FIELD OF THE INVENTION:
The present invention is directed to a continuous process of manufacturing of Khoa and
in particular to a continuous manufacture of Khoa which would on one hand favour
required hygienic conditions for bulk production of quality storage stable Khoa and on
the other hand ensure that the Khoa manufactured has the colour, texture and
consistency similar to that of the vigorous hand scrapping manual intervention based
conventional Khoa manufacture. The invention further provides the system for achieving
such continuous manufacture of Khoa under hygienic conditions by selective combination
of manufacturing stages and equipments thereof including advantageous involvement of
industrial scraped surface vacuum evaporators maintaining the desired required
consistency in the end product for variety of end uses/consumption. Importantly also the
invention addresses the required hygienic conditions for large scale production of Khoa
without sacrificing the quality and storage stability to meet diverse end
uses/consumption of Khoa. The present invention also achieves reduction in fuel
consumption as much less heat is required per unit weight of appropriate consistent
quality of Khoa produced by the present process, and resultant higher fuel efficiency and
less pollution as compared to the conventional open fire hearths (bhatties). The
invention is thus directed to make manufacture of Khoa simple, cost-effective and more
importantly hygienic and storage stable apart from maintaining the desired colour,
texture and consistency required of Khoa for its wide scale and varies
application/consumption.
BACKGROUND ART:
The traditional process of manufacture of Khoa using kadahi on an open fire is being
practiced over the ages. The rural artisans in India usually carry out the production of
Khoa that is sold in the city/urban markets for use by the traditional sweet meat makers.
Alternatively, the sweet makers themselves manufacture Khoa for their own use. The
demand for Khoa is highly seasonal in Indian markets and the highest demand being
during the traditional Indian festive occasions, viz., Dusshera or Diwali period and the
lowest demand during November to March when the milk production is highest in the
country. Since most of the Khoa is produced under not very hygienic conditions, its
storing or self-life is low and it usually develops moulds on long storage. Most of the
Khoa is therefore used fresh or used within a couple of days after its production. The
high demand for Khoa during festivities puts pressure on the traditional sources of
supplies and thus jacking up prices during the peak seasons.
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Khoa is traditionally produced by continuously boiling milk that is initially concentrated
by boiling in a Kadahi, similar to a Chinese wok, and continuously stirring usually to
about 70-75 % milk solids. The stirrer-scraper is used to distribute the heat uniformly
through out the entire mass of milk and the bottom and walls of vessel scrapped at
regular intervals with the stirrer-scrapper to prevent localized burning of milk solids. In
the latter stage of concentration, the amount of heat is reduced and the product is
rapidly spread over the heating surfaces and rigorously scrapped at quick succession to
prevent charring. Finally, the Khoa reaches a semi-solid state and is gathered as a pat
which is spread over and over again on the inner surface of the kadahi so as to reach the
right texture and concentration. Khoa looses its stickiness as it starts oozing milk fat
after the desired level of consistency has been obtained it is usually put into a metal
container for cooling and hardening of the pat. The final pat of Khoa is usually stamped
by the Khoa maker with an engraved metal stamp to establish the identity of the Khoa
producer. It has been estimated that some six percent of India's milk production is
converted into Khoa which amounts to over 1.2 million tones Khoa valued at Rs. 6000
crores annually. Khoa is usually converted into sweats valued at around Rs. 20,000
crores annually.
The major problem with existing traditional means of production of Khoa is that the
same is mostly batch manufacture under complete manual intervention apart from being
of poor microbial quality and low shelf-life. A still further problem of the traditional
process is the high rate of fuel consumption in open fire type hearth and low efficiency of
fuel used. In open pan evaporation, the amount of heat required to evaporate 1 kilo of
water is substantially more than a kilo of steam. It is well known that the evaporation of
water using vacuum evaporators, consumes as low as 0.2 kilos of steam to evaporate 1
kilo of water. Therefore, reducing the amount of heat needed for the production of Khoa,
can bring in significant saving not only of the energy but also reduce the pollution caused
by using open fire hearths.
The traditional practice of manufacturing Khoa in a continuous - batch manner is to use
a long bhatti or open hearth that has several stoves to accommodate multiple number of
kadhai, using the first one for boiling milk and it is placed on the first stove nearest to
the open fire to receive maximum heat flux. In these types of hearths the fire is lit at
one end of the long bed of hearth and the flue gases escapes from the other end,
distributing the heat through its hot flue gases/flames at the stoves located at different
positions during its passage. The kadhais are progressively and manually moved from
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the hottest end of the hearth to the coolest end ensuring exposure to lesser heat flux as
the concentration of milk goes more and more. Though this process of making Khoa
raises the production capacity, it does not help in the hygienic production of Khoa.
Attempts have been made in the past to manufacture Khoa in industry based commercial
scale deploying mechanical equipments and efficient heating medium. A stainless steel
conical vat with Nylon Scrapped surface agitators has been successfully developed for
hygienic production of Khoa, in a batch process, which simulates the action of a scrapper
inside a vessel/kadhai, by using rotary scrapper that covers the entire heating surface
for milk and Khoa. The limited capacity of the machine and its batch processing
technique are the major limiting factors. Two versions of the continuous scrapped
surface heat exchangers have been successfully developed which have limited capacities
of usually 500 litres to 1000 litres of milk per hour that is too small a quantity for
viability of an industrial unit. A vertical scrapped surface heat exchanger coupled with an
evaporator has also been used to manufacture Khoa. Although the unit is able to
concentrate milk to the desired level of milk solids, the final product lacked consistency
and needed to be finished in a batch type conical scrapped surfaced heat exchanger.
There has therefore been a continuous need in the art for developing an industry
oriented manufacturing method and set-up for continuous production of Khoa involving
mechanized equipments that would simulate the conventional manual process of
manufacturing Khoa with desired colour, texture and consistency such as that produced
in kadhai and further ensuring preventing charring of milk solids and the coating on the
heating surfaces with milk solids.
OBJECTS OF THE INVENTION:
It is thus the basic object of the present invention to provide for continuous manufacture
of Khoa which would on one hand favour required hygienic conditions for bulk production
of quality storage stable Khoa and on the other hand ensure that the Khoa manufactured
has the colour, texture and consistency similar to that of the continuous hand scrapping
manual intervention based conventional Khoa manufacture.
Another object of the invention is directed to the required hygienic conditions for large
scale production of Khoa without sacrificing the quality and storage stability to meet
diverse end uses/consumption of Khoa.
4

A further object of the present invention is directed to the reduction in fuel consumption
in manufacture of Khoa such that much less heat is required per unit weight of
appropriate consistent quality of Khoa produced by the present process, and resultant
higher fuel efficiency and less pollution as compared to the conventional open fire
hearths (bhatties).
Yet another object of the present invention is directed to the continuous manufacture of
Khoa which would be simple and cost-effective and importantly also hygienic and storage
stable apart from maintaining the desired colour ,texture and consistency required of
Khoa for its wide scale and varies application/consumption.
A further object of the present invention is directed to developing a continuous process
of Khoa manufacturing in industrial scale wherein the process of heating is highly fuel
efficient, energy saving and much less polluting compared to open fire hearths in
conventional processes.
SUMMARY OF THE INVENTION:
Thus according to the basic aspect of the invention there is provided a method of
continuous production of Khoa comprising:
(i) evaporating the whole milk to about 40 preferably about 40 to 55 percent milk
solids;
(ii) subjecting the evaporated milk to a step of complete de-naturing of milk proteins and
in the process increasing the viscosity of the product;
(iii) providing the pre heated concentrated product with de-natured milk protein into a
continuous evaporator with scrapper provision and increasing the concentration of milk
solids therein;
(iv) cooling the product to obtain the Khoa.
According to a preferred aspect of the present invention there is provided a method of
continuous production of Khoa comprising:
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(i) evaporating the whole milk to about 40 preferably about 40 to 55 percent milk
solids;
(ii) subjecting the evaporated milk to a step of complete de-naturing of milk proteins and
in the process increasing the viscosity of the product;
(iii) providing the pre heated concentrated product with de-natured milk protein into a
scrapped surface heat exchanger and increasing the concentration of milk solids therein;
(iv) cooling the product to obtain the Khoa.
In accordance with yet another aspect of the present invention there is provided a
method of continuous production of Khoa comprising:
(i) providing milk concentrate by recombining milk powder in either milk or water
containing 40 to 55 percent milk solids with or without evaporation;
(ii) subjecting the milk concentrate to a step of complete de-naturing of milk proteins
and in the process increasing the viscosity of the product;
(iii) providing the pre heated concentrated product with de natured milk protein into a
continuous evaporator with scrapper provision preferably a scrapped surface vacuum
heat exchanger and increasing the concentration of milk solids therein;
(iv) cooling the product to obtain the Khoa.
It is thus possible by way of the above to provide for an industrial continuous process of
manufacture of Khoa, using selectively scrapped surfaced vacuum evaporator such as to
obtain preferred rate of heating and subjecting/exposing high concentration milk to
higher heat, while simulating the scrapping action by mechanical means, favoring
completely denaturing milk proteins in milk concentrates containing 40-55 % milk solids,
before final stage of evaporation. Importantly, in the above process of Khoa
manufacturing in industrial scrapped surfaced vacuum evaporators the desired
consistency is obtained at the end of final stage of evaporation, providing the color,
texture and taste comparable to the traditional characteristics of Khoa. The above
process of Khoa making is totally hygienic and that the microbial quality and the shelf-
life of the end product is superior compared to that obtained in the conventional process.
6

Advantageously, the method of continuous production of Khoa of the invention achieves
during the process of heating the milk concentrate a phase inversion from milk solids in
water to water in milk solids increasing the viscosity of the product substantially.
In accordance with an aspect of the present invention the method of continuous
production of Khoa is attended wherein the pre-heated concentrate with de-natured
proteins is pumped into a scrapped surface heat exchanger which increases the
concentration of milk solids to about 70 to 75 percent.
In the above method of continuous production of Khoa the final product after cooling is
preferably suitably packed for desired subsequent end use/consumption.
According to a further aspect of the invention in the above method of continuous
production of Khoa the milk is concentrated preferably to about 50 percent solids by
addition of whole milk powder and the recombined concentrated milk heated to 80 to
100 ° C for said de-naturation of proteins. The continuous process of manufacturing
Khoa involving industrial scrapped surfaced vacuum evaporator after completely
denaturing the milk proteins in milk concentrates can be attended by recombining the
milk powder in either milk or water containing 40-55 % milk solids.
Thus the above process of the present invention is directed to a simple , cost-effective
and fuel efficient method of continuous production of Khoa wherein in step (ii) the
complete de-naturing of milk comprise subjecting the evaporated milk to heating in the
temperature range of 80 to 100 ° C in a tubular heater to complete de-nature the milk
proteins.
According to yet another aspect of the present invention there is provided a system for
carrying out the method of continuous production of Khoa as discussed above
comprising:
(i) evaporator means for evaporating the whole milk to about 40 percent preferably
about 40 to 55 percent milk solids;
(ii) means for complete de-naturing of milk proteins and in the process increasing the
viscosity of the product;
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(iii) a continuous evaporator preferably a scrapped surface vacuum heat exchanger to
increase the concentration of milk solids therein;
(iv) cooling means to cool the Khoa .
It is thus possible by way of the present invention to provide a manner of continuous
manufacture of Khoa which would on one hand favour required hygienic conditions for
bulk production of quality storage stable Khoa and on the other hand ensure that the
Khoa manufactured has the colour, texture and consistency similar to that of the
continuous hand scrapping manual action of conventional Khoa manufacture .
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING EXAMPLES AND ILLUSTRATIONS:
The details of the invention, its objects and advantages are explained hereunder in
relation to non-limiting exemplary illustrations as per the following non-limiting
examples.
Example - I :
In this exemplary illustration, the continuous Khoa making process in accordance with
the present invention was carried out as detailed hereunder:
Whole milk was evaporated to about 40-50% milk solids and the evaporated milk was
next heated to 80-100°C in a tubular heater to completely denature the milk proteins.
During the process of heating of the milk concentrate, there was a face inversion from
milk in milk solids in water to water in milk solids and the viscosity of the product
increased substantially. The pre-heated milk concentrate with denatured proteins was
then pumped into a scrapped surfaced heat exchanger to thereby increase the
concentration of the milk solids further to about 75%. The final product was cooled to
achieve the desired consistency so as to ensure the microbial quality and self-life
enhancement.
The characteristics of the Khoa produced was next testes and copared to the desired
characteristics of the traditional manual intervention based Khoa manufacture. The test
results confirmed that the color, texture, consistency and the mouth-feel of the Khoa
8

produced according to the invention were closely comparable with that of the
conventional characteristics of the conventional Khoa available at the market.
Example - II:
In an alternative embodiment of the continuous Khoa manufacturing in industrial
scrapped surfaced vacuum evaporator according to the present invention, milk was
concentrated to 50% solids by addition of whole milk powder. The recombined
concentrated milk was heated to 80-100°C for favored complete denaturation of milk
proteins. The concentrated milk was then evaporated further in a scrapped surfaced
evaporator to increase the concentration further to 72-75%% solids.
The characteristics of the Khoa produced was next testes and copared to the desired
characteristics of the traditional manual intervention based Khoa manufacture. The test
results confirmed that the color, texture, consistency and the mouth-feel of the Khoa
produced according to the invention were closely comparable with that of the
conventional characteristics of the conventional Khoa available at the market. The Khoa
produced thus showed the above consistency with enhanced self-life and superior
microbial quality.
The above exemplary illustrations confirm the provision of a continuous process of Khoa
making involving mechanized means for industry scale manufacture in batches/bulk
Khoa of the desired consistency and self life which is the key desirable criteria for Khoa
manufacture. The present invention is thus directed to a technological approach to the
continuous production of Khoa instead of simple direct use of engineering appliances and
means that has either capacity limitations and either fail to meet the desired quality
characteristics or are found economically not viable. The present invention involves
selective simulation of scrapping action on continuous basis to avoid charring of the milk
solids and the coating of the heating surfaces with the milk solids and also ensures
desired consistency of the end product by selective processing of the milk concentrate in
stages to reach to the desired characteristics. The process involves selective and
advantageous combination of an industrial scrapped surfaced vacuum evaporator such
that the concentrated milk is heated to high temperatures to favor obtaining the desired
semi-solid consistency and other characteristics of the Khoa, ensuring complete
denaturation of milk proteins before the final stage of evaporation.
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The present invention thus favours to obtain a method for continuous manufacture of
Khoa by controlled rate of evaporation of milk by adopting using scrapped surface
vacuum evaporator/ heat exchanger preferred heat input at a desired rate to arrive at
desired consistency and enhance the shelf-life of the milk solids produced having
selective viscosity and favored microbial characteristics following an industrial
commercial scale and yet through a hygienic process.

WE CLAIM:
1. A method of continuous production of Khoa comprising:
(i) evaporating the whole milk to about 40 percent preferably about 40 to 55
percent milk solids;
(ii) subjecting the evaporated milk to a step of complete de-naturing of milk
proteins and in the process increasing the viscosity of the product;
(iii) providing the pre heated concentrated product with de natured milk protein
into a continuous evaporator with scrapper provision and increasing the
concentration of milk solids therein;
(iv) cooling the product to obtain the Khoa.
2. A method of continuous production of Khoa comprising:
(i) evaporating the whole milk to about 40 percent preferably about 40 to 55
percent milk solids;
(ii) subjecting the evaporated milk to a step of complete de-naturing of milk
proteins and in the process increasing the viscosity of the product;
(iii) providing the pre heated concentrated product with de natured milk protein
into a scrapped surface vacuum heat exchanger and increasing the concentration
of milk solids therein;
(iv) cooling the product to obtain the Khoa.
3. A method of continuous production of Khoa comprising :
(i) providing milk concentrate by recombining milk powder in either milk or water
containing 40 to 55 percent milk solids with or without evaporation;
11

(ii) subjecting the milk concentrate to a step of complete de-naturing of milk
proteins and in the process increasing the viscosity of the product;
(iii) providing the pre heated concentrated product with de natured milk protein
into a continuous evaporator with scrapper provision preferably a scrapped
surface vacuum heat exchanger and increasing the concentration of milk solids
therein;
(iv) cooling the product to obtain the Khoa.
4. A method of continuous production of Khoa as claimed in anyone of claims 1 to 3
wherein in step (ii) the complete de-naturing of milk comprise subjecting the
evaporated milk to heating in the temperature range of 80 to 100 ° C in a tubular heater
to complete de-nature the milk proteins.
5. A method of continuous production of Khoa as claimed in anyone of claims 1 to 4
wherein during the process of heating the milk concentrate there is face inversion from
milk in milk solids in water to water in milk solids and the viscosity of the products
increased substantially.
6. A method of continuous production of Khoa as claimed in anyone of claims 1 to 5
wherein the pre-heated concentrate with de-nature protein is pumped into a scrapped
surface vacuum heat exchanger which increase the concentration of milk solids to about
70 to 75 percent.
7. A method of continuous production of Khoa as claimed in anyone of claims 1 to 6
wherein the final product after cooling is packed.
8. A method of continuous production of Khoa as claimed in anyone of claims 1 to 7
wherein the milk is concentrated preferably to about 50 percent solids by addition of
whole milk powder and the recombined concentrated milk heated to 80 to 100°C for said
de-nature of proteins.
9. A method of continuous production of Khoa as claimed in Claim 8 wherein the
milk is concentrated by recombining milk powder in either milk or water containing 40 to
55 percent milk solids.
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10. A system for carrying out the method of continuous production of Khoa as
claimed in anyone of claims 1 to 9 comprising:
(i) evaporator means for evaporating the whole milk to about 40 percent
preferably about 40 to 55 percent milk solids;
(ii) means for complete de-naturing of milk proteins and in the process increasing
he viscosity of the product;
(iii) a continuous evaporator preferably a scrapped surface vacuum heat
exchanger to increase the concentration of milk solids therein;
(iv) cooling means to cool the Khoa.
11. A method of continuous production of Khoa substantially as herein described and
illustrated with reference to the accompanying examples.
Dated This 11th day of May ,2007

A continuous process of manufacturing of Khoa and which would on one hand favour
required hygienic conditions for bulk production of quality storage stable Khoa and on
the other hand ensure that the Khoa manufactured has the colour, texture and
consistency similar to that of the vigorous hand scrapping manual intervention based
conventional Khoa manufacture. The continuous manufacture of Khoa under hygienic conditions achieved by selective combination of manufacturing stages and equipments thereof including advantageous involvement of industrial scraped surface vacuum evaporators maintaining the desired required consistency in the end product for variety of end uses/consumption. Importantly, required hygienic conditions for large scale production of Khoa without sacrificing the quality and storage stability has been met for diverse end uses/consumption. The process also achieves reduction in fuel consumption as much less heat is required per unit weight of appropriate consistent quality of Khoa resulting in higher fuel efficiency and less pollution. The present process is simple, cost-effective and having wide scale end uses with improved shelf life.