Dairy products

17 important questions on Dairy products

Building a dairy product value chain

Raw whole milk ((3.5% protein /4.5% fat)
  • Semi-skimmed milk (3.5% protein / 1.5% fat)
  • Cream (2.5% protein / 40% fat
    • Butter (80% fat)
    • Buttermilk

What do we produce from 850 billion kg of milk?

Afbeelding
  • liquid milk / fresh dairy
  • cheese
  • butter /butteroil
  • milk powder
  • condensed milk
  • whey ingredients
  • water

There are 3 key elements when going from milk to dairy products:

Raw materials
  • (standardized) milk
  • Cream
  • Whey

Ingredients
  • Lactic acid bacteria (cheese, yoghurt)
  • Enzymes (cheese)
  • Salt, sugar etc

Processes
  • Heat treatment
  • Drying
  • Fermentation
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What are the 4 objectives about liquid milk products

  1. Absence of pathogenic micro-organisms (phosphatase negative)
  2. Prolonged shelf life
  3. Flavour, taste and nutritive value close to fresh raw milk
  4. No creaming during storage (homogenisation)

When looking at heat treatment there are desired and undesired effects, name them

Food safety / shelf life

  • Inactivation of pathogens
  • Inactivation of spoilage bacteria
  • inactivation of enzymes


Sensory / nutrition
  • Denaturation of proteins
  • Aggregation of proteins
  • Maillard reactions
  • Degradation of lactose
  • Off-flavour formation
  • Degradation of vitamins

What is the basic process of pasteurised milk products?

  • Thermization to inactivate micro-organims
  • Separation /standardization to achieve the right composition
  • Homogenization to prevent creaming
  • Pasteurization to inactivate micro-organisms and enzymes
  • Cold storage to limit microbial growth and enzyme activity
  • Achievable shelf-life: several weeks during cold storage

When looking at pasteurised milk, the shelf life depends on (7)

  1. Initial number of bacteria
  2. Number of Bacillus cereus spores
  3. Pasteurisation conditions
  4. Recontamination after filling
  5. Storage temperature
  6. Growth rate of bacteria
  7. Activity of natural inhibitors

What is the basic process of sterilised milk products?

  • Thermization to inactivate micro-organisms
  • Separation / standardisation to achieve the right composition
  • Homogenization to prevent creaming
  • Sterilization to inactivate micro-organisms and enzymes
  • Aseptic packaging to prevent any recontamination
  • Order of steps can differ
  • Ambient storage
  • Achievable shelf-life: several months or even years

When talking about sterilised milk the product quality and shelf life depends on (6)

  1. Decimal reduction time of heat-resistant spores
  2. Residence time distribution
  3. No bacterial enzymes present that cannot be fully inactivated
  4. Inactivation of enzymes naturally present in milk
  5. Aseptic packaging (or in bottle sterilisation)
  6. Low oxygen content


Shelf-life of sterilised products is typically limited by sensory and physical stability

High quality milk should be low in

  • Low number of bacteria
  • Low number of psychrotrophic bacteria which form heat-resistant proteases and lipases (sterilised milk)
  • Low number of Bacillus ceraus (pasteurised milk)
  • Low number of very heat resistant spores (sterilised milk)
  • Low somatic cell count, low free fatty acid content
  • No antibiotics

How does age gelation occur

Zie afbeelding

What are the characteristics, main variants and use of butter


  • Product should contain minimum 80% milk fat
  • Product should not contain more than 16% water
  • Salt and starter cultures may be added


Main variants
  • Sweet (non-fermented) or cultures (fermented)
  • Salted or non-salted


Use
  • At home use
  • Ingredient
  • Base material for milk fat products

Cream fermentation in butter

Lactic acid formation
Diacetyl formation

Cooling and churning of cream to make butter -->

Pre-cooling regime of cream
  • Part of milk fat must be crystallized
  • starter bacteria must be active
  • fatty acid composition determines butter consistency
  • different temp/time combinations for butter in summer and winter

Churning temperature important; 8-12 *C

Industrial method for butter making

Improvements compared to traditional butter
  • FFA in butter cream
  • Butter milk can be dried
  • Fat crystallisation not influenced by temperatures needed for starter growth
  • Continuous process
  • Sweet buttermilk!

Kneading butter granules, how?

  • Excessive moisture squeezed out
  • phase inversion from oil-in-water to water-in-oil
  • large water droplets disrupted

The quality of milk for butter making

  • Fat content
  • Fatty acid composition
  • Absence of off-flavours
    • animal feed
    • short chain fatty acids after lipolysis
    • fat oxidation
  • Absence of fat soluble chemical contaminants (PCB, dioxins, pesticides)

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