FOOD PROCESSING
Nagamani Balagurusamy
KAREN A. AVENDAÑO, MIRIAM ANGUIANO,
CARLOS E. LÓPEZ, LILIA E. MONTAÑEZ,
LUCIO SIFUENTES, NAGAMANI BALAGURUSAMY*
*Corresponding author
Laboratorio de Bioremediación,
Facultad de Ciencias Biológicas,
Universidad Autónoma de Coahuila,
Carretera Torreón-Matamoros km 7.5,
Torreón Coahuila, México
Microbial enzymes
Applications in food processing
KEYWORDS: Microbial enzymes, food industry, dairy, meat, bakery, beverages.
Abstract
Microbial enzymes play a significant role in different food processes due to their easiness in production
and availability. They are mainly used by the food industry to optimize the process, improve the
efficiency, quality, shelf life and most importantly to achieve desired organoleptic characteristics of the final product. While, lactase,
lipase, protease, transglutaminase, asparaginase, pectinase are employed widely by for removing lactose, cheese ripening, meat
tenderization, minimising acrylamide formation and clarification respectively, other enzymes such as phytase, laccase, complex of
xylanase and cellulase are gaining importance in various food process technologies to improve bioavailability of minerals, minimize
off-odours and stabilization of beverages and production of nutraceuticals respectively. In this paper, source of these different
microbial enzymes, their function and role in different food processes are discussed.
INTRODUCTION
Enzymes are employed by different industries, such as food,
detergents, textiles, leather, pulp and paper, diagnostics and
therapy (1). Enzymes aid in catalysing and accelerating reactions
(2, 3), can be obtained from different sources, viz., animals, plants
and microorganisms (4), aren’t toxic and can be inactivated
once the desired reaction has been completed. Enzyme
inactivation prevents unfavourable changes (appearance and
organoleptic properties) in final product as continuous enzyme
activity is prevented (2, 3, 5, 6). In the case of food industry,
enzymes are used to improve characteristics in the final product
such as texture, shelf life, colour, flavour, odour and more (7).
Currently, enzymes are also being used for monitoring the
food process, increasing the bioavailability of minerals, and as
therapeutic agents (1, 2). In general, enzymes are used for three
purposes: additive, ingredient and to favour the process (5, 8, 9)
related to dairy products, meat, baking, fermented beverages
and juice (8, 10). Food processing industry uses around 29% of
total enzymes produced, and 58% of these enzymes are obtained
from fungi, 28 and 5% from bacteria and yeast respectively
(1, 5). Enzymes of microbial origin have been employed since the
decades of 80’s due to their easiness in production, availability
(2, 3, 11) and cost-efficiency (10, 12). The application of microbial
enzymes in different areas of food industry are given importance
in this review and compilation of different enzymes employed by
food industry and their microbial origin is presented in Table 1.
cream, cheese, butter, ice cream and yogurt. The principal
function of microbial enzymes is to improve the process
or characteristic of final products, such as flavour, colour,
consistency, composition, appearance and structure.
One of the principal focus of dairy industry is the
development of lactose-free products. Lactose intolerance
index varies according to ethnic origin; 5% among North
Europeans, North Americans and Australasians, about 17%
British and over 50% in South America, Africa and Asia
(13). Lactose low or free product allows lactose intolerant
people to consume low lactose fermented milk, ice cream
and milk drinks (3,5,9). Lactose is removed either by partial
hydrolysis by β-amylase (EC 3.2.1.2) (12), or complete
hydrolysis by lactase (EC 3.2.1.23). Lactase hydrolyses the
glycosidic bond (8) resulting in the union of hydrogen in the
extreme oxygen and union of OH- to free carbon, obtaining
glucose and galactose (Figure 1).
Figure 1.
Mechanism
of lactose
hydrolysis by
lactase.
DAIRY PRODUCTS
Dairy products represent a wide area in the food industry,
which produces a large variety of products such as milk,
Agro FOOD Industry Hi Tech - vol. 27(4) - July/August 2016
63
Among other enzymes, acid proteases (EC 3.4.23.X), like
chymosin (EC 3.4.23.4), are employed as coagulants
in cheese making. Chymosin represents around 20-30%
of milk coagulants used worldwide (3, 12). Proteinases (EC
3.4.22.X) favours cheese ripening by accelerating protein
hydrolysis, which is the most important biochemical event
at this stage and has a high impact on texture and flavour.
Additionally, peptidases (EC 3.4.11.X) are used to remove
bitterness produced by proteinases during ripening (14, 15).
Transglutaminases (EC 2.3.2.13) aids in cross-linking of
peptide bonds and enhance functional properties of dairy
products (16).
Lipases (EC 3.1.1.X) are used for development of
characteristic flavours, these enzymes hydrolyse short chain
fatty acids, thus decreasing the formation of trans-fatty
acids (1, 2, 7, 9, 11, 17) and obtaining about 15-30 times
more flavour than traditional process (14). Types of cheese
is dependent upon the process of ripening, which gives
characteristic textures and aromas (18, 19). In ripening,
lipases play a major role in hydrolysis of triglycerides,
diglycerides, monoglycerides, fatty acids and glycerol to
free fatty acids, which are responsible for characteristic
flavor development (18-20). Ripening process with lipases
is about 2 to 5 times faster than without it (20). However, it
is important optimize the amount of enzyme added and its
enzymatic activity, as high levels of lipases could lead to
rancidity and reduction in yield (7, 9, 14, 18, 19).
(EC 3.4.21.53) and lipases enhance elasticity and quality
of dough by way of formation of a homogenous and fine
structure. In addition, provides colour, crumb, softness,
freshness, shelf life, higher volume and decrease off-flavour of
the final products (1-3, 5, 8, 9, 12, 17, 24).
Haertlé (12) mentioned that maillard reaction can generate
off-colours during baking, but the use of glucose oxidase (EC
1.1.3.4) prevents these unfavourable changes and further
reduces the fermentation time. In 2005 the Swedish National
Food Administration announced that foods processed and
cooked at high temperatures contain relatively high levels of
carcinogenic acrylamide (25). Sugars along with asparagine
contained in the flour produce acrylamide through the
maillard reaction. Asparaginase (EC 3.5.1.1) inhibits acrylamide
formation during baking by the hydrolysis of free-asparagine
to aspartic acid; which do not favour Maillard reaction (Figure
2). According to Fraatz et al., (5), acrylamide concentration
decreased by 95% without affecting sensorial characteristics in
final products (12, 26). Food and Agriculture Organization (FAO)
evaluated asparaginase and observed that the activity of this
enzyme depends of factors such as dose, reaction conditions
and ingredients employed in the process (26).
MEAT
Meat products are a major source of food proteins, and also
of minerals and vitamins (21). Improvement of organoleptic
characteristics is a huge challenge to the meat industry.
Tenderization of meat by use of proteolytic enzymes helps to
avoid the use of chemicals and brines (3). Although, papain
(EC 3.4.22.4) and ficin (EC 3.4.22.3) are used, transglutaminase
is widely employed (22). The first microbial transglutaminase
was produced by Streptoverticillium mobarence in early
1980’s (23). Some advantages of transglutaminase over
other enzymes are the low cost, also this enzyme is used in
food processing to enhance nutritional value as it can add
essential amino acids in protein matrices (12). This enzyme
helps in binding of small pieces of meat creating larger
pieces. Further, it also improves texture, firmness, elasticity,
emulsifies and homogenizes meat products such as sausages
leading higher quality and more varieties (3, 12, 16). They
also permit the use of low quality raw materials like collagen
by enhancing their nutritional value by supplementing with
deficient amino acids (12, 16). Together with proteases,
thermolysin (EC 3.4.24.27) is used to produce food protein and
for accelerating the ripening of dry sausages (3).
Figure 2. Reduction of acrylamide formation by microbial
asparaginase during food processing (Modified from 26).
On the other hand, phytases (EC 3.1.3.X) are employed to
increase the volume and improve the texture of bread (2).
In addition, they reduce phytate content in final breads, apart
from reducing dough fermentation time without affecting its pH
and gumminess and chewiness (27, 28). Sulfhydryl proteases (EC
3.4.22.39) also improve elasticity and firmness of dough as well as
viscoelastic properties, gas retention and thermoset properties
of baking products (3). Transglutaminases have also been
reported to enhance elasticity and a 14% increase in volume
over traditional methods (16). Transglutaminase is used along
with laccase to obtain gluten-free breads (3, 10, 12). It is well
established that the use of enzymes significantly improves shelf life
of bread and reduces bread staling (24).
BAKING
The main characteristics of bakery products are softness,
longer freshness and crunchy cover in bread. Apart from
compensating the variations in flour, microbial enzymes are
important in improving the flavour and contributes to more
than a quarter of the world bakery market (10).
Lipoxygenases (EC 1.13.11.X) whitens flour and provides
viscoelastic properties in the dough, while, α-amylase (EC
3.2.1.1), laccase (EC 1.10.3.2), xylanase (EC 3.2.1.8), protease
64
BEVERAGES
In fermented beverages such as wine and beer, primary concerns
are process optimization, yield improvement and maintaining or
enhancement of colours and flavours. Enzymes contribute with
these factors and also reduce beer calories and sulphur levels,
apart from improving clarity to wine (5, 9). Specifically, sulfhydryl
proteases enhance clarity (3), acetolactate descarboxylase (EC
Agro FOOD Industry Hi Tech - vol. 27(4) - July/August 2016
4.1.1.5) removes butter
odour in beer caused by
diacetyl presence as a
fermentation product.
β-glucanases (EC
3.2.1.39) are used for the
reduction of beer viscosity
by β–glucan hydrolysis.
Pectinases (EC 3.2.1.X)
play an important role
in wine and beer by
making easy the steps of
extraction and filtration,
improving juice yield,
flavour, odour (16) and
clarification process (29).
Although, pectinases
with low activity are
naturally present in fruits
and vegetables juices,
microbial enzymes are
mainly used in industry
because of their
stability and resistance
to fermentation
conditions (30).
In the case of flavoured
beverages, fruit and
vegetables juice
producers are interested
in solving problems
related to stability,
quality, clarification,
viscosity and yield during
elaboration, which are
critical to consumer
acceptance. Different
enzymes that are being
employed to improve
juice characteristics are
presented in Table 1.
First step in elaboration
of juice is maceration of
fruits and vegetables
and enzymes employed
are pectinases,
cellulases (EC 3.2.1.X)
and hemicellulases (EC
3.1.1.73). They are also
known as macerating
enzymes, which
catalyses degradation of
heteropolysaccharides like
cellulose and pectin into
simple sugars and thereby
to increase yield (6, 8).
Besides their use in juice
extraction, cellulases
enhance stability and
texture by decreasing
viscosity in nectars and
purees (8, 16, 31).
In addition, pectinases
help to maintain the
mixture stability, decreasing
viscosity and turbidity
of nectars and pulps.
Pectinases increase juice
yield by 41-214% (3, 6, 8, 15,
16, 29, 32) and represent
around 25% of total enzymes
used by food industry.
Laccases are widely
employed to decrease
juice off-flavours caused by
phenolic compounds and
to enhance stabilization
of beverages (5, 9).
Peroxidases (EC 1.11.1.X)
are also employed to
eliminate undesirable colours
and flavours in juice (3).
Transglutaminases helps
to maintain shelf life and
freshness for more time
because they facilitate
development of protein films,
which acts as a barrier on
fruits and vegetables (16).
Other important enzyme
is naringinase (EC 3.2.1.40)
which removes bitterness
in citric juice, and also
has antioxidant properties
and maintains product
stability and organoleptic
characteristics (16).
OTHER ENZYME
APPLICATIONS IN FOOD
PROCESSING
Table 1. Microbial enzymes employed by different food processing industries.
Agro FOOD Industry Hi Tech - vol. 27(4) - July/August 2016
At present, nutritional value
of food products is a very
important characteristic
to consumers. Enzymes
like α-galactosidase (EC
3.2.1.22) and phytases are
used for food improvement
in foods, especially in
products originating from
legumes and cereals (1, 5).
Phytate is well known for
its anti-nutrient character
by way of chelating
divalent and multi-valent
cations and for its binding
with positively charged
proteins and thereby
reduces the bioavailability
of these nutrients. Phytase
aids in efficient phytate
dephosphorilation, releasing
minerals and thereby
increases their bioavailability
and nutrition (27, 28, 33). The
utility of phytase in reducing
65
nutraceutical produced
mineral deficiencies in
from lignocellulosic
vulnerable groups such as
biomass and is used as
strict vegetarian and childan artificial sweetener
bearing women are well
(44). Xylanase is
documented (33, 34).
employed to extract
Sweeteners represent a
xylan (hemicellulose)
large area of opportunity
and to obtain XOS (45).
for enzymes; amylases and
β-galactosidase is used
glucoamylases (EC 3.2.1.X)
to hydrolyze lactose
catalyse starch hydrolysis
in order to obtain milk
with a conversion rate of
oligosaccharides, which
around 95%. Invertases (EC
are beneficial to improve
3.2.1.26) aid in reduction
the defense system in the
of sweetness intensity and
infants (45).
thermolysin is employed in
On the other hand,
production of aspartame,
around 80% of bacterial
a secure sweetener for
infections are associated
diabetic patients (1, 5,
with biofilms formation,
8, 16). Hypoallergenic
and dairy products are
foods offer another
very susceptible. Removing
potential area of market
a
biofilms is an important
development. Foods such
task and enzymes can
as wheat, peanut, soya,
be used for this purpose.
chickpea, milk and eggs
Pathogenic bacteria,
have antigenic proteins
Salmonella sp. has been
that can cause allergic
detected in meat, poultry,
reactions. More specific
etc., widely transmitted
and efficient enzymes like
Nutraceuticals
through food and is very
proteases, actinase (EC
difficult to remove from
3.4.24.31), alcalase (EC
food products. Enzymes
3.4.21.X), flavourzyme (EC
such as proteases, dispases
34.11.1) and neutrase (EC
(EC 3.4), cellulases,
3.4.24.28) help to reduce
glycosidases (EC 3.2.1.X)
the allergens, providing a
and amylases have been
health benefit (1, 35-38).
reported in removal of
Another application of
biofilms (46).
enzymes in food industry
Fraatz et al. (5) mentioned
is in monitoring process
b
that enzymes can also
quality parameters. Use
contribute to maintain
of enzymes as biosensors
the security and shelf life
(39) aid in monitoring and
of food by controlling
detection of the target
microbial populations.
compounds by tightly
For example, lysozyme
combining biorecognition
(EC 3.2.1.27) is a natural
elements and physical
antimicrobial agent
transducers (40).
employed in foods since it
Clark and Lyons
prevents growth of gram
developed the first
positive bacteria in cheese
biosensor as early as
life
and enhances spoil control
1962, but it was in 1967
in wines, beer, meat, etc.,
when Updike and Hick
and prolongs shelf life
reported the first enzymatic
(47). The use of enzymes
biosensor based on
such as glucose oxidase
glucose oxidase (41, 42)
Table 2. Brief list of enzymes, commercial name, producers and their
as antioxidants also helps
and is used to monitor
applications in different food sectors.
to increase shelf life of
fermentation of wine and
foods. They can be used to
beer (39). There are other
remove oxygen and reactive oxygen species, thus reducing lipid
enzymatic biosensors for determination of fructose, lactose, lactic
hydroperoxides (48). Transglutaminase is another enzyme involved
acid, malic acid and acetic acid.
in food conservation. Ahhmed (49), reported that a smart film
Recently nutraceuticals are gaining worldwide importance. They
generated by transglutaminase is efficient in meat preservation
are substances or part of food that provide medical benefits,
and preventing contamination. A brief list of different microbial
either for prevention or as treatment for diseases (43). Of late,
enzymes, their commercial name, potential applications and
potential application of different enzymes for nutraceutical
producer are presented in Table 2.
production is being explored. Xylooligosaccharides (XOS), is a
66
Agro FOOD Industry Hi Tech - vol. 27(4) - July/August 2016
FUTURE PERSPECTIVES
The use of microbial enzymes in food processing have
acquired great importance in recent years and the list of their
potential applications is growing. Apart from increasing the
nutrient value, quality and shelf life of food products, enzymes
as biosensors and for production of nutraceuticals is an area of
interest. Increasing world population and associated nutrient
deficiency among children and poor is a cause for concern.
Emerging microbial enzyme technologies are to be tuned and
applied in a manner specific to region and in traditional food
process among such population can minimize the nutrient
deficiency and improve the health status of population living
below poverty line. Apart from process optimization, improving
organoleptic characteristics and yield, application of enzymes
will reduce the environmental impact and toxicity of wastes
and wastewaters generated by the food industry. In addition,
advances in metabolic engineering of microorganisms is
leading to new, efficient engineered enzyme systems, which
could help to change the food industry into a sustainable,
organic and environmental friendly process.
9.
10.
11.
12.
13.
14.
15.
16.
CONCLUSIONS
Bacterial, fungal and yeast are the principal sources of
microbial enzymes employed by food processing industry.
It can be observed here that microbial enzymes have
contributed to the development and growth of food industry
such as, process optimization, process efficiency and yield. In
parallel, they have also contributed to improve organoleptic
characteristics, nutritive value, quality, conservation and shelf
life of the product. Of late, role of enzymes in monitoring and
quality control of the process and products is significant in
various sectors of food industry such as dairy, meat, baking
and other applications. It can be concluded that the recent
advances in development of recombinant enzymes with
improved catalytic properties for specific applications will lead
the food industry to meet the challenges of the world with
respect to nutrient deficiency and a sustainable future.
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