MILK

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MILK
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Objectives

• Define the term milk
• Describe quality control during the production of
  milk and milk products
• Explain pasteurization and homogenization
• Identify three methods of pasteurization
• Describe the solids composition of milk
• Discuss the separation of butterfat and its use
• List four beverage milk products
• Describe butter
• Name 5 concentrated or dried dairy products
• List the steps in the cheese making process
• Identify 3 bacteria used to produce dairy
  products
• Name 5 fermented dairy products
• List the steps in making and ice cream and make
  ice cream
• Describe the USDA quality grade shields

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Terms To Know

• Buttermilk
• Churning
• Coalesce
• Curd
• HTST
• Lipolysis
• LTLT
• Rennet
• Ripening
• Ropey
• Solids-not-fat
• Standard plate count (SPC)
• standardized

• Ropey
• Solids-not-fat
• Standard plate count (SPC)
• standardized
• Thermization
• UHT
• Ultrapasteurization
• Vaccum evaporation
• Whey

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Introduction

• Milk the first food for young mammals
• Provides high quality protein, vitamins and
  minerals and is a source of energy
• Worldwide many mammilian species are used to
  produce milk and milk products
• Goats, sheep, horses, yaks
• However, our focus will be on milk from dairy cows

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Fluid Milk
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Fluid Milk

• Collodial dispersion of the protein caesin and
  the whey proteins. It is an emulsion with fat
  globules suspeneded in the water phase
• Composed mainly of water
• 87-89
• Milk solids make up the other 12-13
• Solids include the carbs, lactose, fat, protein
  and minerals
• Solids-not-fat
• Excludes the fat and includes the caesin, whey,
  lactose, proteins, minerals

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Production Practices

• Fewer cows are producing more milk
• Daries are becoming larger
• In major production areas daries are 1,000 cows
  or more
• Milk fresh from the cow is virtually sterile
• Post handling must maintain the milks nutritional
  value and prevent deterioration caused by
  physical and biological changes
• Equipement must be maintained to government and
  industry standards

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Production Practices

• Cows are milked twice a day
• Some farms milk 3-4 times/day
• Milk is immediately cooled from the body
  temperture of the cow to below 41 degrees F
• It is then stored at the farm under refrigeration
  until it is picked up by tanker trucks at least
  every other day
• A sample of the milk is collected at this time
  for later lab analysis

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Quality Control

• On the farm
• Inspectors monitor herd health, farm water
  supply, sanitation, milk temperture, holding
  times, bacteria counts
• Violations of health standards result in heavy
  penalties up to and including suspension from
  business
• Inspections occur both at the farm and processing
  plants on a regular on-going basis
• Inspectors have full authority to suspend plant
  operations in order to conduct detailed
  examinations of all equipment, facilities and
  products
• The dairy industry works hard to ensure that they
  comply with or exceed all regulations

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Quality Control

• Finished dairy products
• Tested regularly by state inspectors to ensure
  compliance with
• Standards of Identity
• Refers to criteria such as mouisture, butterfat,
  protein content
• Purity
• Refers to pathogens and residues criteria
• The Food and Drug Administration (FDA) sets the
  standards of identity for beverage milk products

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Processing

• When milk arrives at the plant it is checked to
  make sure that it meets the standards for
  temperture, total acidity, flavor, odor, tanker
  cleanliness and absence of antibiotics
• Butterfat and solids-not-fat content is analyzed
• These amounts will vary with the feed, breed of
  cow and time of year
• These are also used along with the volume to
  determine what the producer will be paid
• Once the milk passes these receiving test it is
  pumped into large refrigerated silos

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Pasteurizing

• Heating the raw milk to kill all pathogenic
  microoranisms that may be present
• Not sterilization
• After pasteurization some harmless bacteria may
  still be present
• these are the bacteria that cause milk to go
  sour
• Refrigeration is the best way to slow the growth
  of these organisims

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Pasteurizing

• Low Temperture Longer Time (LTLT)
• Heats milk to at least 145 degrees F for at least
  30 minutes
• Can cause a cooked flavor
• Not used by some milk plants for fluid milk
  products
• High Temperture/Short Time (HTST)
• Heats milk to at least 161 degrees F for at least
  15 seconds
• Milk is immediately cooled to below 40 degrees F
  and packaged in plastic jugs or plastic coated
  cartons
• Ultrapasteurization
• Heating milk to 280 degrees F or higher for 2
  seconds followed by rapid cooling to 45 degrees
  or less
• Ultrahigh Temperture Processing
• Sterilizes the milk
• Heats it to 280-302 degrees for 2 to 6 seconds
• Milk is aseptically packaged and does not require
  refrigeration until it is opened

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Butterfat

• Several different types of product
• Whole milk, 2, 1, nonfat, Half Half
• Seperated using separator that separates the
  cream and skim portions of the milk
• For example During the separation of whole milk
  two streams are produced the fat-depleted
  stream, which the above mentioned beverage milks
  are made of skim milk for evaporation and/or
  drying and the fat-rich stream, the cream

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Butterfat Cream

• Comes from the separator with a fat content of
  35-45
• Used for further processing in the dairy
  industryice cream, butter

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Homogenization

• Prevents the cream from rising to the top
• A homogenizer forces milk under high pressuure
  through a valve that breaks up butterfat globules
  to such a small size that they will not coalesce
  (stick together)
• Does not affect the nutrion or quality

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Beverage Milk

• Most raw milk fat content is 4 or higher
• Most beverage milk is 3.4
• Lower fat contents- 2, 1, Skim
• These products are produced by partial or
  complete skimming and then adding cream back to
  achieve the final desired fat content

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Nutritional Qualities

• Vitamins may be added
• A D most often due to their loss
• A during fat separation and heating
• D because it is not present in milk
• Supplemeted in the form of a water-soluble
  emulsion
• Many states have milk standards that require the
  addition of milk solids
• These represent the natural mineral, protein, and
  sugar portion of nonfat dry milk

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Quality Control

• Numerous test on raw and paterurized product
• Microbial organisims are tested for using the
  standard plate count (SPC) and ropey milk test
• Equipment used to analyze butterfat and
  solids-not-fat is calibrated on a regular basis
  to ensure consistency
• All products have a sell-by date
• Samples of the products packaged each day are
  saved to confirm they maintain their freshness 7
  days after the sell-by date

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Packaging

• Once milk is separated, standardized, homogenized
  and pasteurized it is held below 40 degrees F
• Then it is packaged into gallon, ½ gallon, quart,
  pint and half pint containers
• Packaging machines are maintained under strict
  standards
• All equipment is washed daily
• Automatic clean-in-place systems guarantee
  consistent sanitation with minimum manual
  handling to reduce the risk of contamination
• Once packaged the products are conveyored to cold
  storage where they are stored for a short time
  before being shipped to supermarkets where they
  are kept in cold storage or refrigerated display
  cases

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Milk Products and By-Products
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Milk Products and By-Products

• Include
• Butter
• Concentrated and dried milk
• Cheese
• Whey products
• Yogurt
• Fermented products
• Ice Cream

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Butter

• Made by churning pasteurized cream
• Churning breaks up the fat globule membrane
• This breaks the emulsion, fat coalesces and the
  water (buttermilk) escapes
• Federal law requires that it contain at least 80
  milkfat, nutritionally butter is a fat.
• Salt and coloring may be added
• Today commercial butter making is a product of
  knowledge and experience gained over the years

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Butter Make-Up

• Normal Salted Butter
• Fat 80-82
• Water 15.6-17.6
• Salt 1.2
• Proteins, Calcium, Phosphorous 1.2
• Also contains fat soluble vitamins A, D, E

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Butter

• Should have uniform color
• Be dense
• Taste clean
• Water should be dispersed in fine droplets so
  that the butter looks dry
• Consistency should be smooth so that it is easy
  to spread and melts readily on the tongue

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Making Butter

• From storage tanks the cream goes to
  pasteurization
• This destroys enzymes and microorganisms that
  would impair the keeping quality of the butter
• Next, ripening
• Here the cream is subject to a program of heat
  treatments designed to give the fat the necessary
  crystaline structure so it solidifies on cooling
• Takes 12-15 hours
• Churning
• Cream is violently agitated
• This breaks down the fat globules, causing the
  fat to coagulate into butter grains, leaving the
  liquid part (buttermilk)
• Butter is salted and worked to ensure even
  distribution
• Packaged
• Sent to cold storage

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Butter Churns From the Past
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Todays Butter Churn
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Concentrated and Dried Dairy Products

• Concentrated products have partial water removal
• Dried products have water removed to less than 4
• Benefits of both products are
• Increased shelf life
• Convenience
• Product flexibility
• Decreased transportation costs
• Storage

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Concentrated and Dried Dairy Products

• Concentrated Products
• Evaporated skim or whole milk
• Sweetened condensed milk
• Condensed buttermilk
• Condensed whey

• Dried Products
• Milk Powder
• Whey Powder
• Whey Protein concentrates

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Cheese

• Traditionally cheese was made as a way of
  preserving the nutrients of milk
• Cheese- the fresh or ripened product obtained
  after coagulation and whey seperation of milk,
  cream, or partly skimmed milk, buttermilk or a
  mixture of these
• THOUSANDS of varieties

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Cheese Making Steps

• Treat milk
• Additives
• Inoculation and milk ripening
• Coagulation
• Enzyme
• Acid
• Heat-acid
• Curd Treatment
• Cheese ripening

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Yogurt

• Semisolid fermented milk product
• Originated in Bulgaria
• Milk from a variety of animals is used in yogurt
  production but most of the industrialized nations
  use cows milk
• Starter culture used in most yogurt production is
  a blend of Streptococcus salivarius thermophilus
  (ST) and Lactobacillus delbruekii bulgaricus (LB)

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Making Yogurt

• Milk is clarified and separated into cream and
  skim milk
• Standardized to achieve the desired fat content
• Various ingredients are blended together in a mix
  tank equipped with a power funnel and an
  agitation system
• Mixture is then pasteurized
• Once the homgenized mix has cooled to an optimum
  growth temperature, the yogurt starter culture is
  added

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Fermented Milk Beverages

• Cultured Buttermilk
• Once a by-product of butter production, now
  produced from whole or skim milk
• Acidophilus Milk
• Traditional milk fermented with LA which is
  thought to have therapeutic benefits in the
  gastrointestinal tract
• Sour Cream
• Others

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Ice Cream (start)

• Greater than 10 milk fat by legal definition
• As high as 16 fat in some premium ice cream
• 9-12 milk solids-not-fat
• Also contains 12-16 sweeteners-usually a
  combination of sucrose and glucose-based corn
  syrup sweeteners
• 0.2-0.5 stabilizers and emulsifiers
• 55-64 water from the milk or other ingredients
• When frozen about half the volume of ice cream is
  air
• All ice cream is made from a basic white mix

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Basic Steps In Manufacturing Ice Cream

• Blending of the mix ingredients
• Pasteurization
• Homogenization
• Aging the mix
• Freezing
• Packaging
• Hardening

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Quality Products

• Established by USDA
• Grades are used to describe different grades of
  quality in butter, cheese (Cheddar, Colby,
  Monterey, Swiss)
• FDA established the Grade A designation for fluid
  milk products, yogurt and cottage cheese
• Grade standards are used to
• Identify levels of quality
• Provide a basis for establishing prices at
  wholesale
• Supply Conumers with a choice of quality levels

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Milk Substitutes

• Margarine
• Frozen desserts
• Coffee whiteners
• Whipped toppings
• Soy milk
• All are made by combining nondairy fats with
  certain classes of milk components

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Reduced Fat Products

• Brought on to the market in the effort to reduce
  calories, saturated fat, cholesterol
• When fat is replaced the replacement must perform
  the same functions as the fat.
• It must give the product the same texture or
  mouth feel
• Why?
• What would consumer repsonse be if it didnt?

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Summary

• Milk provides high quality protein, energy,
  vitamins, minerals
• Dairy industry provides a variety of milk
  products
• USDA and FDA maintain quality standards
• Milk is pasteurized to protect consumers against
  pathogens
• Milk is homogenized to keep milk fat in
  suspension
• Butterfat is separated from the milk to be added
  back in in the desired amounts
• Concentrated and dried products increase shelf
  life and convenience and decrease transportation
  costs
• USDA established grade standards for butter,
  cheese and instant nonfat dry milk
• FDA established grade designations for fluid
  milk, yogurt, cottage cheese
• Only officially graded products carry a grade
  shield
• In an effort to meet consumer demands the food
  industry has developed milk and milk substitutes
  and reduced fat products

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Lab

• Making Butter

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STUDENT ACTIVITY

• Develop a presentation comparing BUTTER to
  MARGARINE
• Compare their make-up (ie-butter is made from
  milk fat and margarine is made from vegetable
  oil)
• Compare their healthfullness
• Find pictures
• Make a poster