Transcript File - Future is BioTechnology.

Food Biotechnology
Elective Subject
B.Tech. (Biotechnology) 7th Semester
Prepared by: Dr. A. K. Gupta (AEC, Agra)
Food Biotechnology
B. Tech.
Dr. A. K. Gupta
Food spoilage
1
Microbial Role in food spoilage
1-15
Unit 1
Course
• Role of microbes in food spoilage
• Food preservation (Principles, Operations
and production)
• New protein Foods-SCP
• Mushroom
• Food yeast
• Algal proteins
Food Spoilage
• Around a quarter of the world’s food supply is
lost to spoilage by microbes and insects.
• Over the years man has developed many ways
of preserving foods and today’s food
technologists have refined the techniques and
come up with new ones.
• spoilage is not necessarily a bad thing. It shows
us that a food has not been made or kept in the
best conditions, alerting us to the possible
presence of pathogenic microbes.
• Decomposition returns the chemicals in food
back to the environment, to be used again in the
life cycles of Earth.
Examples of food spoilage
Role of microbes in food spoilage
• Like us, microbes need food to stay alive. The
foodstuffs that keep us healthy also provide the
ideal nutrients for the growth of microbes.
• Microbes are all around us – in the air, the soil,
water and our bodies.
• Microbes can soon get into food and, if the
conditions are right, multiply rapidly.
• Unfortunately, when certain microbes grow on
food, it soon begins to smell nasty, look slimy,
change colour, taste awful or even acquire a furry
coating.
• The food ‘goes off’ – it is spoiled. Even though it
may not harm us, it is inedible and must be thrown
away. There is also a chance that pathogenic
microbes are present along with the spoilers.
Microbes causing food spoilage
Three main types of microbes cause spoilage
Bacteria
• Single-celled microbes that reproduce by splitting in two.
• Each individual bacterium is capable of carrying out all of
the activities needed to metabolise and reproduce.
• There are more than 5,000 known species of bacteria, with
new ones constantly being discovered.
•
Familiar species of bacteria include: E.coli, Salmonella,
Bacillus
Growth conditions for bacteria
• Bacteria prefer moist conditions and can live in a
wide range of temperatures. Most cannot grow
at low pH (i.e. in acid conditions).
• In the right conditions of warmth, acidity and
moisture they can multiply very fast, producing
millions of cells in a few hours. Some bacteria
form spores which are resistant to drying and
heating. When conditions become favorable
again, they germinate and an active cell is
released.
The different shapes of bacteria.
Salmonella bacteria have flagella which they use to move around.
Types of bacteria
•
1.
2.
3.
4.
•
•
•
•
•
•
•
Bacteria cells have four basic shapes:
spheres
rods
spirals
commas.
They can be found as single cells, in pairs, chains or
clusters.
A bacterial cell has a wall which maintains its shape and
protects it. Some bacteria can move.
Usually they use flagella, which are like little corkscrews.
These rotate from the base like a ship’s propeller.
The flagella may be distributed randomly over the whole
cell surface, in groups or singly.
Some bacteria have numerous fringe-like projections
called fimbriae which enable them to stick to each other.
Other bacteria produce a sticky substance around the
cell wall. This provides protection and helps them to
Fungi
• Fungi are a large and diverse group of
organisms. Their main characteristics are:
• Their cells have membrane-bound nuclei (we
call them eukaryotic)
• They do not use photosynthesis
• They form spores
• They have rigid cell walls
• Respiration takes place in bodies called
mitochondria in the cytoplasm.
• Fungal cells have an elaborate arrangement of
internal membranes. Fungi can be divided into
two broad groups: filamentous fungi (including
moulds and mushrooms) and yeasts
• Fungi reproduce by sexual and asexual means.
• Most produce spores which in some types are
borne on bodies called sporangia.
• Both spores and sporangia vary widely in size
and form, depending on how they are spread –
by wind, water, mechanical means or vectors.
• Macrofungi produce large fruiting bodies which
are familiar to us as mushrooms and toadstools.
• These produce spores in huge numbers and
disperse them into the environment. In
favourable conditions, these spores germinate
and produce hyphae.
Moulds
• Moulds are filamentous (thread-like) fungi. A single
filament is called a hypha. The hyphae branch as they
grow forming a network called a mycelium.
• Each hypha grows from the tip and divides repeatedly
along its length. The hyphae penetrate their food source
(usually dead, but sometimes living, plant and animal
matter). They excrete enzymes which break down the
complex organic molecules into simpler substances. The
soluble nutrients pass through the cell wall and
membrane, enabling the fungus to grow.
• In most moulds the hyphae are divided by cross walls
called septa which help to make filaments rigid but also
control nutrient flow.
• Moulds can grow in dry and acid conditions and can
tolerate a wide range of temperatures. These fungi
produce airborne spores.
• Examples of moulds are: Penicillium, Mucor, Aspergillus.
Potato blight is caused by a mould growing on the leaves of the plant.
Yeasts
• These are microscopic.
• single celled fungi that are usually round or oval in shape.
• Most reproduce by budding.
• When yeasts respire anaerobically they convert sugars into ethanol
and carbon dioxide by a process known as fermentation.
• They are mainly used to make fermented foods such as beer, wine
or bread,.
• The biochemical activities of yeasts can have unwanted effects in
some food products. Yeasts can tolerate dry and acid conditions.
• Examples of yeasts include: Saccharomyces cerevisiae, Candida
Food Biotechnology
2
Food preservation Principles
B. Tech.
Dr. A. K. Gupta
15-28
Pasteurization
• Pasteurization is a process which slows
microbial growth in foods.
• The process was named after its creator, French
chemist and microbiologist Louis Pasteur.
• The first pasteurization test was completed by
Louis Pasteur and Claude Bernard on April 20,
1862.
• The process was originally conceived as a way
of preventing wine and beer from souring.
Pasteurizer
Pasteurization Process
• Unlike sterilization, pasteurization is not
intended to kill all pathogenic micro-organisms in
the food or liquid.
• Instead, pasteurization aims to reduce the
number of viable pathogens so they are unlikely
to cause disease (assuming the pasteurization
product is refrigerated and consumed before its
expiration date).
• Commercial-scale sterilization of food is not
common because it adversely affects the taste
and quality of the product.
• Certain food products are processed to achieve
the state of Commercial sterility.
• Pasteurization typically uses temperatures below boiling
since at temperatures above the boiling point for milk,
casein micelles will irreversibly aggregate (or "curdle").
• There are two main types of pasteurization used today:
High Temperature/Short Time (HTST) and Extended
Shelf Life (ESL) treatment.
• Ultra-high temperature (UHT or ultra-heat treated) is also
used for milk treatment.
• In the HTST process, milk is forced between metal
plates or through pipes heated on the outside by hot
water, and is heated to 71.7 °C (161 °F) for 15-20
seconds.
• UHT processing holds the milk at a temperature of 138
°C (280 °F) for a fraction of a second. ESL milk has a
microbial filtration step and lower temperatures than
HTST.
• Milk simply labeled "pasteurization " is usually treated
with the HTST method, whereas milk labeled "ultrapasteurization " or simply "UHT" has been treated with
the UHT method.
• The HTST pasteurization standard was designed to
achieve a 5-log reduction, killing 99.999% of the number
of viable micro-organisms in milk.
• This is considered adequate for destroying almost all
yeasts, mold, and common spoilage bacteria and also to
ensure adequate destruction of common pathogenic
heat-resistant organisms (including Mycobacterium
tuberculosis, which causes tuberculosis and Coxiella
burnetii, which causes Q fever).
• HTST pasteurization processes must be designed so
that the milk is heated evenly, and no part of the milk is
subject to a shorter time or a lower temperature.
• Pasteurization is typically associated with milk,
first suggested by Franz von Soxhlet in 1886.
HTST pasteurized milk typically has a
refrigerated shelf life of two to three weeks,
whereas ultra pasteurized milk can last much
longer when refrigerated, sometimes two to
three months. When UHT treatment is combined
with sterile handling and container technology
(such as aseptic packaging), it can even be
stored unrefrigerated for 3-4 months.[citation
needed]
• In addition to the standard HTST and UHT
standards, there are other lesser-known
pasteurization techniques.
• The
first
technique,
called
"batch
pasteurization“.
• It involves heating large batches of milk to a
lower temperature, typically 63 °C (145 °F) for
30 minutes, followed by quick cooling to about 4
°C (39 °F).
• The other technique is called higher-heat/shorter
time (HHST), and it lies somewhere between
HTST and UHT in terms of time and
temperature.
• Pasteurization causes some irreversible and
some temporary denaturation of the proteins in
milk.
• Milk pasteurization has been subject to
increasing scrutiny in recent years, due to the
discovery of pathogens that are both widespread
and heat resistant (able to survive pasteurization
in significant numbers).
• Researchers have developed more sensitive
diagnostics, such as real-time PCR and
improved culture methods that have enabled
them to identify pathogens in pasteurized milk.
• Some of the diseases that pasteurization can
prevent are tuberculosis, diphtheria, salmonella,
strep throat, scarlet fever, listeriosis and typhoid
fever.
Food Biotechnology
B. Tech.
Dr. A. K. Gupta
Food Preservation
3
Food Preservation Operations
28-
Flash Pasteurization
• Flash pasteurization, also called "High Temperature
Short Time" processing.
• It is a method of heat pasteurization of perishable
beverages like fruit and vegetable juices, beer, and dairy
products.
• Compared to other pasteurization processes, it
maintains color and flavor better.
• It is done prior to filling into containers in order to kill
spoilage microorganisms, to make the products safer
and extend their shelf life.
• The liquid moves in a controlled, continuous flow while
subjected to temperatures of 71.5 °C (160 °F) to 74 °C
(165 °F), for about 15 to 30 seconds, a ratio expressed
as pasteurization units.
• Flash pasteurization is widely used for fruit juices.
• Tropicana Products has used flash pasteurization since
the 1950s.
Food irradiation
• Food irradiatio is the process of exposing food to
ionizing radiation to destroy microorganisms, bacteria,
viruses, or insects that might be present in the food.
• Further applications include sprout inhibition, delay of
ripening, increase of juice yield, and improvement of rehydration.
• Irradiation is a more general term of deliberate exposure
of materials to radiation to achieve a technical goal (in
this context 'ionizing radiation' is implied).
• As such it is also used on non-food items, such as
medical hardware, plastics, tubes for gas-pipelines,
hoses for floor-heating, shrink-foils for food packaging,
automobile parts, wires and cables (isolation), tires, and
even gemstones.
• Compared to the amount of food irradiated, the volume
of those every-day applications is huge but not noticed
by the consumer.
• The genuine effect of processing food by ionizing radiation relates to
damages to the DNA, the basic genetic information for life.
• Microorganisms can no longer proliferate and continue their
malignant or pathogenic activities.
• Spoilage-causing micro-organisms cannot continue their activities.
Insects do not survive or become incapable of proliferation. Plants
cannot continue the natural ripening or aging process.
• The speciality of processing food by ionizing radiation is that the
energy density per atomic transition is very high; it can cleave
molecules and induce ionization (hence the name), which is not
achieved by mere heating.
• This is the reason for both new effects and new concerns. The
treatment of solid food by ionizing radiation can provide an effect
similar to heat pasteurization of liquids, such as milk. However, the
use of the term "cold pasteurization" to describe irradiated foods is
controversial, since pasteurization and irradiation are fundamentally
different processes.
• Food irradiation is currently permitted by over 40 countries and
volumes are estimated to exceed 500,000 metric tons annually
world wide.
Canning
• In 1809, a French confectioner and brewer, Nicolas Appert,
observed that food cooked inside a jar did not spoil unless
the seals leaked, and developed a method of sealing food in
glass jars.
• The reason for lack of spoilage was unknown at the time,
since it would be another 50 years before Louis Pasteur
demonstrated the role of microbes in food spoilage.
However, glass containers presented challenges for
transportation.
• Glass jars were largely replaced in commercial canneries
with cylindrical tin or wrought-iron canisters (later shortened
to "cans") following the work of Peter Durand (1810).
• Cans are cheaper and quicker to make, and much less
fragile than glass jars. Glass jars have remained popular for
some high-value products and in home canning.
• Tin-openers were not invented for another thirty years — at
first, soldiers had to cut the cans open with bayonets or
smash them open with rocks.
Food Biotechnology
B. Tech.
Dr. A. K. Gupta
Food Preservation
4
Food Preservation Operations
28-
Food Canning Process
Canning is a method of preserving food in which the
food is processed and sealed in an airtight
container.
• The packaging prevents microorganisms from
entering and proliferating inside.
• To prevent the food from being spoiled before and
during containment, quite a number of methods are
used: pasteurization, boiling (and other applications
of high temperature over a period of time),
refrigeration, freezing, drying, vacuum treatment,
antimicrobial agents that are natural to the recipe of
the foodstuff being preserved, a sufficient dose of
ionizing radiation, submersion in a strongly saline,
acid, base, osmotically extreme (for example very
sugary) or other microbe-challenging environments.
• From a public safety point of view, foods with low
acidity (a pH more than 4.6) need sterilization
under high temperature (116-130°C).
• Foods that must be pressure canned include
most vegetables, meats, seafood, poultry, and
dairy products.
• The only foods that may be safely canned in an
ordinary boiling water bath are highly acidic ones
with a pH below 4.6, such as fruits, pickled
vegetables, or other foods to which acidic
additives have been added.
• Modern double seams provide an airtight seal to the tin
can. This airtight nature is crucial to keeping bacteria out
of the can and keeping its contents sealed inside. Thus,
double seamed cans are also known as Sanitary Cans.
Developed in 1900 in Europe, this sort of can was made of
the traditional cylindrical body made with tin plate. The two
ends (lids) were attached using what is now called a
double seam. A can thus sealed is impervious to the
contamination by creating two tight continuous folds
between the can’s cylindrical body and the lids. This
eliminated the need for solder and allowed improvements
in manufacturing speed, reducing cost.
• Double seaming uses rollers to shape the can, lid and the
final double seam. To make a sanitary can and lid suitable
for double seaming, manufacture begins with a sheet of
coated tin plate. To create the can body rectangles are cut
and curled around a die and welded together creating a
cylinder with a side seam.
• Rollers are then used to flare out one or both ends of
the cylinder to create a quarter circle flange around
the circumference. Precision is required to ensure that
the welded sides are perfectly aligned, as any
misalignment will cause inconsistent flange shape,
compromising its integrity.
• A circle is then cut from the sheet using a die cutter.
The circle is shaped in a stamping press to create a
downward countersink to fit snugly in to the can body.
The result can be compared to an upside down and
very flat top hat. The outer edge is then curled down
and around approximately 140 degrees using rollers
to create the end curl.
• The result is a steel tube with a flanged edge, and a
countersunk steel disc with a curled edge. A rubber
compound is put inside the curl.
Nutrition Value
• Canning is a way of processing food to
extend its shelf life. The idea is to make
food available and edible long after the
processing time. Although canned foods
are often assumed to be of low-nutritional
value (due to heating processes or the
addition of preservatives), some canned
foods are nutritionally superior -- in some
ways -- to their natural form. For instance,
canned tomatoes have a higher, available
lycopene content.
Food Biotechnology
B. Tech.
Dr. A. K. Gupta
Food spoilage
5
New Protein Foods
1-15
Single Cell Protein (SCP)
• The dried cells of microorganisms (algae, bacteria,
actinomycetes and fungi) used as food or feed are
collectively called microbial protein.
• Microorganisms which are allowed to grow on waste
products from agro based industries produce a large
amount of proteins and store them in their cell
bodies. These organisms are called as single cell
proteins.
• Number of microorganisms are the part of diet since
ancient time.
• Fermented yeast (Sacchromyces sp.) recovered as
aleavening agent for bread (2500 B.C.).
• The worldwide food protein deficiency is becoming
alarming day to day. During World War II, when there
were stortages in proteins and vitamins in the diet, the
Germans produced yeasts and a mould (Geotrichum
candidum) in some quantity for food; this led to the
idea to produce edible proteins on a large scale by
means of microorganisms during 1970s.
• Several industrial giants investigated the possibility of
converting cheap organic materials into protein using
microorganism. Single-Cell Protein (SCP) is a term
coined at Massachusetts Institute of Technology by
Prof C.L. Wilson (1966) and represents microbial cells
(primary) grown in mass culture and harvested for use
as protein sources in foods or animal feeds. Many
scientists believe that single-cell protein production are
possible solution to meet out the shortage of protein.
Palatibility of mushroom was
also recognized in Rome.
•
Single cell protein has the potential to be developed into a very large source of
supplemental protein that could be used in livestock feeding. In some regions single
cell protein could become the principal protein source that is used for domestic
livestock, depending upon the population growth and the availability of plant feed
protein sources. This could develop because microbes can be used to ferment some
of the vast amounts of waste materials, such as straws; wood and wood processing
wastes; food, cannery and food processing wastes; and residues from alcohol
production or from human and animal excreta. Producing and harvesting microbial
proteins is not without costs, unfortunately. In nearly all instances where a high rate of
production would be achieved, the single cell protein will be found in rather dilute
solutions, usually less than 5 % solids. Methods available for concentrating include,
filtration, precipitation, coagulation, centrifugation, and the use of semi-permeable
membranes. These de-watering methods require equipment that is quite expensive
and would not be suitable for most small-scale operations. Removal of the amount of
water necessary to stabilize the material for storage, in most instances, is not
currently economical. Single cell protein must be dried to about 10 % moisture, or
condensed and acidified to prevent spoilage from occurring, or fed shortly after being
produced. Caution: Microbial protein has a high nucleic acid content, so levels need
to be limited in the diets of monogastric animals. Some organisms can also produce
mycotoxins. Source: Single cell protein can be produced on a number of different
substrates, often this is done to reduce the Biological Oxidation Demand of the
effluent streams leaving various type of agricultural processing plants.
• Microbial protein term is replaced by single
cell protein during the first international
conference on microbial protein at MIT.
• Some actinomycetes and filamentous
fungi were reported to produce protein
from various substrates.
Advantages of producing SCP
•
•
•
•
Rapid succession of generations
High protein content
Easily modifiable genetically
Large no of raw materials can be used for
the production of SCP
• Production in continuous culture
B. Tech.
Food Biotechnology
Dr. A. K. Gupta
Protein Food
6
Mushroom
28-
Mushroom
• A mushroom is the fleshy, spore-bearing fruiting body of a fungus,
typically produced above ground on soil or on its food source. The
standard for the name "mushroom" is the cultivated white button
mushroom, Agaricus bisporus, hence the word mushroom is most
often applied to those fungi (Basidiomycota, Agaricomycetes) that
have a stem (stipe), a cap (pileus), and gills (lamellae, sing. lamella)
on the underside of the cap, just as do store-bought white
mushrooms.
• The word "mushroom" can also be used for a wide variety of gilled
fungi, with or without stems, and the term is used even more
generally, to describe both the fleshy fruiting bodies of some
Ascomycota and the woody or leathery fruiting bodies of some
Basidiomycota, depending upon the context of the word.
• Oyster mushroom (Pleurotus ostreatus)
cultivated using artificial logs made from
compacted sawdust in plastic containers,
harvested early morning.
• The button mushroom (Agaricus bisporus),
one of the most widely cultivated
mushrooms in the world.
•
•
Edible mushrooms are used extensively in cooking, in many cuisines
(notably Chinese, European, and Japanese). Though mushrooms are
commonly thought to have little nutritional value, many species are high in
fiber and provide vitamins such as thiamine, riboflavin, niacin, biotin,
cobalamins, ascorbic acid. Though not normally a significant source of
vitamin D, some mushrooms can become significant sources after exposure
to ultraviolet light, though this also darkens their skin.[6] Mushrooms are
also a source of some minerals, including iron, selenium, potassium and
phosphorus.
Most mushrooms that are sold in super markets have been commercially
grown on mushroom farms. The most popular of these, Agaricus bisporus,
is generally considered safe for most people to eat because it is grown in
controlled, sterilized environments, though some individuals do not tolerate
it well. Several varieties of A. bisporus are grown commercially, including
whites, crimini, and portobello. Other cultivated species now available at
many grocers include shiitake, maitake or hen-of-the-woods, oyster, and
enoki.
•
•
•
•
There are a number of species of mushroom that are poisonous, and
although some resemble certain edible species, eating them could be fatal.
Eating mushrooms gathered in the wild is risky and should not be
undertaken by individuals not knowledgeable in mushroom identification,
unless the individuals limit themselves to a relatively small number of good
edible species that are visually distinctive. However even A. bisporus
contains 'agaritine' which metabolises when eaten into hydrazine, which is
carcinogenic, but this chemical is largely or completely removed by
cooking.[7]
More generally, and particularly with gilled mushrooms, separating edible
from poisonous species requires meticulous attention to detail; there is no
single trait by which all toxic mushrooms can be identified, nor one by which
all edible mushrooms can be identified.
Additionally, even edible mushrooms may produce an allergic reaction, from
a mild asthmatic response to severe anaphylaxis shock.
People who collect mushrooms for consumption are known as
mycophagists, and the act of collecting them for such is known as
mushroom hunting, or simply "Mushrooming".
• Medicinal mushrooms
• Currently, many species of mushrooms, which have been used in Asian folk
medicine for thousands of years, are under intense study by ethnobotanists
and medical researchers. Maitake, shiitake, Agaricus blazei, chaga, and
reishi are prominent among those being researched for potential anti-cancer,
anti-viral, and immunity-enhancing properties.
• In Europe and Japan, Polysaccharide-K (brand name Krestin), a chemical
derived from Trametes versicolor, is an approved adjuvant for cancer
therapy.[9][10] In China a clinical drug has been developed from Trametes
versicolor, it is called PSP and serves a similar purpose as PolysaccharideK. Some countries have not embraced these chemicals as drugs, believing
they're power is over-stated. However, chemicals like Polysaccharide-K
have well documented pharmaceutical value and are extremely safe with
minimal side-effects.
• The shiitake mushroom has produced a clinical drug lentinan, for cancer
treatment, which is approved in various countries including
Japan.[11][12][13]
• Human clinical studies are currently being conducted in the United States to
investigate potential anti-cancer properties of the common table mushroom.
[14]
• Research has indicated certain mushrooms have antiaromatase and anti-5-alpha reductase activity.
• Oyster mushrooms are a natural source of statin
drugs, specifically, isomers of lovastatin[16].
• In 2009, a case-control study of the eating habits of
2,018 woman, revealed that women who consumed
mushrooms had an approximately 50% lower
incidence of breast cancer. Women who consumed
mushrooms and green tea had a 90% lower incidence
of breast cancer.[17]
• Psilocybin, a naturally occurring chemical in certain
psychedelic mushrooms like Psilocybe cubensis, is
being studied for its ability to help people suffering
from psychological disorders, such as obsessivecompulsive disorder. Minute amounts have been
reported to stop cluster and migraine headaches.
A double-blind study, done by the John Hopkins
Hospital, showed that psychedelic mushrooms could
provide people an experience with substantial personal
meaning and spiritual significance.
In the study, one third of the subjects reported that
ingestion of psychedelic mushrooms was the single
most spiritually significant event of their lives.
Over two-thirds reported it among their five most
meaningful and spiritually significant events.
• Mushrooms can be used for dyeing wool and other
natural fibers. The chromophores of mushrooms are
organic compounds and produce strong and vivid
colors, and all colors of the spectrum can be achieved
with mushroom dyes. Before the invention of synthetic
dyes mushrooms were the source of many textile
dyes.
• Some fungi, types of polypores loosely called
mushrooms, have been used as fire starters (known
as tinder fungi).
• Mushrooms and other fungi play a role in the
development of effective biological remediation and
filtration technologies. The US Patent and Trademark
Office can be searched for patents related to the latest
developments in mycoremediation and mycofiltration.
Psychoactive mushrooms
• Psilocybin mushrooms possess psychedelic
properties.
• They are commonly known as "magic mushrooms"
"mushies" or "shrooms" and are available in smart
shops in many parts of the world, though some
countries have outlawed their sale.
• Because of their psychoactive properties, some
mushrooms have played a role in native medicine,
where they have been used in an attempt to effect
mental and physical healing, and to facilitate visionary
states.
• One such ritual is the Velada ceremony. A practitioner
of traditional mushroom use is the shaman and
curandera (priest-healer).
• Psilocybin mushrooms are not the only
psychoactive fungi. Amanita muscaria pictured
above is also psychoactive.
• The active constituents are Ibotenic acid and
Muscimol.
• The Muscaria chemotaxonomic group of
Amanitas contain no amatoxins or phallotoxins,
and are not hepatoxic.
• Some dry these in the sun to transform the
Ibotenic acid into the more psychoactive
Muscimol.
Questions
•
1 What are the main unit operations and their functions in anaerobic
digestion? What are five application of this process?
•
2 Compare the principles, advantages, and disadvantages of aerobic and
anaerobic composting for treatment of the organic fraction of municipal solid
waste.
•
3 What is the approach for bioremediation of toxic compounds in soil?
•
4 What are the sources and methods of mitigation of microorganism
pollutants in indoor air (see Lecture 14 for more detailed information)?
•
5 What are the two major purposes of fermenting food?
•
6 What are the main unit operations and their functions in wastewater
treat? Give two examples of fermented milk, vegetables, fruits, breads,
and meats.
Unit 2
• Fermentation as a method for preparing
and preserving foods
• Food additives
• Coloring
• Flavoring
• Vitamins
Food Biotechnology
2
Fermentation
B. Tech.
Dr. A. K. Gupta
1
Fermntation as a method of preserving foods
59-64
Fermentation
(as a method for preparing and preserving foods)
• Fermentation in food processing typically refers
to the conversion of sugar to alcohol using yeast
under anaerobic conditions.
• A more general definition of fermentation is the
chemical conversion of carbohydrates into
alcohols or acids.
• When fermentation stops prior to complete
conversion of sugar to alcohol, a stuck
fermentation is said to have occurred.
• The science of fermentation is known as
zymology.
• Fermentation usually implies that the action
of the microorganisms is desirable, and the
process is used to produce alcoholic
beverages such as wine, beer, and cider.
• Fermentation is also employed in
preservation to create lactic acid in sour
foods such as pickled cucumbers, kimchi
and yogurt.
Fermentation: Historical Background
• Fruits ferment naturally.
• Fermentation precedes human history.
Since prehistoric times, however, humans
have been controlling the fermentation
process.
• The earliest evidence of winemaking dates
from eight thousand years ago, in Georgia,
in the Caucasus area.
• Seven-thousand-year-old jars containing
the remains of wine have been excavated in
the Zagros Mountains in Iran, which are now
on display at the University of Pennsylvania.
•
• There is strong evidence that people were
fermenting beverages in Babylon circa 5000
BC, ancient Egypt circa 3150 BC, preHispanic Mexico circa 2000 BC, and Sudan
circa 1500 BC.
• There is also evidence of leavened bread in
ancient Egypt circa 1500 BC and of milk
fermentation in Babylon circa 3000 BC.
• French chemist Louis Pasteur was the first
known zymologist, when in 1854 he
connected yeast to fermentation. Pasteur
originally
defined
fermentation
as
"respiration without air". Pasteur performed
careful research and concluded;
• The primary benefit of fermentation is the
conversion of sugars and other carbohydrates,
e.g., converting juice into wine, grains into beer,
carbohydrates into carbon dioxide to leaven
bread, and sugars in vegetables into
preservative organic acids.
• Food fermentation has been said to serve five
main purposes:[8]
• enrichment of the diet through development of a
diversity of flavors, aromas, and textures in food
substrates.
• preservation of substantial amounts of food
through lactic acid, alcohol, acetic acid and
alkaline fermentations.
• Biological enrichment of food substrates
with protein, essential amino acids,
essential fatty acids, and vitamins.
• Detoxification
processing.
during
food-fermentation
• A decrease in cooking times and fuel
requirements.
Food Biotechnology
B. Tech.
Dr. A. K. Gupta
Fermentation
1
Fermntation as a method of preserving foods
59-64
• Fermentation has some uses exclusive to foods.
Fermentation can produce important nutrients or
eliminate antinutrients.
• Food can be preserved by fermentation, since
fermentation uses up food energy and can make
conditions unsuitable for undesirable microorganisms.
For example, in pickling the acid produced by the
dominant bacteria inhibit the growth of all other
microorganisms. Depending on the type of fermentation,
some products (e.g., fusel alcohol) can be harmful to
people's health.
Stuck fermentation
• A stuck fermentation is where a fermentation has
stopped before completion; i.e., before the anticipated
percentage of sugars has been converted by yeast into
alcohol or carbohydrates into carbon dioxide.
• Typically, a stuck fermentation may be caused by:
– 1) insufficient or incomplete nutrients required to allow the
yeast to complete fermentation;
– 2) low temperatures, or temperature changes which have
caused the yeast to stop working early; or
– 3) a percentage of alcohol which has grown too high for the
particular yeast chosen for the fermentation.
• Corrections to stuck fermentations may include: 1)
repitching a different yeast 2) incorporation of nutrients
in conjunction with the repitched yeast; 3) restoration of
accommodative temperatures for the given yeast.
Worldwide Fermented food utilization Pattern
•
alcohol, wine, vinegar, olives, yogurt, bread, cheese
•
Asia
– East and Southeast Asia: amazake, asinan, bai-ming, belacan, burong
mangga, com ruou, dalok, doenjang, douchi, jeruk, lambanog, kimchi ,
kombucha, leppet-so, narezushi, miang, miso, nata de coco, nata de
pina, natto, naw-mai-dong, pak-siam-dong, paw-tsaynob in snow ,
prahok, ruou nep, sake, seokbakji, soy sauce, stinky tofu, szechwan
cabbage , tai-tan tsoi, chiraki, tape, tempeh, totkal kimchi, yen tsai , zha
cai
– Central Asia: kumis (mare milk), kefir, shubat (camel milk)
– India: achar, appam, dosa, dhokla, dahi (yogurt), gundruk, idli, mixed
pickle
Africa: fermented millet porridge, garri, hibiscus seed, hot pepper sauce,
injera, lamoun makbouss, laxoox, mauoloh, msir, mslalla, oilseed, ogi, ogili,
ogiri
Americas: chicha, elderberry wine, kombucha, pickling (pickled vegetables),
sauerkraut, lupin seed, oilseed, chocolate, vanilla, tabasco, tibicos
Middle East: kushuk, lamoun makbouss, mekhalel, torshi, boza
Europe: rakfisk, sauerkraut, ogórek kiszony, surströmming, mead,
elderberry wine, salami, prosciutto, cultured milk products such as quark,
kefir, filmjölk, crème fraîche, smetana, skyr.
Oceania: poi, kaanga pirau (rotten corn), sago
•
•
•
•
•
Fermented foods Classification
• Bean-based
miso, natto, soy sauce, stinky tofu, tempeh
• Grain-based
Batter made from Rice and Lentil (Vigna mungo)
prepared and fermented for baking Idlis and Dosas
• amazake, beer, bread, chouj, injera, makgeolli, murri,
ogi, sake, sikhye, sourdough, rice wine, Malt whisky,
grain whisky, Vodka, batter
• Vegetable-based
• kimchi, mixed pickle, sauerkraut
• Fruit-based
• wine, vinegar, cider, brandy
• Honey-based
mead, metheglin
• Dairy-based
cheese, kefir, kumis (mare milk), shubat (camel
milk), cultured milk products such as quark, filmjölk,
crème fraîche, smetana, skyr, yogurt
• Fish-based
bagoong, faseekh ,fish sauce, Hákarl, heshiko,
hidal khunda[verification needed], jeotgal, rakfisk,
shrimp paste, surströmming
• Meat-based
salami, prosciutto
Risks of consuming fermented foods
• Alaska, despite its small population, has
witnessed a steady increase of cases of botulism
since 1985. It has more cases of botulism than
anywhere else in the United States of America.
• This is caused by the traditional Eskimo practice
of allowing animal products such as whole fish,
fish heads, walrus, sea lion and whale flippers,
beaver tails, seal oil, birds, etc., to ferment for an
extended period of time before being consumed.
The risk is exacerbated when a plastic container
is used for this purpose instead of the oldfashioned method, a grass-lined hole, as the
botulinum bacteria thrive in the anaerobic
conditions created by the plastic.
Food Additives
• Are substances added to food to preserve flavour
or improve its taste and appearance.
• Some additives have been used for centuries; for
example, preserving food by pickling (with
vinegar), salting, as with bacon, preserving
sweets or using sulfur dioxide as in some wines.
• With the advent of processed foods in the second
half of the 20th century, many more additives
have been introduced, of both natural and
artificial origin.
• To regulate these additives, and inform consumers,
each additive is assigned a unique number.
• Initially these were the "E numbers" used in Europe
for all approved additives.
• This numbering scheme has now been adopted and
extended by the Codex Alimentarius Commission to
internationally identify all additives, regardless of
whether
they
are
approved
for
use.
• E numbers are all prefixed by "E", but countries
outside Europe use only the number, whether the
additive is approved in Europe or not. For example,
acetic acid is written as E260 on products sold in
Europe, but is simply known as additive 260 in some
countries.
• Additive 103, alkanet, is not approved for
use in Europe so does not have an E
number, although it is approved for use
in Australia and New Zealand.
• Since 1987 Australia has had an
approved system of labelling for
additives in packaged foods. Each food
additive has to be named or numbered.
The numbers are the same as in Europe,
but without the prefix 'E'.
• The United States Food and Drug
Administration listed these items as
"Generally recognized as safe" or GRAS
and these are listed under both their
Chemical Abstract Services number and
FDA regulation listed under the US Code
of Federal Regulations
Some food additives
• Acids
– Food acids are added to make flavors "sharper", and also act as
preservatives and antioxidants. Common food acids include vinegar, citric
acid, tartaric acid, malic acid, fumaric acid, lactic acid.
• Acidity regulators
– Acidity regulators are used to change or otherwise control the acidity and
alkalinity of foods.
• Anticaking agents
– Anticaking agents keep powders such as milk powder from caking or
sticking.
• Antifoaming agents
– Antifoaming agents reduce or prevent foaming in foods.
• Antioxidants
– Antioxidants such as vitamin C act as preservatives by inhibiting the effects
of oxygen on food, and can be beneficial to health.
• Bulking agents
– Bulking agents such as starch are additives that increase the bulk
of a food without affecting its nutritional value.
• Food coloring
– Colorings are added to food to replace colors lost during
preparation, or to make food look more attractive.
• Color retention agents
– In contrast to colorings, color retention agents are used to preserve
a food's existing color.
• Emulsifiers
– Emulsifiers allow water and oils to remain mixed together in an
emulsion, as in mayonnaise, ice cream, and homogenized milk.
• Flavors
– Flavors are additives that give food a particular taste or smell, and
may be derived from natural ingredients or created artificially.
• Flavor enhancers
– Flavor enhancers enhance a food's existing flavors.
They may be extracted from natural sources (through
distillation, solvent extraction, maceration, among
other methods) or created artificially.
• Flour treatment agents
– Flour treatment agents are added to flour to improve
its color or its use in baking.
• Humectants
– Humectants prevent foods from drying out.
• Tracer gas
– Tracer gas allow for package integrity testing to prevent foods from being
exposed to atmosphere, thus guaranteeing shelf life.
• Preservatives
– Preservatives prevent or inhibit spoilage of food due to fungi, bacteria
and other microorganisms.
• Stabilizers
– Stabilizers, thickeners and gelling agents, like agar or pectin (used in jam
for example) give foods a firmer texture. While they are not true
emulsifiers, they help to stabilize emulsions.
• Sweeteners
– Sweeteners are added to foods for flavoring. Sweeteners other than
sugar are added to keep the food energy (calories) low, or because they
have beneficial effects for diabetes mellitus and tooth decay and
diarrhea.
• Thickeners
– Thickeners are substances which, when added to the mixture, increase
its viscosity without substantially modifying its other properties.
• With the increasing use of processed foods since the 19th
century, there has been a great increase in the use of food
additives of varying levels of safety. This has led to
legislation in many countries regulating their use.
• Boric acid was widely used as a food preservative from the
1870s to the 1920s, but was banned after World War I due
to its toxicity, as demonstrated in animal and human
studies.
• In the USA, this led to the adoption of the Delaney clause,
an amendment to the Federal Food, Drug, and Cosmetic
Act of 1938, stating that no carcinogenic substances may
be used as food additives. However, after the banning of
cyclamates in the USA and Britain in 1969, saccharin, the
only remaining legal artificial sweetener at the time, was
found to cause cancer in rats. Widespread public outcry in
the USA, partly communicated to Congress by postagepaid postcards supplied in the packaging of sweetened soft
drinks, led to the retention of saccharin despite its violation
of the Delaney clause.
• In 2007, Food Standards Australia New Zealand published an
official shoppers' guidance with which the concerns of food additives
and their labeling are mediated [5].
• Cases like these highlight the controversy associated with the risks
and benefits of food additives. Some artificial food additives have
been linked with cancer, digestive problems, and neurological
conditions such as ADD, or diseases like heart disease or
obesity.[citation needed] Even "natural" additives may be harmful,
whether because of overuse (for example table salt) or because of
natural toxicity. An example is safrole, which was used to flavour
root beer until it was shown to be carcinogenic. Due to the
application of the Delaney clause, it may not be added to foods,
even though it occurs naturally in sassafras and sweet basil.[6]
List of food additives as organized by the Codex
Alimentarius Committee.
• The International Numbering System numbers below
(INS #) are assigned by the committee to identify each
food additive. The INS numbers generally correspond to
E numbers for the same compound - e.g. INS 102,
Tartrazine, is also E-102. INS numbers are not unique
and in fact, one number may be assigned to a group of
like compounds.
• On packaging in the European Union, approved food
additives are written with a prefix of 'E'. Australia and
New Zealand do not use a prefix letter when listing
additives in the ingredients.
• In the table below, food additives approved for Europe
are listed with an 'E'[citation needed], and those
approved for Australia and New Zealand with an 'A' . See
also the list of E numbers.
INS #
Approvals Names
Type
100
A
E
turmeric, curcumin
colour (yellow and orange)
101
A
E
riboflavin (vitamin
B2)
colour (yellow and orange)
102
A
E
tartrazine
colour (yellow and orange) (FDA:
FD&C Yellow #5)
103
A
alkanet, chrysoine
resorcinol
colour (red)
104
A
E
Quinoline Yellow
WS
colour (yellow and orange) (FDA:
D&C Yellow #10)
E
Yellow 2G
colour (yellow and orange)
107
110
A
E
Sunset Yellow FCF
colour (yellow and orange) (FDA:
FD&C Yellow #6)
111
?
E
Orange GGN
colour (orange)
120
A
E
Cochineal, carmines colour (red)
Food colour
• The color of food is an integral part of our culture and
enjoyment of life.
• Even early civilizations such as the Romans
recognized that people "eat with their eyes" as well as
their palates.
• Saffron and other spices were often used to provide a
rich yellow color to various foods. Butter has been
colored yellow as far back as the 1300's.
• Today all food color additives are carefully regulated by
federal authorities to ensure that foods are safe to eat
and accurately labeled.
• Technically, a color additive is any dye, pigment or substance
that can impart color when added or applied to a food, drug,
cosmetic or to the human body.
• The Food and Drug Administration (FDA) is responsible for
regulating all color additives used in the United States. All color
additives permitted for use in foods are classified as "certifiable"
or "exempt from certification“.
• Certifiable color additives are manmade, with each batch being
tested by manufacturer and FDA. This "approval" process,
known as color additive certification, assures the safety, quality,
consistency and strength of the color additive prior to its use in
foods.
• Color additives that are exempt from certification include
pigments derived from natural sources such as vegetables,
minerals or animals, and man-made counterparts of natural
derivatives.
• Caramel color is produced commercially by heating sugar
and other carbohydrates under strictly controlled
conditions for use in sauces, gravies, soft drinks, baked
goods and other foods.
• Whether a color additive is certifiable or exempt from
certification has no bearing on its overall safety. Both types
of color additives are subject to rigorous standards of
safety prior to their approval for use in foods.
• Certifiable color additives are used widely because their
coloring ability is more intense than most colors derived
from natural products; thus, they are often added to foods
in smaller quantities.
• Of nine certifiable colors approved for use in the United
States, seven color additives are used in food
manufacturing .
• Regulations known as Good Manufacturing Practices limit
the amount of color added to foods. Too much color would
make foods unattractive to consumers, in addition to
increasing costs.
Why Are Color Additives Used In
Foods?
• Color is an important property of foods that adds to our enjoyment of
eating. Nature teaches is early to expect certain colors in certain
foods, and our future acceptance of foods is highly dependent on
meeting these expectations.
• Color variation in foods throughout the seasons and the effects of food
processing and storage often require that manufacturers add color to
certain foods to meet consumer expectations. The primary reasons of
adding colors to foods include:
• To offset color loss due to exposure to light, air, extremes of
temperature, moisture and storage conditions.
• To correct natural variations in color. Off-colored foods are often
incorrectly associated with inferior quality. For example, some treeripened oranges are often sprayed with Citrus Red No.2 to correct the
natural orangy-brown or mottled green color of their peels (Masking
inferior quality, however, is an unacceptable use of colors.)
• To enhance colors that occur naturally but at levels
weaker than those usually associated with a given food.
• To provide a colorful identity to foods that would
otherwise be virtually colorless. Red colors provide a
pleasant identity to strawberry ice while lime sherbet is
known by its bright green color.
• To provide a colorful appearance to certain "fun foods."
Many candies and holiday treats are colored to create a
festive appearance.
• To protect flavors and vitamins that may be affected by
sunlight during storage.
• To provide an appealing variety of wholesome and
nutritious foods that meet consumers' demands.
How Are Color Additives
Regulated?
• In 1900, there were about 80 man-made color additives available for
use in foods. At that time there were no regulations regarding the
purity and uses of these dyes.
• Legislation enacted since the turn of the century, however, has greatly
improved food color additive safety and stimulated improvements in
food color technology.
• The Food and Drug Act of 1906 permitted or "listed" seven man-made
color additives for use in foods. The Act also established a voluntary
certification program, which was administered by the U.S. Department
of Agriculture (USDA); hence man-made color additives became
known as "certifiable color additives".
• The Federal Food, Drug & Cosmetic
(FD&C) Act of 1938 made food color
additive certification mandatory and
transferred the authority for its testing from
USDA to FDA. To avoid confusing color
additives used in food with those
manufactured for other uses, three
categories of certifiable color additives
were created:
• Food, Drug and Cosmetic (FD&C) - Color
additives with application in foods, drugs or
cosmetics;
• Drug and Cosmetic (D&C) - Color additives
with applications in drugs or cosmetics;
• In 1960, the Color Additive Amendments to the FD&C
Act placed color additives on a "provisional" list and
required further testing using up-to-date procedures.
• One section of the amendment known as the Delaney
Clause, prohibits adding to any food substance that has
been shown to cause cancer in animals or man
regardless of the dose.
• Under the amendments, color additives exempt from
certification also are required to meet rigorous safety
standards prior to being permitted for use in foods.
• According to the Nutrition Labeling and Education Act of
1990, a certifiable color additive used in food must be
listed in the ingredient statement by its common or usual
name. All label printed after July 1, 1991 must comply
with this requirement.
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Certifiable
Colors
Colors Exempt from Certification
FD&C Blue No.1 (Dye and
Lake), FD&C Blue No.2 (Dye
and Lake), FD&C Green No.3
(Dye and Lake), FD&C Red
No.3 (Dye), FD&C Red No.40
(Dye and Lake), FD&C Yellow
No.5 (Dye and Lake), FD&C
Yellow No.6 (Dye and Lake),
Orange B*, Citrus Red No.2*
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Flavor
• Flavor or flavour is the sensory impression of a food
or other substance, and is determined mainly by the
chemical senses of taste and smell.
• The "trigeminal senses", which detect chemical irritants
in the mouth and throat, may also occasionally
determine flavor.
• The flavor of the food, as such, can be altered with
natural or artificial flavorants, which affect these
senses.
• Flavorant is defined as a substance that gives another
substance flavor, altering the characteristics of the
solute, causing it to become sweet, sour, tangy, etc.
• Of the three chemical senses, smell is the main
determinant of a food item's flavor.
• While the taste of food is limited to sweet, sour, bitter,
salty, and savory (umami) – the basic tastes – the smells
of a food are potentially limitless.
• A food's flavor, therefore, can be easily altered by
changing its smell while keeping its taste similar.
Nowhere is this better exemplified than in artificially
flavored jellies, soft drinks and candies, which, while
made of bases with a similar taste, have dramatically
different flavors due to the use of different scents or
fragrances.
• The flavorings of commercially produced food products
are typically created by flavorists.
Flavorants or flavorings
• Flavorings are focused on altering or enhancing the
flavors of natural food product such as meats and
vegetables, or creating flavor for food products that do
not have the desired flavors such as candies and other
snacks.
• Most types of flavorings are focused on scent and
taste. Few commercial products exist to stimulate the
trigeminal senses, since these are sharp, astringent,
and typically unpleasant flavors.
• There are three principal types of flavorings used in
foods, under definitions agreed in the E.U. and
Australia: [1]
• Natural flavoring substances: Flavoring substances
obtained from plant or animal raw materials, by
physical, microbiological or enzymatic processes.
• They can be either used in their natural state or
processed for human consumption, but cannot contain
any nature-identical or artificial flavoring substances.
• Nature-identical flavoring substances: Flavoring
substances that are obtained by synthesis or
isolated through chemical processes, which are
chemically identical to flavoring substances
naturally present in products intended for human
consumption. They cannot contain any artificial
flavoring substances.
• Artificial flavoring substances: Flavoring
substances not identified in a natural product
intended for human consumption, whether or not
the product is processed
Smell
• Smell flavorants, or simply, flavorants, are engineered and
composed in similar ways as with industrial fragrances and fine
perfumes.
• To produce natural flavors, the flavorant must first be extracted
from the source substance. The methods of extraction can involve
solvent extraction, distillation, or using force to squeeze it out.
• The extracts are then usually further purified and subsequently
added to food products to flavor them. To begin producing artificial
flavors, flavor manufacturers must either find out the individual
naturally occurring aroma chemicals and mix them appropriately to
produce a desired flavor or create a novel non-toxic artificial
compound that gives a specific flavor.
• Most artificial flavors are specific and often complex mixtures of
singular naturally occurring flavor compounds combined together
to either imitate or enhance a natural flavor.
•
• These mixtures are formulated by flavorist to
give a food product a unique flavor and to
maintain flavor consistency between different
product batches or after recipe changes.
• The list of known flavoring agents includes
thousands of molecular compounds, and the
flavor chemist (flavorist) can often mix these
together to produce many of the common
flavors. Many flavorants are esters.
• The compounds used to produce artificial flavors are
almost identical to those that occur naturally, and a
natural origin for a substance does not necessarily
imply that it is safe to consume.
• In fact, artificial flavors are considered somewhat
safer to consume than natural flavors due to the
standards of purity and mixture consistency that are
enforced either by the company or by law.
• Natural flavors in contrast may contain toxins from
their sources while artificial flavors are typically
more pure and are required to undergo more testing
before being sold for consumption
• Flavors from food products are usually the result of
a combination of natural flavors, which set up the
basic smell profile of a food product while artificial
flavors modify the smell to accent it.
Flavor creation
• Most food and beverage companies do not create their own flavors
but instead employ the services of a flavor company.
• Food and beverage companies may require flavors for new
products, product line extensions (e.g., low fat versions of existing
products) or due to changes in formula or processing for existing
products.
• The flavor creation is done by a specially trained scientist called a
"flavorist.“
• The flavorist's job combines extensive scientific knowledge of the
chemical palette with artistic creativity to develop new and distinctive
flavors.
• The flavor creation begins when the flavorist receives a brief from
the client.
• In the brief the client will attempt to communicate exactly what type
of flavor they seek, in what application it will be used, and any
special requirements (e.g., must be all natural).
• The communication barrier can be quite difficult to overcome since
most people aren't experienced at describing flavors.
• The flavorist will use his or her knowledge of the available chemical
ingredients to create a formula and compound it on an electronic
balance.
• The Federal Food, Drug & Cosmetic (FD&C) Act
of 1938 made food color additive certification
mandatory and transferred the authority for its
testing from USDA to FDA. To avoid confusing
color additives used in food with those
manufactured for other uses, three categories of
certifiable color additives were created:
• Food, Drug and Cosmetic (FD&C) - Color
additives with application in foods, drugs or
cosmetics;
• Drug and Cosmetic (D&C) - Color additives with
applications in drugs or cosmetics;
• The flavor will then be submitted to the client for testing.
Several iterations, with feedback from the client, may be
needed before the right flavor is found.
• Additional work may also be done by the flavor company.
For example, the flavor company may conduct sensory
taste tests to test consumer acceptance of a flavor
before it is sent to the client or to further investigate the
"sensory space.“
• The flavor company may also employ application
specialists who work to ensure the flavor will work in the
application for which it is intended.
• This may require special flavor delivery technologies that
are used to protect the flavor during processing or
cooking so that the flavor is only released when eaten by
the end consumer.
Unit 3
• Organisms and their use for production of
fermented foods and beverages
• Pickling
• Alcoholic beverages
• Cheese
• Sourkrat
• Idli
• Vinegar
B. Tech.
Food Biotechnology
Dr. A. K. Gupta
Fermented
foods
1
Cheese
1-15
Cheese
• Cheese comes in many varieties. The variety determines
the ingredients, processing, and characteristics of the
cheese.
• The composition of many cheeses is defined by
Standards of Identity in the U.S. Code of Federal
Regulations (CFR).
• Cheese can be made using pasteurized or raw milk.
• Cheese made from raw milk imparts different flavors
and texture characteristics to the finished cheese.
• For some cheese varieties, raw milk is given a mild heat
treatment (below pasteurization) prior to cheese making
to destroy some of the spoilage organisms and provide
better conditions for the cheese cultures.
• Cheese made from raw milk must be aged for at least 60
days, to reduce the possibility of exposure to disease
causing microorganisms (pathogens) that may be
present in the milk. For some varieties cheese must be
aged longer than 60 days.
• Cheese can be broadly categorized as acid or rennet
cheese, and natural or process cheeses.
• Acid cheeses are made by adding acid to the milk to
cause the proteins to coagulate.
• Fresh cheeses, such as cream cheese or queso fresco,
are made by direct acidification. Most types of cheese,
such as cheddar or Swiss, use rennet (an enzyme) in
addition to the starter cultures to coagulate the milk.
• The term “natural cheese” is an industry term referring to
cheese that is made directly from milk.
• Process cheese is made using natural cheese plus
other ingredients that are cooked together to change the
textural and/or melting properties and increase shelf life.
•
Ingredients
• The main ingredient in cheese is milk.
• Cheese is made using cow, goat, sheep, water buffalo or
a blend of these milks.
• The type of coagulant used depends on the type of
cheese desired. For acid cheeses, an acid source such
as acetic acid (the acid in vinegar) or gluconodeltalactone (a mild food acid) is used.
• For rennet cheeses, calf rennet or, more commonly, a
rennet produced through microbial bioprocessing is
used.
• Calcium chloride is sometimes added to the cheese to
improve the coagulation properties of the milk.
• Flavorings may be added depending on the cheese.
• Some common ingredients include herbs, spices, hot
and sweet peppers, horseradish, and port wine.
•
Worldwide, cheese is a major agricultural product. According to the Food
and Agricultural Organization of the United Nations, over 18 million
metric tons of cheese were produced worldwide in 2004. This is more
than the yearly production of coffee beans, tea leaves, cocoa beans and
tobacco combined. The largest producer of cheese is the United States,
accounting for 30% of world production, followed by Germany and
France.
Top cheese producers
(1,000 metric tons)
United States
4,275 (2006)
Germany
1,927 (2008)
France
1,884 (2008)
Italy
1,149 (2008)
Netherlands
732 (2008)
Poland
594 (2008)
Brazil
495 (2006)
Egypt
462 (2006)
Argentina
425 (2006)
Australia
395 (2006)
Top cheese exporters (Whole Cow Milk only) - 2004
(value in '000 US $)
France
2,658,441
Germany
2,416,973
Netherlands
2,099,353
Italy
1,253,580
Denmark
1,122,761
Australia
643,575
New Zealand
631,963
Belgium
567,590
Ireland
445,240
United Kingdom
374,156
Germany is the largest importer of cheese. The UK and Italy are the
second- and third-largest importers
Top cheese consumers - 2003
(kilograms per person per year)
Greece
27.3
France
24.0
Italy
22.9
Switzerland
20.6
Germany
20.2
Netherlands
19.9
Austria
19.5
Sweden
17.9
Bacterial Cultures
• Cultures for cheese making are called lactic acid
bacteria (LAB) because their primary source of energy is
the lactose in milk and their primary metabolic product is
lactic acid.
• There is a wide variety of bacterial cultures available that
provide distinct flavor and textural characteristics to
cheeses.
• Starter cultures are used early in the cheese making
process to assist with coagulation by lowering the pH
prior to rennet addition.
• The metabolism of the starter cultures contribute
desirable flavor compounds, and help prevent the growth
of spoilage organisms and pathogens.
• Typical starter bacteria include Lactococcus lactis subsp.
lactis or cremoris, Streptococcus salivarius subsp.
thermophilus, Lactobacillus delbruckii subsp. bulgaricus,
and Lactobacillus helveticus.
• Adjunct cultures are used to provide or enhance the
characteristic flavors and textures of cheese. Common
adjunct cultures added during manufacture include
Lactobacillus casei and Lactobacillus plantarum for
flavor in Cheddar cheese, or the use of
Propionibacterium freudenreichii for eye formation in
Swiss.
• Adjunct cultures can also be used as a smear for
washing the outside of the formed cheese, such as the
use of Brevibacterium linens of gruyere, brick and
limburger cheeses.
• Yeasts and molds are used in some cheeses to provide
the characteristic colors and flavors of some cheese
varieties.
• Torula yeast is used in the smear for the ripening of brick
and limberger cheese.
• Examples of molds include Penicillium camemberti in
camembert and brie, and Penicillium roqueforti in blue
cheeses.
•
General Manufacturing Procedure
• The temperatures, times, and target pH for
different
steps,
the
sequence
of
processing steps, the use of salting or
brining, block formation, and aging vary
considerably between cheese types.
• The following flow chart provides a very
general outline of cheese making steps.
• The general processing steps for Cheddar
cheese are used for illustration.
General Cheese Processing Steps
Standardize Milk
Pasteurize/Heat Treat Milk
Cool Milk
Inoculate with Starter & Non-Starter
Bacteria and Ripen
Add Rennet and Form Curd
Cut Curd and Heat
Drain Whey
Texture Curd
Dry Salt or Brine
Form Cheese into Blocks
Store and Age
Package
•
Processing Steps in Cheddar Cheese
Production
The times, temperatures, and target pH values used for cheddar cheese will depend on individual
formulations and the intended end use of the cheese. These conditions can be adjusted to
optimize the properties of Cheddar cheese for shredding, melting, or for cheese that is meant to
be aged for several years.
• 1. Standardize Milk
•
Milk is often standardized before cheese making to optimize the protein to fat ratio to make a good
quality cheese with a high yield
• 2. Pasteurize/Heat Treat Milk
•
Depending on the desired cheese, the milk may be pasteurized or mildly heat-treated to reduce
the number of spoilage organisms and improve the environment for the starter cultures to grow.
Some varieties of milk are made from raw milk so they are not pasteurized or heat-treated. Raw
milk cheeses must be aged for at least 60 days to reduce the possibility of exposure to disease
causing microorganisms (pathogens) that may be present in the milk.
• 3. Cool Milk
•
Milk is cooled after pasteurization or heat treatment to 90°F (32°C) to bring it to the temperature
needed for the starter bacteria to grow. If raw milk is used the milk must be heated to 90°F (32°C).
• 4. Inoculate with Starter & Non-Starter Bacteria and Ripen
•
The starter cultures and any non-starter adjunct bacteria are added to the milk and held at 90°F
(32°C) for 30 minutes to ripen. The ripening step allows the bacteria to grow and begin
fermentation, which lowers the pH and develops the flavor of the cheese.
• 5. Add Rennet and Form Curd
•
The rennet is the enzyme that acts on the milk proteins to form the curd.
After the rennet is added, the curd is not disturbed for approximately 30
minutes so a firm coagulum forms.
• 6. Cut Curd and Heat
•
The curd is allowed to ferment until it reaches pH 6.4. The curd is then cut
with cheese knives into small pieces and heated to 100°F (38°C). The
heating step helps to separate the whey from the curd.
• 7. Drain whey
•
The whey is drained from the vat and the curd forms a mat.
• 8. Texture curd
•
The curd mats are cut into sections and piled on top of each other and
flipped periodically. This step is called cheddaring. Cheddaring helps to
expel more whey, allows the fermentation to continue until a pH of 5.1 to 5.5
is reached, and allows the mats to "knit" together and form a tighter matted
structure. The curd mats are then milled (cut) into smaller pieces.
•
•
•
•
•
• 9. Dry Salt or Brine
For cheddar cheese, the smaller, milled curd pieces are put back in
the vat and salted by sprinkling dry salt on the curd and mixing in the
salt. In some cheese varieties, such as mozzarella, the curd is
formed into loaves and then the loaves are placed in a brine (salt
water solution).
• 10. Form Cheese into Blocks
The salted curd pieces are placed in cheese hoops and pressed into
blocks to form the cheese.
• 11. Store and Age
The cheese is stored in coolers until the desired age is reached.
Depending on the variety, cheese can be aged from several months
to several years.
• 12. Package
Cheese may be cut and packaged into blocks or it may be waxed.