Shelf Life of IceCream

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Shelf Life of Ice-Cream

• Ayça YUMLU
• Sükran SOMUNCUOGLU
• Pinar KOCAMAZ
• Duygu GÜREL

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• Ice cream is a complex food emulsion of
  dispersed water and fat phases incorporating air,
  emulsifiers, stabilisers and flavourings
• Typical ice cream composition
• ? Milk fat (10-16)
• ? Milk solids (10-12)
• ? Sweeteners (12-16)
• ? Stabilizers and emulsifiers
  (0,2-0,5)
• ? Water (55-65)

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Blending
Pasteurisation
Cooling
Ageing
Freezing
Packaging
Hardening
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Loss of Quality

• Physical Assessment
• Ice recrystallization
• Lactose crystallization
• Chemical Assessment
• Oxidation
• Microbiological Assessment
• Nutritional Assessment

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Physical Assessment

• Ice recrystallization
• Recrystallization
  
• any change in the number, size, shape,
  orientation, or perfection of crystals following
  completion of initial solidification
• ! unstable grow larger fewer
  
• 
  in number

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• Recrystallization
• promoted when a product stored at conditions
• where the mobility of molecules is high
• Occurs more rapidly at temperatures close to
• the melting point
• ! Temperature fluctuations
• larger fluctuations rapid
  crystallization

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• Recrystallization phenomena is affected by
• initial crystalline state
• subsequent processing steps
• storage conditions
• product formulation

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• Lactose crystallization
• high content of milk solid storage at
• ideal temperatures lactose crystallizes
• from
  unfrozen phase
• Unfrozen phase
• - dissolved sugars - milk solids
• - stabilizers
• sandy texture

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• Parameters influence lactose crystallization
• the level of MSNF
• sweeteners and stabilizer
• insoluble components
• storage conditions

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Chemical Assessment

• Oxidation
• autooxidation copper and certain
  other metals with oxygen and air
• initiated in the phospholipids of the fat globule
  membrane
• photooxidation light induced
• strong lightening in grocery stores
• riboflavin and free-fat content

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• Oxidation reactions lead to
• a loss in flavor quality
• development of off flavors
• interaction of these two leading to
• uncharacteristic flavor generation

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Microbiological Assessment

• ice cream is a suitable medium for
• microbiological growth
• containing milk
• having high nutritional value
• long storage life
• nearly neutral pH value

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• hazards can be eliminated during
• pasteurization (spores can be survived)
• freezing
• hardening
• ! if there is any improper operation between
  pasteurization and freezing, microbiological
  growth and spoilage can be observed

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Nutritional Assessment

• Nutritional value of ice cream mainly
• depends on
• milk fat content
• riboflavin content
• If oxidation reactions occur during
• storage, the nutritional value decreases

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Maintaining Shelf Life

• Glass Transition
• Tg temperature for the
• stability of
  foods
• the relative mobility of molecules is extremely
  low
• it is difficult for the molecules to rearrange
  into more ordered states

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• processes that depend on molecular mobility occur
  very slowly
• non-enzymatic browning
• oxidation
• enzymatic changes
• rate of rxns decreased below Tg

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• storage no changes in ice
• below Tg crystal size
  distribution
• For standard ice cream
• Tg value -35oC to -40oC
• storage temp -10oC to -20oC
• ! above the Tg stability of ice cream can be
  maintained by usage of stabilizers

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• Stabilizers
• hydrocolloids contribute to the body, texture,
  flavour release and freeze thaw stability of ice
  cream

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• used for
• smoothness in body and texture
• retarding or reducing ice and lactose crystal
  growth during storage
• providing uniformity of product
• resistance to melting
• slow down moisture migration from the product to
  the package or the air

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• Action of polysaccharides in ice-cream
• result from their ability to form gel-like
• structures in water and to hold free water
• reduction in the growth of ice crystals
• (recrystallization) by reduction in water
• mobility

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• Other Application to Extent Shelf Life
• Formulating ice cream properly
• Providing effectiveness of all processing steps
• Freezing quickly in a well-maintained barrel
  freezer

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• Hardening the ice cream rapidly
• Avoiding temperature fluctuations
• during storage and distribution
• Providing low and constant
• temperatures
• Educating retailers and consumers
• about shelf stability

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