Lecture for the general student (third year) at faculty of veterinary medicine, Benha university. the lecture was taken on 20.2.2020. it presented a summary in cheese technology including some faults occur during storage and manufacture. in addition the nutritive value of cheese.

1. Cheese

2. It is a product made from curd obtained from whole, partial skimmed or skimmed
milk with or without cream addition --- by coagulation of protein by (rennet , lactic
acid, or suitable enzyme or acids) with or without further treatments of final product
(heating , pressing, ripening)
Cheese classification, more than 3000 name according to IDF described 510 cheese
Varieties differing according to moisture%, processing, ripening.
Cheese

3. 1- Milk used
2- Consistency
3- Processing
4- Ripening
5- Country produced
6- Holes

4. Major classification
Soft cheese
55-80% moisture
unripened ripened
Kareish
Cottage
Mozzerella
ricotta
Feta
Camembert
Brie
Pickled soft cheese
High fat
(Domiati)
Hard cheese
45-50% moisture
Hard grating
Parmensen
Ras cheese
Hard cheese
Ripened by bact.
As swiss
chedder
Semi-hard cheese
Edam & gouda
cheese, Roquefort
Processed
Whey cheese
as Ricotta
Cheese spread

5. Technology & Manufacture
Coagulation of casein curd by:
Organic acids
( acetic ,citric acid)
More acid curd&
Bad texture
(GDL)
Lactic acid by LAB
bacteria
Acid casein,lower yield
Bad texture
Rennet
Ca para caseinate
Higher yield & good
texture
Microbial rennin-
like enzyme
From mucor spp or
bacillus
Most common cheese making using both S.C (LAB) and rennet to produce good quality cheese

6. Rennet
Commercial extract of rennin extracted from abomasum of newly born calves(2 weeks)(??).
Recently most manufactures are using microbial rennin in the form of powder or tablet as a
Substitute of animal rennin but due to their shortage due to the mass cheese production
There is Microbial rennin –like enzyme and is preferred due to its purity( no pepsin) ,
easy production , Accepted by customers (no risk of animal disease and halal certified).
Factors affecting curdling efficiency by rennin enzyme (renneting)
1- Temperature : 30-36C
2- Acidity or pH : 5.4
3-Ca salt: as heat treatment leads to ppt Ca so, essential to add 0.02% for curd formation.
4- Purity of rennet: with more pepsin leads to low yield and bitter taste.
5- Time of reaction: ranged from 40-60 min.

7. Most standard technological steps of hard cheese
1)Selection & preparation of milk
-Color& flavour abnormalities
-Free from inhibitory substances
-TBC shouldnot exceed 300,000 cfu/ml
- SCC with permissible limit
2)Milk treatment
-Clarification under centrifuagtion 35ºC
-Storage 9-11ºC to easy whey off
-Thermisation 63ºC/15sec. Then cool 5ºC.
-Standardization: chedder 4% fat
-Pasteurization:HTST
-Concentration:UF
-Bactufugation: spore (blowing)
-Homogenization:
-Additives :?????
3)Addition of S.C
Addition of S.C /20-60min/35ºC
0.22% acidity help curdling
Some enzymes
4)Addition of coloring matters
pH:5.4
Temp:30-35ºC
Stirring/5 min.
Incubate 45-60min
6)Curd treatment
-Cutting
- healing& stirring
-Scalding
-Stretching
-De-wheying
- Milling
?????
7)Moulding& pressing
8)Salting, packaging, Ripening
5)Renneting

8. Additives :?????
Substances added to cheese milk for :
-Reducing salt in balance in casein micelles .. Ca –phosphate,citrate 15-20g/100 litter milk.
- elimination of spore forming bacteria by adding 0.04% H2O2/30min. Then add catalase enz.
To remove it.
-Provide cheese with special color as annatto , carotene
- addition of Co2 ---Toxic to pschrotrophs
-Sod. Nitrate 20g/100kg –edam cheese, gouda cheese to prevent gas forming acteria

9. Curd treatment
Cutting Curd is cut using cheese knives to initiate &encourage synersis,0.5cmfor cubes.
Stirring
Cuts remains undistributed for 5-15 min to firm cut curds (heal time).
Stirring for 20-30 min to expel more whey and get harder curd.
Scalding Or cooking vary 30-35C/ 45-60min according to the desired hardness, with
Continuous stirring to enhance synersis .
Stretching
De-wheying (cheddering)
In Mozzarella cheese , the curd stretched &Kneaded in hot water to develop
Stringy and fibrous body.
Drain whey & coalesce of particles (texture as chicken breast)
Milling Cheese mill to cut curd into slabs to get rid of whey. Salt may be added before milling

10. Cutting of the curd
Stirring the curdMilling the curd
Salting the curd

11. Salting
By using dry salt before milling or by pickling in brine solution after moulding:
-It enhance cheese flavour.
-It act as preservative by inhibition the bacterial growth.
-It controls the rate of ripening to assist the physico-chemical changes in the curd.
-It regulates the pH.
-Reduce the metabolic activity of LAB & assist the elaboration their intracellular enzymes
-Reduce moisture content in the curd &improve texture.
Ripening
It is a process specific to hard cheese production. It involves changes in chemical & physical
Properties accompanied by development of characteristic flavour. These changes are brought
By enzymes from LAB .

12. Changes occurred during ripening process
2- Microbial changes1- Chemical changes
Protein
proteolysis
Fat
lipolysis
Lactose
glycolysis
3- changes in the body &texture
Pencillum
Camemberti in
white cheese
Pencillum
roquiforti in
blue cheese
Like softening or firmness of the curd (body), presence of holes (open
cheese) , texture all are improved during ripening process under
enzymatic and formation of holes(Co2) from propionobacteria.

13. By the action of enzyme to Casein destruction into amino acids then into polypeptides+
peptones+ ketones+ aldhydes ( flavour compounds).
Protein proteolysis
Fat lipolysis
With liberation of free fatty acids (flavour compounds).
Breakdown of lactose producing lactic acid which responsible for flavor of cheese.
Lactose glycolysis

14. Advantage of UF (ultrafiltertion) in cheese
1- increase cheese yield. (100 Kg milk/ 40kg cheese while without UF 25kg.)
2- Get rid of excess amount of wheu (water, lactose,mineral).
3- need small amount of S.C + rennet.
4- more easier processing
5- uniform texture.

15. Role of S.C in cheese making
1- Lactic acid production (this important for rennin activity & curd texture)
2- Flavour compounds &gas production.
3- Enzymes as lipase & peptidase enhance flavour during ripening.
4- Color as mould starters.
5- Beneficial health.
6- prevent microbial growth by its bacteriocins.

16. Soft cheese manufacture ( Domiati)
1)Selection & preparation of milk
-Color& flavour abnormalities
-Free from inhibitory substances
-filtered through cheese cloths
Divided in to two portions
other part
salted & heated
Renneting : by mix two portions , Cool till 35C then renneting
one is raw act as
ca source
Cutting by cheese knives
Pickling in tins with addition salted whey /10days
Then storage 2-3 months
Moulding in cheese mould then pressing

17. Soft cheese manufacture ( Kariesh)
Home method: from clotted skim milk (after cream removal)---- then put in the mats
and drained overnight by gravity--- salted----pressed
Cottage cheese
As domiati cheese but prepared from pasteurized skim milk with addition of Ca salts,
SC (lactococcus & leuconostoc) before renneting --- no salting.
Brie cheese
As in cottage cheese but from high milk fat and its blocks smeared by penicillum caseicolum.
Camemert cheese
As in brie cheese and its blocks smeared by penicillum camemerti.

18. Processed cheese
1- it is mixture of different cheese or cheese powder, then blended with emulsifying
salts at 2% (Na citates) & water to give the desired flavor.
2- heat to 80-85C /5-8min in steam jacket vats till desired degree of consistency &
coloring matter.
3- the cheese is cooled & formed into portions before packing.
Cheese spread manufacture
Like processed cheese but water content is higher, whey or skim milk may be added.
Ricotta cheese or whey cheese
The whey produced from cheese making y traditional methods contains lactalbumin
and lactoglobulin. By acidification of whey by citric acid & heating to about 85C

19. Nutritive value cheese
1- variable content of fat.
2- concentrated source of protein
3- good source of vitamins and minerals especially Ca &phosphorus.
4- low lactose content for lactose intolerance people.

20. Cheese defects
(blowing , gassiness,or
openness)
Early blowing
(superfacial)
Late blowing
(Deep)
1- Microbial defect 2- non-Microbial defect
(souring)
(bitterness)
(rancidity) (fruitiness)
(slimness) (color defects)
Early days
Coliforms
Yeast(torula)
Circular holes
Covered /mucous
Fishy eye
Not change by
cutting
Cl . Perferinges
Large holes
Hard cheese
High sc
Prolong
Incubation
LAB
Proteolytic
M.Os
Lipolytic
M.Os
Proteus alkalig.
acrhromobacter
Yeast or torula
Black,red
,pink

21. Cheese defects
2- non-Microbial defect1- Microbial defect
Chemical faultsTechnological defect
Dryness , brittle
High acidity or salt
High cooking temperature
Long cooking time
Oxidative rancidity
(sunlight)
Fishy flavour

26. Thank you for attention
Presented by :
Dr. Dina A. B. Awad
Lecturer of food hygiene department
Faculty of veterinary medicine
Benha university , Egypt