Lab Exam 212

16 tablespoons=

1 cup

4 quarts=

1 gallon

28 grams=

1 ounce

2 cups=

1 pint

16 ounces=

1 pound

454 grams=

1 pound

4 cups=

1 quart

3 teaspoons =

1 tablespoon

What are the 2 main advantages of a short cooking time for fruits and vegetables?

1. A more flavorful fruit and veggie (taste and texture) 2. Minimize the loss of nutrients

Three basic leavening agents used in baking products:

1. Air 2. Steam 3. Carbon Dioxide

Name 4 ways to minimize enzymatic browning:

1. Applying certain types of food additives (antioxidants) 2. Lowering the pH 3. Adding certain solutions or syrup- glucose 4. Blanching

5 Primary Tastes

1. Sweet 2. Salty 3. Sour 4. Bitter 5. Umami (savory)

Essential Ingredients in yeast Bread (4)

1. Yeast 2. Flour 3. Liquid 4. Salt

5 1/3 tablespoons=

1/3 cup

4 tablespoons=

1/4 cup

Vegetable oil

100% fat Oil extracted from seeds

Shortening

100% fat. Hydrogenated vegetable oil

Optimum brewing temp for tea

185-203 F

1 kilogram=

2.2 pounds

Ideal temp range for deep frying

375 F 365-395F Higher for small pieces Lower for large pieces

Optimum brewing duration for tea

4 minutes

Most starches are about ____% amylopectin and ___% amylase

75% amylopectin 25% amylase

1 cup=

8 fluid ounces

Margarine composition

80% fat 16% water 4% milk solids

Butter composition

80% milk fat 16% water 4% milk solids

How does the temperature of whipping cream influence the quality of the foam? Why?

A cooler temperature results in a larger and more stable initial foam volume. The room temperature whipped cream was thicker and lumpier compared to the chilled whipping cream which was smooth and creamy. The temperature of the whipping cream influences the quality of the foam because of the high fat content. When the temperature is cooler, the fat is more solidified and stable making the foam smooth and creamy.

Describe a foam.

A foam is a collection of small bubbles formed on or in liquid. In a whipped foam structure, air bubbles are suspended in fat globules. The addition of air allows for 2-3x expansion.

What is cheese?

A gel of casein and mineral salts from which most of the whey has been removed.

What is rennet?

A mixture of enzymes found in animal's stomach. Very effective to coagulate CASEIN proteins. Casein is coagulated, whey is the liquid stuff.

Advantages and disadvantages: cooking with oil (in frying)

Advantage: has a higher smoke point than water Can provide a savory flavor, texture and appearance Disadvantage: can start a grease fire. Popping when steam leaves oil can cause harm.

Advantages and disadvantages: cooking with water (in frying)

Advantage: taste more of the food rather than the oil. Disadvantage: cannot get as hot as oil

Cookies that had the palest color

Air-bake. Best for sugar cookies.

Amylose

Alpha 1, 4-linkage Thicker

Amylopectin

Alpha 1, 4-linkage and Alpha 1, 6- linkage Not as thick

Sensory Characteristics

Appearance, flavor (taste and aroma), texture, mouthfeel

What was the effect of the coating on the appearance, flavor and mouth feel of the fried zucchini?

Appearance: dry, crispy Flavor: Salty, fatty Mouthfeel: crunchy

Describe a high quality muffin. How does amount of mixing influence muffin quality?

Appearance: top surface is rough and golden brown Shape: slightly crowned top, symmetrical in shape Interior: small air cells, all same size Tenderness: slight resistance to chew If over-mixing occurs: gluten forms, making muffins dense and unable to fully rise

Why does enzyme-coagulated curd have a different texture than acid-coagulated curd?

As acidity increases, the more "solid and compact" the cheese is.

Assuming the solution of ascorbic acid and vinegar have the same pH, which would you predict would be more effective in preventing browning? Why?

Ascorbic acid would be more effective because it is an antioxidant. Vinegar is not an antioxidant and will only prevent browning because of its acidic properties. Ascorbic acid destroys the oxidizer.

Chemical leaveners used in muffins and why

Baking powder, sugar and whole milk are used for a rapid rising and short preparation time

Compare the colors of the veggies cooked in acid and alkaline cooking water. Which are the predominant pigments in these veggies?

Baking soda (the base) made the veggies a dark color. Cream of tartar (the acid) made the veggies a bright/ vibrant color. Predominant pigment in red cabbage: anthocyanin Predominant pigment in carrots: carotenoid

What conditions are required for baking soda and baking powder to react and give off CO2

Baking soda combines with an acid to form the CO2. Baking powder produces an acid when in solution. Both need water. Baking soda needs and acid and water.

Brewing tea for too long can result in (describe taste and why)

Bitter taste due to extraction of large amounts of tannin

Which components of black tea contribute to the color?

Black leaves have been fermented (crushed, amber color)

What do cake and bread flour have in common? Differences?

Bread flour rises higher. Bread flour has double the protein- which is related to how much gluten can be formed. Gluten helps create structure and texture. Low protein content= less gluten. Cake flour has a higher percentage of starch- which absorbs more liquid. Moister more tender products.

Compare the muffins with the different types of flour. Which type was most affected by over-mixing. Why?

Bread flour rose highest. Gluten free rose the least. Whole wheat was most affected by over mixing due to its high protein profile.

NOT the ideal choice for deep frying

Butter & margarine They contain water and have a lower smoke point. Olive oil and sesame oil also both contain a little water so they are not ideal and they also have their own flavor when you might not want that.

Describe the color of veggies cooked with baking soda

Cabbage: turned dark green Carrots: turned dark, dull orange

Paper towel/ towel Fire

Can use water.

Paring Knife

Controlled peeling, slicing Ideal for: fruits, vegetables, designs

Cookies that had the brownest bottom

Cookies from the vary dark cookie sheet

Which starches had a stringy and cohesive gel paste

Corn

Starches high in amylose

Corn, wheat

Why is the curd cut in making cottage cheese? What is the liquid observed when the curd it cut?

Cottage cheese is made by adding an acid to pasteurized milk which causes a separation of the milk solids from the whey. After the curd is formed, cutting it into pieces allows additional whey to drain from the curds.

Cookies that were baked on the dark cookie sheet were..

Crisp, darker bottomed

What will the finished product be like if the dough is over-kneaded?

Dense bread because there is too much gluten and the gas cannot expand. Small volume.

What is dough-kneading, and what changes occur both microscopically and macroscopically?

Dough kneading is mixing the ingredients, forming gas cells and forming gluten. Microscopically, molecules are being kneaded together. Microscopically, dough is being formed.

Retrogradation

Extension of gelation process. Tightening of starches as cooling occurs.

What fats are best to use when deep frying? Why?

Fats that are 100% fat- shortening or vegetable. Not olive or sesame oil, because they are not 100% fat. Contain some water. Fats and oils reach higher temps than water and can be used to flavor.

Why is dough fermented and proofed? What is ideal fermentation temp?

Fermentation forms CO2, causing the dough to rise. Proofing is continuing fermentation, allowing the dough to rise and achieve a greater height /lightness. Proof box: optimal proof conditions. (temp, humidity) Optimal fermentation temp: 81-100 F. Temp too high: yeast killed, sour aftertaste Temp too light: not enough CO2 released

Self-rising Flour

Flour with baking powder and a little bit of salt already added.

Flavor and color of black tea

Full flavor, amber color

Yeast

Fungus. Reacts with sugars in the flour and release CO2 as waste. Usually add yeast to flours, sugar and some liquids. No yeast= thick dense blob.

What causes dough to rise?

Gas- leavening agents

Function of salt in yeast bread:

Has a stabilizing influence on yeast fermentation.

How do heat and acid affect the green chlorophyll molecule?

Heating causes them to turn a bright green, longer heating time turns olive/brown. Acid can split off he phytyl group to form cholorphyllin.

Function of liquid in yeast bread:

Hydrates proteins and starch. Essential for gluten development

Function of yeast in yeast bread:

Leaven the dough by producing CO2. CO2 is formed as the result of the fermentation of sugars naturally present in flour.

Cookies that were baked on the air-bake sheet were..

Light in color (pale), thin, soft center

How is energy transferred to foods fried in deep-fat?

Look at notes for picture. Stages: - moisture transfer - fat transfer - crust formation - Interior cooking Heat diffuses from the foods hot surface into its core through molecules and transfer their thermal energy. As the moisture (steam and volatile compounds) leaves the food, the deep-fried crust forms.

What will the finished product be like if the dough is under-kneaded?

Lower gluten production. The structure is less sound and the bread is more likely to collapse when gas expands and escapes.

Cheese coagulation

Milk + enzyme (rennet) --> Solid portion (cheese curd) Milk + acid --> Liquid portion (whey)

Baking Powder

Mixture of baking soda, cream of tartar and sometimes cornstarch. Used to generate CO2 and H2O. Double acting= contains two different types of acids that will react at different times. First reaction: gases created when liquid is mixed. Second reaction: gases created when exposed to heat.

Grease Fire

Most common. Use baking soda or powder to put out or put on the lid. NEVER use water. Can use fire extinguisher.

Describe the texture of veggies cooked with baking soda. Why is this so?

Mushy. Veggies get their firmness from acidity, and baking soda (a base) increases the pH.

Concept of chemical leavening= acid + base EQUATION IS:

NaHCO3 + H+ --> Na+ + H20 + CO2 H+ is from an acid. CO2 is released as a gas

Why do you not want to overmix

Over mixing will cause gluten to form.

Discuss the techniques used to prevent enzymatic browning . Which technique was most effective?

Pinapple juice, lemon juice, fruit fresh, sugar, ascorbic acid solution, cream of tartar solution, sucrose solution, plastic wrap. Lemon juice did best overall, it had the lowest pH.

Smoke point

Point at which fat or oil begins to smoke

Which starches had a clear gel paste

Potato and tapioca

Starches high in amylopectin

Potato, tapioca, waxy maize (100%)

Gelation occurring is dependent upon:

Presence of amylase

What gives flour its strength, and how can we obtain gluten?

Protein. Strong flour is high in protein and has a greater visco-elasticity. Strong flour also has a better ability to absorb water. We obtain gluten by kneading the dough-pressing the glutenin and gliadin molecules together.

Function of flour in yeast bread:

Provides the proteins from which gluten is developed. Contains sugars which ferment and form CO2.

What is the purpose of scalding the milk? What would be the result of adding the yeast to the scalded milk before cooling?

Purpose: to inactivate the enzymes and kill any bacteria. Scalding milk breaks down whey. Too hot milk can kill the yeast and stop the fermentation process.

Deep frying- how it works

Quickly cooked. Stages: - moisture transfer -fat transfer - crust formation -interior cooking

How did the characteristics of the reconstituted nonfat dry milk and the skim milk differ? Why was there a difference?

Reconstituted nonfat dry milk and skim milk are similar in the fact that they both contain 0 grams fat. The difference between the two is the sugar content. Skim milk has 4 grams of sugar in ⅓ cup, whereas the reconstituted nonfat dry milk has 6 grams of sugar in ⅓ cup. Sugar increases stability, so the reconstituted nonfat dry milk would be more stable than the skim milk.

How does salt affect yeast dough? What will the finished product be like if the salt is omitted? If too much salt is added?

Salt helps with flavor and firmness. Salt tightens the gluten network (stability) and improves texture. Omitting salt: fermentation would occur too quickly because salt helps control yeast growth. If there's too much salt: yeast activity is inhibited, reducing CO2 production and decreasing volume.

Why do you think zucchini was sliced in circles rather than in small cubes?

So it would cook faster and more evenly

Whys is active yeast sprinkled on water and allowed to sit before stirring? Why is sugar added to the water?

So yeast growth begins. When sugar is added, it serves as a food (energy) source for the yeast.

Baking Soda

Sodium bicarbonate- a base. Reacts with liquid and acidic ingredients to produce CO2. Makes batter nice and fluffy.

Cookies that were baked on the light cookie sheet were..

Soft, chewy, light golden

Gelation

Some starches experience this. Not all do. Formation of a 3-dimension starch network. (Solidification by cooling)

Leaveners used in quick breads

Steam, air, CO2, baking soda, baking powder, milk and sugar dissolve and the steam leavens the bread

What is the difference between stir-frying and oven frying? How would you expect these methods to affect the fat content as compared to deep-fat frying?

Stir frying generally minimizes the amount of fat absorbed by the foods. Oven fry seemed more oily than stir fry. Stir fry more tender.

Flavor and color of green tea

Subtle flavor, slightly bitter, pale yellow-green

Compare the cornbread prepared with and without sugar. What are the functions of sugar in this recipe?

Sugar slows down gluten development by absorbing H2O.

Which components of black tea contribute to the flavor?

Tannins and other flavor compounds. Influenced by brewing time and temp

Serrated Knife

Tears easily Ideal for: Breads/cakes

What causes the browning on the bottom of the saucepan?

The browning is the result of a maillard reaction. This reaction occurs when sugar combines with the protein in milk to give a light brown color due to scorching. The denatured proteins precipitate to the bottom of the pan and can cause scorching.

Gelatinization

The changes that occur when a starch is heated in the presence of water. ALWAYS happens. Starch granules increase in: volume viscosity translucency

What occurs during cheese curing and ripening process? How does the length of the curing period impact the flavor and cooking characteristics of cheese?

The cheese is aging during curing and ripening. The curd is developing flavor, aroma and texture. The curing exposes the cheese to controlled temp and humidity. Ripening changes the chemical and physical aspects during the curing period. It can take weeks to years. Big picture: Time influences flavor, aroma and texture.

Which milk components form the precipitate on the bottom of the saucepan?

The denatured whey proteins are the precipitate on the bottom of the pan. Applying heat to whey or serum proteins destabilizes the proteins by removing the water shell.

Compare the textural differences observed between apples cooked in water and apples cooked in a sugar solution.

The fruit heated in only water: water diffuses into the fruit to equalize the differing solute concentrations. The fruit tissues swell and burst, producing a soft, mushy texture. Fruit heated in sugar syrup:Water diffuses out of the tissues, producing a firm texture.

What occurs during the fermentation of yeast bread?

The generation of gas by yeast in the presence of water, ideal pH and food (sugar, for yeast) Can be done with or without oxygen

What was the pH of fresh whole milk? At what pH did thickening begin? At what pH was curd formation apparent?

The pH of the fresh whole milk was 6.71, making it slightly acidic. Thickening began at a pH of approximately 5.3. Curd formation becomes apparent at a pH around 4.6

Define/describe visco-elasticity

The property of a substance being both viscous and elastic. Applying stress causes temporary deformation as long as the stress is removed fast, but if the stress is maintained then the shape is permanently deformed. (think:flour)

Will heavy whipping cream, evaporated milk, or reconstituted nonfat milk solids result in a foam with the largest volume? Why?

The reconstituted non-fat milk will have the largest volume. This is because it contains no fat. Fat molecules stabilize foam by surrounding air bubbles and holding them in place, which results in a smaller volume because it doesn't allow for as much expansion. The absence of fat allows for a larger foam expansion. Another reason the NFMS produces the largest volume is because foam production creates a protein film surrounding all the air bubbles, allowing for expansion. Large volume is achieved in part because NFMS is a concentrated protein mixture.

When milk is heated, what milk components are found in the skin formed on the surface?

The skin is formed from the evaporation of water from the heated milk. The evaporation produces a concentration of casein, milk fat, and calcium and phosphate salts at the surface of the milk.

How does the stability of the whipping foams compare?

The stability of these foams depends on the fat content (the more fat the more stable), the temperature of the cream and of the equipment used (lower temperatures are more stable, fat globules are more dispersed at higher temp), the age of the cream (the older the more viscosity, more stable), the sugar content (increases stability), and the length of the whipping time (over whipping results in destabilization of fat globules). This means that the heavy whipping cream will be the most stable because of its high fat content. The NFMS will be the least stable due to the lack of fat. The evaporated milk has a fat content in between the other two, making it less stable than the heavy whipping cream but more stable than the NFMS.

What happens when sugar is added to a starch paste

The starch paste experiences a decrease in viscosity due to sugar's ability to tie up water

What is the purpose of an emulsifier?

To achieve the right consistency of a product. Allows liquids to be dispersed in another liquid with which it is usually immiscible.

Why is yeast dough kneaded

To mix the ingredients, form numerous gas cells and to develop gluten. (necessary for gas retention)

Electrical Fire

Unplug device. Smother flames with blanket. Can use fire extinguisher. No water.

Chef Knife

Versatile. Long blade, shapes vary. Ideal for: Meats, chopping vegetables, mincing, slicing

Which starches had an opaque gel paste

Wheat

Which protein in milk is most affected by heat? Which protein is most affected by acid?

Whey or serum proteins are greatly affected by the addition of heat. The heat removes the water shell, which destabilizes the protein. Casein proteins are greatly affected by the addition of acid. The casein molecule has a net negative charge, which is neutralized by adding the acid.

Explain the differences between whole milk, evaporated milk, condensed milk, and buttermilk.

Whole milk - full fat fresh milk. Evaporated milk - fresh fluid milk where 50% of the water has evaporated. Condensed milk - concentrated milk product. The same as evaporated milk but also contains 44% sucrose added to it. "Real buttermilk" - liquid remaining when cream is churned and the resulting butter is removed. Commercial buttermilk - produced by adding a bacterial culture to fluid milk which converts some of the milk's lactose to lactic acid.

Which starch pastes formed a gel at 32 F

Whole wear and all purpose flour

Equation of fermentation for yeast bread WITH oxygen:

yeast + 6O2 + C6H12O6 -----> 6CO2(gas) + 6H20 oxygen glucose carbon dioxide water * more gas is produced compared to fermentation without oxygen

Equation of fermentation for yeast bread WITH OUT oxygen:

yeast + C6H12O6 -----> 2C2H5OH + 2CO2 (gas) glucose ethanol carbon dioxide * yeast fermenation without oxygen generates alcohol