Cheese

1
Cheese
2
(No Transcript)
3
Cheese

• Rennet-coagulated
• Cheddar, Mozzarella, Kasar, White
• Acid-coagulated
• Cottage, Quarg
• Acid/heat coagulated
• Ricotta, Queso Blanco, Lor

4
Principles of cheese making

• Clotting of the milk
• Removal of whey (syneresis)
• Acidification
• Salting
• Moulding
• (Salting)
• Ripening

5
Clotting

• Rennet
• 80 Chymosin, 20 pepsin
• Endopeptidase Aspartyl proteinase
• Higher activity at a lower pH
• At pH 6.7, 105Phe-106Met bond of ?-casein is
  cleaved
• Some chymosin become adsorbed onto paracasein and
  transferred into cheese
• Lower the pH more adsorption

6
Clotting

• 1. Enzymatic reaction
• Limited by diffusion of enzyme molecules
• Temperature has a slight effect increases the
  diffusion
• Ca2 activity has a little effect
• A certain ionic strength is required
• At decreasing pH, the affinity of enzyme for the
  micelles increases
• if too low, enzyme is strongly adsorbed onto
  micelles, cannot be released and diffuse to
  another molecule
• Local enzyme effect

7
Rennet

• Extracted from stomach of calves or kids or lambs
  by using 15 NaCl
• Porcine, bovine, chicken pepsin
• Rhizomucor miehei
• Cryphonectria parasitica
• Recombinant microbial rennet
• Chymosin cloned in Kluyveromyces lactis, E. coli,
  Aspergillus niger
• R. Miehei proteinase cloned in A. oryzae

8
Rennet

• Measurement of rennet coagulation time
• Rennet added to milk at 30 C and formation of
  visible flocs observed
• Formograph
• Hot wire sensor

9
Clotting

• 2. Flocculation
• Occur when 70 of casein is split
• The more hairs removed, the faster flocculation
• Ca2 activity
• Neutralizing charges
• Forming bridges between paracasein micelles
• T gt 20C
• At lower T, protruding hairs of ?-casein prevent
  flocculation

10
Clotting

• Renneting time
• Time required for visible flocs to occur
• Inversely proportional to enzyme concentration
• Determined by the slower reaction
• At low temperature, no flocs
• At very high T, inactivation of enzyme
• Ca2 activity
• Low activity, slow flocculation
• Flocculation not fastened after a certain amount,
  due to rate of enzymatic reaction determining the
  rate
• pH
• Low pH affect enzymatic reaction
• Too low pH, local splitting and local flocculation

11

• Heated milk
• High heat treatment
• Increased clotting time, a weaker curd, an
  impaired syneresis
• Rate of enzymatic reaction affected a little
• Flocculation becomes much slower
• Not only due to decrease of Ca2 activity
• Associated serum protein increases micelle
  stability
• Addition of CaCl2 and lowering pH improve
  rennetability
• pH cycling, lowering below 6 and increasing again
  6.4

12
Syneresis

• Gel formation and syneresis
• When viscosity approaches infinity, a gel is
  formed
• Modulus of the gel increases by micelle
  aggregation
• Then by strengthening of the junctions by fusion
• A particle gel
• Strands of casein particles, three particles in
  thickness, 10 particles long, alternated by some
  thicker nodes of particles
• Pores in ?m width
• Exhibit syneresis, expel liquid
• Particles form bonds with many particles
• Result in compaq packaging of the particles
• Some bonds are broken, some bonds are formed
  inducing syneresis
• pH 5.25, maximum syneresis
• pH 4.6 minimum syneresis
• Syneresis increases with increase in T cooking

13
Acidification and cultures

• Lactic acid bacteria
• Produce acid, reduce redox potential, anaerobic
  environment
• Lc. lactis ssp. cremoris Cheddar, Dutch, Blue
• Thermophilic Lactobacillus, St. thermophilus
  Swiss, Mozzarella
• Leuconostoc species Dutch cheeses
• Diacetyl, CO2 from citrate
• Secondary cultures
• Propionibacterium shermanii in Swiss cheese
• Penicillium camemberti in Camembert and Brie
• Yeast and Brevibacterium linens in Munster,
  Limburger, Tilsit, Trapist
• Penicillum roqueforti in Roquefort cheese
• Adjunct culture
• Intensifying or modifying flavor, accelerated
  ripening
• Mesophilic Lactobacillus ssp. or lactose(-)
  Lactococcus ssp. in Cheddar
• Galactose() Lactobacillus in Mozzarella

14
Moulding

• When desired pH and moisture obtained, curd
• are separated from the whey and placed into
• moulds
• Large size retain gas
• Pressure is applied for low moisture cheeses
• Scalding for Pasta filata cheeses (Mozzarella,
  Provolone, Halloumi, Kasar)
• Heated in hot water (70-75 C), kneaded and
  stretched when the pH reaches about 5.2-5.4
• Fibrous texture obtained

15
Salting

• Dry salting of the curd Cheddar
• Dry salting on the surface of the cheese
  Romano, Blue cheeses
• Brine salting White, Kasar, Mozzarella
• 14-23 salt in brine
• 0.7 Emmental
• 7-8 Domiati, Bulgarian White cheese
• aw, growth and survival of bacteria
• Promote syneresis, reduce moisture content of
  cheese
• Positively affects flavor

16
Chemical changes

• Lactic acid formation
• Lower pH to 5.1
• Dissolution of CCP
• Rate of syneresis, fusion of curd
• Flavor compounds produced
• Reduction of redox potential, low pH, lactic
  acid, antibiotics, anaerobic conditions produced
  by LAB, inhibit nonstarter organisms
• Moisture loss
• Salt diffusion

17
Ripening

• 3 weeks for Mozzarella, 2 years for Parmesan
• Glycolysis, lipolysis, proteolysis
• Native enzymes
• Plasmin, lipase
• Coagulant
• 6-20 rennet
• Rennet paste (Romano, Provolone)
• Starter bacteria
• Extracellular proteinase in Lactococcus,
  Lactobacillus, Streptococcus
• Intracellular peptidases, esterases and
  phosphatases, lysis required
• Nonstarter bacteria
• Mesophilic lactobacilli, Micrococcus, Pediococcus
• Secondary and adjunct cultures
• Propionibacterium shermanii in Swiss cheese
• Penicillium camemberti in Camembert and Brie
• Yeast and Brevibacterium linens in Munster,
  Limburger, Tilsit, Trapist
• Penicillum roqueforti in Roquefort cheese
• Diffusion of salt and water

18
Compositional Factors

• Casein and fat content determine the yield of
  cheese
• Fat/casein ratio determine fat content in dry
  matter, affect syneresis, ultimate water content
  of cheese
• Lactose content determines potential for lactic
  acid production, affect pH, water content
• pH of cheese depend on the buffering capacity of
  the dry matter
• Ca2 activity determine rennetability and
  syneresis tendency
• Mastitis, low lactose content, low ratio of
  casein in total protein, slow clotting, poor
  syneresis
• Presence of antibotics prevent bacterial growth
• Flavor defects in milk is transferred into cheese

19

• Accelerated ripening
• Elevated ripening temperature
• Exogenous proteinases and/or peptidases EMC used
  as ingredients
• Attenuated (freeze-shocked, heat-shocked) LAB
• Adjunct cultures (mesophilic lactobacilli)
• GM starters

20

• Acid-coagulated cheeses
• Spread or ingredient
• Mostly produced from skim milk and are consumed
  fresh
• Acidification by using a Lactococcus starter or
  an acidogen to pH 4.6
• Quarg, cottage, cream cheese
• Acid/heat- coagulated cheeses
• pH 5.2, 80-90 C
• Produced from whey (or from mixture of whey with
  milk)
• Ricotta, Queso Blanco, Lor

21

• Processed cheese
• Blending shredded natural cheese of the same or
  different varieties and at different degree of
  maturity with emulsifying agents
• Heating the blend under vacuum with constant
  agitation until a homogeneous mass is obtained
• Emulsifying salts
• Citrates, orthophosphates, pyrophosphates,
  polyphosphate, aluminium phosphates
• Not emulsifying, not surface active
• Supplement emulsifying properties of cheese
  proteins by sequestering calcium, solubilizing,
  dispersing, hydrating and swelling the proteins
  and stabilizing pH

22

• Cheese analogues
• Cheese-like products made from casein,
  emulsifying salts, water, oil
• Used for pizza
• Meltability and stretchability