Unemployment in the states, II Refer to the previous exercise. Th e December 2000 unemployment rates for the 50 states had a symmetric, singlepeaked distribution with a mean of 3.47% and a standard deviation of about 1%. Th e unemployment rate for Illinois that month was 4.5%. Th ere were 42 states with lower unemployment rates than Illinois. (a) Write a sentence comparing the actual rates of unemployment in Illinois in December 2000 and September 2008. (b) Compare the percentiles for the Illinois unemployment rate in these same two months in a sentence or two. (c) Compare the z-scores for the Illinois unemployment rate in these same two months in a sentence or two.
Exam Date: 4/12/16 NHM 253 Exam 3 - Baking Science Ingredients Involved in Baking Flour provides structure due to starch and protein content • Leavening agent gives rise to baked products • •increases volume of baked goods increases temperature of gelatinization (which gives the gases more • time to expand and allows the product to rise more) Sugar •food for yeast •contributes to moistness and tenderness •aids in browning reactions •enhances ﬂavor/mouthfeel Fat •increases volume and strength •contributes to richness and moisture •aids in tenderization by shortening gluten strands Liquid •serves as a dispersing agent (helps ingredients to combine) •Salt • develops ﬂavor Flavor additives • strengthens gluten network (frees sulfur atoms, allowing them to cross link) • slows yeast activity • preservative • Milling of Flour 1. Kernels are cracked by rollers. 2. Bran and germ are removed via shifting and separation. 3. Remaining endosperm is ground into ﬂour. • Flour - The protein content of ﬂour is the most important. - Starch is responsible for absorbing moisture during baking and providing structure. • Gelatinization - the disruption of starch’s molecular structure which allows starch to absorb water in the presence of heat 1 Exam Date: 4/12/16 - Glutenin and gliadin are ﬂour proteins that are responsible for forming a gluten network (a tough, rubbery network of water held in coiled proteins). • The gluten network gives rise to breads, enabling the dough to retain trapped gases. This is what provides the structure and texture of baked goods. Gluten-forming proteins are present in ﬂour but gluten is not formed until: • - water is added (hydration step) - mixture is stirred (manipulation step) • Keys to Controlling Gluten - type of ﬂour (content of glutenin and gliadin) - amount of water - amount and dispersion of fat • Fat coats the ﬂour particles and makes it difﬁcult for the water to interact with the ﬂour. - mixing/manipulation of dough/batter - acidic ingredients • Acidic ingredients break disulﬁde bonds in gluten. - Flour that has a high protein content forms a strong gluten network, yielding more dense products like bagels. - Flour that has a low protein content forms a weak gluten network. - More on Flour… • Refrigeration does extend shelf life, but it may cause the ﬂour to take on moisture or odors. • Specialty Flours - whole what - self-rising (contains salt and baking powder) - composite (mixture of wheat and non-wheat) - non gluten ﬂours (corn, rice, soy, peanut) 2 Exam Date: 4/12/16 • Flour is predominantly starch and it contains a smaller amount of protein and an even smaller amount of fat. • Enriched ﬂour contains thiamin, riboﬂavin, niacin, iron, and folate. • Flour is treated with potassium bromate or chlorine dioxide to speed up the aging process. - Potassium bromate is a potential carcinogen but it is not carcinogenic at the level it is used in the aging process. Leavening Agents - give rise to baked goods by producing gases that expand upon • heating and get trapped in the gluten network. Categories of Leavening Agents Physical • air and steam (part of every baking process) Biological • yeast and bacteria Chemical baking powder and baking soda • - Leavened Breads • Quick bread - leavened with air, steam, and/or carbon dioxide • Yeast bread - leavened by yeast respiration (which produces carbon dioxide) - Carbon dioxide is the greatest leavener. • Dough vs. Batter - Batter has a higher water content and gluten formation is minimal. - Dough has a lower water content. • The role of chemical leaveners is to release carbon dioxide through reactions between acids and bases in the presence of a liquid. 3 Exam Date: 4/12/16 Baking Soda Baking Powder • Alkaline/basic • Contains both an acid and a base (complete leavening agent) • The base involved is baking soda and the acid is cream of tartar • Releases carbon dioxide in the presence of acid • Releases carbon dioxide twice (double acting) and moisture • Carbon dioxide is released when: • Common acids include: • exposed to water buttermilk exposed to heat • • • sour cream • lemon juice • honey, molasses, fruit • Once incorporated, the recipe should be baked • Because carbon dioxide is released twice (the immediately because it will only release carbon second time being in the presence of heat) the dioxide once. recipe does not need to be baked immediately. - Recipe development: If a recipe contains an acidic ingredient, use baking soda. If it does not contain an acidic ingredient, use baking powder. Sometimes, it will be necessary to use both baking soda and baking powder to achieve the desired texture of an acid-containing recipe. • Retrogradation - seepage of water out of an aged gel - This is how baked products become stale. - The product is dried out and the moisture that has seeped out allows for microbial growth. 4 Exam Date: 4/12/16 Classifying Ingredients According to Function Tougheners- protein-rich ingredients that provide • ﬂour structure and strength to the ﬁnal product • eggs • milk Tenderizers - interfere with gluten formation • fats • acidic ingredients Moisteners - necessary for gluten formation and • liquids (water, milk, egg) starch gelatinization Drying agents - absorb moisture • any dry ingredients • baking soda Leavening agents • baking powder • yeast • salt Flavoring agents • chocolate • nuts • anything Fate of Ingredients in the Baking Process Gases trapped by gluten network and expand Starches hydrate, gelatinize, and stale (retrograde) Proteins provide structure and texture by forming gluten network Fats melt to form pockets where gases collect and expand Water evaporates, forming steam that becomes trapped in the gluten network Sugars carmelization **Large tunnels within a baked product are a result of over-manipulation. - Dairy Science • Composition of Milk - The majority of milk is water. - Protein is the most important component of milk (makes up 3.4% of milk). - Lactose intolerance is an absence of the enzyme lactase (breaks down the sugar lactose). • Milk Proteins - Casein - responsible for coagulation/thick texture 5 Exam Date: 4/12/16 • forms curd (semi-solid product of milk coagulation) • 80% of protein in milk - Whey - liquid portion that remains after cheese production • processed into protein powder • 18% of protein in milk • More about milk… - Fortiﬁcation - adding something to a processed product that was not present in the raw form • vitamin D (aids in calcium absorption) • vitamin A - rBGH (recombinant bovine growth hormone) - a hormone given to dairy cattle to make them produce 10% more milk • It is not considered a food additive by the FDA because it is not added to the milk, it is given to the cattle. • Steroid use is not permitted for dairy cattle but it is permitted for cattle raised for meat. • Cows that produce organic milk do not receive rBGH. - There is a potential relationship between added hormones and early maturation in humans. But the amount of rBGH in milk is ver small. - Probiotics - live microorganisms that live in the gut and are beneﬁcial to the health of the gut These helpful bacteria inhibit the growth of harmful bacteria. • • Prebiotics - food for probiotics • common probiotics: Lactobacillus and Biﬁdobacterium • Probiotics are added to dairy products and delivered to the intestine. 6 Exam Date: 4/12/16 Milk Processing Homogenization Pasteurization • the process of dispersing fat globules by • the process of heating milk to destroy pathogenic reducing their size, preventing them from bacteria clumping and rising to the surface as a layer of cream purpose: quality purpose: safety • • • no effect on nutritional value • minimal impact on nutritional value and ﬂavor • creamier texture and more consistent mouthfeel • proteins are broken down from quaternary to tertiary structure • How to test that pasteurization was successful: test for the presence of the enzyme alkaline phosphatase. If the enzyme is not present, pasteurization was successful. • Ultra High Temperature Pasteurized Milk - nearly sterile - does not have to be refrigerated/has a longer shelf-life - does not make chess as well as normally pasteurized milk • Proteins: Precipitation and Coagulation - pH of milk: 6.6 (very close to neutral) - 3 ways to cause casein and whey to separate: • addition of a food-grade acid addition of enzymes that cleave the proteins apart • addition of bacteria (Lactobacillus produces lactic acid) • - Cheese Production • Coagulation (curdling/curding) - the grouping of casein after the addition of acids or enzymes - examples of enzymes: • rennin pepsin • • Curd Processing 7 Exam Date: 4/12/16 Aging • - Cheeses are aged from 4 weeks to 4 years. • The longer the aging process, the more distinct the ﬂavor and the harder the texture. - Curing - impacts texture/dehydrates the cheese - Ripening - relies on lipases, proteases (break down proteins) • impacts ﬂavor (because of smaller lipids and proteins) - Bacteria and mold can also be added. Enzyme vs. Acid Coagulation Enzymes Acid • Enzymes cleave casein from whey. • Causes calcium to ionize and stay with the whey • Calcium is retained, allowing for a ﬁrmer textureprotein •ex. cheddar and parmesan • Results in a softer curd •nutritionally superior because of calcium • ex. mozzarella and cottage cheese Classifying Cheese by Moisture Content • - Fresh - > 80% moisture cottage cheese, cream cheese, ricotta • - Soft - 50-75% moisture • brie, camembert - Semi-hard - 40-50% moisture • cheddar, monterrey jack, provolone - Hard - 30-40% moisture • parmesan, asiago - Very hard - 30% moisture - As a product decreases in moisture, it increases in shelf life. • Processed Cheese 8 Exam Date: 4/12/16 - longer shelf-life - no more than 43% moisture - at lease 47% fat - Egg Chemistry Anatomy of an Egg • composed of calcium carbonate • porous, allowing for the exchange of gas with the environment Shell • Color is NOT an indicator of quality. • protected by cuticle/bloom (slows release of gases and water, increasing shelf-life) Shell membranes • 2 layers of membranes that adhere to the inside of the shell • slow the release of gases and moisture • composed of lipids, cholesterol, lecithin (emulsiﬁer), vitamin A Yolk • Color intensity depends on the diet of the hen. • Beneﬁcial additives can be added to increase color intensity (beta carotene). • pocket of air at the larger end of the egg Air cell • As eggs age, the air cell increases in size because gases and moisture are lost through the shell so the white and yolk lose volume. • purpose: shock absorption Albumin (egg white) • composed of protein, water, B vitamins, antimicrobial compounds • USDA Egg Grades - AA, A, B - Albumin index -a measure of the height to width ratio of the albumin when the egg is broken onto a ﬂat surface • Younger eggs have a higher amount of water, so they have a higher albumin and a higher yolk. The egg is destroyed during testing. • - Candling - intact eggs are viewed over a light source • Is the cell broken • How big is the air cell size • Is the yolk in the center of the egg 9 Exam Date: 4/12/16 • Are there blood spots • This is the best process for grading eggs. • Inﬂuence of Time on an Egg - Shrinkage - air cell enlarges as yolk and albumin lose moisture and gases - pH increases - carbon dioxide (acidic) is released from the egg - Liqueﬁcation - whites thin as albumin proteins break down, yolks ﬂatten and enlarge • Egg Safety - Eggs are considered a potential hazardous food due to their high protein and water content. - Bacteria of concern: Salmonella and Listeria - The inside of the egg is sterile, but bacteria can accumulate on the shell and contaminate the egg once it has been cracked open. This is why it is important to cook eggs to a safe temperature (160° F). • Whole eggs are often irradiated to destroy bacteria on the shell. - Liquid eggs are pasteurized. • Iron Sulﬁde (Green Egg Syndrome) - Upon exposure to high heat for prolonged time, the sulfur in the egg whites reacts with the iron in the yolk to form iron sulﬁde. A green ring around the yolk is an indication of overcooking. • Egg Substitutes - Complete egg substitute - made from soy or milk proteins - Albumin-based egg substitute - still contains part of the egg - Egg Substitute Composition • Vegetable oil replaces the fat of the egg yolk (fat content is still low) • Beta carotene is added for color. • Proteins to replace albumin proteins. • Functions of Eggs 10 Exam Date: 4/12/16 - emulsiﬁcation • An emulsifying agent is an amphiphilic (has both polar and nonpolar components) molecule that allows 2 immiscible (un-mixable) liquids to mix. - thickening and coagulation - binding and coating - foaming - color 11