Eggs, Milk & Cheese: Functions and Effects in Culinary Science
School
University of Guelph**We aren't endorsed by this school
Course
HTM 2700
Subject
Communications
Date
Dec 10, 2024
Pages
3
Uploaded by ProfessorBaboon4569
HTM*2700winter2023UNDERSTANDING FOODSEGG, MILK and CHEESE LABORATORY REPORT1.Describe function of the egg whites are performing in the Cheese soufflé (Product , Egg lab) (5marks)Answer:The function of the egg white in this recipe as providing part of structural material in the bakedcheese souffle which is the “Foam formation” .During beating the egg white, not just air hasbeen incorporated in the egg white, the protein which forms 80% of the egg white has beendenatured too. The protein molecules disturbed and the hydrogen bond break that result inunfolded protein chain to produce more random arrangement. (denaturation processes)The denatured protein collect on the surface of the air bubbles, forming a network whichstabilizes the foam( protect the bubbles from rupturing or collapsing). In addition, thedenatured protein coagulate and result in permanent foam during baking the cheese souffle. (coursepack: pg. 104, 121)2.Explain why an egg white foam is created more quickly when cream of tartar is added. (4marks)Answer:Each protein has its own isoelectric point ( IEP ) and proteins are less stable at their IEP thuseasily denature. The addition of an acid ingredient such as “cream of tartar to eggs causeschanges to the pH of the egg and lowered it to the isoelectric point of the protein thereforeaccelerating the rate of denaturation processes. Therefore will be a lot of denatured protein collecton the surface of the air bubbles, forming a network which stabilizes the foam( protect the bubblesfrom rupturing or collapsing) and more quickly foam builded up.(course pack: pg. 113,120)3.Explainthe effect of under-beating egg whites when preparing an egg white foam? (2 marks)Answer:Under-beating eggs white result in too few denatured proteinscollecting on the air bubblesand a less stable foam which collapse more quickly.(course pack: pg. 104).4.What effect does milk have on the function of the eggs in the Baked Custard (Product II, EggLab) (4 marks)Answer:Dilution of the egg proteinby adding hot milk to the beating egg mixture . The denaturedproteins will separate from each othertherefore Gel becomes less firmer. Another effect,the temperaturewill be affected and need to be higher to facilitatethe denaturation andcoagulation of the egg protein in this recipe. (Egg live lecture: week7)
5.Explain what the ideal temperature is for beating whipping cream into a stable, high volumefoam. (7 marks)Answer:Greatest volume and the most stable foam is achieved , when the whipping cream ,beater andthe bowl are chilled to refrigerator temperature (4C) or belowbecause the fat globulesbecome more solid; therefore the cream becomes thicker, make iteasier to incorporatemore air bubbles“Higher volume” .Also the solid fat globules clump to gather moreeasilyon the surface of the air bubble-More stable foam.(coursepack: pg.136)6.a) If the Hot Cocoa (Product VII, Milk & Cheese Lab) is prepared in a pot that sits directly onthe stove, instead of using a double boiler, what will you notice when you go to clean the pot.Explain what this is and how it formed (4 marks)Answer:Milk contain whey protein which isLactalbumin and lactoglobulin. When you heated the milkdirectly on the stove without using the double boiling, something will stick and burn at thebottomed of the pot. It is the denature whey protein (Lactalbumin and lactoglobulin)participated out of the colloidal dispersion and settled on the bottom of the pot and burned dueto direct heat. So to avoid denature the whey protein and burn , using double boiling isrecommended. (coursepack: pg.135) b) You didn’t get to drink your hot cocoa right away and when you sat down to enjoy it younotice a film / skin on the surface. Explain what caused a film / skin to form. Explain how itcan be avoided. (4 marks)Answer:It’s a layer of concentrated casein. When the hot cocoa left for a long time without coveringand exposed to the air , the water will evaporates from the cocoa and will concentrate thedrink. We can avoided by covering the cup with a lid or plastic wrap , and prevent water fromevaporation.(Milk and cheese live lecture)7.After the vinegar is added to the milk-cream mixture (Step #3) when making the HomemadeRicotta Cheese (Product VI, Milk & Cheese Lab) the mixture quickly changes in appearance.Describe and explain what is happening (8 marks)Answer:Milk contain two type of proteins whey 18% and casein 82% ,that found in colloidal dispersion.Each protein has its own isoelectric point (IEP)and proteins are less stable at their IEPthuseasily denature . The addition of an acid ingredient such as “vinegar” to the milk-cream mixturelowered the pH to the isoelectric point of the casein protein (pH of 4.6).And acidcontribute +H ions which neutralize the (–)charges around the(casein Micelles).At this IEP the (Casein Micelles) readily denatureand adhere together forming largermolecules “unstable” .These molecule participate out of the colloidal dispersionandhave a curdled appearance. Also, the casein protein will quickly denature duringcooking in the presence of the acid( vinegar). (coursepack: pg. 125,135)
8.What preventative steps are being done in the Macaroni and Cheese with Tomatoes (ProductIII, Milk & Cheese Lab) to prevent curdling of the cheese sauce? (3 marks)Answer:By minimizing the heat(keep<100C) ,in this recipe microwave macaroni mixture onmedium(50%power) until bubbling and hot (5-6min) rotating dish a ¼ turn every 2min .Moreover, minimize the time acid and casein protein together, the chopped tomato andcooked macaroni have been added at the end to the cheese mixture. Tomato has a acidicpH ,which it will accelerate the denaturing processes.Another step curdling can be prevented, by thickening the water phasearound the caseinmicelles with starch ”adding macaroni to cheese “. That’s will prevent the denatured caseinmicelles from sticking together and falling out of colloidal dispersion.(Milk and cheese live lecture)9.Explain whether Swiss cheese can be substituted for old cheddar cheese in the Welsh Rarebitrecipe (Product VI, Milk & Cheese Lab). Consider the melting and blending properties of bothcheeses when answering the question. (6 marks)Answer:The melting and blending properties of various cheese depends on moisture and fat content aswell as the amount of ripening.The cheddar and Swiss cheese have an medium moisture and heigh fat (7.5g-9.8g),thereforeboth of them have a good melting properties.Also chedder and swiss cheese have been ripened (1-12 month),so both of them can blendwell.In this recipe, cheddar was placed in double boiler for melting , after that mixed/blend with milk,butter and later with beaten egg yolk. As we can see, Swiss cheese can be substituted for oldcheddar cheese in the Welsh Rarebit recipe because both of them have the same melting andblending properties. Swiss cheese will melt well due to medium in moisture plus high fatcontent. Also, will blend well as a result of melting very well in addition to swiss cheese hasbeen ripened. (coursepack:pg. 128,136)10.From the description of Welsh Rarebit (Product VI, Milk & Cheese Lab) given in lab you wereexpecting to see a smooth, homogeneous sauce on slices of toast. Instead you saw a stringy,oily mixture. Explain what happened. (5 marks)Answer:Over coagulation happenedto the denatured protein, due to either was cooking under heightemperatureor for too long. polypeptide chain compress together and water is squeezed outwhen excess hydrogen bond form. Over Coagulation will lead to tough and stringy like texture.Moreover,Overheating of the cheese will causes breakage of the fat emulsion layer,therefore an oil mixture appears on the topof the cheese. (Milk and Cheese (Live Thursday Lecture)TOTAL = ________ = ________5210