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Identify three factors that influence the melting point of a fatty acid and describe the effect of each factor.
a. Length of carbon chain: Short chain fatty acids lower melting points. long chain fatty acids are more likely to be solid at mixing temperatures. When fats are hard we have a high melting point
b. Degree of saturation: Saturated fatty acids have higher melting points. The higher the degree of unsaturation (more double bonds in fatty acids) lower melting points.
c. Cis and trans: If double bond is in the cis form melting point is lower than when double bond is the trans form.
Why is the crystalline form of a fat important in making shortened cakes?
Finer fat crystals produce shortened cakes with finer texture.
Is the crystalline form of a fat of concern when selecting a fat for frying? Explain
No because the crystals melt when heated for deep-fat frying.
Carefully describe the development of oxidative rancidity and of hydrolytic rancidity. Be sure to include chemical formulas and reactions to clarify each of the processes.
Describe chemically the degradative changes that an oil undergoes when it is being used for frying over an extended period of time.
T/F olive oil has more polyunsaturated fatty acids than lard does?
T/F a short chain fatty acid has a higher melting point than one with long chain
T/F a double bond raises the melting point of a fatty acid
T/F a solid fat with beta crystals gives better results in cakes than one with beta prime crystals
T/F when a molecule of acrolein is formed, one molecule of water is formed
T/F oxidative rancidity is accelerated by the presence of some water
T/F hydrolytic rancidity requires oxygen
T/F frying a potato can cause the formation of acrylamide
T/F oxidative rancidity occurs at the ester linkage between glycerol and a fatty acid.
Explain the winterizing of oils. Why is this an important step in processing salad oils?
Winterized salad oils can be used in salad dressings that are stored in the refrigerator without crystallization. This step is a refining step in which oils are chilled carefully to precipitate and remove fractions with high melting points that would interfere with the flow properties of salad dressings or other products containing oils.
What is the purpose of tempering a fat? How is this accomplished?
Tempering is a process in which temperature is carefully controlled by removing the heat as it Is released when liquid fats crystallize. The fat is being held at a specific temperature for the time required for the crystals to form and to stabilize in the flavored crystal form. Tempered fats can be stored with some variations in temperature, sometimes more than 25 degrees Celsius, and still retain their textured qualities.
Describe the process of (a) hydrogenation and (b) interesterifcation
a. Hydrogenation addition of hydrogen to an unsaturated fatty acid in the presence of a catalyst to reduce the unsaturation of the molecule and raise the melting point.
b. Interesterification treatment of a fat, usually lard, with sodium methoxide or another agent to split fatty acids from glycerol and then to reorganize them on glycerol to form different fat molecules with less tendency to form coarse crystals
Why may interesterification be preferred to hydrogenation in the manufacturing margarine?
Unsaturated fatty acids do not add hydrogen during interesterification, which may be desirable for nutritional reasons.
Name and write the chemical structures of two fatty acids
a. Docosahexanoic acid (DHA)
b. Eicosapentanoic acid (EPA)
Why may oryzanols and tocotrienols be of potential nutritional interest? Identify a food source of these compounds.
a. Because it contains two types of sterols and have high antioxidant purposes
b. Rice bran and palm oil
What is a possible mechanism for a fat or oil in tenderizing a baked product?
Interfering with water interacting easily during gluten development.
What can be done to minimize the absorption of fat in frying foods?
Maintain fat at correct frying temperature, control amount of food being fried at a time so fat stays hot, fry food just until done, and drain on absorbent paper towels.
Identify an example of each of the following types of fat replacements: protein based, carbohydrate based, and fat based
a. Protein based: simplesse
b. Carbohydrate based: N-lite, stellar, splendid, oatrim, rice* trin 3 complete, avicel, litesse, paselli excel, kelcogel, olestra
c. Fat based: Olean, caprenin, benefit, olestra
T/F equal weights of butter and shortening contain the same amount of fat.
T/F olive oil is pressed from the seed of olives.
T/F winterizing is done to remove fatty acids with high melting points
T/F tempering is done to control crystal size in shortening.
T/F shortening power is a term used to describe the role of fats in cakes
T/F lecithin is effective as a shortening agent in making pastry
What are the two major categories of proteins in muscles? Identify and briefly describe at least three proteins in each category.
a. Myosin: principal protein, long thin molecule
b. Actin: myofibrillar protein existing primarily in two form (F(long) G(smaller))
c. Tropomyosin: very small least abundant of the three principal myofibrillar proteins
Name and describe four types of proteins in connective tissue
c. Pyrrolidine ring:
Describe the chemistry of collagen in some detail, being sure to discuss its unique amino acid composition.
Is of importance in meats because it is the fibrous protein found in structural sheaths both within and between muscles. It is rather complex protein that contains strands of tropocollagen, which are produced by the cells and then transferred to the ground substance for actual integration into molecules of collagen.
Explain the organization of a muscle, beginning with the composition of myofilaments
Begins with the association of protein molecules into myofilaments
Describe the chemical changes and the resulting color shifts that occur when myoglobin is subjected to different conditions.
myoglobin and hemoglobin are closely related cjemically, for they both are iron containing pigments with heme as the common component. They differ only in their protein component. Myoglobin has only one strand of protein polymer and a molecular weight of about 17,000. Myoglobin has a purplish-red pigment consisting of heme-containing ferrous iron and a polypeptide polymer (globin).
Why is cured meat different color than uncured meat?
What changes occur in the carcass after slaughter?
Describe the changes that occur in meats when heated.
Fat melts and proteins are denatured when meats are heated.
Muscle fibers undergo changes in dimension as a result of heating. shrinkage.
Other changes in muscle ensue.cracking in the I bands.
Muscle proteins in meat become less tender when heated.
Connective tissue needs to be considered for tenderness. elastin not modified. collagen molecules slowly change in moist heat
Conversion of collagen to gelatin has a considerable effect on the tenderness
What are the effects of extending ground meats with textured soy protein?
By mixing textured soy protein with ground meats, a given quantity of meats can serve an increased number of people an reduce the food cost. The comparatively low cost of soy protein contrasted with beef makes the use of textured soy protein as an extender attractive when beef prices are high. The water binding capability of textured soy protein and other soy products enhance the juiciness in part because of the water content. higher fat content in this when the textured soy protein is added
What is surimi and how is it used?
Purified and frozen minced fish containing a preservative, intermediate seafood product used in making structured seafood products. It is washed thoroughly to eliminate fat, pigments, and other compounds that would present flavor and storage problems during frozen storage
How does the chemical nature of gelatin influence its physical behavior in food preparation?
When gelatin is used in food prep the first step is to convert it from a firm, friable substance to one that is soft and pliable. The elongated gelatin molecules have many polar groups exposed, making it possible for water to be bound by hydrogen bonds at many points along each molecule. As water is bound the gelatin swells. The swelling of gelatin when it is absorbs water is influenced by the pH and the presence of salts. Swelling is bimodal in that it is less at its isoelectric point.
What factors influence the temperature at which gelatin mixtures from gels?
It is influenced by the rate of cooling. The temperature of gelation will be lower is the sol is cooled rapidly by adding ice to the dispersed gelatin or by packing the bowl containing the sol in ice than if the gel is cooked slowly at refrigerator temperature.
T/F dry heat meat cookery tenderizes meat.
T/F beef cuts from the loin are best when prepared using a moist heat method.
What are the merits and disadvantages of whole-wheat flour in baked products?
The nutritive value of whole-wheat flour is somewhat higher than refined flour, and it adds a slight color and coarser texture, characteristics that some consider assets and some do not. The gluten strands are shortened a bit because sharp bran particles cut some of them during mixing.
Describe the milling process and explain how the streams used in making various flours influence the characteristics of the resulting flours.
Flour production involves grinding and refining cereal grains by a process called milling. basic objective is to produce a comparatively fine powder consisting of some portion or almost all of the grain, depending on specific product desired. Milling begins with whole grains of wheat (or other cereals) which first subjected to a brief tempering treatment with steam to ease removal of outer bran layers. The one variety of wheat (or other grain) may be blended together and any unsound grains removed.
Identify the three overall categories of proteins in flour. What proteins are included in each category? What is the contribution of each category to baked products?
The three overall proteins in flour include
Describe both fractions of protein constituting gluten and explain how each contributes to the behavior of gluten in batters and doughs.
How many flours from cereals other than wheat be used in baked products? Why might there be an advantage in including triticale flour, cornmeal, rye flour, soy flour, or potato flour?
Realistically none of them really have ideal advantages because the wheat flour is the only one that contains the gluten and can give the adequate texture desired for breads and such.
Briefly explain the roles of each of the following in baked products: flour, liquid, eggs, fats, sugar, salt, and leavening agents
Liquid: Gluten development, Dissolve sugar, Dissolve baking powder to activate it, Starch gelatinization, Steam for some leavening, Some liquid
Eggs: Protein structure
Fats: Flavor, Tenderness, Influence texture, color
Sugar: Flavor, Color-maillard browning, Tenderness
Volume, Food for yeast in yeast-containing products
Salt: Flavor, Limit yeast growth
Leavening agent: Volume
Compare the effectiveness of air, steam, and carbon dioxide as leaveners in baked products.
a. Air is always a leaving agent in baked products because some air always is trapped within the mixture while the ingredients are blended. essential to the formation of the many cells needed to produce light & pleasing baked products w/expected cell size.
b. Steam is far more effective leaving agent than air, because volume is increased 1600-fold as water is converted to steam. Comparing to air which expands to a volume by 1/273 for each degree Celsius that the temperature increase
saccharomyces exigus and saccharomyces inusitatus produce carbon dioxide in acidic (sour) bread doughs, such a sourdough bread. These two yeasts are active at or below a pH 4.5 and function well in the use of lactobacillus sanfrancisco. Also contribute to good volume because of the saccharomyces exigus and saccharomyces inusitatus.
Why is lactobacillus sanfrancisco not used alone as a source of leavening?
Because it produces lactic acid, which reduces the pH of the dough to the range where saccharomyces exigus and saccharomyces inusitatus can generate carbon dioxide effectively but where s.cerevisisiae is not the preferred yeast.
What are the characteristics of an ideal baking powder? Evaluate SAS-phosphate baking powder against the criteria.
T/F gluten is present in most flours except rice flour
T/F unbleached flour produces lighter, higher quality baked products.
T/F starch contributes to the structure of baked products
T/F saccharomyces cerevisiae is the type of yeast used as a leavening agent because it produces carbon dioxide from glucose
T/F baking powder and baking soda can be substituted in equal amounts for each other in cakes?
Describe the changes that occur in muffin batter and the baked muffins as a result of stirring 10 strokes, 25 strokes, and 200 strokes and explain why these changes happen.
25 strokes will still be noticeably lumpy but there will not be any large aggregates of dry mix ingredients. Sufficient mixing of 25 strokes will achieve this appearance and the batter will be ready to baked.
200 strokes: excessive gluten development will occur. peaked pointed muffin tops
Explain the reasons for the steps used in making biscuits by the biscuit method.
Fat is cut in to promote a flaky texture, but much of the tenderizing potential from the fat is not available. All of the fat on the interieor of each flour coated piece is unable to come in contact with and lubricate the flour proteins during mixing. The kneading action in making biscuits is basically a folding action, which also promotes the development of flaky layers. In the oven, the fat gradually melts and spreads out, leaving a space where steam and carbon dioxide can collect and expand.
Carefully describe the desirable characteristics of angel food cakes, sponge cakes, and chiffon cakes. What causes the differences among these three foam cakes?
Angel food and sponge cakes are fairly tender; sponge cakes are a little less tender because of the slight toughening provided by the yolks. Chiffon cakes are more tender than the other foam cakes because of the oil, which is very effective in tenderizing them.
Identify the factors that influence volume of an angel food cake and discuss the effect of each factor.
Volume is an important attribute to angel food cakes. The quality and temperature of egg whites are key factors determining the foam volume and the final cake volume.
What changes need to be made when honey is substituted for part of the granulated sugar in the shortened cake? Why is each change necessary?
When using honey in baking it is advised to compensate for the liquid that honey contributes, ¼ a cup of liquid should be depleted from the recipe for each cup of honey used. Since the acidity of honey quite variable in different honeys; between 1/12 and ½ teaspoon of soda may be needed to neutralize a cup of honey, but the batter can remain more acidic in most cases
Outline the steps in preparing shortened cakes by the conventional, pastry-blend, and single-stage methods. What are the advantages and disadvantages of each method?
Cite the factors that can cause a shortened cake to fall and explain why each factor has this result.
Excess baking powder
Opening of oven door too early in baking
Too little baking powder
Too low of temp during baking.
What roles are preformed by each of the ingredients in pastry?
a. Water and fat influence the tenderness to a pastry.
b. Enhanced by cutting fat into small pieces
c. Minimal mixing also enhances the tenderness of a pastry
What factors influence flakiness of pastry? Explain the effect of each.
Flakiness is promoted by leaving the fat in coarse particles, which block water from some of the gluten and then creates areas where pressure creates many thin layers of dough which is then separated readily by steam during baking
T/F yeast breads require more time to prepare than quick breads because carbon monoxide needs to be produced in the dough.
T/F biscuits are a type of yeast breads
T/F the method that is considered best to use to make a shortened cake with optimal qualities is the muffin method
T/F when making pastry, the ratio of flour to fat is much more important than the amount of water.
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