Food Nutrtion 11: Fats And Oils

FATS AND OILS Differences between Fats and Oils? FAT STATE AT ROOM TEMPERATURE (18-25°C) SOURCE

OIL

Solid

Liquid

Animal

Plant

* Fats and Oils belong to a group of compounds known as lipids LIPIDS: an organic molecule composed of carbon, hydrogen and oxygen in varying proportions; can be dissolved in organic solvents (benzene, chloroform, acetone and ether) Three major groups of edible lipids: 1. triglyceride The attached fatty acid may be: a. Saturated (no double bonds) - from meat, milk, cream, cheese, butter, lard, chocolate, beef tallow, suet and coconut, cottonseed & palm oils b. Monounsaturated (one double bond) - from olives, peanuts, avocado, canola oil, grapeseed oil, ground nut oil, sesame oil, corn oil, popcorn, whole grain wheat, cereal, oatmeal, safflower oil, sunflower oil, tea-oil Camellia c. Polyunsaturated (two or more double bonds) - from vegetable oil (corn, cottonseed, soybean) and fish oil - omega-3 and omega-6 fatty acids 2. phospholipid - a good emulsifier because of its dual nature (hydrophobic and hydrophilic) 3. Sterol - an important class of organic molecules naturally occurring in plants, animals and fungi; most familiar type of animal sterol: cholesterol (vital to cellular function, and a precursor to fatsoluble vitamins and steroid hormones) Classification of fats based on: 1. Appearance a. Visible - easily seen and feels greasy; ex. butter, oils and pork fats b. Invisible - hidden and not easily recognized; ex. egg yolk, cream, avocado and lean meat 2. Sources a. Animal (ex. bacon, butter, etc.) b. Plants (ex. coconut cream, corn oil, vegetable oil)

Some market forms of fats and oils 1. Tallow - Animal fat from cattle or sheep 2. Suet - Clear white, solid fat obtained from kidneys and loins of cattle and sheep 3. Lard - fat derived from swine; highest quality lard is called leaf lard 4. Butter - A product of ripened cream is churned until the butterfat separates from the buttermilk; contains at least 80% fat 5. Margarine - Product made to resemble butter; emulsified cultured milk and fat (prerequisite: should not come from milk fat) 6. Oils – from seeds (rapeseed, soybeans, etc.) and fruits (avocado, coconut, olive oil) 7. Hydrogenated oil - plant oil that has undergone hydrogenation (hydrogen atoms are introduced to the double bonds in MUFA and PUFA) 8. Winterized oil - Vegetable oil that has undergone winterizing (process that removes fatty acids in oils) 9. Refined oil - A process used to remove free fatty acids Fat replacer: any ingredient that replaces fat; it physically resembles fat and is used to replace fat in recipes Three main groups of fat replacers (based on its chemical structure): 1. Carbohydrate-based: from cellulose, dextrins, fiber, gums & starches; could impart the texture, mouthfeel & opacity of fat; brand names: Avicel, Amylum, Opta, Kelcogel, Amalean 2. Protein-based: from whey, egg proteins and corn proteins that are either microparticulated or modified; Simplesse and Dairy-Lo 3. Lipid-based: fat with chemically modified structures; Salatrim and Olestra General characteristics of fats and oils: 1. Hydrophobic 2. Less dense than water 3. Absorbs odor and flavor Properties of fats and oils: 1. Melting Point - Affected by ratio of saturated to unsaturated fatty acid, length of carbon chain, cis-trans configuration and size of crystals 2. Smoke Point - The temperature at which fats or oils begin to smoke; the presence of free fatty acid, previous heating, amount of surface area exposed and presence of fine food particles hasten the time of reaching the smoke point * ACROLEIN 3. Flash Point - The temperature at which tiny wisps of fire streak to the surface of a heated oil; use of fire extinguishers marked with B 4. Fire Point - The temperature at which a heated substance bursts into flames and burns for at least 5 seconds 5. Rancidity - Chemical deterioration of fats a. Hydrolytic Rancidity: lipase and heat

b. Oxidative Rancidity: oxygen, heat and metals (Cu, Ni, Fe) c. Preventing rancidity: (1) hydrogenation, (2) addition of

antioxidants (vitamin C, E, BHA and BHT) and (3) proper storage of fats: cool and dark place, tightly covered

Uses 1. 2. 3. 4.

of fats and oils in food preparation: Shortening Medium of Heat Transfer Dressing Condiment

Fat as a medium for heat transfer:  Shallow frying (sautéing and stir-frying): uses the least amount of fat; uses high temperature to cook foods easily and prevents escape of natural juices  Pan-Broiling (placing food in a very hot frying pan and pouring off fat as it accumulates) and Pan-Frying (uses moderate amount of fat - ½ inch deep)  Deep frying: food is completely covered in fat; usually coated with breading or batter How • • • •

is food cooked in deep frying? Moisture Transfer Fat Transfer Crust Formation Interior Cooking

Implications of fat absorption in fried foods 1. Affects palatability 2. Affects digestibility 3. Nutritive quality 4. Cost Factors affecting absorption 1. Cooking time 2. Cooking temperature 3. Surface area of the food exposed to oil/fat 4. Composition of food Pointers to remember in frying 1. Choose fats suitable for frying: tasteless, odorless, neutral or colorless with a smoke point above 200°C 2. Choose a suitable cooking utensil 3. Fry at the recommended temperature (180 + 10°C; size and moisture content) • how to check if oil is hot: bubbles around the turner, water drop, use of bread cubes 4. Strain the food particles from the fat before frying 5. Fry only a small amount of food at a time

6. Lower the amount of water in food 7. Drain fried foods on absorbent paper 8. Clarify oil when it’s still useful 9. Strain fat after use and store in a cool dark place EMULSIONS Emulsion: A liquid dispersed in another liquid with which it is usually immiscible (ex. cake batter, cream puff and ice cream) Two types of emulsion 1. OIL IN WATER  milk, raw egg yolk, gravies, mayonnaise, salad dressing, cheese sauce, puddings, cream soups & batters 2. WATER IN OIL  butter, margarine & cream Parts of an emulsion 1. Discontinuous  Dispersed Phase / internal phase (oil) 2. Continuous  External phase 3. Emulsifier  the stabilizing compound Common emulsifiers 1. Naturally occurring  egg yolk  mono- and diglycerides  phospholipids (lecithin) & lipoprotein 2. Manufactured  propylene glycol & sorbitan 3. Powdered herbs and spices: mustard, paprika, ground black pepper Characteristics of a good emulsifier 1. Reduces the surface tension of one liquid 2. Stabilizes the emulsion 3. Prevents the globules from coalescing with each other 4. Must not compete with, nor dominate the ODOR and FLAVOR of the food to which it is added Types of emulsions according to stability 1. Temporary emulsions  least viscous, and the least stable 2. Semi-permanent emulsions  with added stabilizers to decrease the tendency to separate 3. Permanent emulsions  very viscous and stable to the point that they do not separate

Factors affecting stability of an emulsion 1. Kind of emulsifier 2. Concentration of emulsifier 3. Viscosity of the emulsifier 4. Particle size 5. High temperature 6. Freezing 7. Optimum agitation 8. Depth of mixing container Common emulsions 1. French Dressing: oil + vinegar+ white pepper 2. Mayonnaise: oil + vinegar + egg yolk 3. Cooked dressing/salad dressing: less oil is added; starch is added Mayonnaise  A stable emulsion of vegetable oil and egg yolk, flavored with vinegar or lemon juice and frequently with mustard Ingredients and materials  vegetable oil (65% edible oil, unsaturated, room T°)  egg yolks (fresh, room T°)  acetic acid (usually vinegar)  optional ingredients: paprika and mustard  bowl and wire whisk or hand mixer Demulsification: the separation or breaking of an emulsion due to  Incomplete preliminary emulsification  Too rapid addition of oil  High ratio of oil to emulsifier  Inefficient method of beating Reforming broken mayonnaise: ** Add the broken mayonnaise a little at a time to: - 1-2 Tbsp processed or commercial mayonnaise OR - 1 Tbsp beaten egg white/egg yolk OR - 1 tsp vinegar or water Cream Puff:  a quick bread that could be described as having hollow shells, crisp and brown crust and slightly moist and soggy interior; among the types of pastries this has the highest amount of liquid  characteristics: light volume, shell surface is cauliflower-like, hollow and moist interior; mildly sweet and egg flavor Step 1: prepare the ingredients and the oven Ingredients: 1 c AP flour, ½ c butter, 1 c water & 4 pieces eggs  Preheat oven to 425°F: to make evaporation occur at a single point

Step 2: Heat water & butter in a saucepan until boiling Step 3: Add ALL the flour at the same time & stir vigorously (PRE-COOKING STAGE) Step 4: Stir until the mixture pulls away from the sides of the pan (Note: When it has formed a ball, continue stirring as you extend cooking for 2-3 minutes.) Step 5: Remove from heat source. Let it cool to 60°C. Beat in the needed amount of eggs, one at a time. *** ENDPOINT: SATINY, SHINY and SILKY Step 6: Shape the cream puffs by spooning it or piping it on a greased baking sheet (4 cm diameter) and allow 3-inch space in between puffs Step 7: Bake • 1st stage: 425°F for 15-20 minutes • 2nd stage: reduce temperature to 325°F for 15-20 minutes Step 8: Allow the puffs to cool. Then fill with cream or desired filling.