Ch. 22 Fats and Oils
CHO Base (fat replacers)
- derivates of cellulose, maltodexrins, gums, modified starches, pectin, polydextrose - similar mouthfeel but altered taste *Polydextrose: similar to gluocse, used for fat or sugar substitute - bulking agent - texturized - humectant (maintains moisture) - maltodextrins, oatrim, Z-trim
Fats Continued
*Fat absorption - composition of the food (fat, flour, etc) - amount of surface expose to the fat - temp of fat (low temp, high absorb) - length of cooking time - temperature of food (frozen) - overloading will slow down cooking; batch cooking
Properties of fat
*Flavor - flavor contributed by butter, bacon, olive oil, sesame oil, & veggie sauteed in fat *Smoke point - butter at 260 F and soybean oil 495 F
Deterioration of Fat
*Hydrolytic Rancidity: breaking of chemical bonds; butyric and caproic acid found in butter are affected *Oxidative rancidity: requires oxygen or heat; Most susceptible are unsaturated fatty acids such as linoleic acid (omega-6, fatty acid)
Molecular structure of different fatty acids
*Saturaded fat - single bong of carbons w/ 4 hydrogens on either side *Cis - double bonded carbon; 2 hydrogen *Trans-unsaturated - double bond carbon; hydrgens opposite sides
What we eat in America
- 1970-2003 percent of fat has increased 16% resulting in avg., of 523 additional cals per day - 2005; 87 lbs of fat consumed per year, per person; increase of 31 lbs since 1970 *now; more veggies consumed than meat fat
Reduced Fat Dressings
- 1990 Nutrition Education and Labeling Act *mayo may be called: reduced fat mayo fat free mayo *other approved descriptions provided to mayo: has been only modified from the Standard of Identiy as the label indicates the term reduced fat, fat free, etc., meets legal definitions
Health Implications
- 90% TFA (trans fatty acids) found in partially veggie oils - TFA has a linear relation to cholesterol - What is being done? mcD's changed to a low trans fatty acid cooking oil for fries; summer '03 manufactures are developing and marketing low trans fatty acid shortening labelings of tfa content is required on nutrition label facts if <0.5 gms; may be labeled trans-fat free
Pressing oil
- Chemical solvents = Hexane - Mechanical structure: w/ high pressure - Expeller: pressing/centrifuge - Cold pressing
Valuable part of fat diet
- EFA, fat-solublable vitamins, source of energy - contains Linoelic acid (omega-6 polyunsaturated fatty acid [PUFA]) - provides 9 cals/kg
Functions of Fats in Foods
- Heat transfer: sauteing, pan frying, deep frying - Shortening power: biscuits, pastries, cakes, cookies - Emulsions: mayo, salad dressing, sauces, gravies, pudding, cream soups - Varying melting points: candies - Plasticity: confections, icings, pastries, other baked goods - Solubility: fat's don't dissolve in water, yielding unique flavor/texture and foods (i.e., salad dressing) - flavor/mouthfeel: flavor (butter, bacon, fried foods), lubricity, thickness, cooling - textures: creaminess, flakiness, tenderness, elasticity, ease of cutting, viscosity - appearance: sheen, oilness, color - satiety: fats contribute to "feeling full" - nutrients: provide engery: 9 kcal/g; carry fat-soluble vitamins
Trans Fatty Acids
- Hydrogen atoms are on opposide sides of the double bond - they're associated w/ the elevation of cholesterol levels - most trans fatty acids in diet from hydrogenated oils *Interesterification: way to produce hydrogenated fats w/ fewer trans fatty acids (possbiy by 50%)
2 Kinds of Fat
- Invisible: includes milk, poultry, fish, dairy products, eggs, nuts and seeds - Visible: usually 100% fat; examples include shortening, lard, salad dressings, cooking oils, margarine, butter; some of these fats may be invisible because of use (i.e., manufacturers, food prep)
Fat
- Lard: fat rendered from hogs not commonly used now primarily/still used in mexican foods great tenderizer for pic crust (flakey) becomes rancid quickly
Fat Replacers --> Fat Based
- Olestra, brand Olean - long-chain fatty acid combined as esters w/ sucrose - not digested or absorbed - may cause GI discomfort - fat soluble vitamins have been added - triglycerides used --> Salatrim and Benefat - Emulsifiers can be used to "stretch" fat
Types of Emulsions
- Permanent: may be held or stored w/o separation of oil and water components ex. mayo and hollandaise -Temporary: emulsion formed by shaking or beating ingredients together; separate on standing ex. vinaigrette; french and italian dressings
Different Oils
- Saturated oils: animal fats and tropical oils and palm oil -Monosaturated fatting acids: some veggie oils, such as olive and canola, are rich in these fatty acids - Polyunsaturated fatty acids: many veggie oils are rich in these
Properties of Fat
- Solubility: fat is insoluble in water (proper cleaning agent required) soluble in chloroform, ether, and petroleum ether (in a lab setting) oils that are solid at room temperature are called = fats - oils that are liquids at room temperature are called = oils - each differ in roles in food preparation and nutrition
Protein base (fat replacers)
- eggs, milk, whey soy, gelatin, wheat gluten - generally not stable w/ heat - used in dairy products, salad dressings, frozen desserts, margarines - Simplesse: brand name, made from milk and eggs
Emulsions
- emulsions are needed because one liquid is dispersed in another liquid w/; it is immiscible (will not stay together) - examples include: oil & water - emulsifiers are amphiphillic (one part attracted to water and another part attracted to fat)
Winterization - Processing
- tryglyceride molecules may crysallize at cold temps *Winterization: desirable for salad oils; oil is chilled; crystallized triglycerides are filtered out; oil remains liquid at cold temps
Roles of Fats in Food Preparation
- fats provide flavor and mouth feel; contributes to palability and eating pleasure - in baked pruducts fat "shortens" strangds of the protein, gluten, making it more tender - some fats help to add aid to batters and dough - higher temps are better for frying food - a part of an emulsion --> Lecithin (phospholipid)
Olive Oil
- good grades have not been processed - Extra virgin: first pressing, top grade, low acid - Virgin: from first pressing - Pure: mixture of olive oils, cheaper, less flavor
Hydrogenation - Processing
- liquid oils turned into solid plastic shortening *increases heat stability (used for frying) *becomes plastic (creamed w/ sugar) *reduces tendency to become rancid - Hydrogenation --> chemical reaction; hydrogen is added to molecule; trans form is more common
Unsaturated Fatty Acids
- usually derived from plant sources - liquid at room temp - beneficial health effect of posing less risk for heart disease - levels of saturation *Monounsaturated: one double bond *Polyunsaturated: more than one double bond
Fat absorption
- low temps increase absorption - Doughnuts example of absorption: high % sugar --> higher fat absorption high lecithin --> higher fat absorption soft wheat/doughs increases gluten manipulation, decreses type of fat has same absorption properties - types of fat may affect flavor - French fries: tallow/oil mixture -- discontinued - most oils are highly refined - high smoke points of 422 F
Maragines
- made from soybean oil and cottonseed oil - oils are refined and partially hydrogenated to the desired consistency to make margarine - margarine is a water-in-fat emulsion; standards of identify for margarine est., by FDA state that margarine must contain less than 80% fat - other ingredients allowed are vitamins A + D
Butter
- made from the cream that separates from milk when milk is agitated - butter is a watter (blue) in oil (yellow) emulsion: water is dispersed through out the oil - sweet, cultured, and clarified - cultured butter has lactic acid bacteria added - Clarified butter contains only the butter fat - Can be salted or unsalted - Color of butter depends on cow's feed - Grade standards: U.S. Grade AA and U.S. Grade A - Flavor contribution: Diacteyl --> formed from bacterial actions
Melting point of fat
- melting point is temp at whcih a solid becomes a liquid oil - fats are solid at room temperature *generally high saturated - oils are liquid at room temerature *generally MONOsaturated (oleic acid) or polyunsaturated (linoleic acid) - other factors: *trans form: higher melting point than cis form longer chain fatty acids have higher melting point
Processing of Oils
- obtained from fruits, seeds, and nuts - soy and palm are two most used oils in the world - RBD: an oil that has been refined, bleached, and deodorized - Kinds of oils soybean, cottonsead, olive, canola, sunflower, safflower, peanut, and corn *tropical: coconut, palm palm kernel *New oilds: genetic engineering/plant breeding to increase stability to oxidation and nutritional effects
Use of Fat in Salad Dressings
- oil is typical base for many dressings - properties considered in oil: flavor, melting point (oils should remain liquid under refrigeration)
Flavor Reversion
- oxidative deterioration - produces an off taste/smell - soybean oil: painty, beany, haylike, grassy, finally, fishy - not fat is entirely free from tendencic - prevent: store in fridge, no light, moisture, air
Cooking w/ Fats
- pan frying (oils, butter, margarine) - deep-fat frying (follow temp guide) - over heated fats break down --> smoke point - released substance: Acrolein - know temps needed for different food items and fat used - fat turnover
Fat properties contribute to
- plasicity: fat can be molded or shapes - fat may appear solid; it contains solid fat crystals & liquid oil; not brittle, but plastic - plastic fats may be creamed and air is incorporated
Antioxidants & Prevention of Rancidity
- storage in refigerator, no light, moisture, or air - antioxidants used since 1947 to stabilize fats - Vitamin C: beta-carotene, Vitamin E - Synthetic: BHA, BHT, TBHQ, propylgallate
Fat Consumption and Nutritive Value
- the American Heart Association and Surgeon General recommend a diet that is no more than 30% total fat, and only 10% of fats comes from saturated fats - if you eat 2000 kcal diet = 30% fat is equal to 600 kcals; 10% is equal to 200 kcal - total dietary fat is associated w/ some types of cancer and health problems; saturated/trans fat intake has been been associated w/ coronary heart disease and high blood cholesterol
Prepared Dressings/Sandwich spreads
- Standards of Identity (FDA): mayo; may contain at least 65% by weight of veggie oil and egg yolk - Salad dressing; must contain at least 30% by weight of veggie oil; may contain cooled starch paste or egg yolk
Basic Salad Dressings
- Vinaigrette basic french dressing temporary emulsion of oil & vinegar, seasonings (3 parts oil/1 part vinegar) - Mayonnaise emulsified sauce balance of vinegar, oil, lecithin (egg yolk) and agitation one yolk can emulsify approx., 7 ounces of oil
Smoke points of frying fats & oils
- butter (regular) = 250-300F - veggie shortening + emulsifier = 356 -370F - lard = 361 - 401 - most olive/virgin oils = 391F - corn oil = 440F - clarifeid butter (ghee) = 485F - soybean oil = 492F
Care of Eats
- check temps on fryer - high use: filter daily - remove food particles - starts foaming throw out - store fat in cold place w/ no light
Fat Replacers
- chemically and physically resemble triglycerides - stable at cooking and frying temps -Mimetic: imitate sensory properties - modified common ingredients: starch and cellulose
Types of Oils Used
- coconut oil; corn; olive; palm; peanut; rape seed; safflower; sesame; sunflower; almond; grapeseed; lemon/orange seed; flaxseed; some grains
Saturated Fatty Acids
- come from animal sources - solid at room temperature - have been implicated as promoting a higher risk for heart disease
Low Fat Diet
- consists of 2000 cal diet - 20% cals from fat - 400 cals/9cals - 45 grams fat per day
