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H2 O

ENZYME TECHNOLOGY

Enzymes speed up metabolic reactions by
lowering energy barriers
• A catalyst is a chemical agent that speeds up a
reaction without being consumed by the reaction
• An enzyme is a catalytic protein
• Hydrolysis of sucrose by the enzyme sucrase is
an example of an enzyme-catalyzed reaction

© 2011 Pearson Education, Inc
...


A

B

C

D

Free energy

Transition state

A

B

C

D

EA

Reactants
A

B
G  O

C

D

Products
Progress of the reaction

How Enzymes Lower the EA Barrier
• Enzymes catalyze reactions by lowering the EA
barrier
• Enzymes do not affect the change in free
energy (∆G); instead, they hasten reactions
that would occur eventually

© 2011 Pearson Education, Inc
...


Substrate Specificity of Enzymes
• The reactant that an enzyme acts on is called the
enzyme’s substrate
• The enzyme binds to its substrate, forming an
enzyme-substrate complex
• The active site is the region on the enzyme
where the substrate binds
• Induced fit of a substrate brings chemical groups
of the active site into positions that enhance their
ability to catalyze the reaction

© 2011 Pearson Education, Inc
...


1 Substrates enter active site
...

Substrates
Enzyme-substrate
complex

Active
site

Enzyme

1 Substrates enter active site
...

Substrates
Enzyme-substrate
complex

3 Active site can
lower EA and speed
up a reaction
...


1 Substrates enter active site
...

Substrates
Enzyme-substrate
complex

3 Active site can
lower EA and speed
up a reaction
...

Enzyme

5 Products are
released
...

Products

Effects of Local Conditions on Enzyme
Activity
• An enzyme’s activity can be affected by
– General
environmental
factors,
such
as
temperature and pH
– Chemicals that specifically influence the enzyme

© 2011 Pearson Education, Inc
...


Rate of reaction

Optimal temperature for
Optimal temperature for
typical human enzyme (37°C) enzyme of thermophilic
(heat-tolerant)
bacteria (77°C)

60
80
Temperature (°C)
(a) Optimal temperature for two enzymes
0

20

40

Rate of reaction

Optimal pH for pepsin
(stomach
enzyme)

0

5
pH
(b) Optimal pH for two enzymes
1

2

3

4

120

100

Optimal pH for trypsin
(intestinal
enzyme)

6

7

8

9

10

Cofactors
• Cofactors are nonprotein enzyme helpers
• Cofactors may be inorganic (such as a metal in
ionic form) or organic
• An organic cofactor is called a coenzyme
• Coenzymes include vitamins

© 2011 Pearson Education, Inc
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(a) Normal binding

(b) Competitive inhibition

(c) Noncompetitive
inhibition

Substrate
Active
site

Competitive
inhibitor

Enzyme

Noncompetitive
inhibitor

Enzymes in food processing

Enzymes in food processing
...

Enzymes are proteins with powerful catalytic function
...
Their action on food components other
than their substrates are negligible, thus resulting in the
formation of purer products with more consistent properties;
 They are more environmentally friendly and produce less
residuals (or processing waste that must be disposed of at
high costs) compared to traditional chemical catalysts
...

 Work under mild conditions of temperature, pressure and
pH
...

 Control of enzyme activity and reaction rate
...


Undesirable effects:
 Enzymes like proteases, lipases, and carbohydrases break down
biological molecules (proteins, fats, and carbohydrates, respectively)
which, if not controlled, may adversely impact flavor, texture, overall
product quality
...
g
...
g
...

 Polyphenol oxidases (PPO) and lipoxygenases (LOX) promote oxidations
and undesirable discolorations and/or color loss in fresh vegetables and
fruits
...
C)
in foods
...

Enzymes have been used inadvertently or deliberately in food
processing since ancient times to make a variety of food products, such as:





breads,
fermented alcoholic beverages,
fish sauces,
cheeses
...


Sources of food enzymes (plant, animal, microbial, and
recombinant)
...

Industrial enzymes have traditionally been derived from:
Plants: α-amylase, β-amylase, bromelain, β-glucanase, ficin,
papain, chymopapain, and lipoxygenase
Animals: trypsins, pepsins, chymotrypsins, catalase, pancreatic
amylase, pancreatic lipase, and rennin (chymosin)
Microorganisms: α-amylase, β-amylase, glucose isomerase,
pullulanase, cellulase, catalase, lactase, pectinases, pectin lyase,
invertase, raffinose, microbial lipases, and proteases
...

Advantages of microorganisms as a source for enzyme
production:





Easy and fast grow
...

Relatively cheep culture compounds
...


Saccharification enzymes
Production of maltose syrup:
Fungal α-amylase: exo-amylase, which hydrolyses the alpha1,4-linkages in liquefied starch (amylose and amylopectin); A
prolonged reaction results in the formation of large amounts
of maltose
...

β-amylase are exo-enzymes, which attack amylose chains
resulting in maltose production
...


Maltose syrups (maltose content from 50 to 80%) are
produced by saccharifying liquefied starch with maltogenic
exo-enzymes - fungal α-amylase or barley β-amylase, also
known as malt extracts
...

 Because of the low glucose content, high maltose syrups
show a low tendency to crystallize
...


Production of glucose syrup:
Glucoamylase (amyloglucosidase):
(exo-amylase) which
hydrolyses alpha-1,4-linkages as well as alpha-1,6-linkages in
liquefied starch (amylose and amylopectin)
...


Eventually, almost complete conversion of starch into glucose
can be obtained
...


Isoamylase and pullulanase (de-branching enzymes)
Isoamylase and pullulanase hydrolyse alpha-1,6-glycosidic
bonds of starch, which has been partly hydrolyzed by
alpha-amylase
...


with pullulanase generates

Using heat-stable and acid-stable pullulanase in
combination with saccharification enzymes makes the
starch conversion reactions more efficient
...

A sweetener alternative to white
sugar (sucrose) produced from
sugar cane or beets
...

Glucose can reversibly be isomerized to fructose
...


The isomerization reaction can only be economically
efficient by using immobilized enzyme
...

The enzyme granules must be rigid enough to
prevent compaction during the operation
...

The immobilization procedure consists of a
disruption of a cell concentrate through with a
homogenizer
...
The concentrated aggregate is
extruded and finally fluid-bed dried and sieved
...


Saccharification products and their application

Use of enzymes in dairy products manufacturing
Proteases: To act on milk proteins to modify texture and
solubility properties of milk and other dairy products;
accelerate cheese ripening and improve flavor intensity
...
It is a coagulant which degrade kapa-casein to
produce cheese curds
...


Genetic technology has been used for the commercial production
of a 100% pure chymosin product from microbes
...

The microbes used for the production of this type of rennet include
nonpathogenic microorganisms
 Escherichia coli K-12,
 Kluyveromyces marxianus var
...
awamori
...
Fermentation
follows to produce pro-chymosin, cell destruction, activation
of the prochymosin to chymosin (by cleavage of 42 amino acids), and
harvesting/producing large yields of pure, 100% chymosin
...


Lactose is present in milk (about 4
...
Lactose has
low solubility resulting in crystal formation at concentrations above 11 %
...
Therefore, it can be used in the
production of ice cream and sweetened flavored and condensed milks to
prevent “sandy” taste
...

It also improves the 'scoopability' and creaminess of the product
...

Of the Thai, Chinese and Black American populations, 97%,
90% and 73% respectively, are reported to be lactose
intolerant
...

Severe tissue dehydration, diarrhea and even death may
result from feeding lactose containing milk to lactoseintolerant children and adults
...
g
Aspergillus oryzae
biotech
...
co
...
gif

www
...
uni-regensburg
...
/E/Ueberbl
...


www
...
com/SCD%20Lactose%20Free
...
Stronger flavored cheeses, for example, the Italian cheese,
Romano, are prepared using exogenous lipases
...

Animal lipases are obtained from kid, calf and lamb
...

Microbial lipases are readily available for cheese-making, but less
preferred, since they are less specific in what fats they hydrolyze
...

Hydrolysis of the shorter fats is preferred because it results in the desirable
taste of many cheeses
...


Bio-protective enzymes (preservatives)
Bio-protective enzymes offer a natural means to improve food safety and
reduce costs associated with microbial contamination during storage
...
These bacteria can cause swelling of the cheese shape
and/or development of unpleasant taste and smell
...
Useful in non-thermally processed dairy
products
...


Use of enzymes in meat and seafood products
manufacturing
Proteases- heat stable forms preferred , e
...
, papain, ficin, and
bromelain (mixture of enzymes found in pineapples)





To modify texture and induce tenderness in meats and squid,
To improve chewability and digestibility,
To reduce bitterness and improve flavor as well as nutritive value,
Produce hydrolysates from meat scraps, underutilized fish species
and fish processing discards;
 Enhanced flavors in fermented herring (fish)
...
It can be described as a pleasant "meaty" taste with a long
lasting, mouthwatering and coating sensation over the tongue
...

GMP and IMP amplify the taste intensity of the sodium glutamate
...


Enzymatic mash treatment: why are exogenous enzymes needed?
Cell walls contain high-molecular weight compounds
...

In addition, polymers of xylose, galactose, and arabinose (hemicelluloses)
form a link with cellulose
...

The goal:
Enzymatic mash treatment (for example, in juice production) is performed
to: improve the pressabiliy of the mash and, respectively juice yield
...
Pectinases with a high proportion of
pectinesterase and liquefying polygalacturonases are suitable for mash
treatment
...
More juice can be released from the mash
...

 Greater yield and press capacity
...

They are, however, allowed without any legal restrictions for
vegetable processing
...
Their proportion
depends on the strain used for the enzyme production
...
These enable further viscosity
reduction and facilitate solid/liquid separation

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