American Cheese Society First Cheese Plant in U.S. started by Jesse Williams in 1851 ... which influence rheological properties ... " Cheese Influences texture,

American Cheese Society

Montreal Canada August 2011

Rex C. Infanger

History of Cheesemaking• Earliest record of cheese consumption approximately 2000 B.C.

– First cheeses may have resulted from milk carried in stomach pouches– Agitation during travel would have started fermentation due to naturally-

occurring bacteria and enzymes, resulting in curd formation• First Cheese Plants at Monasteries in Europe approximately

1100 A.D. • First Cheese Plant in U.S. started by Jesse Williams in 1851• First Modern Cheese Culture isolated by Lister in1879

– Streptococcus lactis– Name later changed to Lactococcus lactis ssp lactis

• Storch (Denmark), Conn (USA), Weigmann (Germany) all determine that the fermentation of milk is due to naturally-occurring bacteria present in the milk in 1890

• Hammer establishes that citric acid is the source of flavor compounds in 1920

• Dr. Hugh Whitehead reports bacteriophage in 1935

Functions of Cultures• Acid Production

– Fast Acid Strains will coagulate milk in 18 hours at 69.8o F• Flavor

– Acid production of lactic oxaloacetic, actetic, pryruvic, and proprionic

– Glycolitic pathway produces diacetyl– Proteolytic pathway produces ammonia, acetaldehyde,

ketones and esters– Lipolytic pathway produces free fatty acids

• Syneresis (Moisture Loss)• Protein Agglomeration (Curd Formation)• Gas Production (Eye Formation & Flavor)

Culture Growth Stages

• Lag Phase• Growth Phase• Logarithmic Phase• Stationary Phase• Death

Mesophilic Cultures (52-104o F)

• Lactococcus lactis ssp. Cremoris (Streptococcus)

• Lactococcus lactis ssp. lactis• Lactococcus lactis ssp. lactis,diacetylactis

(taxonomically not recognized)• Leuconostoc mesenteroides ssp. cremoris

(homofermentative acid production)

Mesophilic Cultures (52-104o F)

Thermophilic Cultures (86-122o F)

• Streptococcus thermophilus• Lactobacillus delbrueckii ssp. bulgaricus • Lactobacillus helveticus• Propionibacterium shemanii

Thermophilic Cultures (86-122o F)

9

All Mesophilic Choozit MCCHOOZIT™ MC Cottage Cheese Starters

Tested in Pasteurized Milk - 1% Milk Fat, 90°F (32.2°C), Inoculation Rate = 1 bag of 1000 DCU per 1000 gal

4

4.5

5

5.5

6

6.5

7

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0

Time (Hours)

pH

MC70 MC71 MC72 MC76 MC77 MC78 pH 4.65

4.65

10

Meso/Thermo Cultures for Cottage Cheese

Choozit MCT Culture RangeTest in Pasteurized Milk - 1% fat, 95°F (35°C)

Inoculation Rate = 1 bag of 1000 DCU per 1000 gal

4

4.5

5

5.5

6

6.5

7

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8

Hours

pH

MCT 170 MCT 171 MCT 172 MCT 176 MCT 177 MCT 178 Target pH 4.65

4.65

Influence of temperature on a S. thermophilus

12

CHOOZIT™ MTDRobust on medium to high scalding temperature

Incubation on thermic cycle1/2 skim milk pasteurised

4

4.5

5

5.5

6

6.5

7

0 2 4 6 8 10 12Time in hours

pH

30

31

32

33

34

35

36

37

38

MTD rangeT

13

Acidification curves of CHOOZITTMMTD on Candia milk Inoculation level : 5 DCU

3,5

4

4,5

5

5,5

6

6,5

7

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

time (h)

pH

25°C

30°C

35°C

37°C

40°C

43°C

CHOOZIT™ MTDRobust on medium to high scalding temperature

Flexibility of use : medium to high scalding temperatureRobustness and consistencyA optimized cost in use associated with the key benefits of a freeze dried culture

Time to reach pH = 5.2

626

582

676

462

427 47

3

333

305

297

303

279

264279

255

240

255

223

214

364

375

366

0

100

200

300

400

500

600

700

800

2,5 5 7,5

Inoculation level (DCU)

min

25°C

30°C

35°C

37°C

40°C

43°C

49°C

14

• Physiological Role– Cell protection– Adhesion– Cell-cell interactions– Other roles

• Functionality– Total amount of polymer

produced– Molar mass– Monosaccharide composition– Linkage types– Interactions with milk proteins

LOOSE POLYMER (ROPY)LOOSE POLYMER (ROPY)CELL CAPSULESCELL CAPSULES

Bacterial Expolysaccharides (EPS)

Courtesy of J.Broadbent, USU

15

EPS Production

LACTOSE

LACTOSE-6P

galactose-6P glucose

tagatose-6P

tagatose-16dP

triose-P

glucose-6P

fructose-6P

fructose-16dP

glucose-1P dTDP-glucose dTDP-4K-6D-mannose

UDP-glucose UDP-galactose dTDP-rhamnose

REPEATING UNITS

HETEROPOLYSACCHARIDE

glyceraldehyde-3P pyruvate lactate

CELL WALL

16

EPS diversity in S. thermophilus

Used for S. thermophilus typing and key for yogurt texture

Cultures• Mesophilic and thermophilic

Lactococcus lactis, Lactobacillus(L.bulgaricus, L.helveticus), Streptococcus thermophilus

• Heteropolysaccharide (mixed sugar)

• Diverse compositions and structures which influence rheological properties

• Production - linked to growth phase, enhanced by suboptimal growth temperatures, near neutral pH and high C:N ratios

• Genetic instability

• Studies on engineering EPS

Applications• Grade A

(yogurt, sour cream, buttermilk, cream cheese)

Imparts or enhances texture and viscosity, controls syneresis.

• Cheese

Influences texture, moisture binding.

• Technical Issues

– Culture rotation – matching EPS characteristics in application

– Interactions with added stabilizers

– Capsular vs. ropy – excessive EPS in whey

Applications – Texture Strains

Stainless Steele Conveyor Belt

LAB Sources of Bacteria • Biofilms

• Production of starter cultures

The culture is first grown from a master seed inventory which is stored at ultra low temperatures

The culture grown from the master seed vial is then grown in a large fermentation vessel under optimal conditions for that strain

The cultures are then concentrated 15-20 times approximately using ultra filtration for maximum cell numbers and activity

• Production of Frozen Pellets– The concentrated liquid culture is then

pelletized and frozen rapidly in liquid nitrogen

– The frozen pellets are stored at ultra low temperatures ready for blending and packaging

• Freeze-dried cultures– The concentrated frozen pellets are placed in

a freeze-drier– Using low vacuum pressures they are slowly

heated to accelerate vaporization (sublimation)

– The vaporized water is collected on super chilled plates (condenser)

– When the product is completely dry (Takes 2-3 days) it is milled into powder form

– It is then QC tested and ready for packaging

Culture Format

• Single Strain (DSS)• Mixed Defined Strains• Mixed Undefined Strains

Culture Format – Mother CultureUsed as base for bulk starter and DVI starter preparation

• Lyophilized– Refrigerated storage up to one year– Reduced shipping costs– Higher production costs– Stable culture state – 45-60 minute hydration time

• Frozen– Lower production costs– Higher Shipping costs– Stability dependant on storage temperature

• -20o F: 2-6 Weeks• -40o F: 6-12 Weeks• -80o F: 12-24 Weeks• -346o F: Stable

– Thaw in cool, 100 ppm chlorinated water until product will just leave the container.

Culture Format – Bulk Starter• Lyophilized

– Refrigerated storage up to one year– Reduced shipping costs– Higher production costs– Stable culture state – 45-60 minute hydration time

• Frozen– Lower production costs– Higher Shipping costs– Stability dependant on storage temperature



Culture Format Direct Vat Inoculation (DVI)

• Lyophilized–Refrigerated storage up to one year–Reduced shipping costs–Higher production costs–Stable culture state –45-60 minute hydration time


• Frozen – Can– Lower production costs– Higher Shipping costs– Stability dependant on storage temperature




• Frozen – Pellet– Lower production costs– Higher Shipping costs– Stability dependant on storage temperature


– Do Not Thaw– dip bag in 50 ppm chlorinated water and add direct to vat

Adjunct Cultures

• Lactobacillus plantarum• Lactobacillus casei• Lactobacillus rhamnosus• Lactobacillus para-casei• Brevibacterium linens

Adjunct Cultures

Probiotic Cultures

• Lactobacillus plantarum• Lactobacillus casei• Lactobacillus rhamnosus• Lactobacillus para-casei• Lactobacillus acidophilus• Bifidobacterium lactis• Bifidobacterium bifidum

Molds

• Bleu– Penicillium roqueforti– Penicillium glaucum

• White– Penicillium camemberti– Geotrichum candidum

Antibacterial Agents – Bacteriostatic• Detergents• Acids• Antibiotics• Diacetyl• Niacin• Diplococcin• Hydrogen Peroxide• pH < 5.0 or >9.0

Antibacterial Agents – Bacteriocidal• Chlorine – 220 ppm

for 2 minutes• Iodophors – Acid

Iodine Solutions• Quaternary Ammonia

Compounds– 3 ppm inhibits– 50-100 ppm stops

acid development• Antibiotics

Antibacterial Agents – Bacteriophage

Life Cycle• Absorption of the phage to the cell wall• Injection of DNA• Cell synthesis of phage protein• Phage particles formed• Cell lyses with phage release

– 2-200 phage released– 35 phage average burst size– 30 minute replication

Bacteriophage Control

Stages of Reproduction (Lytic Cycle)

TRANSCRIPTION mRNA

INJECTION

DNA

PHAGE STRUCTURE PHAGE PROTEIN &DNA REPLICATION

ADSORPTION

LYSIS

PACKAGING


Control of Phage – Culture Rotation• Limited culture use of low-phage titer phage

unrelated culture• Defined cultures with known acid production• Undefined cultures may carry pro-phage• Routine phage testing• Use phage resistant cultures

– Adsorption resistance• Phage resistant media Ca++ chelation with phosphates

– Abortive resistance


Control of Phage – Cleaning• Destruction

– 50 ppm contact chlorine solution– 400 ppm aerosol chlorine solution

• Drains• Floors • Air Intake• Equipment

Typical Lactococcus lactis Bacteriophage

•A Virus that infects bacteria

•1/1,000 the size of bacteria

•requires calcium to attach

•airborne

•destroyed by sanitizers

•destroyed by extreme heat

•filtered out below 0.45 µm.

•High rate of mutation


BACTERIABACTERIA

11 22 44


BACTERIOPHAGEBACTERIOPHAGE

11 150150 22,50022,500


• How many bacteriophage is a problem?

– 100 ø/ml can slow down fermented dairy manufacture.

In 6000L (13,650 lbs.) of milk 2.5ml of phage contamination can cause a slow down.

Bacteriophage Control• Indications that I may have a Bacteriophage problem.

– Slow starter activity test results.

– Increased starter usage.

– Longer make times through a given production run.

– Difficulty achieving end pH targets.

• Bacteriophage is not a “static” problem, but instead develops quickly.

Bacteriophage Control• How to confirm bacteriophage contamination.

– Brom Cresol Purple (BCP) milk test.• Uses pH color indicator.• 6 hour test time required.• Less accurate method.

– Standard Plaque Assay• Phage Titer Assay.• Uses enumeration by plaque counts.• 16 hour test time required.• Most accurate method.

BCP-MILK ACTIVITY TEST

XXXWHEYVAT 10

BCP- ACTIVITY MILK+

INOCULATE WITHINDIVIDUAL

STARTER STRAINWHEY SAMPLE

MILK BLANK

WHEYBLANK

STARTERCONTROL

INDIVIDUAL STARTER STRAINS + WHEY


Standard Plaque Assay


XXXWHEYVAT 10

WHEY SAMPLE

SERIALDILUTIONS

OF WHEY

DILUTIONSPLATED ONTO

BACTERIAL LAWN

COMPLETE LYSIS TOO NUMEROUSTO COUNT

COUNTABLE PLAQUES(TITER)


• Characteristics that will be affected by phage.

– Acid Vs. Body Vs. Flavor cultures and resultant Bacteriophage affects.

• American cheese: Acid• Cottage cheese: Acid• Italian cheese: Acid and Flavor• Yogurt: Acid and Flavor and Body• Buttermilk/Sour cream: Acid and Flavor and

Body

Bacteriophage Control• Phage Control (Sanitation Issues)

– Vat refills• Rinse with chlorine between sets.

– Foot-baths/Boot spray.

– Hand-dips/Hand-wash/gloves.

– Floors,Walls,and Equipment Exterior/ Keep free of product at all times

– Garbage Cans in production area should be emptied and sanitized ever day

– Traffic/ Limit between raw and pasteurized side


• Phage Control (Starter Room Guidelines)

– Utilize proper HEPA filters for the starter room and sterile air filters on the tanks.

– Use flooring and wall material that can be easily foamed and cleaned.

– Provide a stationary fogging device near the ceiling for regular fogging.

Thank YouAny Questions ?

Documents

American Cheese Society First Cheese Plant in U.S. started by Jesse Williams in 1851 ... which influence rheological properties ... " Cheese Influences texture,