Milk Composition and Properties Quiz

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Questions and Answers

What is the main type of protein found in milk?

Whey protein

Albumin

Casein (correct)

Collagen

Which vitamin is commonly fortified in low-fat and non-fat milk due to its reduced fat content?

Vitamin E

Vitamin K

Vitamin B12

Vitamin D (correct)

What percentage of water is typically found in cow's milk?

87-88% (correct)

90-92%

95-97%

80-85%

What type of acid is primarily present in the fat content of milk?

Linoleic acid Signup and view all the answers

Which mineral is NOT typically present in milk?

Iron Signup and view all the answers

Which enzyme is specifically associated with the hydrolysis of triglycerides in milk?

Lipase Signup and view all the answers

What component accounts for the majority of the fat content in whole milk?

Triglycerides Signup and view all the answers

What is the significance of casein micelles in milk?

They can coagulate with acid Signup and view all the answers

Which of the following is a non-animal milk substitute?

Soy milk Signup and view all the answers

What is the main purpose of adding Streptococcus lactis to buttermilk production?

To ferment the milk for acidity Signup and view all the answers

Which bacterial strains are utilized in the production of yogurt?

Lactobacillus bulgaricus and Streptococcus thermophilus Signup and view all the answers

What is the alcohol content in kefir typically around?

1% Signup and view all the answers

What effect does cooling cream have on its properties?

Increases viscosity Signup and view all the answers

What happens if whipped cream is overbeaten?

It separates into butter and whey Signup and view all the answers

What bacterial strain is responsible for breaking down lactose in acidophilus milk?

Lactobacillus acidophilus Signup and view all the answers

What is the main reason for adding sugar to whipped cream?

To enhance the stability of the foam Signup and view all the answers

What defines kefir as a '21st-century yogurt'?

It is produced using a mixed flora of bacteria and yeasts Signup and view all the answers

What distinguishes heavy cream from lighter cream variants?

The percentage of milk fat it contains Signup and view all the answers

What characteristic is significant for whipped cream stability?

Temperature of the cream Signup and view all the answers

What is the moisture content classification for soft cheeses?

Over 80% Signup and view all the answers

Which step has the greatest influence on the classification of cheese?

Milk selection Signup and view all the answers

Which of the following methods is NOT used to aid coagulation in cheese production?

Mechanical agitation Signup and view all the answers

What type of emulsion does butter predominantly represent?

Water-in-oil emulsion Signup and view all the answers

How is processed cheese primarily created?

By blending cheese with other ingredients Signup and view all the answers

Which factor does NOT influence the quality of ghee?

Presence of butyric acid Signup and view all the answers

What is the main purpose of curing in cheese production?

To expose cheese to controlled temperature and humidity Signup and view all the answers

Which of the following is NOT a criterion used for grading cheeses?

Nutritional value Signup and view all the answers

What is the maximum recommended storage period for unopened sour cream?

1 month Signup and view all the answers

Which milk product should ideally be consumed within 3 to 4 days after purchase?

Buttermilk Signup and view all the answers

Which storage condition is NOT suitable for unopened cans of evaporated milk?

Direct sunlight exposure Signup and view all the answers

What happens to riboflavin (B2) in milk when it is exposed to light?

It triggers oxidation Signup and view all the answers

Which of the following types of milk can be stored at room temperature before opening?

Ultrapasteurized milk Signup and view all the answers

What causes the spoilage of butter?

Hydrolysis of triglycerides Signup and view all the answers

After opening, how should all types of dry milk and ultrapasteurized milk be treated?

Refrigerated like fresh milk Signup and view all the answers

Which pigment may contribute to the yellow color of butter?

Carotene Signup and view all the answers

What is the approximate pH level range for fresh milk at 25°C?

6.5 - 6.7 Signup and view all the answers

Which factor does NOT significantly affect the viscosity of milk?

Amount of minerals present Signup and view all the answers

Which process is used to eliminate pathogens in milk?

Pasteurization Signup and view all the answers

What is the primary purpose of homogenization in milk production?

To break up fat globules Signup and view all the answers

Which compound contributes to the light ivory color of milk?

Calcium complexes Signup and view all the answers

What is the boiling point of fresh milk?

100.2°C Signup and view all the answers

What is a characteristic of ultrapasteurized milk?

It can be stored unrefrigerated for up to 3 months. Signup and view all the answers

Which statement about the flavor of fresh milk is correct?

It is mild and slightly sweet. Signup and view all the answers

What is the significance of alkaline phosphatase in milk processing?

It indicates when pasteurization has been achieved. Signup and view all the answers

Which of the following compounds is typically present in fresh milk to contribute to aroma?

Methyl ketones Signup and view all the answers

Study Notes

Milk

Milk is the lacteal secretion obtained from healthy cows.
Soy milk, rice milk, almond milk, and coconut milk are not animal milk but resemble milk in color and texture.

Composition of Milk

Milk is mostly water (87-88%).
Milk contains carbohydrates, mainly lactose.
Milk contains 3-4% fat, including fat-soluble vitamins, cholesterol, and phospholipids.
Milk contains 3-4% protein, including casein, whey proteins, and other protein components like enzymes.
Milk contains vitamins A, B6, B12, C, D, K, E, thiamine, niacin, biotin, riboflavin, folates, and pantothenic acid.
Milk contains minerals like calcium and phosphorus, along with chloride, magnesium, potassium, sodium, and sulfur.

Physical Properties of Milk

Milk's pH is 6.5-6.7 at 25°C.
Milk's viscosity depends on fat content, fat globule size, and clustering of globules. Homogenization and aging affect viscosity.
Milk's freezing point is -0.55°C.
Milk's boiling point is 100.2°C.

Color and Flavor Compounds of Milk

Milk's light ivory color comes from fat, casein, calcium complexes, and riboflavin.
Carotene in milk fat contributes to the yellowish tinge of butter.
Milk's mild, slightly sweet flavor is attributed to emulsified fat, proteins, lactose, and milk salts.
Acetone, acetaldehyde, methyl ketones, and SFAs in fresh milk provide aroma.

Terminology

Pasteurization: Heat treatment to eliminate pathogens and extend shelf life. Destroys 100% of pathogenic bacteria, yeasts, and molds.
Ultrapasteurization: Heating milk at or above 280°F (138°C) for at least 2 seconds.
UHT milk: Milk pasteurized at very high temperatures, aseptically sealed, and can be stored unrefrigerated up to 3 months.
Homogenization: A mechanical process to break down fat globules, preventing clumping and creating a fine emulsion.
Coagulation: Clot formation due to denatured proteins separating from the liquid.

Types of Milk

Buttermilk: Traditionally, liquid leftover from churning butter. Now, it's cultured by adding bacteria to nonfat, reduced-fat, or low-fat milk.
Yogurt: Created by adding Lactobacillus bulgaricus and Streptococcus thermophilous bacteria to pasteurized milk, incubated at a warm temperature.
Acidophilus Milk: Cultured with Lactobacillus acidophilus, breaking down lactose into glucose and galactose.
Kefir: Yellowish white, acidic, viscous, and slightly alcoholic fermented milk, containing yeasts, LAB, and acetic acid bacteria.
Sour Cream: Cream soured by bacteria or acidifying agents.
Cream: Collection of fat droplets floating on non-homogenized whole milk. Fat content varies from 18% to 36%.

Milk Products in Food Preparation

Whipped Milk Products: Foams created by whipping air into liquid milk products.
Whipped Cream: Cream expands when whipped; higher fat content leads to stability.
Butter: Concentrated form of fluid milk produced by churning pasteurized cream. Fat content is around 80%.
Ghee: Clarified butter made by simmering butter and removing residue.

Storage of Milk Products

Refrigerated: Most fluid milk should be stored in the refrigerator.
Dry Storage: Dry milk, ultrapasteurized milk, evaporated milk, and sweetened condensed milk can be stored at room temperature.

Cheese

Cheese types are classified by moisture content: fresh, soft, semi-hard, hard, very hard.

Cheese Production

Cheese production involves milk selection, coagulation, curd treatment, curing, and ripening.
Coagulation is achieved through enzymes or acid.
Curd treatment includes cutting, heating, salting, and optional knitting or pressing.
Curing involves controlled temperature and humidity during aging.
Ripening refers to the chemical and physical changes during aging.

Purchasing Cheese

USDA grades for cheese include AA, A, B, and C, based on variety, flavor, texture, finish, color, and appearance.

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Description

Test your knowledge on the composition and physical properties of milk, including various types and their nutritional content. This quiz covers key facts about animal milk and plant-based alternatives, as well as their chemical characteristics and health benefits.