Ch 6 Cheesemaking Flashcards
What will be the determining factor in final cheese yield?
The amount and ratio of milk solids (protein and fat)
What factors can influence an animals milk yield?
- stage of lactation
- nutritional condition
- species/breed
- overall health
What standards must raw milk meet (in general terms) for cheesemaking?
Free of antibiotics
Meet the regulatory limits on somatic cell count and bacterial counts
What feed can lead to off flavors in cheese, especially if eaten close to the time of milking
Silage
Wild onions
Other byproduct feed
What can be passed on to the milk if silage was fed to the animal?
Thermoduric bacteria (streptococcus and lactobacillius) and spore forming bacteria (bacillus and clostridium)
What impact can thermoduric bacteria have on cheese?
Can cause late gas blowing or unwanted gas production
Scientifically speaking, how much can pasteurization reduce microbial populations?
Five log reduction for all major pathogens of concern. Ex: listeria of 1,000,000 down to 10
What is the principal of pasteurization?
That each particle of milk be heated to a specific temperature for a specific time
What is cut in/cut out?
The forward flow of raw milk (cut in) into a HTST pasteurization mechanism vs the diversion of milk (cut out) when there is an issue with the pasteurizer
What is a Bactofuge?
A milk separator designed to remove bacteria or spores from milk, usually installed inline with a pasteurizer
How does one test to see if pasteurization was successfully completed?
Phosphatase testing
note that this can reappear in pasteurized milk if too much time has elapsed since pasteurization
What are some specific varieties of cheese that are legally mandated to use pasteurized milk, other than the soft cheeses due to the 60 day aging rule?
Monterey Jack
Munster
Mozzarella
Higher or lower? Which pH in cheese will lead to greater risk of pathogenic bacteria?
Higher
What role do starter cultures play in cheesemaking?
-convert lactose into lactic acid (preparation for curd formation)
- releases enzymes which impact proteolysis and lipolysis (flavor)
- impact on elasticity
- may produce gas which can give open texture
What is the OPTIMAL growth range for Mesophilic bacteria?
86-104F
What is the OPTIMAL temperature range for Thermophilic bacteria?
98-113F
Which are more sensitive to salt; Mesophilic or Thermophilic cultures?
Thermophilic
Which tend to have less of an impact during the aging of the cheese, Mesophilic or Thermophilic?
Thermophilic
Which cultures can help protect from slow acid production due to overheating of the vat?
Thermophilic
What are NSLAB?
Non starter lactic acid bacteria
If using direct vat set cultures and you’re not able to use the entire lot, how should the cultures be added?
Dissolve the whole batch in milk to ensure that the full blend of cultures is used.
How are direct vat set cultures stored?
Frozen
Which are less expensive, bulk set or direct vat set cultures?
Bulk set
Which produces more consistent results: direct set or bulk set cultures?
Direct set
Which has the higher risk of bacteriophage contamination: direct set or bulk cultures?
Bulk
What is an easy way to help reduce the risk of bacteriophage?
Rotate the cultures used in cheese; since phages are strain specific, eliminating a particular strain-even if only for a few days- can have an impact
How do you know if there has been a bacteriophage attack?
Initial acid production is slowed or stops altogether in cheese production
When receiving direct vat set cultures, what should you look for?
Product should be packed with dry ice
Should be free flowing; not clumpy (indicates temp abuse)
What ruminant milk types have a “buffering” effect, causing the pH to naturally rise?
Sheep and Water Buffalo
What are some examples of cheeses that are directly acidified?
Ricotta
Mozzarella
Paneer
What cultures are added to cheese to impact flavor development and texture
Adjunct or secondary cultures
What are Listex and Holbac?
Two protective cultures, designed to target specific pathogenic bacteria
New Science-may become more important in future of cheesemaking
What type of annatto is used in cheesemaking?
Water soluble
What is a drawback to using annatto in cheesemaking?
Can cause pinking when exposed to light
How does the addition of calcium chloride affect cheese?
Increase in curd firmness
What are the types of rennet?
- Animal “traditional”
- Fermentation Produced Chymosin FPC
- Microbial - produced from molds/yeasts
- Vegetable - cardoon thistle
_______ is the stage between culture addition and coagulant addition.
Ripening
How long is the ripening stage?
30-90 minutes, depending on cheese produced
What is the purpose of ripening?
Starter bacteria will reconstitute (if dried) or thaw (if frozen) and begin to convert lactose into lactic acid.
What happens during ripening?
Lactic acid bacterial growth will start small but will increase as they acclimate to the milk.
The time when the pH changes is when rennet enzymes are added
What is the set temperature for most cheeses?
86-96F
What is the set temperature?
The initial temperature milk is brought to, raw or pasteurized, before coagulation
Why is ripening important?
It gives time for more lactic acid bacteria have time to reproduce, leading to a faster acid production throughout the cheesemaking process
What would happen if you were using a higher temperature during ripening?
- Shorter coagulation time
- too high, May inactivate and have no coagulation
- may lead to tough, rubbery curd
How should coagulants be added to milk?
Dissolved in cool water (40-50F) and stirred
As soon as the coagulant is added, STOP stirring! Don’t want to break up the curd as it’s forming
Single strength rennet is defined in the US as:
1:15,000 basis
1 unit of rennet will coagulate 15,000 units of milk
Milk from animals with mastitis leads to milk with a _______ pH
Higher (more alkaline )
How is casein affected when using milk with high somatic cell counts?
Break down of casein and slow coagulation
What is flocculation?
The initial step of coagulation where particles suspended in the solution begin to form flakes (flocs)
What is a standard set time?
The amount of time the cheesemaker has determined needs to elapse during the coagulation phase before curd is to be cut
If coagulating a cheese through heat (as in ricotta) what can be added to help with curd formation?
Acid - enables the cheese to coagulate at a lower temp and risk a “burnt” taste due to excessive heat
If a cheese has been coagulated using an enzyme method, how should the coagulum be cut and treated?
Cut into small pieces, heated, pressed
If a cheese has been coagulated using a heat set method, how should the coagulum be cut and treated?
Scooped from the vat and formed into molds
If a cheese has been coagulated using an acid set method, how should the coagulum be cut and treated?
May be put into bags to drain
What are possible outcomes if the coagulum is too weak when cut?
Curd will shatter, resulting in loss of fat and protein to the whey; loss of yield
Lower moisture content
What are possible outcomes if the coagulum is too firm when cut?
Higher moisture content as the curd cannot contract properly to expel whey
Possible over acidification
What tools are used for cutting curd?
Harp (vertical and horizontal)
Knife
Ladle/dipper
What is healing?
Allowing the cut curds to sit, without stirring, for up to 10 minutes after cutting.
Why is the healing of cheese important?
Curds are fragile just after cutting; allowing them to sit gives helps the edges of the curd to set and develop
When would cheese not be healed?
If using an automated or round vat where cutting can take up to 10 minutes. Healing may cause an unwanted knitting of curd.
What is the purpose of cooking and stirring cut curds?
Whey removal
When cooking curd, how should the heat be applied?
Want to achieve 40% of the increase in temperature within the first half of the cooking time with the remaining 60% in the later half.
Essentially, slower warming at the beginning with higher temps at the end. About 10-12F per 30 minutes
What are reasons to wash curds?
- aid in achieving cooking/cooling temp
- removal of lactose, acidity
- texture (think cold water w/ Colby)
What cheeses are washed/cooked curd?
Continental styles (Gouda, Havarti, etc)
Monterey Jack, Colby
What is the temperature of water used for continental cheeses? Colby/Monterey Jack?
Continental-warm at the beginning of cook time
Colby-cool at the end of cook time
How can whey be drained away from the curds?
- By pump, directly into molds
- by ladle
- direct opening of valve on vat
What is the purpose of knitting curds?
More whey removal
What are the three ways that curd can be knitted?
- in the vat (cheddars)
- in a press (Goudas)
- in a draining hoop (blues)
What are two types of milling cheese?
- Peg milling - tears curd apart
- Cutting mill - cuts curd with knives/blades
Type of mill used will impact fat and moisture retention
What types of salt are traditionally used in cheese making?
- cheese salt (ultra fine ground, non-iodized rock salt)
- kosher salt
What types of salt SHOULD NOT be used for cheese?
- iodized salt
- coarse grain salt
- unrefined sea salt
- solar salt
What are the three ways that salt can be added to cheese?
Dry salting BEFORE pressing
Dry salting AFTER pressing (surface rubbed)
Brining
How should salt be added if dry salting?
In increments, stirring well and allowing about 5 minutes between each addition
What controls the thickness of a natural rind cheese?
The humidity and temperature within the aging chamber
What should the salt content of a brine be?
About 23%. The brine should also be acidified to be the same pH as the cheese
What can be added to a brine to keep rind defects from forming?
Calcium Chloride; want it to match the amount of calcium in the cheese
What can be added to a brine to keep rind defects from forming?
Calcium Chloride; want it to match the amount of calcium in the cheese
Why is salt added differently between hard cheeses and soft cheeses?
Salt inhibits bacterial growth and acid development. With soft cheeses, you need the initial pH to be more acidic; these cheeses are salted AFTER they have been fermented overnight and achieve the desired pH.
What is one major difference between hard and soft cheeses in regards to salt?
When the salt is added to the cheese. Soft cheeses normally salted the following day after shaping
What can influence rind development?
- temperature
- humidity
- airflow
- cheese composition
Which cheese aging environment inherently is a high risk for pathogen contamination and growth?
Soft and mold ripened cheeses (both blue and white mold)
At What temperature are hard cheeses best aged?
46-64F
At what temperature should bacterial washed cheese be held?
53-57F
At what pH do smear ripened cheeses start out?
Around 4.75-4.9; will increase as the cheese ages
What is the temperature range needed for aging alpine style cheeses?
57-75F with 80-85% humidity
The warmer the room and the time in the warmer room, will help to determine the size of the eyes within the body. Warmer=larger eyes
How should wood boards used for aging be cleaned?
- pressure washed and scrubbed with 140F chlorinated alkaline solution in water
- rinse with 140F
- sanitized with either 200ppm chlorine solution or 10% hydrogen peroxide solution
- air dried and kept clean and quarantined until use
- can dry in kilns as well
Is there a legal requirement for cheese mite presence in cheese
No, but the FDA suggests that having more than 6 mites per square inch of cheese surface could be grounds for regulatory action
How can cheese mites enter a facility?
- on workers clothes (most common spread)
- outside materials
- via air currents
What is a way to mitigate cheese mites?
All workers in aging areas should use new uniforms, especially when moving from space to space
How long does it take a generation of cheese mites to reach adulthood and reproducing?
10 days.
Adults can live 2-5 months
At what temperatures do cheese mites grow best?
42- 86F
Other than temperature, what is another option to reduce cheese mite growth?
Diatomaceous earth; rubbed and brushed on the surface
What temperature inhibits cheese mite growth?
35-41F. However, this range is not ideal for aging of natural rind cheeses and will significantly slow ripening
What can affect how thick or tough a rind will develop on cheese?
- the brining process
- oil and/or salt rubs
- temp/humidity of the aging room
How does a salt rub on the surface of the cheese affect rind growth?
- dehydrates surface
- creates a barrier that influences microflora as the rind will be high in salt and low in moisture
What can affect how smear ripened cheeses rind develops?
- The temperature and humidity of the aging room
- the moisture and pH level of the cheese will greatly determine the time needed to ripen
At what temperature will the aging process slow?
52F
When aging smear ripened cheeses, why is pH so important?
The pH of the brine used should be at the same pH as the cheese.
- if higher than the cheese, can breakdown proteins on the surface, causing a weak rind.
- need it to be a hospitable pH for B. linens growth
What are some issues that can occur during rind development?
- undesired flora
- mechanical splits in the rind
- migration of calcium phosphate from the cheese to the surface (causes off flavor and cardboard texture)
What causes calcium phosphate to leach from the cheese to the surface?
Poor aging room temp control
When aging cheese, what is the ideal condition (in general) for aging rooms?
Should be kept consistent for temp and humidity, gradually decreasing as the rind develops
What effect does bandaging a cheese have on the cheese body?
Will result in a drier, flakier body. Usually done on cheddars
How is flavor impacted by bandaging a cheese?
The molds and/or mites attack the fats in the bandage of the cheese rather than the cheese body itself
What fats are generally used in bandaged cheese?
Bacon fat or lard
How is affinage carried out with bandaged cheeses?
-mold growth begins in about 1 month
- should be brushed away from the surface of the cheese to encourage even mold growth and remove mites. Don’t use circular strokes as it digs into the body.
- recommended to brush at least once, every other week
How should cheese brushes be cleaned?
- cleaned with chlorinated alkaline cleaner
- sanitized with either chlorine, PAA, or iodine based sanitizer
- air dry
- can also boil or use a dishwasher with sanitizing option
- Deptil Acid San is used for soaking of brushes
Why is cheese waxed?
- create mold barrier
- reduce moisture loss
- make cheese attractive and easier to handle
Why use paraffin wax?
Provides good CO2 permeability; flexible
At what temperature should paraffin be heated to when coating cheese?
Initial dip at 225-240F to flash off any surface moisture or unwanted bacteria/molds
Following dips at 160-180 until desired thickness achieved
What is the usual coating for goudas?
PVA (polyvinyl acetate)
- addition of natamycin (mold inhibitor) allows for low maintenance aging
What happens to the rinds of cheese that have been vacuumed packed?
Nothing. The cheese will remain as it was packaged
Only faulting packaging will result in mold
What are characteristics of a cheese for successful vacuum packing?
Cheese needs to be drier; must have the legal composition as outlined by the CFR prior to being sealed.
Any excess whey present in the cheese will pool within the package, causing calcium lactate to form.
What type of packaging is used on Swiss cheese?
Non barrier films as they allow oxygen into the package. Important as these cheeses develop carbon dioxide during aging.
Which ages better: cuts or whole pieces?
Whole
What pathogen can be a risk for vacuum packed cheeses due to its anaerobic environment?
Clostridium botulinum
What affect does vegetal ash have on cheese?
Decreases the acidity on the surface of the cheese, allowing white mold to develop earlier in the aging process.
According to the FDA’s 21 CFR 101.100, what is a processing aid?
A substance added to food for technical or functional effect during processing but are present in the finished food at such insignificant levels and have no technical or functional effect.
Are processing aids required on ingredient labels by the FDA?
No
What does GRAS stand for?
Generally Regarded as Safe
Why are ash ripened cheeses wrapped in paper rather than wax or plastic?
Wax and plastic would cut off oxygen supply to the cheese, killing molds and create excess moisture.
