Understanding Food Chapter 12: Cheese

Classification of Cheeses They can be defined by their: Microbial characteristics Appearance Mode of packaging Place of origin The most common ways of classifying cheeses are by the: Processing method Milk source (cow, sheep, goat, etc.) Moisture content The most common ways of classifying cheeses are by the: Processing method Milk source (cow, sheep, goat, etc.) Moisture content

Classification of Cheeses Cheeses classified according to their moisture content: Fresh. Moisture content is over 80%, and they are not aged. Soft. Water content ranges from 50 to 75% and are aged for just a short time.. Semi-hard. 40 to 50% moisture. Hard. The moisture content ranges from 30 to 40%. Cheddar and Swiss are examples. Very hard. Water content of approximately 30% and are aged the longest.. Fresh They include cottage cheese, cream cheese, ricotta, farmer’s, pot, and feta cheeses. Soft Cheeses like Brie, Camembert, and many Hispanic cheeses Semi hard Examples are Roquefort, blue, Muenster… Very hard Parmesan and Romano are classified among the hardest cheeses

Cheese Production No two cheese varieties are produced by exactly the same method, but the basic steps common to them all include: Milk selection Coagulation Curd treatment Curing Ripening The yield from 10 pounds of milk is approximately 1 pound of cheese and 9 pounds of whey.

Cheese Production Milk selection has the greatest influence on classification of cheese. Any mammal’s milk can be made into cheese. U.S.: pasteurized cow’s milk Europe and the Middle East: sheep’s or goat’s milk Iran and Afghanistan: camel Lapland: reindeer Mongolia: horse Philippines , India, and Italy: water buffalo China and Tibet: yak and zebu

Cheese Production Cheese-making starts with the coagulation of the casein protein in milk. The type of method used determines many of the characteristics of the resulting cheese. The two main methods to aid coagulation are the action of: Enzymes Acid

Cheese Production The curd produced by acid has a soft and spongy texture. This texture is influenced by pH, becoming more solid and compact as the acidity increases.

Cheese Production The curd may be treated to remove more whey by: Cutting Heating Salting Further optional treatment includes knitting and/or pressing

Cheese Production Curing: To expose cheese to controlled temperature and humidity during aging. Ripening: The chemical and physical changes that occur during the curing period.

Cheese Production Processed cheese: A cheese made from blending one or more varieties of cheese, with or without heat, and mixing it with other ingredients.

Purchasing Cheese Grading USDA-defined U.S. Grades AA, A, B, and C. Graded cheeses are evaluated based on their: Variety Flavor Texture Finish Color Appearance Exceptions to these criteria are: Colby cheese, in which color is not considered. Swiss cheese, which is graded additionally for its salt level and eyes (holes). Graded cheeses are evaluated based on their: Variety Flavor Texture Finish Color Appearance

Food Preparation with Cheese Cheese is most often used as an ingredient to add: Flavor Color Texture …in a variety of ways—on pizza, in a taco, etc. The two most important principles when preparing foods with cheese are: Select the best cheese. Keep temperatures low and heating times short.

Food Preparation with Cheese Selecting a Cheese The chemical composition of a cheese determines its functional properties and dictates how it will be used in food preparation. Some of these functional properties include: Shredability Meltability Oiling off Blistering Browning Strechability

Storage of Cheese Cheese must be stored properly to prevent deterioration. Most cheeses should be refrigerated. Some can even be frozen. Processed cheese products can be stored in a cool, preferably dark, cupboard until ready for use... Though refrigeration more effectively retains desirable qualities.

Understanding Food Chapter 13: Eggs

Composition of Eggs Just a few examples of how eggs are used in food preparation: Structure Thickening Color Emulsifying Leavening Binding Coating Glazing Clarifying Giving a foam structure to cakes and meringues Thickening custards and puddings Adding color to lemon meringue pie and eggnog Emulsifying mayonnaise and hollandaise sauce Leavening soufflés and popovers Binding ingredients in meatloafs and casseroles Coating foods prior to breading Glazing pastries and breads Clarifying liquids for soups

Composition of Eggs The egg has five major components: Yolk Albumen (egg white) Shell membranes Air cell Shell Each of these plays an important role in the egg’s unique attributes that make it invaluable in food preparation.

Composition of Eggs Chalaza (pl. chalazae): The ropy, twisted strands of albumen that anchor the yolk to the center of the thick egg white. Vitelline membrane: The membrane surrounding the egg yolk and attached to the chalazae. Cuticle (bloom): A waxy coating on an eggshell that seals the pores from bacterial contamination and moisture loss.

Composition of Eggs

Purchasing Eggs Inspection The Egg Products Inspection Act of 1970 requires that egg processing plants be inspected and that their eggs and egg products be: Wholesome Unadulterated Truthfully labeled This law is enforced by the USDA Poultry Division and applies to all eggs, whether imported or shipped intra- or interstate.

Purchasing Eggs Grading The best-quality eggs are graded USDA Grade AA, followed by USDA Grade A. USDA Grade B, the lowest grade. The grades sold at supermarkets. Available to food service establishments and not sold directly to consumers.

Purchasing Eggs Candling: A method of determining egg quality based on observing eggs against a light.

Purchasing Eggs Haugh Units The freshness of an egg can be detected by cracking it open onto a flat surface and looking at the height of its thick albumen. Fresh egg whites sit up tall and firm, while older ones tend to spread out.

Purchasing Eggs Sizing is not related to grading in any way. Eggs are sold in cartons by various sizes determined by a minimum weight for a dozen eggs in their shell.

Purchasing Eggs

Functions of Eggs in Foods Eggs are often combined with other ingredients. Their unique ability to: Flavor Color Emulsify Thicken Bind Foam Interfere Clarify …makes them nearly indispensable in cooking. Foam- beating causes egg whites to denature (unfold). When they rearrange around air cells foam structure is created. During heat, cells expand and set when protein is coagulated. Interfering – interfere with formation of ice crystals in frozen desserts. Smoother texture Clarify- egg proteins (whites primarily) in clold liquid and then heated causes the proteins to solidify, attract other particles that may be clouding the liquid and to rise with them to the surface for removal. Done in soups.

Increased time of coagulation with dilution (milk)- increases volume, dec stability Sugar – increased temp of coagulation add near end very fine texture Acid- decreased temp of coagulation Mech beating – coagulates protein (beaten egg whites) Temp – whites best at room temperature Beater- wire whisk, rotary beater, or electric. Hand beater best quality, electric fastest Container- avoid plastic (hard to remove fat) Salt – decreases stability Sugar inhibits denaturization, stable, smooth, inc beating, very fine texture Cr of tartar- delays, aids in stabilizing Fat- retards formation Soft – shiny, tips bend, slips in bowl Stiff- won’t slip in bowl, stands up Dry- volume starts to decrease, looks dry Weeping due to failure to denature protein Beading due to over baking

Functions of Eggs in Foods Clarify: To make or become clear or pure.

Preparation of Eggs Changes in Prepared Eggs The key to cooking eggs is to keep the temperature low and/or the cooking time short. Egg whites and yolks coagulate at different temperatures. Adding other ingredients to eggs changes their coagulation temperature. Undesirable color changes may occur during egg preparation Factors of Coagulation Temperature Whites - 140-149 F Yolks - 149-158 F Coagulation- clumping together of partially denatured proteins Physical change in proteins Form gel network Slow rate at low temp, faster at high temp

Preparation of Eggs Dry-heat preparation of eggs primarily involves frying and baking. Egg dishes that are commonly fried are fried eggs, scrambled eggs, and omelets. Prime (season): To seal the pores of a pan’s metal surface with a layer of heated-on oil. Baked egg dishes include shirred eggs, meringues (both soft and hard), and soufflés. Weeping (syneresis): The escape of liquid to the bottom of a meringue or the formation of pores filled with liquid. Beading :The formation of tiny syrup droplets on the surface of a baked meringue.

Preparation of Eggs Moist-Heat Preparation Eggs can be prepared by moist heat using a variety of methods. Most common among these are: “Boiled” eggs Coddled eggs prepared in a cup Poached eggs A variety of custards Eggs that are prepared using the microwave In all cases, eggs are cooked at simmering temperatures.

Preparation of Eggs Hard or Soft “Boiled” Hot-Start Method: Soft: 3 to 4 minutes Medium: 5 to 7 minutes Hard: 12 to 15 minutes Cold-Start Method: Soft: 1 minute Medium: 3 to 5 minutes Hard: 10 minutes

Preparation of Eggs Microwaving Eggs cook extremely rapidly in a microwave oven. Special caution should be taken to avoid overcooking. Manufacturer’s instructions should be followed for microwave egg cooking. Whole eggs with intact shells should never be microwaved. Steam expanding within the shell can cause them to burst. The same principle applies to whole eggs out of the shell. Egg yolks will burst if not punctured with a toothpick or the tip of a knife prior to going into the microwave.

Storage of Eggs Eggs begin to deteriorate as soon as they are laid and lose quality very rapidly at room temperature. An egg will age more in one day at room temperature than in one week in the refrigerator. To ensure the freshness of whole or liquid eggs, they may be: Refrigerated Frozen Dried Use eggs promptly-3-5 wks hard cooked - 1 week leftover yolk & whites - 4 days Freeze for longer use - 1 y Handle safely wash hands, utensils, equip & work area before and after contact with eggs

Storage of Eggs The size of an egg’s air cell provides another indication of its age.

Storage of Eggs Frozen Freezing a whole egg is not possible because it will crack under the expanding liquids. Food manufacturers solve this dilemma by breaking the eggs open at the processing plants where the contents are frozen Whole (whites and yolk mixed together) Separated as whites or yolks

Storage of Eggs Safety Tips The chances of an egg being internally contaminated are relatively low, less than one in 10,000 commercial eggs. It is more common for contamination to occur during handling and preparation after the egg has been removed from its shell. Avoid eating soft-cooked or runny eggs Use safe egg recipes - 160 F USDA – “potentially hazardous food” About 80% of cases from raw or undercooked eggs (cook whites till done and yolks start to thicken to be safe) 1 day at room temp = 1 week in the fridge Shell is covered with organic material that prevents invasion of microorganisms. Wash just prior to use if dirty.