ULTRAFILTRATION in DAIRY PROCESSING

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ULTRAFILTRATIONinDAIRY PROCESSING

• GID523E Advanced Technologies in Dairy Processing
• Yrd.Doç.Dr.Meral Kiliç
• H. Eda Bakir 506051503

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Contents

• Introduction
• UF in Dairy Industry
• Main areas
• Categories
• Advantages Disadvantages
• Cheese quality
• Studies on UF in Dairy Products
• Conclusion

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Introduction

• What is Ultrafiltration (UF)?
• Selective separation technique
• MW 1000-200 000 Da
• Cross-flow over a membrane surface
• lt1000 kPa pressure
• UF membranes pore sizes 1 to 100 nm
• a polyethersulfone membrane for milk
  concentration process

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UF produces from milk

• Permeate
• contains water, lactose, soluble minerals,
  non-protein nitrogen and water-soluble vitamins
• Retentate
• contains proteins, fat and colloidal salts
  increased in proportion.

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UF in Dairy Industry

• Most commonly used membrane technology in dairy
  industry (together with reverse osmosis)
• Most widely used membrane technology in cheese
  industry
• In 2001, gt450 000 t of cheese produced

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UF in Dairy Industry

• Most successful commercial application of UF in
  cheese manufacture
• Feta in Denmark
• Quarg, Ricotta, Cream cheeses in Germany other
  European countries
• Standardization of milk protein to 4-5 for the
  production of Camambert and other varieties.

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UF in Dairy Industry

• Application of whey ultrafiltration in the dairy
  industry started with the separation and
  concentration of whey proteins from whey in 1972.
  
• The application of ultrafiltration in cheese
  processing started in 1983 for production of
  cottage cheese and soft varieties

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Three main areas in cheesemaking

• Low concentration factor ultrafiltration
• Medium concentration factor ultrafiltration
• High concentration factor ultrafiltration

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Low concentration factor ultrafiltration (LCF-UF)

• 1.5 2.0X
• standardization of milk to a fixed protein level
  to obtain a more consistent end product
• variations in gel strength at cutting, buffering
  capacity, and rennet casein ratio are minimized

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Medium concentration factor ultrafiltration

• increased cheese yield associated with retention
  of whey proteins
• increased moisture when whey proteins are
  denatured prior to filtration
• main commercial application in the production of
  high-moisture, unripened cheeses (Quarg, Cream
  cheese) and of cheeses that are not very
  dependent on proteolysis during ripening for
  flavor development (Feta)

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High concentration factor ultrafiltration (HCF-UF)

• gt6.0X
• widely used as an alternative to centrifugation,
  for concentrating the gelled milk in the
  commercial production of fresh acid-curd cheeses,
  such as Quarg and Cream cheese
• allows complete recovery of whey proteins and
  gives higher yields of cheeses of very acceptable
  quality
• used in commercial manufacture of rennet-curd
  cheeses, including cast Feta in Denmark and
  Cheddar in Australia

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Three categories in cheesemaking

• protein-standardized milk
• seasonal variations in milk
• intermediate or medium concentrated retentates
• main application manufacture of structured Feta
  cheese
• liquid pre-cheeses (LPC)

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Advantages of UF

• increases yield (16 to 20 increase in cheese)
• reduces production costs (reduction of the
  quantity of coagulant used by 80)
• new cheese varieties
• allows the manufacture of curd in such a way that
  less, or even no, syneresis occurs

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Disadvantages of UF

• Fouling is the limiting factor in all
  applications of membrane filtration of milk
• The amount of deposition on the membrane must be
  minimized, because the flux decreases and the
  selectivity of the seperation is affected
• Different fouling mechanisms adsorption, pore
  blocking, cake layer formation, and depth fouling.

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Properties of UF retentates

• Buffering capacity
• The buffering affect of pH 6.7 UF retentates
  leads to higher numbers of lactic starter
  bacteria in curd and resulting cheese
• Rheological behaviour
• The viscosity of UF retentates increases markedly
  with an increase in their protein content

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Cheese quality

• Texture
• texture defects of UF cheeses are caused by the
  higher content of Ca salts if UF retentates of pH
  6.7 are used for making cheese
• mineralization of the drained curd (total Ca and
  repartitioning of Ca between the casein matrix
  and the soluble phase) play an essential role in
  the rheology of the cheese variety. The mineral
  content may be adjusted.

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Cheese quality

• Proteolysis and ripening characteristics
• UF cheese ripens more slowly than traditional
  cheese
• the larger the amount of whey proteins
  incorporated, the slower the flavour development
• The rate of flavour development may be improved
  by adding flavour-producing enzymes or cell
  extracts
• Non-starter bacteria or slow-acidifying lactic
  microorganisms may be used for their proteolytic
  and flavour production potential

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Cheese quality

• Functionality
• characteristics such as melting behaviour,
  shredding ability, viscosity and strachability
  became important when cheese is used as
  ingredient.
• meltability of processed cheeses manufactured
  from Cheddar cheese base made from ultrafiltered
  milk is lower than that from regular Cheddar

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Studies on UF in Dairy Products

• Soejima, T., et all, 2003 evaluated the
  performance of centrifugal ultrafiltration method
  (UF) in comparison with trichloroacetic acid
  precipitation method (TCA) for the concentration
  of S. aureus enterotoxin in milk and dairy
  products.
• Conclusion UF using a centrifugal
  ultrafiltration membrane can be more readily
  performed and similar to or more reliable than
  TCA.

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Studies on UF in Dairy Products

• Hydamaka, A.W., et all, 2000, used
  ultrafiltration technology for the production of
  direct acidified cheese.
• Sensory evaluation indicated that cheese from
  ultrafiltration was preferred equally to
  traditional manufacture when the cheese was of
  similar composition

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Studies on UF in Dairy Products

• Erdem, Y.K., 2005 investigated the influence of
  ultrafiltration of whole and skim milk on
  rennetability in white pickled cheese
  manufacturing. The white cheese produced from
  unconcentrated whole milk via a traditional
  industrial method was compared with the white
  cheese produced by whole milk retentate (5.5-
  fold).
• It was suggested that producing of white pickled
  cheese from whole milk retentate
  (full-concentrated) was more suitable than
  manufacturing from skim milk retentate and was
  than better the conventional method which uses
  unconcentrated milk.

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Studies on UF in Dairy Products

• Low, Y.H., et all, 2004, treated regular and
  ultrafiltered (UF 1X, 2X and 4X concentrated)
  skim milk samples with a range of enzymes
  including calf rennet, ficin and papain and
  determined the clotting properties, curd casein
  profiles and free amino acid (FAA) contents.
• UF milk samples coagulated faster and formed
  firmer curds irrespective of protein
  concentration. The results suggest that the UF
  process may cause structural changes to proteins
  or other milk constituents with a resultant
  change in clotting properties and proteolysis of
  the casein molecules.

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Studies on UF in Dairy Products

• Erdem, Y.K., 2000 used fluorescent probe binding
  method to explain the changes on the surface of
  milk protein caused by ultrafiltration. Raw
  skimmilk samples were concentrated 2-fold and
  3-fold by ultrafiltration. The hydrophobicity of
  the surface sites of milk proteins in retentates
  and unconcentrated milk was examined.
• It was found that the number of surface
  hydrophobic sites and afinity to the
  hydrophobic/fluorescent marker decreased with
  ultrafiltration. This study suggests that the
  renneting pattern for milk is changed by this
  modification and can be one of the main reasons
  for some problems in hard cheese manufacturing
  from retentate.

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Studies on UF in Dairy Products

• Anhydrous milkfat (AMF) exhibits a broad melting
  point range (.40 to 60 .C) which can be separated
  into fractions of different and narrow melting
  point ranges using membrane technology.
• Abbas, H., et all, 2005 evaluated different
  membranes.
• The results indicate that at the optimum
  operating conditions of pressure (300 psi) and
  moderate stirring speeds (100 rpm), and at
  constant fractionation temperatures (30, 23, 20,
  17, and 13.5 .C) carried out separately, using
  the UF membrane (30 kDa), AMF can be successfully
  fractionated.

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Studies on UF in Dairy Products

• Muthukumaran, S., et all, 2005 used low frequency
  ultrasound to facilitate cross-flow
  ultrafiltration of dairy whey solutions.
• Experimental results show that ultrasonic
  irradiation at low power levels can significantly
  enhance the permeate flux with an enhancement
  factor of between 1.2 and 1.7. The use of
  turbulence promoters (spacers) in combination
  with ultrasound can lead to a doubling in the
  permeate flux.

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Studies on UF in Dairy Products

• Chen, C., et all, 2002, evaluated methods and
  enzymic processing conditions for manufacturing
  low-lactose milk containing oligosaccharides.
  Comparisons were made between the method of using
  b-galactosidase to transform the lactose in milk
  into oligosaccharides directly and the method of
  applying ultrafiltration techniques to separate
  lactose from milk proteins and then transform the
  lactose in the permeate into oligosaccharides.
• a useful procedure for manufacturing low-lactose
  high-oligosaccharides milk would be to separate
  milk proteins from lactose by ultrafiltration
  first, concentrate the UF permeate by
  evaporation, apply enzymic reaction in the
  concentrated permeate, and add the hydrolysate to
  the retentate to obtain the final milk product.

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Studies on UF in Dairy Products

• Erdem, Y.K., 2005 investigated the effect of heat
  treatment on the structure of the milk protein
  system in unconcentrated bovine skimmilk and its
  twofold and threefold ultrafiltered retentates.
• milk protein system was modified during and/or
  after ultrafiltration. The protein surface
  hydrophobicity index (PSH) of unconcentrated milk
  was the highest, followed by that of twofold and
  threefold retentates, respectively. It means that
  the protein system in skimmilk was reorganized to
  a more compact structure by ultrafiltration, and
  this reorganized structure gets stronger when the
  concentration factor was increased and the
  retentate was heat treated.

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Studies on UF in Dairy Products

• Mehaia, 2002, studied manufacturing procedures
  and compositional characteristics for fresh soft
  white cheese (Domiati-type) using
  ultrafilltration (UF) and conventional processes
  and evaluated yields, recovery of protein, fat,
  total solids and sensory characteristics of this
  type of cheese
• An increase of 21 in cheese yields, 2126 in
  protein recovery, 1519 in fat recovery and
  1722 in total solids recovery was achieved by
  the UF process

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Conclusion

• UF has been used widely in dairy industry since
  1970s, and in cheese manufacture since 1980s.
• Several studies has been held on various aspects
  of UF applications in dairy industry.
• UF increases yield and lowers production costs in
  dairy processing.