Transcript Cleaner production of dairy processing

Cleaner production of
dairy processing
continue
• Milk is than cooled using a plate cooler and than
transported to storage vessels
• Empty tankers are cleaned in wash bay, first with
cold water and then cleaned with detergents or
caustic solution
• To avoid milk scale it is necessary to rinse the
inside of the tank with a nitric acid wash
• Solid waste is generated from milk clarification and
consists mostly of dirt, cells from the cows udders,
blood corpuscles and bacteria. If this is discharged
into effluent stream, high organic loads are the
result
Dairy processing
• Basic dairy processing have
changed little in the past
decade
• Specialized processes such as
ultra filtration and modern
drying processes have
increased the opportunity for
the recovery of milk solids that
were formerly discharged
Process overview- milk
production
• Receipt and filtration /clarification of
the raw milk
• Separation of all or part of the milk
fat (for standardization of the market
milk, production of cream and butter
and other fat based products and
production of milk powders
• pasteurisation
Continue milk
production
• Homogenization (if required)
• Deodorization (if required)
• Further product specific
processing
• Packaging and storage included
cold storage for perishable
products
• Distribution of final products
Butter making
• Preparation of the cream
• Destabilization and breakdown
of the fat and water emulsion
• Aggregation and concentration
of the fat particles
• Formation of a stable emulsion
• Packaging and storage
• distribution
Butter making
• Milk destined for butter making must
not be homogenized because the
cream must remain in a separate
phase
• After separation cream to be used
for butter making is heat treated and
cooled under conditions that
facilitate good whipping and
churning
• It may then be ripened with a culture
that increase the content of diacetyl
the compound responsible for the
flavor of butter
Butter making
• Butter made without the
addition of a culture is called
sweet cream butter, most butter
made in the English speaking
world is of this nature
• Both cultured and sweet cream
butter can be produced with or
without the addition of salt
Cheese production
• Virtually all cheese is made by
coagulation milk protein (casein) in
a manner that traps milk solids and
milk fat into a curd matrix
• This curd matrix is then
consolidated to express the liquid
fraction, cheese whey
• Cheese whey contains those milk
solids which are not held in the curd
mass in particular most of the milk
sugar (lactose) and a number of
Milk powder
• Milk used for making milk powder
whether it be whole or skim milk is
not pasteurized before use
• the milk is pre heated in tubular
heat exchangers before being dried
• The preheating temperature depends
on the season and on the
characteristics desired for the final
powder product
• The preheated milk is fed to an
evaporator to increase the
concentration of the total solids
Milk powder continue
• The milk concentrate is then
pumped to the atomiser of a
drying chamber
• Milk powder falls to the bottom
of the chamber from where it is
removed
Impacts of primary
production (dairy farming)
• Manure wastes: in most case applied to
pastures and cultivated land-may be
restricted
1. Dairy effluent and slurries are generally
held in some form of lagoon to allow
sedimentation and biological degradation
before irrigated onto land
2. Sludge generated from biological
treatment of the dairy effluent ca also be
applied to pastures as long it is within
allowable concentrations form specified
pollutants as prescribed by regulations
3. Sludge can also be used in the production
of methane-rich biogas which can then be
used to supplement energy supplies
Impacts of primary
production -continue
• Improper storage and land
application of manure and
slurries can result in serious
pollution of surface waters and
ground water, potentially
contaminating drinking water
supplies
Impacts of primary
production
• Chemical fertilizers : contains high levels
of nitrogen and has resulted in pollution of
the ground water and surface waters
1. Nitrite in drinking water is known to be
carcinogenic and nitrite levels in drinking
water that exceed 25-50 mg/l have been
linked to cyanosis in new born infants
2. Compounds containing nitrogen and
phosphorus if discharged to surface
water can lead to excessive alga growthdepleted dissolved oxygen levels –thereby
causing death of fish etc
Impacts of primary
production continue
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Pesticides are an environmental
concerns
1. Toxic pesticides can accumulate in
body tissues and are harmful to eco
systems and to human health
2. Can end up in agriculture products,
ground water and surface water and
in extreme cases can enter human
food chain through milk
Impacts of primary
production
• Milk contamination
1. Milk contamination of overuse of
antibiotics for treatment of cattle
diseases especially mastitis
2. Strict limitations on the use of
antibiotics, regular testing of milk
for antibiotics residues, rigorous
enforcement of regulations and
education is essential
3. Screening of traces of radioactivity
Impacts of dairy
processing
• Water consumption
1. Requires very large quantities
of fresh water-must be potable
water
Impacts of dairy
processing continue
• Effluent discharge
1. High organic load due to presence of milk
components
2. Fluctuations in ph to the presence of
caustic an acid cleaning agents and
other chemicals
3. High levels of nitrogen and phosphorus
4. Fluctuation in temperature
5. If whey from the cheese making is not
used and discharged along with other
waste waters ,the organic load is
increased
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• Milk is a fluid that consists of water,
milk fat, a number of proteins (both
in suspension and in solution), milk
sugar (lactose) and mineral salts
• Dairy product contain all or some of
above mentioned components and
depending on he nature and type of
product and the method of
manufacturing ,may also contain
sugar, salts (sodium chloride),
flavors, emulsifiers and stabilizers
continue
• In non rural areas dairy processing
effluent is often discharged to municipal
sewage treatments systems.
• In rural areas may also be irrigated to land,
if not managed correctly dissolved salts
contained in the effluent can adversely
affect soil structure and cause salinity.
Contaminants in the effluent can also
leach into ground water and affect its
quality
• In some locations effluent may discharged
directly into water bodies and could have
negative impact on water quality due to
high levels of organic mater and depletion
of oxygen levels
Impacts of dairy
processing
• Energy consumption
1. For cooling and refrigeration
and use of thermal energy
2. Depleting of fossil fuel
resources, air pollution and
green gas emissions are all
linked to global warming
Impacts of dairy
processing
• Solid wastes
1. Breakages and packaging
mistakes should be handled
properly
Impacts of dairy
processing
• Emissions to air
1. Air pollutions includes oxides of
nitrogen and sulphor and suspended
particulate matter
2. In addition discharges of milk
powder from the exhaust of spray
drying equipment can be deposited
on surrounding surfaces. When wet
these deposits become acid and
can cause corrosion
Impacts of dairy
processing
• Refrigerants
1. Loss of CFCs is a
environmental considerationcan cause ozone depletion
2. Replacement to non or
reduced CFC systems is
recommended
Impacts of dairy
processing
• Noise
1. For example the use of
hammer mills to grind the
product (dried casein
production), use of steam
injection, reduced pressure in
evaporation processes etc
,traffic load
Impacts of dairy
processing
• Hazardous waste
1. Oily sludge from gear boxes,
laboratory waste, cooling
agents, batteries, paint etc.
Environmental
indicators
• Water consumption
1. Overall use of water is due to
higher costs of water and effluent
disposal costs in some countries
reduced
2. A modern dairy processing plant
will have a water consumption rate
of 1.3-2.5 liters water /kg of milk
intake however 0.8-1.0 liter
water/kg of milk is possible
Environmental
Indicators
• Effluent discharge
1. The constituents present are
milk fat, protein, lactose and
lactic acid as well as sodium,
potassium, calcium and
chloride
2. Cumulative effect of minor and
on occasions, major losses of
milk
Environmental
indicators effluent
discharge
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The organic pollutant content of dairy
effluent is commonly expressed as:
5 day biochemical oxygen demand -BOD5
or
As chemical oxygen demand-COD
One liter of whole milk is equivalent to
approximately 110000 mg BOD5 or
210000mg COD
Concentrations of COD in dairy
processing effluents vary widely from
180 to 23000mg/l, low values are
associated with milk receipt operations
and high values reflect the presence of
whey from the production of cheese
Environmental
indicators effluent
discharge
• A typical COD concentration for
effluent from a dairy plant is about
4000mg/l.
• This implies that 4% of the milk
solids received into the plant is lost
to the effluent stream given that the
COD of whole milk is 210000mg/l and
that effluent COD loads have been
estimated to be approximately
8.4kg/m3 milk intake
Environmental
indicators effluent
discharge
• Effluent loads depends on: type
product, scale operationbatch/continuous.
• The tendency within the
industry towards larger plants
is thus favorable in terms of
pollutant per unit of production
Environment indicators
effluent discharge
• Milk receipt and storage
1. Poor drainage of tankers
2. Spills and leaks from hoses
and pipes
3. Spills from storage tanks
4. Foaming
5. Cleaning operations
Environmental indicators
effluent discharge
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Pasteurization and ultra heat
treatment
Leaks
Recovery of downgraded product
Cleaning operations
Foaming
Deposits on surfaces of equipment
Environmental indicators
effluent discharge
• Homogenization
1. Leaks
2. Cleaning operation
Environmental indicators
effluent discharge
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Separation and clarification
Foaming
Cleaning operations
Pipe leaks
Environmental indicators
effluent discharge
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Market milk production
Leaks and foaming
Product washing
Cleaning operations
Overfilling
Poor drainage
Sludge removal from separators/clarifiers
Damaged milk packages
Cleaning of filling machinery
Environmental indicators
effluent discharge
• Cheese making
1. Overfilling vats
2. Incomplete separation of whey
from curds
3. Use of salt in cheese making
4. Spills and leaks
5. Cleaning operations
Environmental indicators
effluent discharge
• Butter making
1. Use of salt
2. Cleaning operations
Environmental indicators
effluent discharge
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Milk powder production
Spills during powder handling
Start up and shut down processes
Plant malfunction
Stack losses
Cleaning of evaporators and driers
Bagging losses
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• The disposal of whey produced
during cheese production has
always been a major problem
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• Whey is the liquid remaining after the
recovery of the curds formed by the action
of enzymes on milk
• It compromises 80-90% of the total volume
of milk used in the cheese making process
and
• Contains more than half the solids from
the original whole milk,
• Including 20% of the protein
• And most of the lactose
• It ha s a high organic content with COD of
approximately 60000mg/l
Energy consumption
• Approximately 80% of a plant energy
needs is met by combustion of fossil fuel
to generate steam and hot water for
evaporative and heating process
• Energy consumed depends on the range of
products being produced
• Energy consumption will also depend on
the age and scale of a plant as well on the
level of automation
• Energy consumption depends on the
number of evaporation effects and the
efficiency of the powder dryer
opportunities
• For cleaner production
general
Continue-general
• Are work areas tidy and uncluttered to
avoid accidents
• Is there a good inventory control to avoid
waste of raw ingredients
• Are employees aware of the environmental
aspects of the company operations and
their personal responsibilities
• Is staff trained in good cleaning practices
• Is there a schedule for regular
maintenance to avoid breakdown
Continue -general
• Is equipment optimize and standardized for
each shift
• Are all valves and equipment identified and
marked to reduce the risk that they will be
set incorrectly by inexperienced staff
• Are start up and shut down procedures
improved
• Is waste segregate for reuse and recycling
• Are drip pans installed or trays to collect
drips and spills
opportunities
• For cleaner production
continue
• Analyze water use patterns-water
meters and recording water
consumption
• Survey of all process area and
ancillary operations-install shut off
equipment and restrictors
• Water use for essential process
functions investigate-optimum usage
rate
• Water reuse considerations
continue
• Is there a continuous rather than a batch
process to reduce the frequency of
cleaning
• Is there an automatic cleaning in place to
control and optimize water use
• Are fixtures installed that restrict or
control the flow of water for manual
cleaning processes
• Is there a reuse of clean waste water for
other cleaning steps or non critical
applications
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• Is high pressure used rather than high
volume for cleaning surfaces
• Is recirculated water used for non critical
applications
• Are meters installed on high use
equipment to monitor consumption
• Are floor and equipment pre soaked to
loosen dirt before final clean
• Is compressed air used instead of water
where appropriate
• Are leaks reported and fixed promptly
Opportunities-effluent
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• Are vessels and pipes drained completely
and are pigs and plugs used to remove
product residues before cleaning
• Are level controls and automatic shut off
systems used to avoid spills from vessels
and tanker emptying
• Are spills of solid materials collected
(cheese curd and powder) for reprocessing
or use as stock feed
• Are drains fit with screens and /or traps to
prevent solids entering into effluent
system
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• Are in line optical sensors and
diverters installed to distinguish
between product and water and
minimize losses of both
• Are level controls and automatic
shut off systems on tanks installed
and maintained
• Are dry cleaning techniques used
• Are starch plugs or pigs used to
recover product from pipes before
internally cleaning tanks
opportunities
• energy
continue
• Substantial savings can be
made with no capital
investment through simple
house keeping and plant
optimization efforts
• Cleaner fuels will give more
environmentally benign sources
of energy
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• Are switch off programs implemented and
are sensors installed to turn off or power
down lights and equipment when not in use
• Is insulation improved on heating or
cooling systems and pipe work
• Is more energy efficient equipment used
• Is maintenance improved to optimize
energy efficiency of equipment
• Are optimal combustion efficiencies
maintained on steam and hot water boilers
• Are steam leaks eliminated
• Is low grade energy captured elsewhere
Milk production-receipt
and storage of milk
1. Operators must measure the
quantity of milk and the fat
content
2. The milk is then filtered and /or
clarified using centrifuges to
remove dirt particles as well
udder and blood cells
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1. Empty tankers are cleaned
internally with cold water and
then cleaned with detergents
or a caustic solution
2. To avoid build up of milk scale
it is then necessary to rinse
inside with nitric acid wash
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• Solid waste is generated from
milk clarification and consists
mostly from udders, blood and
bacteria. If discharged into
effluent stream high organic
loads and associated problems
can result
continue
• Opportunities for cleaner production in the area of
receipt and storage of milk:
1. Avoiding milk spillage when disconnecting pipes
and hoses
2. Ensuring vessels and hoses are drained before
disconnecting
3. Facilities to collect spills
4. Identifying and marking all pipeline to avoid wrong
connection
5. Installation in slight gradient to make self draining
6. Level control to prevent overflow
7. Solid discharges should not discharged in sewer
continue
• Using clean in place systems for internal cleaning
of tankers and milk storage vessels thus improving
the effectiveness of cleaning and reducing
detergent consumption
• Improving cleaning regime and training staff
• Installing trigger nozzles on hoses for cleaning
• Reusing final rinse water for the initial rinses
• Collecting wastewaters from initial rinses and
returning them to the dairy farm for watering cattle
Milk production-separation
and standardization
• Dairies that produce cream and
/or butter separate fat from the
raw milk
• Separation takes place in a
centrifuge which divide the milk
into cream with about 40% fat
and skimmed milk with only
about 0.5% fat
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• In general whole milk must contain
around 3.5-4.2% fat
• Semi-skimmed milk around 1.3-1.5%
• Skimmed milk around 0.5%
• The centrifugal separators generate
a sludge material which consists of
udder and blood cells and bacteria
contained in raw milk For standard
separators the sludge is removed
manually during the cleaning phase
continue
• In case of self cleaning
centrifuges it is discharged
automatically. If sludge is
discharged to the sewer along
with the effluent stream it
greatly increases the organic
load of the effluent
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• Cleaner production opportunities:
1. Reducing the frequency with which
centrifugal separators are cleaned
by improving milk filtration at the
receiving stage or by clarification
of the raw milk
2. Collecting the sludge's and
disposing of it with other solids
3. Make cleaning process water and
energy efficient
Milk productionpasteurization and
homogenisation
• In large plants milk is pasteurized in
continuous flow pasteurizers where
smaller dairies may use batch type
• In batch pasteurization process is
typically heated to 62.8-65.6 Celsius
for 30 minutes
• In continuous pasteurization it is
heated to 71.7-78.1 Celsius for at
least 15 seconds
• The milk is than cooled down to
below 10 degrees Celsius
continue
• For some products milk is
homogenized using a pressure pump
which breaks up the butterfat
globules to a size that keeps them in
suspension
• The main environmental issue is the
high levels of energy and water use
resulting in waste water containing
milk solids and cleaning agents
continue
• Cleaner production opportunities:
1. Replacing batch pasteurizer with
continuous process incorporating plate
heat exchanger PHE pasteurizer (more
energy efficient because the heat from
the pasteurized milk can be used to
preheat the incoming milk)
2. Installing new manufacturing equipment
3. Avoids stops in continuous processes
4. Reducing the frequency of pasteurizer
cleaning, optimizing balance tanks before
and after the pasteurizers
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• Planning production schedules so that
product change over coincide with
cleaning regimes
• Collecting and recovering the milky waste
generated of pasteurization and supplying
it to farmers as animal feed
• Optimization of cleaning process
• Reprocessing of excess milk returned from
markets? Penalties for inappropriate
ordering or bonuses for extended periods
Milk productiondeodorization
• In these systems odorous
substances are drawn off by
injecting steam into system
under vacuum
• An environmental issue is the
large volume of water
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• Cleaner production
opportunities:
1. Water recirculation
Milk production-storage
and packaging
• Very extensive storage systems
with associate vessels, piping and
valves
• The storage temperature depends on
the product, the optimum
temperature is usually < 4 degree
Celsius
• The main environmental issues are
the loss of milk products from spills
and packaging mistakes; generation
of waste water and energy
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• Glass recycling systems require
large capital investments and
involve high running costs
• Cartons create solid waste, all
have environmental impacts
including the generation of
leakage from landfills and air
pollution from incineration
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• Cleaner production opportunities:
• Focus on energy efficiency of refrigeration systems
etc:
• clearing milk residues from pipes using
compressed air
• Collecting milk waste after as start up and shut
down for use as animal feed
• Optimizing the accuracy of filling operations
• Improving procedures for recovering milk from
wrongly filled containers and use as animal feed
• Improved insulation, closing doors, good
maintenance and regular defrosting
• Using ammonia base cooling systems
Butter production
• The objective is to conserve the
fatty proportion of the milk in a form
that can be used at a later date
• It is essentially a dehydration
process in which the majority of the
aqueous phase is removed and the
remainder is emulsified into the fat
• Milk is an emulsion of milk fat in
water whereas butter is an emulsion
of water in milk fat
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• From wooden barreled butter churns to stainless steel
churns
• Batch or churn process is still used in smaller diaries
• In batch process :
1. prepared cream is agitated in a special designed vessel butter churn
2. Until phase inversion occurs and the fat breaks from the
cream in the form of butter grains
3. The surrounding liquid –the buttermilk -is then decanted
off
4. The butter grains are washed in fresh chilled water,
salted (if required)
5. And worked by a shearing process to produce a
homogeneous mass with a controlled moisture content
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• In continuous process:
• Process take place in cylindrical ,rotating
chambers which progressively lead the
butter mass to blending augers and final
extrusion
• The continuous process reduces the
amount of waste generated by the
process by eliminating the butter grain
washing step and also by making use of an
internal mechanical system for continuous
recovery of butter fines
Butter production-cream
treatment: ripened cream
processes
• Pasteurization of the cream for
making butter normally at
temperatures up to 110 degrees
Celsius
• The cream may be subjected to
vacuum treatment during
cooling in order to improve
spread ability
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• In the production of ripened
butter, the cream is cooled,
inoculated with a culture and
ripened
1. After ripened period of 12-18
hours at 20 Celsius the cream
is cooled down to below 10
Celsius
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• The optimum temperature for ageing the
cream-allowing all fat to become solid-is
generally lower than the temperature
required for efficient churning
• The most effective temperature for cream
can be achieved by using heat exchangers
with a low pressure drop and a minimum
temperature differential between the
cream and the water. This avoids localized
overheating
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• Environmental issues is the high
organic load in waste water
generated from rinsing and
cleaning pasteurizer
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• Cleaner production opportunities:
1. Reducing water use and loss of product by
minimizing the number of times the
pasteurizer is cleaned (operating
continuous)
2. Installing modern pasteurizing equipment
because improvements in plate design
give a more gentle and constant heat
treatment (high volume pasteurizing units
should be considered)
3. Collecting the more highly concentrated
waste water generated when starting
pasteurizer for use of animal feed
Butter production-butter
churning
• Cream enters the butter maker and fat
globules are disrupted under controlled
conditions to destabilize the emulsion and
agglomerate the milk fat (this is achieved
in the first churning cylinder which is fitted
with a beater driven by variable speed
motor)
• To maintain steady butter making
conditions it is essential that the cream
feed rate is constant. This can achieved by
using a balance tank between the ageing
silo and the pump
continue
• The mixture of butter grains and
buttermilk falls from the first cylinder into
the back section of a second cylinder
where grains are consolidated
• Second cylinder is a larger, perforated,
slow rotating drum which cause the grains
to travel along an inclined rotating screen
with a tumbling action-thus assisting their
aggregation at the same time as they are
drained of buttermilk.
continue
• From the second cylinder the
moist grains of butter fall into
the worker compartment which
uses contra rotating augers to
compact the grains into a
heterogeneous mass expelling
more buttermilk from the grains
as they are squeezed together
continue
• Compacted butter grains are fed
from the auger through a series of
alternating perforated plates and
impeller blades- further
consolidating of the butter grains
and break up the droplets of
buttermilk now remaining in the fat
matrix
• This is now a water in oil emulsion
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• A second worker compartment
operating under vacuum may be
incorporated to obtain a denser finer
textured product
• A second set of augers removes the
butter and forces it through a final
set of orifice plates and blades
which complete the emulsification
before the product is discharged
from the butter maker
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• Environmental issues, unless
the buttermilk is used as a
product or as an ingredient in
other products, the quantities of
buttermilk produced (about 50%
of the original cream volume)
represent a potential
environmental loading
continue
• Cleaner production opportunities:
1. Ensure buttermilk is collected separately
and hygienically so can be used in other
processes such as a base for low fat
spreads
2. Collect all first rinses and separate the
residual fat for use in other processes
3. Prevent build up of milk scale deposits
4. Maintain butter makers
5. Avoid spills by ensuring that buttermilk
collection facilities are large enough
Butter production-butter
packaging
• More commonly butter is discharged to a
butter silo fitted with a pump thus avoiding
any discontinuities in production-and than
pumped to packaging machines through
pressure compensators which control the
shear forces.
• Repackaging of bulk butter into consumer
portions requires that the frozen butter
first be allowed to reach an optimum
temperature of 6-8 degree Celsius under
controlled humidity
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• After temperature adjustment and
before repackaging the butter is
reblended to break down the matrix
of fat crystals and to re-introduce
plasticity. At this stage there is an
opportunity to adjust salt and
moisture content
• The main environmental issues are
the high organic loads in
wastewaters generated from rinsing
and cleaning of equipment
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• Cleaner production opportunities:
1. Reducing first rinses while still
warm and separating the milk fat
residues for use in other processes
2. Reducing disposal of packaging
material by optimizing operation of
packaging machines
Butter production-butter
storage
• Commercial freezing stores operate
at temperatures down to minus 30
degree Celsius
• Butter for immediate consumption is
place in cold storage at 5 degrees
Celsius for 24-48 hours in order to
standardize its consistency and
appearance
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