FIELD OF THE INVENTION
The present invention relates in general to processes for the recovery of whey
protein as paneer from whey and more particularly to a process for
enhancement in the yield of cottage cheese (paneer) by re-circulation of
concentrated whey. It is a closed loop process in which whey, which is produced
by coagulation of milk, is again concentrated and re-processed to produce
cottage cheese (paneer). This process also substantially mitigates
environmental pollution, by recycling whey which is otherwise dumped in the
drains or water bodies.
BACKGROUND AND PRIOR ART
In India, cottage cheese is popularly known by names like paneer and chhena.
Both these names and may be other in different region / language have been
used in this specification to mean cottage cheese. Out of the two, paneer is
more widely known and herein after referred to as paneer only.
Paneer is a heat- and acid-coagulated traditional milk product, mainly consisting
of milk solids obtained from the coagulation of hot milk with organic and / or
inorganic acids and subsequent drainage of the whey, followed by pressing.
Paneer is characterized by its typical mild acidic flavour with a slightly sweet
taste. It has firm, cohesive and spongy body and has a smooth texture. It is
mostly used as a delicatessen in preparation of different dishes as well as in
making sweets, salad, snacks, etc. Paneer is used as a raw material for
preparing various popular dishes such as Paneer bajji, Paneer pakoda, Paneer
masala, Paneer butter masala, Paneer cutlet, baked Paneer and Paneer coconut
balls.
The production of paneer has largely been confined to the unorganized dairy
sector which employs traditional, inefficient methods of manufacture. Mostly,
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the production units discharge the untreated whey into the drains, since only
few such units have effluent treatment plants. Thus this industry as a whole has
a large and adverse impact on the environment. The untreated whey being
discharged in the drains comes in contact with the waste waters in the system
contaminates the entire drainage system and helps in bacterial and fungal
growths.
Present state of art of Paneer manufacturing process:
Following steps are used at present for paneer (cottage cheese) manufacturing:
• Heat treatment of milk
Heat treatment of milk has a profound effect on physico-chemical, sensory and
microbiological properties of paneer. It also affects TS recovery and thus the
yield of paneer. Heat treatment of milk is essential to destroy the pathogenic as
well as spoilage micro-organisms. It also denaturates whey proteins, reduces
solubility of colloidal calcium phosphate, thus co-precipitating them along with
the casein upon acidification of milk. These constituents increase the yield of
curds, which are otherwise lost in the whey. Heat treatment at 90°C for 10–
15 min was necessary to achieve desired yield. Different time-temperature
combinations are adopted by various manufacturers.
Type and strength of coagulant:
Paneer manufacture involves the coagulation of milk proteins to form curd.
During this process large clumps of proteins are formed in which fat and other
colloidal and dissolved solids get entrapped. The coagulation of milk occurs
when pH of milk reaches 4.6 which is the isoelectric point of its major protein,
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casein. The type and concentration of the acid and the mode of delivery into the
hot milk influence the moisture level and product yield.
Several coagulants have been tried, namely, lemon juice, citric acid, tartaric
acid, lactic acid, malic acid, hydrochloric acid, phosphoric acid, acetic acid,
fermented milk, sour/cultured whey, yoghurt and lactic cultures. Calcium
lactate has also been used as coagulant.
The concentration of the coagulant has a profound effect on the body and
texture of paneer. While a low acid strength results in a soft body and smooth
texture, high acid strength results in a hard body.
Strength of coagulants used for paneer making:
The amount of coagulant required for coagulation of milk depends upon the
type of milk, buffering capacity of milk, type of coagulant and the coagulation
temperature employed.
Temperature of coagulation
The temperature and pH of coagulation have a significant effect on the body
and texture, the total solids (TS) recovery and the yield of paneer. The
optimum temperature of coagulation differs for different types of milk and their
composition, including fat. Coagulation temperature influences moisture
retention in paneer. An increase in temperature of coagulation from 60 to 90 °C
decreased the moisture content of paneer from 59.0 to 49.0%. Paneer obtained
by coagulating milk at 70 °C had the best organoleptic quality and has the
desired frying quality namely integrity/shape retention and softness.
A coagulation temperature of 70 °C has been recommended for paneer making
from buffalo milk. Temperatures higher than this resulted in dry and hard
paneer while lower temperature yielded product having a very moist surface. It
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has been recommended by some researchers to use higher (85 °C) and lower
(72°C) coagulation temperature for buffalo milk paneer. Some have
recommended coagulation temperature of 85°C for low-fat buffalo milk.
To obtain good quality paneer, most research workers recommended higher
coagulation temperature for cow milk. The suggested coagulation temperature
for obtaining good quality paneer from cow milk was 80–85°C. Coagulation
temperature of 90o and 70 °C has been recommended when preparing paneer
from ewe’s milk and mixed milk respectively. 90°C of coagulation temperature
has also been suggested by some scientists for making paneer from recombined
cow milk. Low coagulation temperature of 60°C is also known to be used.
pH of coagulation
Variation in the pH of coagulation has a significant effect on the body and
texture, flavour, quality and yield of paneer. It has been reported that with the
fall in pH (5.5-5.0), the moisture retention and yield of paneer decreased.
Paneer made from cows’ milk coagulated at pH 5.0 was sensorily superior to
the one coagulated at pH 5.5. However, at coagulation pH of 5.0 the moisture,
TS recovery and yield were lower. The moisture content and yield of paneer
increased from 50 to 58.6% and from 20.8 to 24.8% respectively, when
coagulation pH increased from 5.1 to 5.4. Sensory quality was best at pH 5.3–
5.35 which is recommended for paneer making from buffalo milk. The pH range
of 5.20–5.25 for cow milk paneer is also recommended by some scientists.
Whey drainage
After coagulation of milk, the curd is allowed to settle down for 5 min without
stirring. During this period the temperature should not be allowed to drop below
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63 °C. Thereafter, the curd along with the whey is transferred into a hoop lined
with muslin cloth to remove the whey. This is already reported.
Hooping and pressing
After the curd is transferred to hoops lined with muslin cloth, it is subjected to
pressing to obtain a compact block of paneer. Different research workers have
used different amounts of pressure for varied time periods for paneer
manufacture. Some applied pressure of 40–45 kg for 10–15 min for paneer
hoop sized 35x28x10 cm for buffalo milk paneer with moisture around 56%.
Others employed a pressure of 2 kg/cm2 for 25 min on wooden hoop (4x4x4
inches) to obtain paneer with 55.0% moisture, while it is also suggested
applying a pressure of 1 kg/cm2 and found moisture level in paneer was
inversely related to the pressure applied. Use of 0.08 kg/cm2 for paneer
preparation from cow and buffalo milk is also reported and this resulted in
paneer with 47.9 and 42.7% moisture respectively. Some scientists have
recommended higher weights of 70–100 kg on hoops for 10–15 min.
Some prevailing knowledge in the existing state of the art of paneer making is
highlighted below:
The application of mechanization to modernize Paneer technology is known. In
order to achieve economy in cost of production, higher yield and uniformity in
product quality, adoption of membrane processing has been reported.
Some researchers have suggested that the yield of Paneer made by ultra
filtration technique, increased by about 25 % due to the higher retention of
whey proteins and moisture. Researcher from Department of Agriculture and
Food Engineering, IIT, Kharagpur, India developed a process for centrifugal
method of Paneer production. The process involved centrifugal pressing of
chhana in a double wall basket centrifuge (30 – 60°C) and chilling of pressed
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chhana inside the centrifuge by chilled water at 4°C in the ratio of 1:5. Pressing
and chilling of chhana in basket centrifuge considerably reduced the time (24
minutes) for Paneer production.
In general the prior art technologies on Paneer production do not emphasize on
advocating a single technology for achieving two vital needs of the hour in
Paneer technology, those being yield enhancement of paneer from milk and/or
recycled whey and controlling environmental pollution by dumping enormous
amount of untreated paneer whey, in nature. This is what the present invention
achieves through a single technology, hitherto not known.
OBJECTS OF THE INVENTION
The primary object of the present invention is to enhance the yield of cottage
cheese (paneer) by re-circulation of concentrated whey.
Another object of this invention is to recover the whey protein as paneer from
waste whey.
Yet another object of the present invention is to reduce environment pollution
by stopping the discharge of untreated whey into water bodies.
Still another object of the present invention is to meet the ever growing
demand for paneer in the market without increasing the quantity of milk.
Yet another object of the invention is to increase the yield of the paneer from
re-cycled whey without compromising with the quality of the paneer so
produced from the re-cycled whey.
How the foregoing objects are achieved will be clear from the following
description. In this context it is clarified that the description provided is nonlimiting
and is only by way of explanation.
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SUMMARY OF THE INVENTION
Accordingly the present invention provides a process for enhancing the recovery
of paneer from milk comprising:
i) collection of milk,
ii) heat treatment for pasteurization and denaturing whey proteins,
iii) collecting product obtained from (ii) above in a mixing tank for desired
duration till the desired pH is achieved,
iv) draining whey by retaining the paneer by hooping,
v) collecting hot whey drained from step (iv) above in a non-reactive tank,
vi) passing the hot whey so collected through heat exchanger to reduce its
temperature to an optimum level,
vii) filtering the cooled whey suitably for removing suspended particle and to
substantially concentrate solid not fat (SNF),
viii) recirculating the concentrated whey by feeding in step (iii) above as
coagulator for paneer making/processing,
ix) repeating steps (iii) to (viii) as above as many times as needed to obtain
desired substantially enhanced yield of recovered paneer and until the residual
liquid contains no proteins and the same liquid be used for other industrial
purposes.
Preferably, the desired number of times in step ix) is ten.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The nature and scope of the present invention will be better understood from
the accompanying drawings, which are by way of illustration of a preferred
embodiment and some non-restrictive examples not by way of any sort of
limitation. In the accompanying drawings:-
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Figure 1 is a flow diagram showing the conventional method of making paneer.
Figure 2 is a flow diagram showing the method of making paneer according to
the present invention.
Fig 3 is a graph showing the relative recovery of paneer from waste whey.
DETAILED DESCRIPTION OF THE INVENTION
Having described the main features of the invention above, a more detailed and
non-limiting description with reference to some non-restrictive examples is
provided in the following paragraphs. The description would be clear on
referring to non-limiting accompanying drawings.
In all the figures, like reference numerals represent like features. Further, the
shape, size and number of the devices shown are by way of example only and it
is within the scope of the present invention to change their shape, size and
number without departing from the basic principle of the invention.
All through the specification including the claims, the technical terms and
abbreviations are to be interpreted in the broadest sense of the respective
terms, and include all similar items in the field known by other terms, as may
be clear to persons skilled in art. Restriction or limitation if any referred to in
the specification, is solely by way of example and understanding the present
invention.
Figure 1 is a self explanatory flow diagram of a conventional method of
manufacturing paneer. Figure 2 is a flow diagram of a preferred embodiment of
the method according to the present invention. Figure 2 is also self explanatory,
and comparing the two diagrams, the basic difference would be very clear. Such
differences would be also very clear from the following description. Further the
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cooling step shown in figure 2 is within 45°C and this is within the scope of the
present invention.
In the conventional method whey is discharged as waste material during the
process of Hooping and Pressing. This waste whey cause contamination of the
water bodies, which results into environmental pollution.
The main crux of the subject invention is lies here. It play two vital roles in
paneer production i.e. the claimed process used the waste whey for enhancing
the paneer production and at the same time eliminates the risk of
environmental pollution which caused by untreated discharge of whey into
environment.
The highlights of the new process are listed below:
Collection of hot whey from paneer production line in non-reactive tanks
It is passed through heat exchanger to reduce the temperature to 45° C or
lower.
Cooled whey is first filtered through microfilter and ultra filtration for removing
any suspended particle.
This filtered whey is passed through nano or RO filtration unit.
After filtration, the volume of whey is reduced to near about 25% that of the
original volume or concentration of Solid Not Fat (hereinafter referred to as
SNF) up to minimum 12% at this stage. The concentration of SNF largely
depends on the quality and type of the milk.
This concentrated whey proteins are retained for recirculation as coagulator for
further paneer making/processing. This recirculation may take place n number
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of times depending upon requirement of degree of enhancement. For example,
it may take place ten times.
Modification in process
Discharged Hot whey is collected in non-reactive metal tanks. It is passed
through Heat exchanger to reduce the temperature to 45°C or lower. Cooled
whey is first filtered through Micron filter & Ultra filtration for removing any
suspended particle. This filtered whey is passed thru Nano or reverse osmosis
(RO) Filtration unit. This stage of unit is designed in such a way that it reduces
the volume of whey to near about 25% than that of the original volume (or
Concentration of SNF up to minimum 12.0% at this stage). The concentration of
the SNF largely depends on the quality and type of milk used at the beginning
of the process. This concentrated whey protein and SNF solutions are retained
for re-circulation as coagulators for further paneer making or processing.
Permeate water, thus collected can be utilized for floor washing or making brine
water for packing the finished tinned product.
Design considerations for process by way of non-restrictive example.
The temperature of whey is a critical design parameter in new state of art.
Collected whey should be brought down to 45°C or less within as soon as
possible of production. For energy conservation & efficiency, heat exchangers
made of non reactive metal are to be used, This step also reduces the chance of
microbial contamination also.
Heat exchanger circuit also has Cleaning in process (CIP) arrangement
consisting of One set of Pumps (1 working + 1 Standby), CIP tank/s fitted with
mixture arrangement. The Material of construction (MOC) for all above including
piping & fittings should be made of non reactive material.
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The Solid Not Fat content of whey is important design parameter for recovery of
Paneer. The efficiency of invented process depends upon concentration of SNF
of whey the best results are obtained at SNF value of more than 12.0%.
Pretreatment of Whey
The cooled whey has particles of coagulated Milk/ curd; these particles could
create the fouling in membranes used for concentration. Therefore Two stage
membrane based pre-filtration process is designed. Whey is passed through
micron filtration of bag type followed by standard micron cartridge filter of 10 &
1 micron. Followed by Ultra filtration membrane in cross flow mode with
Molecular weight cutoff (MWCO) of 1,00,000 Da. or less. The operating pressure
of system is as per membrane manufacturer's’ specifications. The system
should have safety arrangement i.e it shut down itself if pressure is increased to
desired / pre-defined pressure.
Concentration of Whey
This cleared & filtered whey is fed to array of Nano & Low energy reverse
osmosis / regular Reverse Osmosis membrane Elements by set of high pressure
pumps (1 working + 1 standby).
The array has following design requirements by way of example.
• Flow rates minimum cross flow velocity of 0.8 m/s.
• Maximum pressure of 17.5 Kg/Sq. Cm.
• The array is equipped for shutdown in case of feed temperature is more
than 45o C
• Pumps should be shut down in case Trans membrane pressure is more
than 1.5 bar
• All selected membrane has to be sanitised by hot water at 75o C.
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• Membrane configuration is selected in such a way that volume of Whey
is reduced up to near about 1/4th of original volume or SNF is reached up
to around 12.0 % whichever comes first.
• The membrane system should have CIP Circuit and hot water sanitation
arrangement.
• Concentrated whey is stored at less than 15o C temperature.
Use of concentrated Whey as coagulant for making paneer.
The concentrated whey is used in place of coagulant for paneer making.
This is achieved by heating milk, (SNF value up to 8.4), to 70⁰ C and adding
concentrated whey till isoelectric point is achieved (for best results in terms of
body texture, softness of paneer buffalo milk with pH range of 5.3-5.1 is
recommended).
Quantity used of whey as coagulant is dependent upon the type of milk,
buffering capacity of milk, pH of Concentrated whey, lactation period and the
coagulation temperature employed.
It would be clear from the description hereinabove, that the new innovative
process addresses the issue of environment pollution by stopping the discharge
of whey protein into nature and simultaneously enhances the yield of cottage
cheese (paneer) by re-circulation of concentrated whey.
In this process inorganic salts and water are removed from the whey by use of
any or combination of following membranes viz. Micro Filtration (MF), Ultra
Filtration (UF), Nano Filtration (NF) & Reverse Osmosis (RO). The selection of
membrane is dependent of origin of milk. The volume of whey is reduced to 28
%. This concentrated whey proteins & SNF solution are retained for recirculation
as coagulator of further paneer making/ processing.
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This modified process minimizing impact on pollution by Dairy Industry. During
recirculation of concentrate whey, whey protein also gets coagulated during the
processing of Paneer, thus increasing recovery up to 25 % depending upon the
milk composition & lactation period.
COMPARATIVE STUDY TO EVALUATE THE POTENCY OF THE NEW
METHOD OVER THE CONVENTIONAL METHOD
EXAMPLE I
100 lt. of cow milk is started with. In the conventional method the yield of
paneer is approximately 14.1 kg from 100 lt. of cow milk. The yield of paneer
can now increased about 19% by using the waste whey collected from 100 lt. of
cow milk. In the first step the hot whey is collected in non-reactive tanks. The
waste whey contains 7.25% of SNF in its initial stage. It is then passed through
heat exchanger to reduce the temperature to 450C or lower. The cooled whey is
now filtered through microfilter and ultra filtration for removing any suspended
particle. This filtered whey is passed through nano or RO filtration unit. After
filtration, the volume of whey is reduced to near about 28% of the original
volume or concentration of SNF upto minimum 12.9% at this stage for cow
milk. This concentrated whey proteins are retained for recirculation as
coagulator for further paneer making/processing. It is observed that the total
yield of paneer by using the new method is approximately 17.4 kg from 100 lt.
of cow milk. Thus, in an average it is possible to recover 18.97% or more of
paneer from waste whey.
EXAMPLE II
The above experiment is now performed with 100 lt. of buffalo milk. In the
conventional method the yield of paneer is approximately 16.2 kg from 100 lt.
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of buffalo milk. The yield of paneer can now increased about 18% by using the
waste whey collected from 100 lt. of buffalo milk. In the first step the hot whey
is collected in non-reactive tanks. The waste whey contains 7.83% of SNF in its
initial stage. It is then passed through heat exchanger to reduce the
temperature to 450C or lower. The cooled whey is now filtered through
microfilter and ultra filtration for removing any suspended particle. This filtered
whey is passed through nano or RO filtration unit. After filtration, the volume of
whey is reduced to near about 25% of the original volume or concentration of
SNF upto minimum 13.4% at this stage for buffalo milk. This concentrated
whey proteins are retained for recirculation as coagulator for further paneer
making/processing. It is observed that the total yield of paneer by using the
new method is approximately 19.8 kg from 100 lt. of buffalo milk. Thus, in an
average it is possible to recover 18.18% of paneer from waste whey.
EXAMPLE III
The above experiment is now performed with 100 lt. of mixed cow and buffalo
milk in a ratio of 4:6. In the conventional method the yield of paneer is
approximately 15.8 kg from 100 lt. of mixed milk. The yield of paneer can now
increased about 19.43% by using the waste whey collected from 100 lt. of
mixed milk. In the first step the hot whey is collected in non-reactive tanks. The
waste whey contains 7.4% of SNF in initial stage. It is then passed through heat
exchanger to reduce the temperature to 450C or lower. The cooled whey is now
filtered through microfilter and ultra filtration for removing any suspended
particle. This filtered whey is passed through nano or RO filtration unit. After
filtration, the volume of whey is reduced to near about 32% of the original
volume or concentration of SNF upto minimum 12.4% at this stage for mixed
milk. This concentrated whey proteins are retained for recirculation as
coagulator for further paneer making/processing. It is observed that the total
yield of paneer by using the new method is approximately 19.43 kg from 100 lt.
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of mixed milk. Thus, in an average it is possible to recover 18.68% of paneer
from waste whey.
The recovery of paneer from waste whey from different kind of milk is
represented graphically in the accompanying figure 3. The results discussed in
Examples I, II and III are clearly illustrated in the accompanying figure 3.
The present invention has been described with reference to some drawings and
examples purely for the sake of understanding and not by way of any limitation
and the present invention includes all legitimate developments within the scope
of what has been described herein before and claimed in the appended claims.
I CLAIM:
1. A process for enhancing the recovery of paneer from milk comprising:
i) collection of milk,
ii) heat treatment for pasteurization and denaturing whey proteins,
iii) collecting product obtained from (ii) above in a mixing tank for desired
duration till the desired pH is achieved,
iv) draining whey by retaining the paneer by hooping,
v) collecting hot whey drained from step (iv) above in a non-reactive tank,
vi) passing the hot whey so collected through heat exchanger to reduce its
temperature to an optimum level,
vii) filtering the cooled whey suitably for removing suspended particle and to
substantially concentrate solid not fat (SNF),
viii) recirculating the concentrated whey by feeding in step (iii) above as
coagulator for paneer making/processing,
ix) repeating steps (iii) to (viii) as above as many times as needed to obtain
desired substantially enhanced yield of recovered paneer and until the residual
liquid contains no proteins and the same liquid be used for other industrial
purposes.
2. The process as claimed in claim 1 wherein the milk is 100 litres of cow milk
and the yield of paneer obtained is 17.4 kg.
3. The process as claimed in claim 1 wherein the milk is 100 litres of buffalo
milk and the yield of paneer obtained is 19.8 kg.
4. The process as claimed in claim 1 wherein the milk is 100 litres of mixed co
milk and buffalo milk and the yield of paneer obtained is 19.43 kg.
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5. The process as claimed in claim 1 wherein the temperature in step vi) is
45°C or lower.
6. The process as claimed in claim wherein in step vii) the whey is filtered
through microfilter and ultra filtration for removing any suspended particle and
then passed through nano or RO filtration unit.
7. The process as claimed in claim 1 wherein after finishing step ix) the Paneer
is retained in step iv) by hooping in muslin cloth and pressurized to attain the
required moisture, followed by cutting and packing as per sale practice.
8. The process as claimed in claim 1 wherein in step ii) the desired pH is 4.6
which is the isoelectric point.
9. The process as claimed in claims 1 and 7 wherein the desired number of
times in step (ix) is ten.
10. A process, substantially as herein described, particularly with reference to
the examples and the accompanying drawings.