W24 Starch & Egg Lab Report

.pdf

School

University of Guelph *

*We aren’t endorsed by this school

Course

2700

Subject

Communications

Date

Apr 3, 2024

Type

pdf

Pages

Uploaded by ChancellorTank8159

HTM*2700 Winter 2024 UNDERSTANDING FOODS STARCH & EGG LAB REPORT 1. Explain the purpose of using a double boiler when preparing the Chocolate Blanc Mange (Product IV, Starch Lab), rather than cooking the pudding in a pot directly on the stove. (3 marks) Double-boiler broilers used in the Chocolate Blanc Mange recipe are crucial to make certain the ingredients (i.e., milk) are not overcooked/burnt. Double-broilers allow the top ingredients to be heated so slightly by the boiling water on the bottom (Coursepack pg 11) 2. Explain why Vanilla Blanc Mange (Product I, Starch Lab) becomes firmer after being refrigerated for a few hours? What is this process called? (7 marks) Preparing the Vanilla Blan Mange requires the process of gelatinization, wherein starch granules undergo a sol-forming process. This occurs by heating the starch in the presence of water causing the hydrogen bonds to break creating a thick sol. The mixture is added to a chilled area (i.e., fridge) and once thickened an almost jiggle-like retrogradation takes form, causing solidification. Since the mixture cools, the kinetic energy within it reduces causing amylose molecules to diffuse. The abundance of amylose and the retrogradation process leads to water entrapment, yielding a firm gel. (Starch Live Lecture - Week 6, 22/02/2024) b) Explain what happens to the Vanilla Blanc Mange after it is stored in the refrigerator for a couple of days. (3 marks) After being stored in the refrigerator a process called syneris takes place. Once the mixture becomes cool, bonds between the amylose molecules begin to develop at exponential speed. The gel will eventually contact which causes an expulsion of water from within the gel itself. After a couple of days of refrigeration, the Vanilla Blanc Mange goes through a phenomenon that causes seepage of liquid making the recipe not as appetizing (Coursepack pg 85-86) 3. A) Explain what affect the wine is having on the rice in Step#5 in Risotto with Parmesan (Product VI, Starch Lab). Explain whether you would expect a sol or a gel to form. (5 marks) What is expected to form in the Risotto with Parmesan recipe is called a sol. When the wine is added to the recipe it is the “acid” - acids prevent gels from forming since it causes fragmentation of granules, furthermore the wine hydrolyzes the majority of the starch molecules into something called dextrins, and dextrins are known to be less likely to for gels, and more likely to form sols. (Coursepack pg 84-85) 4. a) Explain what causes lumping in a cooked White Sauce like the one prepared for the Salmon Scallop (Product VII, Starch Lab)? (5 marks) Starch granules that are not separated quickly enough before they are heated in a hot pan (or pot) cause lumps to form. The heat and non-separate granules come together and create a gelatinised barrier around the starch which in par leaves a limped sauce/mixture (Coursepack pg 94-95)

b) How is lumping prevented in a White Sauce? (4 marks): NOTE: One (1) mark will be deducted if an inappropriate technique is given . You must mix the fat and starch before a liquid is added to the mixture. Lumps will not form since the starch granules will be covered and protected before the liquid is added. (Coursepack pg 95) 5. Explain what causes curdling in a soft custard (Creamy Citrus Gelato, Product II, Egg Lab). Explain how curdling can be prevented in this product. (5 marks) Curdling occurs in the process of syneresis and over-coagulation. Polypeptide chains constrict leading to the expulsion of water from the product and leaving it with an emergence of new hydrogen bonds. However, to prevent this from happening in the Creamy Citrus Gelato, one should use a double boiler, this prevents an immediate overheat of the liquid ingredients, and lets it rise in heat at an appropriate time. (Coursepack pg 120 + Egg Pre-recorded Lecture Week 7) 6. Describe the function of eggs in the Bacon, Swiss Cheese and Broccoli Quiche recipe (Product VII, Egg Lab). (4 marks) In this recipe, the function of the eggs serves as a gelling/thickening agent. This is attributed to the absence of stirring during the denaturation and coagulation of the egg proteins while cooking in the oven/ The non-stiiring facilitates the formation of gel-like structures, as new hydrogen bonds emerge along the polypeptide chain. (Coursepack pg 120-121) 7. At a family picnic, you notice that very few people are eating the Devilled Eggs (hard cooked eggs, cut in half, the yolk removed, mashed, combined with mayonnaise and then put back into the white) prepared by your aunt. The yolks are a grey-green colour. Explain what caused the problem. Explain what your aunt should have done to prevent the problem (6 marks) Grey-green-coloured egg yolks are a result of a reaction between hydrogen sulphide (egg whites) and iron (egg yolk). This forms ferrous sulfide which gives the appearance of grey-green on the yolk. Something that can be done to prevent this from happening is that once the egg is done being boiled, IMMEDIATELY put it into an ice bath - this reduces the outer pressure on the egg and removes the whites from the yolk. (Egg Live Lecture - Week 7, 29/02/2024) 8. The assistant cook in a hospital cafeteria could see no reason for adding vinegar to the simmering water when poaching eggs (see Product I, Eggs Lab). Explain the role of the vinegar. (5 marks) Vinegar allows the egg white to coagulate and denature rapidly so it in turn stays the same shape when poached since vingear plays as an acid. The H+ ions from the vinegar help to neutralize the charge from the egg protein, this implies that the required temperature for denaturation and coagulation will ultimately decrease (Coursepack pg 109-110) TOTAL = ________ = _______ 47 10

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help