, dependant on their structure at the double bond.

Artificial fats

- Zero-energy fat replacers that are chemically synthesized to mimic the sensory and cooking qualities of naturally occurring fats, but are totally or partially resistant to digestion. - Some products contain artificial fats, while others use conventional ingredients in unconventional ways, or alter preparation methods to reduce fat and calories. - For example we can alter the preparation method by: 1. adding water or whip air into foods 2. adding non-fat milk to creamy foods 3. using lean products instead of high fat 4. baking rather than fry foods

Sweetened condensed milk

- a canned product where approximately half of the water content is evaporated out of the milk prior to canning and to which a high percentage of sugar is added.

Evaporated milk

- a canned product, where over half of the water content (~60%) is evaporated out of the milk prior to canning. - In Canada, evaporated milk is fortified with Vitamins D and C.

Hydrogenation

- a process where hydrogen is added to unsaturated fatty acids (e.g., turning vegetable oil into hard margarine). - hydrogen attaches at the point(s) of unsaturation (the double bond), and the fatty acid becomes saturated (no longer has a double bond). - makes the fatty acid more solid at room temperature and increase the shelf life. - hydrogenated fats are more resistant to oxidation (no points of unsaturation) - are more resistant to breakdown from high cooking temperatures - will have a longer shelf life. - also has a higher smoking point, so is more suitable for frying. - When the hydrogen is added, some of the unsaturated fatty acids become more saturated and the oil hardens and becomes easier to spread. - Once hydrogenated, the unsaturated fats lose their health benefits. - Hydrogenation affects not only the fatty acids in fats, but the vitamins as well. - For example, it decreases the activity of vitamin K in the body.

Protein-Surface Properties

- amphiphilic so can act as a water-oil interface because they exhibit both hydrophobic and hydrophilic characteristics, helping to stabilizing emulsions (food system—salad dressings, bologna, sausages, ice cream, soups, cheese and sauces). - also involved in the production of food foams: foams are unique in that the dispersed phase is a gas within a liquid phase (food system—sponge cakes, whipped toppings, beer froth and ice cream).

Points of unsaturation

- are more vulnerable to oxidation which is when oxygen mixes with the fat, causing it to go rancid, taste "off". - That is why we store cooking oil in tightly sealed containers.

Research on Omega-3 and Omega-6

- began in Greenland and Alaska, with high fat diets, had such low rates of heart disease.

Eicosanoids

- biologically active compounds that regulate body functions. - act somewhat like hormones. They can effect muscle relaxation and contraction, blood vessel dilation and constriction, blood clot formation, blood lipid regulation and immune response to injury and infection. - serve many functions in our body. - Research is showing that EFAs enhance the cognitive abilities in infants.

Amino Acids

- building blocks of proteins. - amino acids in a strand differ from one another - All amino acids have the same chemical backbone: a single carbon atom, with an amine group and an acid group attached. - Each amino acid has a distinctive side chain which gives it its identity and chemical nature. - The side chains make the amino acids differ in size, shape and electrical charge (positive, negative or neutral). - joined together by peptide bonds to form proteins. 2 amino acids = dipeptide 3 amino acids = tripeptide >3 amino acids = polypeptide - Several dozen to 300 amino acids join to form a protein

Major minerals

- calcium (Ca), phosphorus (P), potassium (K), sodium (Na), chloride (Cl), magnesium (Mg) and sulphur (S).

Plant Proteins

- can be divided into four broad groups based on solubility properties. - Albumins: soluble in water. - Globulins: soluble in salt solutions but insoluble in water. - Gliadins: soluble in 70-90% alcohol. - Glutelins: insoluble in neutral aqueous solutions, saline solutions or alcohol. Can only be solubilized by dilute alkaline solution.

Protein

- compounds made up of carbon, hydrogen, oxygen and nitrogen - arranged in strands of amino acids - Several dozen to 300 amino acids join to form a protein - can be found in animal foods (e.g. meats, milk, eggs) as well as some plant based foods (e.g. legumes and cereal grains). - play important roles in food as well: water binding, gel formation, thickening, emulsion, foam formation (e.g., egg whites, whip cream) and the Maillard reaction.

Coagulation

- egg white proteins can set and form a gel during heating. - They can help to bind food mixtures together, such as meat loaf, meat patties and manicotti.

Essential fatty acids (EFAs)

- fatty acids that the body cannot make itself, that we must get from foods - Linoleic acid (which is an example of an omega-6 fatty acid) and Linolenic acid (which is an example of an omega-3 fatty acid) are the only essential fatty acids - EFAs can be used by the body to make eicosanoids

Omega-3 (n-3) Fatty Acids

- get their name because of a double carbon bond 3 carbons from the end of its chain. - Linolenic acid is an example of an omega-3 fatty acid. - DRI recommendation: 0.6-1.2% energy from n-3 fatty acids Sources: flaxseed, flaxseed oil, canola oil, fish (especially deep sea fish) - When given linolenic acid, the body can make other omega-3 f.a's. - Two specific omega-3 f.a's are receiving great interest from research - EPA and DHA, however the body only makes limited amounts of these omega-3's. They are found abundantly in the oils of certain fish (deep sea, fatty fish like salmon, char, mackerel, herring, cod, etc.).

Omega-6 (n-6) Fatty Acids

- get their name because of a double carbon bond 6 carbons from the end of its chain. - Linoleic acid is an example of an omega-6 fatty acid. - DRI recommendation: 5-10% energy from n-6 fatty acids - Sources: vegetable oils, seeds, nuts, whole grain products

Linoleic acid

- has 18 carbon atoms and 2 double bonds. - It is found in most foods especially oilseeds such as canola and soybean.

Lenolenic acid

- has 18 carbon atoms but contains 3 double bonds - is found mostly in soybean and hempseed.

Eggs

- have an outer shell, and have 2 major inner parts- the egg white and the egg yolk. - shell is about 94% CaC03 with small pores that allow C02 and water to escape, while allow 02 in. - They contain protein, fat, vitamins, minerals and a small amount of carbohydrates, with the yolk containing the fat and cholesterol and most of the calories (75%), while the white is the more protein-rich portion. - Major protein of the egg white is ovalbumin, also find conalbumin, ovomucoid, lysozyme and avidin. - Major proteins of the yolk are the lipoproteins- high density lipoproteins and low density lipoproteins.

Minerals

- inorganic nutrients that do not contribute energy, but act as co-factors in energy-yielding reactions. - Sixteen are currently known to be essential in human nutrition and can be broken down into two groups based on their amounts found in the human body: major minerals and trace minerals. - Minerals are heat stable and can impact the chemical and physical properties of foods

Hydrolysis

- involves breaking of chemical bonds due to the addition of water and enzyme activity.

Denaturation and coagulation

- involves unfolding of protein structure without breakage of peptide bonds. - caused by cooking, freezing, changes in pH, salts enzymes and mechanical action. - Denaturation changes the original properties of the protein. - In most cases, denatured proteins are less soluble. - If it is an enzyme, functional ability will be lost - Continuous denaturation (unfolding) can lead to recombination of the protein molecules in different ways to produce a new molecular shape. - The newly shaped molecules may bond together to form a continuous network referred to as coagulation (e.g., coagulation of egg white when heated).

Trace minerals

- iron (Fe), iodine (I), zinc (Zn), chromium (Cr), selenium (Se), fluoride (F), molybdenum (Mb), copper (Cu) and manganese (Mn).

Triglycerides

- major form of fat found in foods and in our body. - made up of 3 fatty acids and a glycerol backbone. -Fats in the diet can affect the type of triglycerides made because dietary fats are often incorporated into triglycerides in the body. - Glycerol is an organic compound 3-carbons long and has 3 hydroxyl groups (-OH). - Very few fatty acids are found free in the body or in foods, most are incorporated into triglycerides. - Fatty acids are made of chains of carbon atoms (-C) and an organic acid terminal (-COOH).

Phytosterols

- manufactured by plants - are not well absorbed from the gastrointestinal tract and may actually interfere with absorption of cholesterol. - Therefore, some types of foods such as margarine (e.g.,Becel's Pro.activ) are fortified with phytosterols to help reduce the amount of cholesterol absorbed into the blood stream.

Ultra high temperature (UHT) milk

- milk heated for approximately 2-6 seconds at 300oF to remove all viable microorganisms, i.e., the product is sterile.

Hydroperoxide

- molecules that readily breakdown into volatile products that have off odours and flavours characteristic of rancid fat (e.g., ketones, alcohols and aldehydes).

Vitamins

- organic nutrients that do not contribute energy - facilitate the release of energy from carbohydrate, fat and protein. - divided into: 1. Fat-soluble - vitamins A, D, E and K. 2. Water-soluble - vitamin C and the 8 B vitamins: thiamin, riboflavin, niacin, pantothenic acid, folate, biotin, B6 and B12. - function only if they are intact. - Due to their organic nature, they are vulnerable to destruction by heat, light, storage conditions and chemical agents. - Cooking vegetables for short times at moderate temperatures, using small amounts of water helps to preserve the vitamins. - Because processing typically results in nutrient loss, foods may have nutrients added back through a process called enrichment. - Foods may also be fortified with nutrients in an attempt to reduce the incidence of specific nutrient deficiencies (e.g. milk is fortified with vitamin D.

Protein complementation

- practice of combining two or more plant protein sources to provide a more complete array of amino acids. - important in a vegetarian lifestyle.

Protein Structure

- primary, secondary, tertiary, quaternary - does not remain in a straight chain - electrical charges of the amino acids (caused by the side chain) cause the strand to bend and coil, as amino acids attract and repel one another. - forms either a globular shape (soluble in water), or a fibrous shape (insoluble in water). - amino acids with electrically charged side chains attract water and are oriented on the outside of the protein structure. - neutral amino acids repel water and are attracted to one another, so orientate in the centre of the protein away from body fluids. - These interactions give each protein a unique structure.

Foaming

- proteins in the egg white have a high capacity to form strong protein films that surrounds air bubbles to produce stable foams. -The foams can become six to eight times the original volume. - Used in foods such as soufflés, fluffy omelets, meringues and some cakes (e.g., angel food).

Fatty Acids: Chain Length

- short: 2-4 carbons - medium: 6-10 carbons - long: 12 or more carbons - Shorter chain fatty acids tend to be softer and melt more readily at room temperature. - Chains can be as short as 4 carbons and can be 24 carbons long or more. - Generally, most fatty acids have an even number of carbon atoms

Phospholipids

- similar to triglycerides, however they have only 2 fatty acids attached to the glycerol backbone and 1 phosphorus molecule - phosphorus molecule makes the phospholipid soluble in water = role of keeping fats dispersed in water (i.e., serve as an emulsifier). - play a key role in the structure of cell membranes. - They are typically present in foods in relatively small amounts but play important roles as emulsifying agents, i.e., substances that facilitate emulsion formation. - Lecithin is a phospholipid found in egg yolk. In mayonnaise, the lecithin blends the vinegar with the oil and keeps it from separating.

unsaturated fatty acids: hydrogenated

- some change shape instead of becoming saturated. - This process creates unusually shaped unsaturated fatty acids that look like saturated fatty acids. - These fatty acids are referred to as trans fatty acids. - Consuming trans fats poses a risk to heart health and arteries by raising levels of bad cholesterol, and lowering levels of good cholesterol in our body. - They also produce inflammation. - The DRI committee recommends that people consume as little trans fat as possible.

Fatty Acids: Degree of Saturation (double bonds, C=C)

- the more hydrogen atoms attached, the more saturated the fatty acid is. - The degree of saturation affects the temperature at which fat melts. - The more unsaturated the fat, the more liquid it tends to be at room temperature, e.g., vegetable oil. - Where there is no hydrogen attached, this is a point of unsaturation, and a double bond occurs. This occurs especially in the fatty acids of plants and fish. 1 point of unsaturation = monounsaturated fatty acid (MUFA) 2 or more points unsaturation = polyunsaturated fatty acid (PUFA) 0 points of unsaturation = saturated fatty acid - Most vegetable and fish oils are rich in PUFAs; some (e.g., canola oil and olive oil) are also rich in MUFAs. - The exception is tropical oils (palm, coconut) which are low in unsaturated fatty acids but high in saturated fatty acids. - Animal fats are generally the most saturated.

Milk and dairy products

- the near perfect food- it is an important source of high quality protein, minerals, B vitamins, and energy, and is fortified with vitamins A and D, however contains very low amounts of iron. - composed of two protein fractions: casein (~80% total milk protein) whey (~20% total milk protein) - During the manufacture of cheese, acid or rennin (an enzyme also know as 'rennet') is added to coagulate most of the casein proteins while the whey is the liquid portion of milk that remains after cheese production - Whey proteins are composed mostly of beta-lactoglobulin, alpha-lactalbumin. - homogenized, a process that decreases the size of the fat globules dispersed in milk so that they are more optimally dispersed. - Freezing destroys this process, hence the fact that when most milk products are frozen and then thawed, there is some separation of fat and liquid. - classified as whole (3.25% milk fat [M.F], reduced fat (2% M.F), low-fat (1% M.F) or fat-free (skim milk, no more than 0.5% M.F). - During processing, fluid milk and yogurt are pasteurized to kill microorganisms.

Cholesterol

- type of sterol - important in the structure of cell membranes, therefore is part of every cell and is necessary for optimal body functioning. - serves as the raw material for making bile, therefore it is important for fat digestion. - also forms the major part of the plaques that narrow the arteries in atherosclerosis, an underlying cause of heart attacks and strokes. - can be made by the body so therefore is not essential.

Protein Hydration

- water binding (hydration) capacity of proteins is related to the amino acid composition. - more charged amino acids, the greater the hydration capacity. - Protein molecules can entrap water because of their hydrophilic characteristics (food system—sausages, cakes and breads). - Gelatin can thicken products and increase viscosityby forming gel matrixes. (food system—soups, gelatin desserts and dairy products).

Three main types of omega-3 fatty acids:

1. ALA (alphalinolenic acid) - from plant sources 2. EPA (eicosapentaenoic acid) - from fish sources 3. DHA (docosahexaenoic acid) - from fish sources

Fatty Acids: Classification

1. Chain length 2. Degree of saturation (double bonds, C=C)

Functional characteristics of eggs

1. Emulsification 2. Foaming 3. Coagulation

Potential benefits of EPA/DHA

1. Heart disease (supported by most studies): - Have been shown to decrease serum triglyceride and cholesterol levels - Both fatty acids have been reported to protect against cardiovascular and inflammatory diseases - Cause relaxation of the blood vessels, resulting in a lowering of blood pressure - May slow the hardening of arteries, slowing the progression of atherosclerosis 2. Infant growth and development (strong evidence) - DHA concentrates in the cortex of the brain, important for normal brain development in infants - DHA helps the retina to form, important for normal vision development in infants 3. Cancer (research promising, but need further evidence) -Cancer development may be inhibited due to altered cell metabolism

Animal Proteins

1. Meat 2. Milk and dairy products 3. Eggs

Monounsaturated

Oleic acid - found in olive oil and canola oil has 18 carbon atoms, one double bond and is unsaturated (monounsaturated).

Amphiphilic

Possessing both hydrophilic (water-loving, polar) and lipophilic (fat-loving) properties.

Saturation

Saturation refers to the number of hydrogen atoms a fatty acid chain is holding.

Emulsifiers

Substances that keep water and fat dispersed in one another (help them to mix together).

Digestibility

amino acids from animal protein are most easily digested and absorbed (>90% of protein absorbed). Legumes are next (~80-90%) followed by grain and plant proteins (70-90%). Cooking with moist heat (e.g., steaming or poaching) improves protein digestibility, where as dry heat methods (e.g., broiling) can impair it.