1. Disclaimer
It is hereby declared that the production of the said content is meant for non-commercial, scholastic and research
purposes only.
We admit that some of the content or the images provided in this channel's videos may be obtained through the
routine Google image searches and few of them may be under copyright protection. Such usage is completely
inadvertent.
It is quite possible that we overlooked to give full scholarly credit to the Copyright Owners. We believe that the non-
commercial, only-for-educational use of the material may allow the video in question fall under fair use of such
content. However we honour the copyright holder's rights and the video shall be deleted from our channel in case of
any such claim received by us or reported to us.
3. • Food Microbiology:
• Food spoilage and microbial flora of fresh foods,
• Preservation of food,
• Microbiological examination of food,
• Fermented products and microorganisms as a food.
• Dairy Microbiology:
• Fermented dairy products: Starter Culture, Dairy fermented foods
(Cheese, yogurt and Indigenous dairy products India),
• Introduction to probiotics, prebiotics,
• Production and application of Baker’s Yeast,
• Application of microbial enzymes in Dairy industry
5. Starter Culture
• Starter culture means a selected strain of food-grade
microorganisms of known and stable metabolic activities and
other characteristics that is used to produce fermented foods of
desirable appearance, body, texture, and flavor.
• Some starter cultures are also used to produce food additives, as
probiotics and for drug delivery.
• This process was found to give better products than those
produced through natural fermentation of the raw materials.
• These starters were mixtures of unknown bacteria. Processing
plants started maintaining a good starter by daily transfer (mother
starter) and produced product inoculum from these.
6. • Bacteriological makeup of these starters (types and proportion of the desirable as
well as undesirable bacteria) during successive transfers was continually susceptible
to changes as a result of strain dominance among those present initially, as well as
from the contaminants during handling.
• Some private companies started supplying mixed cultures of unknown bacterial
composition for cheese manufacture both in the U.S. and in Europe.
• Subsequently, the individual strains were purified and examined for their
characteristics, and starter cultures with pure strains were produced by these
commercial companies.
• Initially, such starter cultures were developed to produce cheeses.
• Currently, starter cultures for many types of fermented dairy products, fermented
meat products, some fermented vegetables, fermented baking products, for alcohol
fermentation, and for other purposes (especially with genetically modified
organisms, GMOs) are commercially available.
8. Fermented dairy product
• Fermented dairy products can be broadly divided into two
groups: fermented milk products and cheeses.
• In fermented milk products, all the constituents of the milk
are retained in the final products, with the exception of those
partially metabolized by the bacteria.
• In cheeses, a large portion of milk constituents is removed in
whey to obtain the final products.
9. General method for production
1. Raw (or Starting) Materials
• A large number of raw materials from plant and animal
sources are used to produce fermented foods.
• These include milk (from cows, buffalo, sheep, goats), meat
(beef, pork, lamb, goat, and fowl), fish (many types), eggs
(chicken and duck), vegetables and vegetable juices, many
fruits and fruit juices, cereal grains, tubers, lentils, beans and
seeds.
• Some are used in combination
10. 2. Microorganisms Used
• Many desirable species and strains of bacteria, yeasts and
molds are associated with fermentation of foods.
• Depends on single predominating species and strain
• Some times mixed populations were used
• Depend on environmental parameters such as nutrients,
temperature of incubation, oxidation–reduction potential and
pH.
11. 3. Fermentation Process
• Foods can be fermented in three different ways, based on the
sources of the desirable microorganisms:
• Natural fermentation,
• Back slopping,
• Controlled fermentation.
12. 1. Natural Fermentation
• Many raw materials used in fermentation (usually not heat
treated) contain both desirable and associated
microorganisms.
• The conditions of incubation are set to favor rapid growth of
the desirable types and no or slow growth of the associated
(many are undesirable) types.
13. • A product produced by natural fermentation can have some
desirable aroma resulting from the metabolism of the
associated flora.
• However, because the natural microbial flora in the raw
materials may not always be the same, it is difficult to
produce a product with consistent characteristics over a long
period of time.
• Also, chances of product failure because of growth of
undesirable flora and foodborne diseases by the pathogens are
high.
14. 2. Back Slopping
• In this method, some products from a successful fermentation
are added to the starting materials, and conditions are set to
facilitate the growth of the microorganisms coming from the
previous product.
• This is still practiced in the production of many ethnic
products in small volumes.
• Retention of product characteristics over a long period may
be difficult because of changes in microbial types.
• Chances of product failure and foodborne diseases are also
high.
15. 3. Controlled Fermentation
• The starting materials (may be heat treated) are inoculated
with a high population (106 cells/ml or more) of a pure
culture of single or mixed strains or species of
microorganisms (starter culture).
• Incubation conditions are set for the optimum growth of the
starter cultures.
• Large volumes of products can be produced with consistent
and predictable characteristics each day. Generally, there is
less chance of product failure and foodborne diseases
16. Microbiology of Cultured Buttermilk Fermentation
• It is produced from partially skim milk through controlled
fermentation with starter cultures
• Starter (Controlled Fermentation)
• Lactococcus lactis ssp. lactis or Lactococcus cremoris is used
for acid and Leuconostoc mesenteroides ssp. Leuconostoc
cremoris for diacetyl and CO2.
17. Growth
• At 72℉, there is balanced growth of the two species, and
balanced production of acid, diacetyl, and CO2.
• Above 72 ℉, the growth of Lactococcus species is favored,
with more acid and less flavor;
• below 72 ℉, the growth of Leuconostoc species is favored,
with less acid and more flavor.
18. • Lactose (transported by PEP-PTS system) is hydrolyzed by b-galactosidase in
Lactococcus spp.:
19. • Lactococcus lactis strains should transport and hydrolyze lactose
(Lac+), metabolize P-galactose by the tagatose pathway,
• Strains will be phage resistant, not produce slime, and not be very proteolytic.
• Leuconostoc species should be able to transport and utilize citrate to
produce more diacetyl and less acetaldehyde and ferment lactose,
• Strains will be phage resistant, and not produce slime.
20. • Strains should not produce inhibitory compounds (such as
bacteriocins) against each other, but can have antimicrobial
activity toward undesirable organisms.
• Through selection and genetic manipulation, strains have been
developed that grow rapidly, produce desirable characteristics,
and are resistant to some phages.
• Current information on genome sequences of Lactococcus and
Leuconostoc strains and their phages will help develop better
strains in the future.
21. Microbial Problems
• Because of too much acetaldehyde production (especially if
biovar diacetylactis is used), green (yogurt flavor) may
develop.
• A slimy texture implies contamination with bacteria that
produce slime (Alcaligenes faecalis) or that starter cultures
(some Leuconostoc lactic strains) are slime formers
(exopolysaccharides).
• A yeasty flavor implies contamination with lactose-
fermentating yeasts, and a cheesy flavor alludes to
contamination with proteolytic psychrotrophs (during
storage).
• Proteolysis by proteases of contaminants in starters can also
cause development of bitter flavor, especially during storage.
22. Yoghurt
Yogurt is a variety of curd. Whole, low fat, skim milks & even cream can
be used to make yogurt.
In production of yogurt, a mixed culture of streptococcus thermophilus,
lactobacillus acidophilus is usually added to to the pasteurised milk & incubated
at 42-46°C.
Increase in folic acid concentration during fermentation.
Fermented milk is useful for a wide variety of disorders like
colitis, constipation, diarrhoea, gastroenteritis, diabetes & hyper
cholesteremia.
23.
24.
25. Microbiology of Yogurt Fermentation
• Plain yogurt has a semisolid mass due to coagulation of milk (skim,
low, or full fat) by starter-culture bacteria.
• It has a sharp acid taste with a flavor similar to walnuts and a smooth
mouth feel.
• The flavor is due to the combined effects of acetaldehyde, lactate,
diacetyl, and acetate, but 90% of the flavor is due to acetaldehyde.
• Many types of yogurt are available in the market, e.g., plain yogurt,
fruit yogurt, flavored and colored yogurt, blended yogurt, sweetened
yogurt, heated yogurt, frozen yogurt, dried yogurt, low-lactose
yogurt and carbonated yogurt.
26. Starters (Controlled Fermentation)
• Frozen concentrates or direct set starters can be used. Normally,
Lactobacillus delbrueckii ssp., Lactobacillus bulgaricus and
Streptococcus thermophilus are used.
• Some processors also combine these two with other species, such
as Lactobacillus acidophilus and Bifidobacterium spp.,
Lactobacillus rhamnosus, or Lactobacillus casei.
• However, in general, they do not compete well in growth with the two
yogurt starters.
• Therefore, they are added in high numbers after fermentation and
before packaging. They may not survive well when present in
yogurt with the regular yogurt starter cultures.
27. Growth
• For balanced growth of the two species, the fermentation is
conducted at 110℉ (43.3℃). At this temperature, both acid
and flavor compounds are produced at the desired level.
• If the temperature is raised above 110℉, the Lactobacillus
sp. predominates, causing more acid and less flavor
production;
• at temperatures below 110℉, growth of Streptococcus sp. is
favored, forming a product containing less acid and more
flavor.
28. Biochemistry
• In Lactose metabolism both species have a constitutive b-galactosidase
system, and lactose (transported by permease systems) is hydrolyzed to
glucose and galactose.
• Both species are homofermentative and produce lactate from glucose
by the EMP pathway.
• Lactobacillus delbrueckii ssp. or Lactobacillus bulgaricus strains have
enzymes for the Leloir pathway to metabolize galactose, but while
actively metabolizing glucose they do not utilize galactose well.
• Most Streptococuss thermophilus strains do not have the enzymes of
the Leloir pathway (or have a very weak system) and thus do not
metabolize galactose.
• As a result, galactose is excreted outside, causing its accumulation in
yogurt.
29.
30. • Phage Resistance.
• Both species have phages; resistant strains need to be developed and used.
• Symbiotic and Synergistic Relationship.
• Strain selection for best combinations is necessary.
• Antagonistic Effect.
• Strains should not produce inhibitory compounds (such as bacteriocins) against
each other.
• Good Survival to Freezing and Drying.
• Possible genetic basis needs to be studied to develop resistant strains to produce
concentrated starter cultures.
31. Yogurt as probiotic food
Yogurt is basically a probiotic food with live and active
cultures. It contains different kinds of bacteria that are
believed to be beneficial toyour overall health.
• Four majorstrains of bacteria to look for:
* Lactobacillus acidophilus,
* Lactobacillus bulgaricus,
* Streptococcus thermophilus, and
* Bifidobacteria
32. YOGURT Nutrifacts-
Yogurt is rich in potassium, calcium, protein
and B vitamins, including B-12
Yogurt is easiertodigest than milk
Yogurt contributes tocolon health
Yoghurt strengthens and stabilizes the
immune system
Research shows women who eat 4
cups of yoghurt/week have lessvaginal
and bladder infections
The lactic acid of yoghurt is a perfect
medium to maximizecalcium absorption
Yogurt can be used as an effectivedouche
33. Yogurt - A rich source of calcium
• An 225g serving of most yogurts provides 450 mg. of
calcium, one-half of a child's RDA and 30 to 40 percent of
the adult RDA forcalcium.
• Because the live-active cultures in yogurt increase the
absorption of calcium, an 225g serving of yogurt gets
more calcium into the body than the same volume of milk
can.
34. Cholesterol control
Although cholesterol is important and necessary for
human health, high levels of cholesterol in the blood
have been linked to damage to arteries and
cardiovascular disease.
Major dietary sources of cholesterol include cheese,
egg yolks, beef, pork, poultry, fish, and shrimp.
Cholesterol contributes to atherosclerosis - a condition
that greatly increases the risk of heart attack and
stroke - by suppressing the activity of a key protein that
protects the heart and blood vessels
35. Yoghurt as Cholesterol Reducer
Yogurt contains a factor that inhibits the synthesis of cholesterol from
acetate.
This factor may be either 3-hydroxy-3-methylglutaric acid
36. Dairy fermented foods -Cheese
• There are many types of cheeses, all require the formation of a
curd, which can be separated from the main liquid fraction, or
whey.
• The curd is made up of a protein, casein, and is usually formed by
the action of an enzyme, rennin (or chymosin), which is aided by
acidic conditions provided by certain lactic acid- producing
bacteria.
• These inoculated lactic acid bacteria also provide the
characteristic flavors and aromas of fermented dairy products
during the ripening process.
• The curd undergoes a microbial ripening process, except for a
few unripened cheeses, such as ricotta and cottage cheese.
37. • Cheeses are generally classified by their hardness, which is
produced in the ripening process.
• The more moisture lost from the curd and the more the curd
is compressed, the harder the cheese.
• Romano and Parmesan cheeses, for example, are classified as
very hard cheeses; cheddar and Swiss are hard cheeses.
• Limburger, blue, and roquefort cheeses are classified as
semisoft; Camembert is an example of a soft cheese.
38. • The hard cheddar and Swiss cheeses are ripened by lactic
acid bacteria growing anaerobically in the interior.
• A Propionibacterium species produces carbon dioxide, which
forms the holes in Swiss cheese.
• Blue and roquefort cheeses are ripened by Penicillium molds
inoculated into the cheese.
• The texture of the cheese is loose enough that adequate
oxygen can reach the aerobic molds.
• The growth of the Penicillillm molds is visible as blue-green
clumps in the cheese.
39. Cheese is made up of casein. Varieties of cheese are differentiated
according to their
Flavour
Texture
Type of milk
CHEESE
Hard
Bacterial
ripening
Cheshire ;
cheddar
Mould
ripening
Stilton
Semi hard
Bacterial
ripening
Gouda
Edam
Mould
ripening
Roquefort
Soft
Bacterial
ripening
Limberger
Mould
ripening
Camembert
Unripened
Cottage
cheese
* Salts & seasoning added
* Type of bacteria & mould species
used in ripening
* Manufacturing & processing method
40. Production of cheese
Maturation, curing ripening & ageing
Pressing & moulding
Milling & salting
Cheddaring
curd cutting & pilling
Curd formation
Pasteurised milk
Curd formation: pasteurised whole milk is brought to a
temperature of 31’C, starter & required colouring matter is added.
After 30 min rennin is added, stirred & allowed to set curd.
Curd cutting: into small cubes
Curd cooking: heated to 38°C & held for 45
min. curd is stirred to prevent matting.
Curd drainage: whey is drained off & curd is allowed to mat.
Cheddaring: cutting matted curd into blocks turning them at 15
min interval & then piling. It is then passed to curd mill which cuts
the slab into strips.
Salting the curd: to draw out the whey from curd & as
preservative.
Pressing: overnight
41. Examples of cheese, the microbes involved and the category
they can be placed
CHEESE MICROORGANISMS
SOFT,
UNRIPENED
Cottage
Lactococcus lactis Leuconostoc
citrovorum
Cream Streptococcus cremoris
Neufchatel Streptococcus diacetilactis
SOFT, RIPENED 1 – 5
MONTHS
Brie
Lactococcus lactis
Penicillium candidium
Streptococcus cremoris Penicillium
camemberti Brevibacterium linens
Camembert
Lactococcus lactis Streptococcus
cremoris Penicillium candidium
Penicillium camembert
Limburger Lactococcus lactis
Brevibacterium linens
Streptococcus cremoris
43. CHEESE MICROORGANISMS
HARD,
RIPENED 3 –
12 MONTHS
Edam
Lactococcus lactis, Streptococcus
cremoris
Gruyere Lactococcus lactis Lactobacillus
helveticus
Streptococcus thermophilus
Propionibacterium sheranii or
Lactobacillus bulgaricus and
Propionibacterium freudenreichii
Swiss Lactococcus lactis Lactobacillus
helveticus
Propionibacterium shermanii or
Lactobacillus bulgaricus and Streptococcus
thermophilus
VERY HARD,
RIPENED
12 – 16
MONTHS
Parmesan Lactococcus lactis Lactobacillus
bulgaricus Streptococcus cremoris
Streptococcus thermophilus
44. Secondary Microbes
Large holes: Propioni bacterium freudenreichii subsp.
Shermaniee
White moulds: Penicillium camembertii, P.
caseiocolum and P. candidum
Blue/green moulds: Penicillium roqueforti, P.
glaucum
Ripening adjuncts: Bacterial or yeast cultures added
in addition to the regular LAB cultures
Attenuated cultures which are not intended to grow
but only to contribute their enzymes.
45. Species
Major Known
Function
Product
Propionibacterium
shermanii
Flavour and Eye
formation
Swiss cheese family
Lactobacillus bugaricus
Lactobacillus lactis
Lactobacillus helveticus
Acid and
flavour
Yoghurt, Swiss, Emmental,
and Italian cheeses
Lactobacillus
acidophilus
Acid Acidophilus buttermilk
Streptococcus
thermophilus
Acid
Emmental, Cheddar, and Italian
cheeses, and yogurt
Streptococcus durans
Streptococcus faecalis
Acid and
flavour
Soft Italian, cheddar, and
some Swiss cheeses.
Leuconostoc citrovorum
Leuconostoc dextranicum
Flavour
Cultured buttermilk,, cottage
cheese, and starter cultures.
Some microbes involved in cheesemaking
46.
47. Contd..
Ripening: 60 days to 12 months depending on the flavour
required under controlled conditions of temperature & humidity.
Changes from a bland tough rubbery mass to a full flavoured
soft product.
Rennin splits protein into peptones & peptides.
Increases the B-vitamins & improves cooking quality.
Cheese has limited keeping quality & requires refrigeration, should be
kept cold & dry i.e., wrapped in wax paper or metal foil.
48. Health Benefits of Cheese
Cheesecontains a lots of nutrients likecalcium, protein, phosphorus, zinc,
vitamin A and vitamin B12. Calcium is one of the important nutrients most
likely to be lacking in the Americandiet.
The high-qualityprotein in cheese provides the bodywith essential building
blocks forstrong muscles.
If you are lactose intolerant, many cheeses, particularly aged cheeses such as
Cheddarand Swiss, contain littleor no lactose and areoften well tolerated.
49.
50.
51.
52.
53.
54. Probiotics
• Probiotics which are also
known as friendly bacteria or
good bacteria can be defined as
living microorganisms that are
beneficial to the health of their
host.
55. Mechanism of action of Probiotics
• Their positive effect is used for the restoration of natural
microbiota after antibiotic therapy.
• Therefore, probiotics may effectively inhibit the development
of pathogenic bacteria, such as Clostridium perfringens,
Campylobacter jejuni, Salmonella enteritidis, Escherichia
coli, various species of Shigella, Staphylococcus, and
Yersinia, thus preventing food poisoning.
• A positive effect of probiotics on digestion processes,
treatment of food allergies, candidosis and dental caries has
been confirmed.
57. • Probiotic microorganisms such as Lactobacillus plantarum, Lactobacillus reuteri,
Bifidobacterium adolescentis, and Bifidobacterium pseudocatenulatum are natural
producers of B group vitamins (B1, B2, B3, B6, B8, B9, B12).
• They also increase the efficiency of the immunological system, enhance the
absorption of vitamins and mineral compounds, and stimulate the generation of
organic acids and amino acids.
• Probiotic microorganisms may also be able to produce enzymes, such as esterase,
lipase and co-enzymes A, Q, NAD, and NADP.
• Some products of probiotics’ metabolism may also show antibiotic (acidophiline,
bacitracin, lactacin), anti-cancerogenic, and immunosuppressive properties
58. • Molecular and genetic studies allowed the determination of
the basics of the beneficial effect of probiotics, involving four
mechanisms:
• (1)Antagonism through the production of antimicrobial
substances
•(2)Competition with pathogens for adhesion to the epithelium
and for nutrients
• (3) Immunomodulation of the host;
• (4) Inhibition of bacterial toxin production.
59.
60. Prebiotics
• Different prebiotics will stimulate the
growth of different indigenous gut bacteria.
• Prebiotics have enormous potential for
modifying the gut microbiota, but these
modifications occur at the level of
individual strains and species and are not
easily predicted priorly.
• Furthermore, the gut environment,
especially pH, plays a key role in
determining the outcome of interspecies
competition.
61. • Both for reasons of efficacy and of safety, the development of prebiotics
intended to benefit human health has to take account of the highly individual
species profiles.
• Fruit, vegetables, cereals, and other edible plants are sources of
carbohydrates constituting potential prebiotics.
• The following may be mentioned as such potential souces:
• Tomatoes, artichokes, bananas, asparagus, berries, garlic, onions, green
vegetables, legumes, as well as oats, barley, and wheat.
62. • Some artificially produced prebiotics are, among others:
• lactulose, galacto oligosaccharides, fructo oligosaccharides, malto oligosaccharides,
cyclodextrins, and lactosaccharose..
• Fructans, such as inulin and oligofructose, are believed to be the most used
and effective in relation to many species of probiotics
63. Mechanism of Action of Prebiotics
• Prebiotics are present in natural products, but they may also be added to food.
• The purpose of these additions is to improve their nutritional and health value.
Some examples are: inulin, fructo oligosaccharides, lactulose and derivatives of
galactose and β-glucans.
• Those substances may serve as a medium for probiotics.
• Prebiotics are not digested by host enzymes and reach the colon in a practically
unaltered form, where they are fermented by saccharolytic bacteria (e.g.,
Bifidobacterium genus).
• The consumption of prebiotics largely affects the composition of the intestinal
microbiota and its metabolic activity.
• This is due to the modulation of lipid metabolism, enhanced absorbability of
calcium, effect on the immunological system, and modification of the bowel
function.
64. Acidophilus Milk
Acidophilus milk, also known as sweetacidophilus milk orprobiotic
milk.
Milk that has been fortified with Lactobacillus acidophilus orother
friendly bacteriaculturessuch as
i. Lactobacillus bulgaricus,
ii. Bifidobacterium bifidum, or
iii. Streptococcus theromphilus.
65.
66. Lactose intolerance
Lactose intolerance, also called lactase
deficiency and hypolactasia, is the inability to
digest lactose,a sugar found in milk and some
dairy products. Lactose intolerant individuals
have insufficient levels of lactase— the
enzyme that metabolizes lactose—in their
digestive system
•SYMPTOMS:
Abdominal bloating and cramps, flatulence,
diarrhea,
• nausea, borborygmi (rumbling stomach)
and/or vomiting after consuming significant
amounts of lactose.
67.
68. Application of microbial enzymes in Dairy industry
• Enzymes produced by microbial sources are biological
molecules that known to catalyze biochemical reactions
which lead to stimulate the necessary chemical reactions, as
well as to the formation of fermented products.
• Microbial protease, lipase and β-galactosidase are important
examples of such interest in industrial food and dairy product.
69. Protease
• Proteases (mixture of peptidases and proteinases) also known as
hydrolytic enzymes, peptidases and proteolytic enzymes.
• They are one of the largest group of enzymes in biotechnology and
most important enzyme which produced on a large scale, nearby 60%
of the world enzyme market.
• This enzyme that catalyze the hydrolysis of protein into amino acid or
smaller peptide fractions, which depends upon the optimum pH.
• They are defined as alkaline, neutral or acidic proteases.
70. • Microbial proteases are classified as exopeptidases and endopeptidases on
basis of site of protein action which recognized into different families
included :
• Serine carboxy proteases (EC 3.4.16),
• Metallo carboxy proteases (EC 3.4.17),
• Serine proteases (EC 3.4.21) family includes trypsin, chymotrypsin,
elastase.
• Cysteine proteases (EC 3.4.22),
• Aspartic proteases (EC 3.4.23) which have two aspartic acid residues in
the catalytic of the active site.
71. • Microbial rennin is also one of the most significant enzymes,
produced by GRAS microorganisms like Mucor pusilis, Mucor
miehei and Bacillus subtilis.
• It has been used instead of calf's rennin in cheese manufacture.
• Thus, this enzyme has a low proteolytic activity and high milk-
clotting activity.
72. • Most of the commercial protease produced from bacteria viz. Bacillus that
is the major source. It is one of the most important industrial enzymes in
the world markets.
• The major application is recognized in dairy industry for cheese ripening,
hydrolyzing whey protein and flavor development.
• Moreover, enzyme used to debittering of protein hydrolysates, synthesis of
aspartame and accelerating cheese ripening times.
• Furthermore, proteases were also used for the production of milk proteins
with low allergenic activity, which used as an ingredients in milk formulas
of baby milk powder.
73. Lipase
• Lipase (EC 3.1.1.3) is also called as glycerol ester hydrolases, a lipolytic
enzyme.
• Lipases are the key enzymes involved in fat digestion, catalyze the
triacylglycerols reaction to fatty acids and glycerol, mono or di-
glycerides and extracellular enzyme.
• They are mainly produced from fungi when induced by adding oils and
fats. Microbial lipases constitute as an important group of
biotechnologically valuable enzymes.
• Nowadays, bacterial lipases are receiving attention due to itʼs function
in extreme conditions
74. • Generally, commercial source of microbial lipase including fungi such as
Aspergillus, Mucor, Rizopus and Candida
• while Pseudomonas, Achromobacter, Staphylococcus and Bacillus reported
as bacterial lipases producers.
• Most of the researches indicated lipase application in dairy industry.
• For acceleration cheese ripening,
• hydrolysis of milk fat,
• development of lipolytic flavours in some cheese ripening which produces a wide
range of compounds by primary and secondary biochemical pathways.
• Moreover, the lipolysis of fat in butter, margarine and cream.
75. β-galactosidase
• β-galactosidase (EC 3.2.1.23) is another name lactase, Lactosase and
Lactosidase enzymes are classified in hydrolases class belongs to family
35 of the glycoside hydrolases (GH- 35).
• This enzyme is located in the border membrane of the small intestine of
humans and other mammals, which responsible to hydrolyze the
glycosidic bond of ß, (1-4) in lactose and produce glucose and galactose.
• This disaccharide is present in mammalian in concentrations up to 10%
(w/w) and foremost sugar present in dairy products. Also, has an ability
to catalyze the reverse reaction of the hydrolysis called as
transglycosylation.
76. • The main function of the β-galactosidase is to hydrolyze lactose into glucose
and galactose.
• The β-galactosidase could reduce the crystallization problem during storage
due to low dissolvability of lactose.
• Developed to a biosensor to apply for the quantitative detection of lactose in
commercial milk samples from two enzymatic activities; one of them is
glucose oxidase and second is β-galactosidase.
77. • Whey lactose hydrolysis has a number of beneficial uses,
which is characterized by high in sweet.
• So, it is a source of "sugars which can be used in the manufacture
of sweets and syrup as an alternative to sucrose used for bread and
pastry, and also in ice cream.
• Moreover, Saccharomyces cerevisae can ferment to the whey
(contain lactose hydrolase) as a carbon source for production
of alcohol and other a wide range of the bio products.
• β-galactosidase is one of the most popular enzyme in the
dairy industry, which works on the Lactose hydrolysis either
from milk to glucose and galactose.
78. • Many characteristics and qualities of the dairy products were
improved such as solubility, flavor, sweetness, digestibility,
problem of crystallization, resulting a sandy or gritty texture
and mealy (in ice cream, condensed milk and frozen milks)
was decreased while increasing of nutritional value by adding
galacto oligosaccharides.
• β-galactosidase could employed to converts the whey lactose
into the useful products such as sweet syrups that are used in
soft drink, confectionery and bakery industry.
79. • On the other hand, milk lactose hydrolyze with β- galactosidase was
also used in the various dairy products such as yoghurt, processed
cheese and some other products.
• They are enzymatically obtained which is considered as a substrate
that is selectively utilized by probiotic bacteria conferring to the health
benefit with the reduction of a significant number of potential
pathogenic bacteria.
Editor's Notes
homofermentative : that produces a single fermentation product
EMP: Embden–Meyerhof–Parnas for glucose catabolism
The organoleptic quality of a food affects how a consumer experiences the food via their senses (look, taste, smell, and touch).
