Dairy Products and Eggs: Composition, Production, and Preparation - Prof. Melinda M. Ander, Study notes of Environmental Science

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Chapter 9- milk

 Casein - the primary protein (80%) found in milk; it can be precipitated (solidified our of solution) with acid or certain enzymes  Whey - the liquid portion of milk, consisting primarily of 93% water, lactose, and whey proteins (primarily lactalbumin and lactoglobulin). It is the watery component removed from the curd in cheese manufacture  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 very fine emulsion  Coagulate - to clot or become semisolid. In milk, denatured proteins often separate from the liquid by coagulation  Ultrapasturization - a process in which a milk product is heated at or above 280⁰ F (138⁰C) for at least 2 seconds  Curd - the coagulated or thickened part of milk  Probiotics - live microbial food ingredients (i.e. bacteria) that have a beneficial effect on human health  Prebiotics - nondigesticle food ingredients [generally fibers such as fructooligosaccharides (FOS) and inulin] that support growth of probiotics  Composition of milk : o Nutrients  Carbohydrates  Protein  Fat  Vitamins  Minerals o Color Compounds o Food Additives  Types of milk : o Fluid Milk and Cream  ½ milk produced in US  Fresh Fluid Cow’s Milk  Whole o 3.25% milk fat 8.25% MSNF o MSNF Total Solids Minus the Fat- 8.24%  Reduced-fat and Low-fat o 2.0 and 1.0 milk fat respectively  Fat-free or nonfat o No more than 0.5% milk fat o Fluid Milk  Fresh Fluid Milk From Other Animals  Goat

 Sheep  Camels  Reindeer  llama  Flavored Fluid Milks  Chocolate  eggnog  Packaging  Carbonated  UHT Ultra High Temperature  Nutritionally Altered Fluid Milks  Imitation Milk o Product defined by FDA  Appearance taste and function of original counterpart but nutritionally inferior  Filled Milk o Milk fat replaced by vegetable fat  Low-sodium milk o 6mg/cup  Low-lactose  Reduced-lactose  Soy beverage  Rice milk  Almond milk  Canned fluid milks  Whole  Evaporated evaporated fat-free  Sweetened condensed o Dry Milk  Nonfat dried  Instant o Agglomerate gather into a mass or ball o Protein particles regroup larger more porous o Cultured Milk Products  Curd coagulated or thickened milk  Buttermilk  Yogurt  Acidophilus  Kefir  Sour cream o Yogurt

 Fermented semi-solid milk  Active yogurt cultures  Ingredients added to yogurt  Definition 8.25% MSNF and 0.5% Acid  Calorie content varies  Probiotics live beneficial bacteria  Prebiotics nondigestible food ingredients FOS support growth of probiotics o Cream and substances  Cream  Fat droplets  Top layer of nonhomogenized whole milk  18-36% milk fat  Cream substitutes  Whipped toppings  Coffee creamers  Dry mixes  Imitatioin sour cream  Milk products in food preparation : o Flavor changes  Bland slightly sweet flavor  Lactose  Salts  Sulfur compounds  SCFA  % fat  Mouthfeel and body  Influences  Heat  Sunlight  Oxidation  Copper  Equipment or utensils  Feed ingested by the source animal  Coagulation and precipitation  Heat  Acid  Enzymes  Polyphenolic compounds  Salts  Acid+milk  casein coagulates

 Milk also coagulates when combined with certain enzymes originating from animal, plant, or microbial sources  Rennin enzymes from inner lining of calf’s stomach sold commercially as rennet  Whipped milk products  Whipped cream o Fat content o Temperature o Age o Sugar o Whipping time  Whipped evaporated milk  Nonfat dry milk  Whipped foam  Structure o During whipping protein is mechanically stretched into think layers that trap:  Air bubbles  Fat particles  liquid  What happens when milk is heated: o  Nutrients found in milk: o  Whipped milk products: what factors influences the finished product? o  Storage guidelines for milk : o Refrigerate o Storage guidelines  Milk < or equal to 3 weeks  Yogurt 1 st^ 10 days or up to 3-4 weeks  Buttermilk 3-4 days or up to 3-4 weeks  Sour cream unopened up to 1 month best used within a few days upon opening o Dry storage  Nonfat dry milk- dry tightly closed containers ~ 1 year  Unopened evaporated and sweetened condensed milk up to 1 year in dry ventilated areas  double that if refrigerated  ultrapasteurized milk unopened at room temperature up to 3 months  stored at or alightly below room temperature

 72⁰F/22⁰C

 Once opened all must be refrigerated

Chapter 10- cheese

 Classification of cheeses: fresh, soft etc. (know examples) o Ways to classify:  Microbial characteristics  Appearance  Mode of packaging  Place of origin  Processing method  Milk source  Moisture content  Fresh country cheese >80% o Cottage o Cream o Ricotta  Soft 50-75% o Brie o Camembert o Hispanic cheeses  Semi-hard 40-50% o Roquefort o Blue o Muenster o Brick o Gouda  Hard 30-40% o Cheddar o Swiss  Very hard 30% o Parmesan o Romano  Basic steps for cheese production: milk selection, coagulation, curd treatment, curing ripening 9reall the text on all these) o Basic common steps  Milk selection

 Coagulation  Curd treatment  Curing  Ripening  10 # milk ~ 1 # cheese + 9 # whey o Milk selection greatest influence  U.S. pasteurized Cow’s Milk  Europe Middle East sheep or goat  Iran Afghanistan camel  Lapland reindeer  Mongolia horse  Philippines india Italy water buffalo  China Tibet yak zebu o Coagulation  Casein protein  Method  Determines  Characteristics  Two methods  Enzymes  Acid o Curd texture  Soft spongy  Influenced by pH  Solid and compact as acidity increases o Curd  Remove more whey  Cutting  Heating  Salting  Knitting optional  Pressing optional o Curing  Temperature and humidity control during aging o Ripening  Chemical and physical changes during curing o Whey and whey products  Low in fat  Rich in nutrients  Water soluble whey proteins  Lactose

 Water soluble vitamins minerals  Processed into  Whey cheeses  Modified whey products  Dry whey o Process processes cheeses  Patented James L. Kraft 1916  Processed cheese  Cold-pack cheese  Process cheese food  Process chese spread  Imitation cheese  Tofu o Food additives in cheese  Preserved food made from milk  Unprocessed typical ingredients  Process- processed- typical ingredients o Processed cheese  Blending 1 or more varieties of cheese, w/ or w/o heat, and mixing w/ other ingredients  Nutrient contet of cheeses  Food preparation with cheese: select the best cheese, and keep temperatures low and cooking times short  Storage of cheese: o Dry storage  Process cheese spreads o Refrigeration  Wrapped in original paper  Prevent drying and absorption of odors o Frozen  Gradually thaw  Not recommended for high-moisture cheese

Chapter 11- Eggs

 List ways eggs are used in food preparation  Composition of eggs:

o Structure:  Yolk 30% wt  Germinal Disc  Vitelline Membrane o Membrane surrounding egg yolk o Attached to Chalazae  Albumen 58% wt egg white  Chalaza pl. chalazae o Ropy twisted strands of albumen o Anchor yolk to center of thick egg white  Shell membranes  Inner outer  Air cell between 2 shell membranes  Shell 12% wt  Calcium carbonate  cuticle or bloom o waxy coating on eggshell o protects against  bacterial contamination and moisture loss  Functions of eggs in foods o Unique qualities of eggs  Flavor  Color  Emulsify  Thicken  Bind  Foam  Interfere  Clarify o Food preparation  Emulsify  Egg yolk  Lecithin  Thicken and stabilize o Salad dressings o Sauces o Mayonnaise  Binding  High preotein content  Foods dipped in egg white before battered  Binder in meatloaf meatballs lasagna

 Foaming  6-8 X original volume  Aerate and leaven o Puffy omelets o Soufflés o Angel food cake o Sponge cake o Meringues  Fresh eggs o Thick egg whites  Dry egg whites o Provide consistent results  Factors affecting foaming  Beating technique o Start slow o Gradually increasing speed  Testing for doneness o Observe peak formation  Avoid overwhipping o Prevent collapse and separation of foam  Temperature o Bowl  Deep bowl  Rounded bottom  Sloping sides  Avoid plastic bowls o Beaters o Eggs o Room temperatures  Separation of eggs o Egg yolk catins fat interferes w/ foam o Egg separators  Careful separation of egg white from yolk imperative  Do not pass egg back and forth between two shell halves  Sugar stabilizes foam o Inhibits mechanical coagulation o Add near end of beating  Fluid increase volume decrease stability  Salt decrease stability and volume o Rarely added

 Acid egg whites alkaline o Lower pH more stable foam  Interfering  Interfere w/ formation of ice crystals or large sugar crystals  Clarifying  Egg white protein attracts particles  Makes product clear and pure  Color  Golden brown from yolk  Nutrient content of eggs  Preparation of eggs: effects of time and temperature; dry heat methods and moist heat methods o Extremely versatile  Prepared alone or in compination  Dry- or moist-heat methods  Changes in prepared eggs  Effects of temperature and time o Keep temperature low o Cooking time short o Coagulation temperatures  Egg whites 140⁰F- 159⁰F (60⁰C-70⁰C)  Egg yolk 144⁰F-158⁰F (62⁰C-70⁰C) o Beaten eggs coagulate at slightly higher temperature ~ 156⁰F (69⁰C)  Effects of added ingredients  Color changes  DRY-HEAT PREPARATION  Frying o Fried eggs  Sunny-side up  Over easy  Over medium  Over hard o Scrambled o Omelets  Prime or season seal the pores of a pan’s metal surface w/ a layer of heated-on oil  Baking o Shirred  Whole eggs o Meringue

 Soft and hard  Egg white foam o Soufflé  Modified omelet  Thick base (white sauce or pastry cream)  Egg white foam  Flavoring ingredients  Stiffly beaten egg whites folded into thick egg yolk mixture  Weeping or syneresis escape of liquid to the bottom of a meringue formation of pores filled w/ liquid  Beading formation of tiny syrup droplets on the surface of a baked meringue  Moist-hear preparation  Variety of methods  “Boiled” o Hard or soft “boiled” methods  Hard-start  Soft 3-4 min  Medium 5-7 min  Hard 12-15 min  Cold-start  Soft 1 min  Medium 3-5 min  Hard 10 min  Coddled eggs o Prepared in a cup  Poached  Custards o Sweet and savory o Ingredients  Milk and/or cream  sweeteners  Sugar  Honey  Flavorings  Vanilla  Nutmeg  Etc.  Eggs or egg yolks o Preparation

 Stirred or baked o Sweet custards  Puddings or as fillings o Savory custard  Nonsweet quiches o Stirred custard  Soft custard or custard sauce  Ingredients stirred while heated o Baked custard  Poured into ungreased custard cups  Placed in the oven  Microwave o Eggs cook extremely rapidly o Special caution taken to avoid overcooking o Manufacturer’s instructions should be followed for microwave egg cooking o Whole eggs w/ intact shells  Never microwaved!!! o Steam expanding within shell can cause eggs to burst o Same principle applies to whole eggs out of the shell o Puncture egg yold w/ toothpick or tip of a knife prior to microwaving  In all cases, eggs are cooked at simmering temperatures  Storage methods for eggs; safety tips o Eggs deteriorate as soon as they are laid and lose quality rapidly at room temperature o An egg ages more in 1 day at room temperature than in 1 week refrigerated o To ensure freshness  Whole or liquid  Refrigerate  Freeze  Dry o Size of an egg’s air cell provides another indication of its age o Restaurants o Food service institutions o Other food manufacturers o Must be especially careful about storing eggs because large quantities are purchased o Storage eggs  Used w/I 1 month  Stored up to 6 months  Eggs treated w/ a light coat of oil or plastic  Stored in high humidity at low refrigerator

 Temperatures very close to egg’s freezing point 29⁰F-32⁰F (-1.5⁰C-0⁰C) o Frozen  Cannot freeze whole egg  It will crack under the expanding liquids  Food manufacturers break the eggs open at the processing plants where contents are frozen  Whole o Whites and yolk mixed  Separated o As whites or yolks o Dried  Drying eggs is a simple process  Whole eggs or separated yolks are spray-dried  Creat a fine powder which is mixed w/ anti-caking substances to prevent clumping o Egg whites  Granule, flake, or milled textures  Stored up to 1 year in refrigerator  Kept in tightly closed containers to prevent clumping that can result from moisture accumulation o Safety tips  Chances of an egg being internally contaminated are relatively low  <1 in 10,000 commercial eggs  More common for contamination to occur during handling and preparation after egg has been removed from its shell

Chapter 12- vegetables and legumes

 Composition of vegetables- read text p. 246-250 on parts, and pigments o Plant cell structure  Cell wall  Fibrous compounds indigestible by humans o Cellulose o Pectic compounds o Hemicelluloses o Lignin

o Gums o Humans  Lack the enzyme necessary to break down cellulose to glucose o Parenchyma cells  Cell type  Vegetables and fruits  Cytoplasm  Compounds for o Starch content o Color o Water volume o Flavor  Plastids  Storage organelles for substances, i.e., starch and pigments o Leucoplasts  Starch and water  Major digesticle portion o Chloroplasts  Chlorophyll essential for CHO synthesis  Green color o Chromoplasts  Carotene or xanthophylls pigments  Orange-yellow color  Vacuoles  Store water and other compounds  Turgor  Rigid firmness of plant cell resulting from being filled w/ water  Organic acids  Cell pH  Flavor and acidity  Parenchyma cells  Intercellular air spaces o Spaces between cells fill w/ air o Add volume and crispness  Closeness of cells o Textural differences in terms of crispness  Fruits and vegetables w/o air o Soft and flaccid o Plant pigments (3 major groups)  Carotenoids  Chlorophylls

 Carotenoids and chlorophylls- plastids  Fat soluble  Flavonoids  Water soluble  Lost in cooking water  Nutrient content of vegetables  Phytochemicals o Nonnutritive compounds  Possess health-protective benefits o Cruciferous  Indole- containing vegetables  Cross-shaped blossoms  Protective effect against cancer o Examples  Broccoli  Brussels sprouts  Cabbage  Cauliflower  Kale  Mustard greens  Rutabaga  Kohlrabi  turnips  What is most important consideration when selecting fresh vegetables? o Consider season of the year when selecting vegetables  Legumes: nutritional content, also read about soybeans o Beans o Peas o Lentils o Excellent sources of:  Fiber  Protein  Iron  Complex CHO o All legumes grow as seeds w/I a pod o Dietary staple since the bronze age o Soybeans  Relatively high PRO and fat  TVP  Meat analogs  Tofu

 Fermented soy  Textured vegetable protein  Meat analogs  Tofu  Fermented soybean foods  Miso  Natto  Sufu  Tempeh  tamari  General guidelines for preparation of vegetables p. 261 o Dry-heat  Baking  375⁰F (191⁰C)  Potatoes  Boiler or baker  Roasting  375⁰F-425⁰F (191⁰C-218⁰C)  Sprinkled w/ oil  Sautéing  Deep-frying o Moist-heat  Simmering  Vegetables ought not be boiled  Steaming  Foil-wrapped vegetables  Braising  Microwaving  Retain texture, color, nutrient content o Serving styles  Plain  Buttered  Creamed  Au gratin  Glazed  Scalloped  Stuffed  Soufflé  Omelet o Handling and preparation  Buying

 Freshest  Amount needed  Storage  Appropriate temp and humidity  Washing  All vegetables  Veggie wash  Cooking liquid  Small amount  Timing  Short as possible o Changes during heating  Texture  Starch felatinizes  Cellulose softens  Flavor  Degorge o Draw out bitter substances  Odor  Pleasant  Pungent- sulfur compounds  Color  Nutrient retention  Minimal water o Legumes  3 soak methods  Overnight  Short soak  No soak  Avoid hard water  Wait to add salt  Acid  Indigestible CHO  GI discomfort  Cooking methods: dry heat and moist heat  Storage guidline, and example of which vegetables should not be stored in refrigerator o Refrigerated  Cooler temperature important factor in reducing respiration rates  Fresh vegetables will last at least 3 days if refrigerated  Prevent moisture loss  Storage times for various vegetables based on the water content

o Special storage requirements  Bean sprouts  Cold water in refrigerator  Ginger root  Frozen or airtight container  Mushrooms  Paper bag or basket  Eggplant  Neither too hot nor cold  Asparagus  Store like flowers in water o Maintaining moisture  Store in refrigerator crisper  Plastic bags w/ tiny holes  Damp paper towels o Freezing  Fresh veggies blanched prior to freezing if frozen at all o Dry storage  Not stored in refrigerator  Tomatoes  Eggplants  Winter squash  Tubers  Dried legumes  Onions  Storing potatoes  Not in refrigerator  not exposed to sunlight  Room temperature a couple of weeks  Controlled-atmosphere storage  MAP  Edible coatings  Plastic-shrink wrap