CHAPTER 12: MILK AND MILK PRODUCTS Flashcards
1
Q
Milk and milk products sold in North America are produced mostly from what?
A
Domestic cows.
2
Q
Milk and dairy products are complex ingredients that contain what?
A
A mix of proteins, sugar (lactose), vitamins, minerals, emulsifiers, and milk fat.
3
Q
Are dairy ingredients essential to baked goods?
A
No, but they are important.
4
Q
Do the US and Canadian federal governments regulate minimum milk fat amounts in milk and milk products?
A
Yes, they also regulate pasteurization, maximum allowable bacterial counts, acidity levels, and additives allowed.
5
Q
Do certain states and provinces have more stringent regulations that are enforced within their borders?
A
Yes
6
Q
Are all dairy products sold in North America pasteurized?
A
Essentially, but certain aged cheeses are an exception.
7
Q
Why do drink boxes of milk not require refrigeration?
A
They’re the modern equivalent of canned milk. The milk has been ultra pasteurized, then cooled and specifically packaged under sterile conditions so that the product inside is essentially bacteria free. The process is called aseptic processing, and no preservatives or food irradiation are involved.
8
Q
Who invented pasteurization?
A
Louis Pasteur in the mid-1800s
9
Q
The most common commercial means of pasteurization.
A
High-temperature, short-time (HTST) pasteurization in which milk is heated to a high temp, at least 161ºF (72ºC) for a minimum of 15 seconds.
10
Q
What is Ultra high temperature (UHT) pasteurization.
A
Ultra pasteurization involves heating the product to an even higher temp, often 280ºF (138ºC), for 2 seconds.
11
Q
Does UHT milk have a slightly different flavor than HTST? Why?
A
Yes, because milk flavor is very heat sensitive.
12
Q
Does UHT milk have a longer shelf life? Why?
A
Yes, because the higher temp is much more lethal to pathogens, destroying essentially all bacteria in milk.
13
Q
Should UHT products be treated like HTST products?
A
Yes, unless specifically packaged to prevent the entry of microorganisms.
14
Q
If fresh milk is taken from the cow and allowed to sit, what rises to the top?
A
Cream
15
Q
To prevent cream from rising to the top, most dairy products in North America are what?
A
Homogenized
16
Q
What is homogenization?
A
A process in which milk is forced under high pressure through small openings in a metal plate, forcing milk fat into tiny droplets.
17
Q
What happens when the droplets form?
A
Milk proteins and emulsifiers surround each one, forming a protective film that prevents them from reuniting. The tiny droplets stay suspended indefinitely.
18
Q
Are homogenized dairy products stable emulsions?
A
Yes, of fat droplets suspended in milk.
19
Q
Is cream easily separated from milk in a milk separator?
A
Yes
20
Q
What is a separator?
A
A type of centrifuge that spins very quickly, causing cream in milk to separate off because of its lighter density. The process is much faster than relying on gravity.
21
Q
Milk directly from the cow contains proteins, lactose, vitamins, minerals, and milk fat. But milk is mainly composed of what?
A
Water
22
Q
Not counting milk fat, the solids in milk are appropriately called what?
A
Milk solids, not fat or MSNF.
23
Q
Other than a slight sweetness, the flavor of milk is relatively _____.
A
mild
24
Q
As the amount of milk fat in milks products increases, the flavor becomes ______.
A
rich (dairy flavor), because most of the dairy flavor is in the fat.
25
Are small amounts of emulsifiers lecithin and mono- and diglycerides also in milk fat?
Yes, as are carotenoid pigments.
26
What provides dairy products with a slight yellowish color?
Carotenoid pigments
27
Mostly, milk fat contains what?
Triglycerides, or fat molecules, especially saturated ones.
28
% of milk fat, proteins, lactose, water and ash in whole milk.
```
Milk fat: 3.3%
Ash: 0.7%
Protein: 3.3%
Lactose: 5%
Water: 88%
```
29
Although whole milk is only 3.5% protein, are these protein important?
Yes
30
Two proteins in whole milk.
Casein and whey.
31
Casein proteins are easily coagulated with what?
Acids or enzymes.
32
Coagulated or clabbered, casein proteins aggregate with one another in a manner somewhat similar to what?
Egg proteins.
33
Like egg proteins, casein proteins _____ and ____ as they coagulate. This is the basis for manufacturing of what?
thicken, gel; cheeses, yogurt, sour cream, and other cultured dairy products.
34
When cheese is made, a clear ______ liquid drains from the cheese curd.
greenish
35
While the coagulated casein proteins form the cheese curd, the clear liquid, known as ______, contains _____ proteins.
whey, whey
36
What do whey proteins form on the bottom of pans and on the surface of milk when it is heated?
Film
37
Why must milk not be left unattended on the heat?
Because a film of whey quickly burns onto the pan bottom , running flavor and color.
38
How can you prevent whey proteins from sticking and coating the bottom of the pan when milk or cream is heated?
Add some or all of the sugar from the recipe before heating.
39
Whey proteins are just one of the nutrients in whey. Whey is also rich in what?
Lactose, calcium salts, and riboflavin.
40
The slight greenish tinge in whey is from what?
Riboflavin, one of the B vitamins in milk.
41
Lactose is also called what?
Milk sugar
42
Lactose makes up how much of the MSNF of milk?
50%
43
Lactose's sweetness, which is about _____ that of sucrose, contributes to the characteristic flavor of _______.
1/5, milk
44
Is lactose a disaccharide? What molecules?
Yes, consisting of a glucose molecule bonded to galactose.
45
Unlike most sugars, lactose isn't what?
Fermented by yeast.
46
What is lactose intolerance?
Intestinal discomfort when because a persons body does not contain high levels of the enzyme--lactase--that breaks down lactose into glucose and galactose. The undigested lactose passes into the lower intestine, where bacteria break it down and produce acid and gas.
47
Is lactose intolerance life threatening?
No
48
What can lactose intolerant people consume?
Products low in lactose such as cultured dairy products and cheese.
49
What is Lactaid?
A product that contains lactase.
50
Why is milk treated with Lactaid sweeter than regular milk?
Because glucose and galactose are sweeter than lactose.
51
Does progressively eating more and more dairy create more enzymes to stop lactose intolerance?
Yes
52
Fluid milk is classified by what?
Its fat content, which is standardized by the processor.
53
Range for fat contents in milk.
3.25% or higher for whole milk to essentially 0% for fat free (skim) milk.
54
The minimum MSNF for milk in the US is what?
8.25%; the rest is water.
55
MSNF stands for what?
Milk solids non fat
56
The minimum MSNF for milk in Canada is what?
8.0%; the rest is water.
57
For freshest dairy flavor, ____ milk is the product of choice.
fluid
58
What milk is best in baked custards, cream pies, vanilla custard sauce, frozen desserts, and pastry cream?
Fluid milk, not dry powder.
59
When using fluid milk in yeast doughs, scald it at what temp? Why?
180ºF (82ºC), this denatures whey protein (glutathione) that interferes with gluten development.
60
What are DMS?
Dry milk solids.
61
How are dry milk solids made?
By removing most--all but 3-5%--of water from fat-free or whole milk.
62
How are most DMS made?
Spray-dry process, in which partly evaporated milk is sprayed as a fine mist into a heated chamber. The milk dries almost instantly and falls to the bottom of the chamber as a powder.
63
Advantages of DMS?
Takes up less space than fluid milk and requires no refrigeration.
64
When DMS is made from whole milk it is sometimes called what?
Dry whole milk or powdered whole milk.
65
Do dry whole milk oxidize easily? Why?
Yes, because it contains milk fat.
66
When DMS is made from fat-free milk it is sometimes called what?
Nonfat dry milk, powdered skim milk, NDM, or NFDM.
67
What is more common in bakeshops, whole milk powder or nonfat fry milk? Why?
Non-fat dry milk because it lasts longer.
68
Does DMS have the same fresh dairy flavor as fluid milk?
No, so it should not be used in custards or creams.
69
What should DMS be used in?
Baked goods such as cookies, breads, and cakes.
70
Can DMS be purchased with varying amounts of heat treatment?
Yes
71
High-heat DMS is held at what temp?
190ºF (88ºC) for a minimum of 30 minutes, then dried.
72
Why is DMS best used in yeast-raised baked goods?
Because the heat treatment denatures whey protein that reduces gluten development and bread quality.
73
Does heat treatment also increase the ability of milk proteins to absorb water?
Yes
74
Is low-heat DMS often used in the bakeshop? Why?
No. While is has a fresher taste than high-heat DMS, low-heat DMS does not provide the added benefits to baked goods that high-heat DMS provides.
75
Where would low-heat DMS be best utilized?
Where dry milk solids are added to increase the solids of ice cream mixes.
76
Example of low-heat DMS in grocery stores.
Instant nonfat dry milk
77
How do you use dry milk solids? Conversion.
For every pound of fluid whole milk, use 2 ounces (0.12lbs) DMS and 14 ounces (0.88lbs) water.
Use 120 grams DMS and 880 grams water for every liter of milk.
78
Can you add DMS to dry ingredients or cream it with fat?
Yes
79
Does DMS easily mix with water?
No, so it is best not to reconstitute it before use.
80
Minimum milk fat standards for cream products sold in the US and Canada: Heavy cream
US: 36%
CANADA: -
81
Minimum milk fat standards for cream products sold in the US and Canada: Whipping cream
US: 30%
CANADA: 32%
82
Minimum milk fat standards for cream products sold in the US and Canada: Cream
US: -
CANADA: 10%
83
Minimum milk fat standards for cream products sold in the US and Canada: light cream
US: 18%
CANADA: -
84
Minimum milk fat standards for cream products sold in the US and Canada: Half-and-Half
US: 10.5%
CANADA: -
85
Is cream sold in North America pasteurized?
Yes, often under UHT (ultra pasteurized) conditions.
86
The main advantage of UHT cream is what?
An extended shelf life.
87
Besides being pasteurized, cream is usually what?
Homogenized
88
Does homogenized cream make whipping more difficult?
Yes, but many heavy creams and whipping creams contain added emulsifiers and stabilizing gums to aid in whipping.
89
At very high levels of fat (around _____%) even homogenized creams whips easily.
40
90
Cream is classified by what?
The amount of milk fat it contains.
91
What forms tiny oil droplets and small solid fat particles that stay suspended when cream is homogenized?
Milk fat, and it's the presence of these droplets that gives cream its smooth , thick consistency.
92
Because cream is high in fat, it is also high in what?
Carotenoid pigments that dissolve in fat, giving it a yellowish tinge.
93
In the US, heavy cream contains how much fat?
Between 36 and 40% milk fat.
94
What is often the only cream stocked in the bakeshop?
Heavy cream
95
ame three other cream products besides heavy cream.
Whipping cream, light cream, half-and-half.
96
Light cream from the US can be made how?
Mixing equal parts heavy cream and whole milk.
97
How can half-and-half be made?
Equal parts light cream and whole milk.
98
Nationally, Canada has two types of cream. What are they?
Cream and whipping cream.
99
Is England known for the quality of its dairy products?
Yes
100
What is single cream?
Equivalent to American light cream.
101
What is double cream?
At over 48% milk fat, is thicker and richer than any cream commonly sold in North America.
102
What is considered to be the finest cream in Great Britain?
Double Devon cream, from Devonshire, England.
103
Name two specialty dairy ingredients that have occasional use in the bakeshop.
Evaporated milk and sweetened condensed milk.
104
How are evaporated and sweetened condensed milk purchased?
Generally in cans, which can be stored at room temp until opened.
105
How are evaporated and sweetened condensed milk made?
By removing water from milk. Evaporated milk is concentrated until it contains twice the milk fat and twice the MSNF of regular fluid milk. Sweetened condensed milk has had more water removed and sugar added.
106
Are low-fat versions of evaporated and sweetened condensed milk available?
Yes
107
Can evaporated and sweetened condensed milk be used interchangeably?
No
108
The main difference between evaporated and sweetened condensed milk is what?
The sugar added to sweetened condensed milk makes it thicker, sweeter, and denser, and has more caramelized color and flavor, than evaporated milk.
109
The color and flavor of sweetened condensed milk when heated is a result of what?
Maillard reaction
110
The added sugar to sweetened condensed milk mean that it can be what?
Left open at room temp for days and not spoil.
111
Do evaporated and sweetened condensed milk cost more than regular milk?
Yes, but they are easier to store and last indefinitely if stored at room temp before opening.
112
What regions would these specialty items be welcome?
Tropical regions where refrigeration isn't plentiful.
113
Mexican flan is traditionally made how?
With milk that has been boiled and evaporated with sugar, which is essentially sweetened condensed milk.
114
What substitutes for cream in certain low fat products?
Evaporated milk.
115
Cultured dairy products are fermented by that addition of what?
Live bacteria, usually lactic acid bacteria.
116
Lactic acid bacteria ferment lactose to what?
Lactic acid and other flavorful products.
117
What does the lactic acid do to the pH of cultured dairy products?
Lowers it and provides a pleasant sour flavor.
118
How does sugar prevent spoilage in sweetened condensed milk?
Microorganisms require more than just food to survive. They require moisture and warmth, and most require oxygen. If moisture is unavailable, they dehydrate and malfunction. Because sugar is hygroscopic, water binds to the sugar and is unavailable to microorganisms. Just as sailors can't quench their thirst at sea with seawater, microorganism cannot quench theirs with sugar syrup. Their cells shrivel and they cannot function. The water activity is said to be lowered and the osmotic pressure raised by the high concentration of sugar or salt. Below a certain water activity and above a certain osmotic pressure, microorganisms cannot survive.
119
What is a probiotic?
Microorganism that is thought to help, maintain the health of the intestinal tract by reducing the growth of undesirable bacteria.
120
Do the benefits of probiotics also help in baked goods?
No, high levels of heat kill the microorganisms.
121
Does lactic acid bacteria help thicken and gel cultured dairy products? Why?
Yes, because the acid causes casein proteins to coagulate.
122
Are lactic acid bacteria considered friendly?
Yes
123
Why do cultured dairy products have a longer shelf life than milk products?
Lactic acid bacteria have positive effects on flavor and texture of dairy products and prevent the growth of undesirable spoilage bacteria in these foods.
124
Why do formulas that contain cultured dairy products often contain baking soda too?
When acid from the dairy product reacts with baking soda, carbon dioxide gas is produced. This can be a significant source of leavening.
125
What if there is more acidic in the dairy product than is needed to react with baking soda?
The excess acid will lower the pH of the mix, tenderizing and whitening.
126
Originally, buttermilk was what?
The fluid remaining after cream was churned into butter.
127
Today, what is cultured buttermilk? Why is it thicker than regular milk?
Made by adding lactic acid bacteria to milk, usually low-fat or fat-free milk. It is thicker than regular milk because of the effect of lactic acid on the casein proteins.
128
Cultured buttermilk is used in buttermilk biscuits and certain other baked goods for what?
Flavor, whitening, tenderizing, and leavening.
129
Can cultured buttermilk also be purchased as a dry powder?
Yes
130
A reasonable substitute for cultured buttermilk.
Sour milk, prepared by adding 1 tablespoon (15 milliliters) vinegar to 8 ounces (225 grams) fluid milk.
131
Is "sour milk" the same as buttermilk?
No, it doesn't have the viscosity and has a sharper sourness, but it does provide the same tenderness, whiteness, and leavening.
132
Is sour milk the same as soured milk?
No, soured milk is milk that has spoiled.
133
Should soured milk ever be used in baked goods?
No, it has an unpleasant flavor and should never be used in baked goods.
134
Other cultured milk products include what?
Kefir cultured milk and acidophilus cultured milk.
135
Are kefir cultured milk and acidophilus cultured milk the same as buttermilk?
Similar to buttermilk but are cultured with different bacteria, giving them distinct flavors.
136
In the US, how is sour cream made?
Adding lactic acid bacteria to light cream (18-20% milk fat).
137
In Canada, how is sour cream made?
Same as US but can be slightly lower in milk fat, 14% minimum.
138
What does lactic acid do to the proteins in sour cream?
Causes the proteins to coagulate to a gelled consistency; gums and starches may be added to further thicken the product.
139
Name three baked goods to use sour cream in.
Cheese cake, coffee cake and certain pastry doughs.
140
Are low-fat and fat-free sour creams available?
Yes, these products are higher in moisture and less rich in flavor than regular sour cream.
141
Low-fat sour cream is essentially what?
Cultured half-and-half (minimum 10.5% milk fat). Often a satisfactory substitute for regular sour cream.
142
What is creme fraiche?
A cultured cream product throughout France.
143
Traditionally way of making creme fraiche.
Set unpasteurized milk in a pan at room temp, allowing cream to rise to the top. After about 12 hours, the cream is skimmed off. During that time, natural bacteria in unpasteurized milk ripen the cream, turning it into a mildly sour, thickened product.
144
Creme fraiche must be a minimum of how much fat?
30%
145
Why is creme fraiche so much smoother, richer, and more velvety than sour cream?
It has more fat.
146
Mexico has a similar product to creme fraiche called what?
Crema fresca
147
How do pastry chefs sometimes make a substitution for creme fraiche?
Adding a small amount of cultured buttermilk or sour cream to heavy cream and allowing it to stand in a warm sport for 8 hours or more before refrigerating.
148
What is clotted cream?
A thick, spreadable dairy product with a minimum fat content of 55%.
149
The most prized clotted cream is from where?
Devonshire, the region in England where it has been made for centuries.
150
Traditional way of making Devonshire clotted cream.
Starts like creme fraiche, with ripened cream rising from milk set out in a shallow pan. Once separated, however, the cream is slowly heated to about 180ºF (82ºC) and held for about an hour until it starts to form a golden-colored crust. The scalded cream is removed from the heat and slowly cooled, and the thick crust of buttery clotted cream is skimmed off the top.
151
Clotted cream is traditionally paired with what?
Paired with jam and served on scones at teatime in England.
152
Is clotted cream still made the same way today?
Some dairy farms in western England still do, but it is more likely to be made from unripened (not cultured0 pasteurized cream.
153
How is cheese made?
When coagulated casein milk proteins--curds--are separated from whey.
154
Most, but not all, cheeses are classified as what?
Cultured dairy products. Meaning that live bacteria produce acid that forms cheese curds.
155
Can cheese be ripened or unripened (aged)?
Yes
156
Name some soft, unripened cheese.
Cream cheese, Neufchatel, bakers cheese, ricotta, and mascarpone are the most common used in a bakeshop.
157
Do ripened cheeses typically have stronger, more distinct flavor?
Yes
158
Examples of ripened cheese.
Parmesan, blue cheese, cheddar cheese, and Brie.
159
What is the simplest cheese to make?
Yogurt cheese.
160
Where is yogurt cheese traditional?
Labneh is traditional in the Middle East.
161
How is yogurt cheese made?
By draining the liquid whey from yogurt.
162
Can any yogurt be made into yogurt cheese? Any to avoid?
Yes, but avoid brands that contain added starches or gums; they prevent whey from draining freely.
163
How do you drain yogurt cheese?
Place yogurt on several layers of cheesecloth and hang over a bowl to catch the whey. Keep it loosely covered and refrigerated. This process only takes a few hours but may take a day or more if you want a drier cheese.
164
Yogurt cheese is similar to what other cheese?
Cream cheese in texture, but it has a stronger acid bite.
165
Are cream cheese, neufchâtel, and baker's cheese similar? Why?
Yes, their curds form from the addition of lactic acid bacteria and often enzymes to milk or cream. Once liquid whey is drained off, the curds are processed until they have the right consistency. All 3 cheeses have a mild, slightly acidic flavor and a soft, smooth texture.
166
What is often added to cream cheese, neufchâtel, and baker's cheese to increase creaminess and firmness?
Gums are often added, especially in lower fat cheeses.Usually a combination of anthem gum and locust bean gum are added.
167
What has the most fat, cream cheese, neufchâtel, or baker's cheese?
Cream cheese contains a minimum of 33% milk fat (30% in Canada), the same as whipping cream. Neufchatel is low in fat (20% minimum) than cream cheese; in fact, Neufchatel is often labeled "low-fat cream cheese." Baker's cheese is essentially fat-free and is sometimes labeled "fat-free cream cheese."
168
Is bakers's cheese less expensive than cream cheese?
Yes
169
Why can low-fat and fat-free versions of cream cheese be successfully used in baked goods like cheesecake?
They often contain a high level of gums. Texture isn't sacrificed but flavor usually is.
170
Why would a low-fat cheesecake not taste the same as a normal one?
Many flavors dissolve in fat, and when fat is removed, flavors are released differently, often more quickly.
171
Do soft, unripened cheeses blend well into other ingredients as long as they are added properly?
Yes, just be sure to soften them first so it comes close to matching whatever consistency the other ingredients are or lumps may form.
172
Describe Ricotta cheese.
Slightly grainy consistency and a mildly sweet dairy flavor.
173
Originally, how did thrifty Italian housewives make ricotta?
Adding acid to liquid whey that was leftover from cheesemaking.
174
Today, how is ricotta made?
Adding acid or bacteria and enzymes to whole milk or part skim milk.
175
What is ricotta used in?
Cannoli, ricotta cheesecake, and other Italian specialties.
176
Mascarpone is an Italian cheese best known as an ingredient for what?
Tiramisu
177
How much milk fat is in mascarpone?
70-75%, almost as high as butter.
178
Flavor and texture of mascarpone are a cross between what?
Cream cheese and butter, or similar to a very rich clotted cream.
179
How is mascarpone commonly made? Explain.
Adding acid to heated heavy cream. The combination of heat and acid coagulates the casein, forming a fine, smooth curd that drains slowly from liquid whey.
180
What should you be careful of when mixing or creaming mascarpone cheese?
Unappealing butter lumps form when it is over mixed, much as cream turns to butter when it is over whipped.
181
How do you avoid over mixing mascarpone cheese?
Mix on low speed no more than necessary.
182
Where did Quark originate?
Germany
183
What is quark?
Mild, unripened soft-curd cheese that is available in different versions with varying amounts of fat.
184
Is quark's texture smoother than ricotta?
Yes, slightly smoother.
185
What can be a substitute if quark is unavailable?
Ricotta can be by blending in a food processor; mix with cream cheese for higher fat content.
186
What is quark used in?
German cheesecake and other pastries.
187
Because dairy ingredients are complex mixtures, they provide many functions in pastries and baked goods. However, the effects are usually not large, except for products like what? What does this mean?
Custard-based products. This means, unlike eggs, fat, or flour, milk is relatively easy to leave out of baked goods. Often simply substituting milk with water is all that is needed. Other times, any number of ingredients can be used in place of milk or cheese, including rice milk, almond milk, soy milk, or soybean curd (tofu). As with low-fat dairy products, the problem often becomes one of balancing flavor, not one of improving texture.
188
The greenish by-product of cheese manufacturing.
Liquid whey
189
What is high in whey proteins, vitamins, minerals, and lactose?
Liquid whey
190
Liquid whey was once discarded as what?
Animal feed
191
Today, what popular product is liquid whey converted into? How is it made?
Whey powder, made by pasteurizing and drying liquid whey. Dry whey is similar in many ways to DMS and can be used in baked goods at a lower cost.
192
Fluid milk and DMS functions: Explain how they increase crust color.
The combination of proteins and lactose, a fast browning sugar, provides the right mix for Maillard reaction. This contributes to color and fresh baked flavor to baked goods.
193
When baked goods are prepared with milk instead of water, baking times and temps may need to be what?
Lowered to reduce excessive browning.
194
Fluid milk and DMS functions: Explain how they delay staling.
Several components in dairy products, including proteins, lactose, and milk fat, prevent starch retrogradation in the crumb of baked goods. This is particularly noticeable in yeast-raised breads, which are usually low in stale-retarding ingredients, like sugar and fat.
195
Fluid milk and DMS functions: Explain how they increase crust softness.
Products like bread and cream puffs that are made with milk instead of water have softer crusts. Just think of the difference between baguettes and pullman or pan bread. Softening occurs because milk proteins and sugar absorb water, delaying its evaporation from the crust.
196
Fluid milk and DMS functions: Explain how they blend flavors and provide richness in flavor.
Milk modifies the flavor of baked goods. In cakes and breads, milk blends flavors and reduces saltiness. In baked custards, vanilla custard sauces, and pastry cream, milk provides a rich, full flavor, especially when they are high in milk fat.
197
Fluid milk and DMS functions: Explain how they provide a fine, even crumb to baked goods.
Some baked goods--yeast breads in particular--have a finer crumb when prepared with milk or DMS. It is likely a combination of milk proteins, emulsifiers, and calcium salts in milk that help stabilize small air bubbles. The smaller the air bubble, the finer the crumb.
198
Fluid milk and DMS functions: Explain how they form a stable foam.
Cream whips into foam if it has a minimum milk fat content of about 28%. Both whipping cream and heavy cream can be whipped satisfactorily, but heavy cream, because of its higher fat content, produces a more stable foam. Milk proteins also form stable foams. Froth on cappuccino is from milk proteins trapping air.
199
Besides using cream with higher fat content, how else can you stabilize cream?
First chilling the bowl and cream to solidify the milk fat; by slowly adding sugar while whipping; or by folding in a gelatin solution or another stabilizer. Many brands of heavy cream contain added emulsifiers such as mono- and diglycerides, to aid whipping.
200
Can evaporated milk be whipped into a stable foam?
Yes, and chilled producing a whipped cream substitute.
201
Fluid milk and DMS functions: Explain how they aid in the creaming of shortening.
The addition of dry milk solids to creamed shortenings aids air incorporation and stabilization. The emulsifiers and proteins in dry milk seem to provide these benefits.
202
How is whipped cream like whipped egg white? How are they different?
Both are relatively stable foams, meaning they contain bubbles trapped in liquid. Both are more stable with the addition of sugar. Beyond that, both are quite different. Proteins in the whites stabilize egg white foam while milk fat stabilizes whipped cream.
203
Explains what happens when cream is being whipped. Is it more effective than egg white proteins?
Whipping disrupts the protective film that surrounds fat globules suspended in cream. The unprotected fat globules form tiny clumps with bits of solidified milk fat. These clumps of milk fat surround each air bubbles, stabilizing them. Fat clumps are not as effective as egg proteins in stabilizing foams, so while egg white increases up to eight times in volume, cream barely doubles.
204
Fluid milk and DMS functions: Explain how they absorb moisture.
Proteins in milk act as driers, absorbing moisture and increasing the water absorption rate of yeast doughs. The amount of extra water needed in yeast doughs is ounce for ounce about the same as the amount of DMS added. This means that yeast doughs made with milk require more liquid than doughs made with water. This ability to absorb water contributes to the ability of milk proteins to delay bread staling.
205
Fluid milk and DMS functions: Explain how they aid in the coagulation of egg proteins.
Custards made with water instead of milk do not firm up properly, because milk aids egg coagulation. Milk has also been known to firm up the crumb of cakes, making them spongier and more resilient. It appears that both milk proteins and calcium salts in milk strengthen egg structure, much as the calcium salts in hard water strengthen gluten structure.
206
Fluid milk and DMS functions: Explain how they provide moisture.
Because fluid milk is about 88% water, anytime it is used in baked goods, it contributes moisture for dissolving sugars and salts and for developing gluten. Even heavy cream is over 50% water.
207
Fluid milk and DMS functions: Explain how they add nutritional value.
Milk contains high quality protein, vitamins--riboflavin, vitamin A, vitamin D--and minerals, especially calcium. This reflects the fact that milk is the sole source of food for the newborn calf. However, milk products--such as heavy cream--are high in saturated fat,which increases blood cholesterol and contributes to coronary heart disease.
208
Do fluid milk and DMS spoil easily?
Fluid milk and reconstituted DMS spoil easily. Bacteria multiply and produce acids and off flavors, souring milk. While it is usually not harmful, soured milk has an unpleasant flavor and should be discarded.
209
Beyond spoilage, the flavor of milk is highly susceptible to other changes, what are they?
Either from absorbing aromas or from chemical reactions that occur from exposure to excessive heat or light.
210
Pasteurized whole milk has a shelf life of how long?
Two weeks, but actual shelf life could depend on many other factors, the main one being how well the product has been stored.
211
What should you always do with your dairy products before using?
Taste and smell.
212
What if a layer of fat forms at the top of cream?
Shake before using; this doesn't necessarily mean spoilage.
213
What temp should milk be upon delivery?
45ºF (7ºC) or less. If warmer, reject.
214
Milk should always be refrigerated at what temp?
34-38ºF (1-3ºC)
215
Should container be closed immediately after using? Why?
Yes, stray microorganisms from the air can land in open cartons and shorten shelf life.
216
How should you maintain you refrigerator for milk products?
Keep it clean. Odors from other foods can pass through containers and be absorbed. Use separate fridge if necessary.
217
Should milk be exposed to light?
No, fluid milk is susceptible to ultraviolet light damage.
218
While cultured dairy products such as buttermilk, sour cream, and yogurt have an extended shelf life, what grows over time?
Their acid content continues to increase and flavor gradually becomes stronger, sharper, and more pronounced. Mold can grow on cultured products that have been improperly stored too long.
219
Are soft, unripened cheeses highly perishable?
Yes, those high is moisture, such as ricotta, are especially perishable.
220
Once opened, ricotta cheese should be used within how many days? What about other soft cheeses? Storage?
2 to 5 days. Cream cheese, bakers cheese, and Neufchatel last a little longer. Once opened, they should be tightly wrapped or covered to prevent drying, and stored in the fridge for no longer than two weeks.
221
How to store nonfat dry milk.
As long as they haven't been reconstituted, DMS should be covered and kept in a cool dry place. This keeps it from absorbing strong odors or clumping and caking with changes in moisture. Shelf life is 1 to 3 years.
222
Will nonfat dry milk eventually darken and brown?
Yes
223
Whole dry milk solids have a maximum shelf life of how long?
6 months, because the fat will eventually pick up rancid, off flavors.
224
Shelf life of sweetened condensed milk and evaporated milk.
They will last for years if unopened. Overtime, however, they develop strong flavors, darken, and change in consistency. Once opened, evaporated milk requires refrigeration.
225
What is light-induced flavor?
UV light from the sun or from fluorescent lighting is high energy and causes chemical changes to occur in foods. Some of these changes produce off flavors in milk stored in transparent containers. These changes can occur quickly, within an hour of exposure.
226
Explain the light-induced chemical change involves riboflavin.
The breakdown of an amino acid in milk protein. This reaction takes place in the presence of the vitamin riboflavin. The result is the production of an off flavor in milk and a loss of riboflavin. It is sometimes described as the smell of burnt feathers or burnt potatoes, and it can happen within minutes of exposure to bright sunlight, longer under fluorescent lighting.
227
Besides riboflavin, what is another light-induced flavor change in milk? Describe it.
Breakdown of vitamin A, which is most likely to occur in low-fat and fat-free milk products. When vitamin A breaks down, it produces an oxidized, off flavor that is sometimes described as the smell of wet cardboard or old oil. Nutritional quality is reduced. Ironically, this change is more likely to occur is plastic containers than milk stored in cardboard containers.
