1. No category

TECHNOLOGY OF RENNET COAGULATED MILK CAKE
Technology Of Rennet Coagulated Milk Cake
By Microwave Processing
R. Kesavan*, A. Sangeetha*, K. Jayaraj Rao**, P. Aravindakshan** and C.N.
Pagote**
* PGP College of Arts and Science, Namakkal (Tamilnadu)
** National Dairy Research Institute (Southern Campus), Adugodi, Bangalore-560 030
Abstract
Indian dairy industry, economically, is in dynamic
phase; as such there is considerable scope for
production and marketing of newer products. In this
paper, a soft cake named rennet coagulated milk
cake (RCMC) developed by texturisation of rennet
coagulum by in-package microwave heating, is being
reported.
Processing
parameters
such
as
concentration of milk, sugar, coconut powder, rennet
concentration and microwave heating time were
standardized. The final product contained fat 8.5%;
SNF 38%; protein 8.2%; lactose 9.7%; sucrose
18.2%; and ash 1.7% and could be stored well for
about two weeks under refrigerated conditions. This
product is being recommended to be used as
analogue of colostrum cake.
Keywords: Rennet, Microwave heating, Milk cake,
Concentrated milk, Texturisation.
Introduction
India’s milk production is estimated to be 133 million
tonnes during 2012-13 accounting for 17% of the
total global milk production (Bhasin, 2013) and the
dairy industry in India is worth Rs 1.1 trillion. Milk
production in India is growing at 4% per year and
there is a considerable scope for further growth of
the industry, as such the industry is constantly looks
for newer products in addition to the varieties
already existing. A wide range of products are being
manufactured and marketed by the dairy industry
which includes ghee, dahi, khoa, paneer, butter,
cream, ice cream, milk powder, buttermilk etc. The
industry always looks for newer products to cater to
the needs of consumers, for example it shows
keenness to push the local products like kunda,
chhana, shrikhand, varieties of peda etc. into the
market to attract more and more consumers.
However, for a new product to be successful it has to
be accepted by the local consumer population.
Several products are locally popular developed over a
period of centuries. These remain to be explored and
in recent years there is an increasing trend to lay
emphasis to work on such indigenous products. One
146
of such products is a sweet soft cake made out of
colostrum. Colostrum is the milk obtained from a cow
or buffalo soon after parturition and up to a period of
about 2 days. This milk is rich in proteins and
antibodies produced especially for the young ones to
provide protection and nutrition to them. When such
milk cannot be utilized for calves, it may be
converted into varieties of products. The colostrum
has a low heat stability because of imbalanced
mineral content and high protein content. Normally,
sugar or jaggery, nuts, dry coconut and cardamom
are added to colostrum, mixed and heated under
steam so that a heat induced coagulum is formed.
However, such product finds acceptance only with
certain pockets of population and for many it may
not be acceptable because of ethical and religious
connotations. In this project, a similar textured
product is intended to be developed by rennet
coagulation of milk and microwave heating. This will
be similar to junkets popular in Western countries.
Junkets are soft cakes eaten as desserts and
available in varieties of flavors including vanilla,
chocolate, caramel etc.
Microwave food processers offer a lot of advantages
such as less start-up time, faster heating, higher
efficiency, selective heating and foods with high
nutritional quality (Decareu and Peterson, 1986).
Microwaves cause the water molecules in food to
vibrate, producing heat that cooks the food. The
microwave energy is changed to heat as soon as it is
absorbed by the food. Thus, it cannot make food
radioactive or contaminated. Microwave technology is
more amenable for in-package heating, that is, a
product can be packed in a container which is sealed
and subjected to heat treatment so that the product
inside the container is heated to kill all the vegetative
forms of microorganisms. Since the post processing
contamination is avoided by prior sealing of the
container, the heat treated product can have a long
shelf life depending, of course, on the water activity.
Such process of in-package heating was successfully
employed
to
produce
tofu
and
paneer
(www.tradekey.com). Attempts were also made to
use ultrafiltered milk for paneer making by
microwave heating. These attempts show that
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
microwave technology can be adapted to produce
cake like products from milk. In the world wide web,
several references may be found for use of
microwave heating applications in cake manufacture.
Rennet coagulation of milk yields a soft cake formed
by aggregation of casein micelles. In such case of
use of high solids milk, it is possible to heat treat the
coagulum inside a package without any significant
whey separation. In the present project, it was
planned to standardize a method for manufacture of
a junket type coagulum resembling colostrum cake
using concentrated milk. It has been envisaged to
take milk in a microwavable container, form rennet
coagulum and then heat treat the coagulum in
microwave oven to complete the texturisation. After
cooling, the cake is ready-to-eat and can be
marketed directly along with the container. The idea
behind this is to standardize a process which is
industry friendly as well as consumer friendly.
Materials And Methods
Fresh cow milk obtained from Experimental Dairy of
the Institute was standardized to 3.5% fat and 8.5%
SNF. The standardized milk (1000g) was taken in a
vessel and heated to boiling. Care was taken by
continuous scraping during desiccation so that
burning of milk was avoided. Three levels of
concentration were tried: 0, 2x, 3x and 4x. After
concentration, 100g of concentrated milk was taken
in 100ml - capacity microwavable container procured
from local supermarket and required quantity of
crystal sugar was added. The sugar was dissolved by
mixing and the mixture was cooled to ambient
temperature (about 30oC). In order to determine the
optimum level of sugar concentration, three levels
were tried viz. 15, 20 and 25 % w/w on concentrated
milk basis. Required quantity of coconut powder was
weighed and added to the concentrated milk in the
container. Three levels of coconut powder were used
viz. 3.0, 5.0 and 7.0% w/w on concentrated milk
basis. The powder was not soluble in the milk, so
mixed thoroughly so that it lay in suspended state.
Cardamom seeds were ground in a pestle and mortar
and the freshly obtained powder was used. The
cardamom powder was added to the above mixture
and stirred well. The cardamom powder was used @
0.15% w/w on concentrated milk basis. Then,
required quantity of the rennet powder (Meito rennet
powder, Arun & Co., Mumbai) was weighed,
dissolved in minimum quantity of water and added to
the concentrated milk. It was mixed well and the
container kept at about 30oC for rennet action to
take place. After allowing for coagulum formation,
the container was taken for microwave application.
Rennet powder was tried at three levels: 0.01, 0.02
and 0.03% on concentrated milk basis. The rennet
action time was tried at two levels: 1 hr, 2 hr and 3
hr. After allowing it for sufficient time for rennet
coagulum formation, the container was transferred to
Microwave oven (Batliboi Microwave oven, 20 lit
capacity). The lid was kept loosened so that during
147
the microwaving, vapours were allowed to escape.
The container was kept on the circular platform of
the oven, the door closed and the knob was turned
on to required power level and the oven started. The
microwaves were applied for 5 min and then turned
off. Three power levels were tried: level 1, 2 and 3.
The container was taken out from the microwave
oven and allowed to cool to ambient temperature
before transferring it to fridge for further cooling
overnight. After cooling, a junket like cake was
formed which was subjected for sensory evaluation
and physico-chemical analyses.
Analyses
Sensory evaluation:
The rennet coagulated milk cake (RCMC) was
subjected to sensory evaluation for determining the
extent of product’s acceptance. The judges (10 No)
were drawn from the Institute’s faculty and student
community, who were initially made aware of the
product’s characteristics. All the sensory evaluation
trials were carried out in the Section’s Sensory
Evaluation Laboratory under the fluorescent lamps.
The RCMC in the container was taken out from the
fridge, the coagulum was removed carefully from the
container and placed in a tray. It was cut into 2 cm
pieces and served to judges for evaluation. The
judges were asked to evaluate the product in terms
of colour and appearance, flavor, body and texture
and overall acceptance, and offer general comments.
A 9-point Hedonic scale (Amerine et al., 1965) was
used for the evaluation purpose. A score of one
indicated ‘dislike extremely’ and a score of nine on
the scale indicated ‘like extremely’.
Analysis of RMRC:
The moisture content of the milk cake was analyzed
by using standard method. Fat percentage of milk
cake was estimated by gravimetric method using
Mojonnier apparatus (BIS 1224, 1977). Protein
content was estimated by Kjeldahl method (John
Blamire, 2003) and lactose and sugar by Fehling’s
method. The total solids content was determined by
gravimetric method (BIS, 1981), total ash content
by the method of Christopher et al. (2004), amount
of calcium was estimated by EDTA Method
(McCormick, 1973) and the phosphorus content by
ash method (Powell et al., 1989). Water activity of
RCMC was determined by Water activity meter
(Rotronic Co., Switzerland, Hygroskop DT model).
The instrument was switched on and stabilized for 15
min before use. The RCMC was made into a paste
and taken in the sample cup up to the specified level.
It was then placed in measuring station and allowed
to equilibrate by switching on built-in fan. The water
activity reading appearing on the screen after
equilibration was recorded.
Statistical analysis
All the sensory evaluation data obtained in the study
were subjected to ANOVA (Analysis Of Variance) in
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
order to determine the treatment effect. For all the
experiments conducted in the study, one way
randomized block design was followed. Analysis of
variance was performed by Microsoft Excel software
of MS Office-2003 version. When F- test was
significant, the mean values were differentiated by
CD (critical difference) values computed by t-test
(Sundarraj et al., 1972) and the level of significance
of treatment effect was determined at 5% level.
Results And Discussion
Standardisation of processing parameters of
RCMC:
Concentration level of milk: In the preliminary
trials, liquid milk containing 3.5% fat and 8.5% SNF
was taken in a glass beaker and added with rennet.
After rennet coagulation, the coagulum was heat
treated in order to firm up the coagulum. Upon
heating the coagulum, it was observed that whey
was oozed out completely immersing the soft
coagulum. Since oozing out of whey was not
desirable, it was decided to increase the total solids
level in the milk so that whey separation on heating
of rennet coagulum could be reduced. Thus, it was
decided to study the effect of TS level in milk or
concentration level in milk on the quality of
coagulum. The standardized milk (one kg) was taken
in a vessel and heated to boiling (open pan heating
and concentration). The desiccation was continued till
required quantity was obtained. The milk was
desiccated to 500g, 330g and 250g corresponding to
2x, 3x and 4x concentration factors. These
concentrated milks had a thick and flowable
consistency. Sample of the concentrated milk (100g)
was taken in a 100 g capacity microwavable plastic
container and added with crystal sugar (25g). After
dissolving the sugar, coconut powder (3g) and
cardamom (0.15 g) were added and mixed
thoroughly. Then, 20 mg rennet powder (dissolved in
minimum quantity of water) was added and mixed.
The milk was allowed for about one hour for rennet
action to take place at 30oC. During this period, milk
got coagulated. The microwavable container with the
coagulum was transferred to a microwave oven and
subjected to microwave heating at low power. It was
observed that during heating, the coagulum became
soft and little whey oozed was out. The oozing of
whey however was slightly higher in low
concentration level of milk. After heating, the
coagulum was cooled to ambient temperature and
transferred to fridge for overnight cooling. During the
cooling process, the oozed out whey was reabsorbed
by the coagulum. The chilled cake was taken out and
cut into pieces and the samples were served to
judges for sensory evaluation. The results are
presented in Table -1 along with CD (critical
difference) values.
The colour and appearance scores for 2x, 3x and 4x
concentration factors were 7.3, 7.6 and 7.4,
respectively indicating that 3 times concentration of
148
milk resulted in maximum score. This was because at
2x concentration, whey oozed out resulting in lower
score. At 4x concentration, the coagulum was
observed to be very firm, hence it was awarded low
score. Milk concentrated to 3x concentration scored
maximum for appearance, because it resulted in
limited whey separation enhancing the visual appeal.
This score was also statistically significant compared
to other concentration factors (P<0.05). The flavour
scores were 7.3, 7.7 and 7.2, respectively for the
three concentration factors tried. The product made
from 3x concentrated milk obtained statistically the
higher (P<0.05) score. The 2x product had lighter
flavour because the flavour was probably distributed
between the coagulum and the separated whey. In
the case of the 4x product, the coagulum was firm
and was not completely cooked or texturised,
affecting the flavour (P<0.05). The body and textural
scores of RCMC were 6.0, 7.4 and 6.5, respectively
for 2x, 3x and 4x products. The scores indicated that
for good texturisation, solids level in milk is an
important factor. The 2x concentrated milk showed a
lot of whey separation, so yielded softer coagulum
resulting in lower score. But 4x concentration
resulted in firmer coagulum, so was not much
preferred by the evaluators. Moreover, texturisation
was not complete in 4x product during microwave
processing resulting in milky taste. 3x concentration
was found to be optimum because it yielded a
product with right texture with little oozing out of
whey. It scored maximum (7.4) differing significantly
from other treatments (P<0.05). During milk gel
formation, the water holding capacity of the gel
depends on several factors including total solids and
heat treatment employed (Gastaldi et al., 2003).
When the rennet coagulum is heated the proteins get
shrunk and expel whey from the network. Higher
solids content will bind more water and hence, show
less syneresis. Similar result was also observed by
Rao (1991) who reported a novel method of paneer
manufacture by in-package heating of concentrated
milk. The extent of syneresis is expected to be higher
as the temperature and duration of heating
increased. Changes in all these sensory attributes
were reflected in the overall acceptance scores,
which clearly indicated the preference of judges for
the 3x product. The overall acceptance scores were
7.1, 7.7 and 7.2, respectively for 2x, 3x and 4x
products. The 3x cake scored highest for all the
sensory attributes. For further trials, 3x concentrated
milk was used.
Sugar level: Sugar was used to enhance the flavour
of the cake as well enhancing the shelf life of the
cake. Three levels of crystal sugar viz. 15, 20 and
25% per 100 g concentrated milk were added to the
concentrated milk (3x) and the RCMC was prepared.
The sensory evaluation results are presented in
Fig.1. It may be observed from the scores that
judges liked sweet taste in the cake, but extent of
liking differed with the sugar concentration. The
colour and appearance scores of the cake prepared
from milk added with 15, 20 and 25% sugar levels
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
were 7.5, 7.8 and 7.8, respectively. Statistical
analysis indicated that these scores did not differ
significantly suggesting that sugar level had no effect
on the appearance of the cake (P>0.05). This may
be understandable because addition of sugar does
not change the colour of products unless the product
is subjected to prolonged heat treatment as in the
case of several milk products like basundi, khoa etc.
However, sugar content had significant effect on the
flavor of the product depending of course on the
sweetness preferences of the judges. The flavor
scores of the cake were 7.0, 7.2 and 7.5,
respectively for 15, 20 and 25 % sugar levels. Out of
these, the 25% sugar product gained significantly
higher (P<0.05) score. It is also beneficial to use
higher sugar in the product because it may bestow
longer shelf life on the product as sugar is a well
known preservative. The sugar level also showed a
positive effect on the body and texture of the cake.
The scores for this attribute were 7.2, 7.3 and 7.5,
respectively for 15, 20 and 25% sugar levels. There
was no difference between the first two sugar levels
but addition of 25% sugar significantly improved
body of the cake (P<0.05). This could be attributed
to the fact that presence of sugar increases the
viscosity (Abu jdayil et al., 2001) and this high
viscosity might have produced firmer coagulum with
optimum
textural
characteristics.
However,
considering the overall acceptance, there was no
difference between 20% sugar (7.5) and 25% sugar
added product (7.7) (P>0.05).
The overall
acceptance scores of the cake were 7.0, 7.5 and 7.7,
respectively for 15, 20 and 25% sugar levels.
Addition of 15% sugar yielded significantly least
overall acceptance score (7.0). Addition of 25%
sugar level was chosen for the subsequent trials
because higher level of sugar is preferable in view of
higher shelf life it imparts to the products by
decreasing water activity (Chamolea et al., 2001).
Coconut powder level: Coconut powder was used in
this study because it not only imparts a pleasant
flavour and texture to the product but also acts as a
source of fiber in the diet. Also, coconut flavour is a
common relish in many households in the South.
Coconut powder was tried at three levels to decide
on the optimum level, 3, 5 and 7% w/w per batch
(100g concentrated milk). The RCMC was prepared
using 3x concentrated milk, 25% sugar level and
0.15% cardamom powder. The sensory scores of the
product containing different levels of coconut powder
are given in Table-2.
The appearance scores of RCMC were 7.7, 7.5 and
7.2, respectively for 3, 5 and 7% coconut powder
levels. As the level increased, the appearance score
decreased, though statistically there was no
difference between 3 and 5% levels. However,
between 3% and 7% levels there was significant
difference (P<0.05). This was because higher
quantity of coconut powder resulted in accumulation
of the particles on one side of the coagulum – top or
bottom portion- which was not preferred by the
judges. Flavour scores were 7.5, 7.3 and 7.2,
149
respectively for the three coconut levels tried. There
was no statistical difference between 3 and 5%, but
there was significant difference between 3% and 7%
powder levels (P<0.05). This indicated that coconut
level was optimum only up to a certain level, but
thereafter it was not much liked. The coconut powder
levels also affected body of the cake. The body and
textural scores of the product were 7.5, 7.1 and 6.8,
respectively for the three powder levels used. There
was no much difference between 3 % and 5% of
powder levels (P>0.05), but use of 7% of coconut
powder level significantly decreased the body and
texture score. Use of coconut powder not only
imparted a pleasant flavour to the cake as
commented by judges, but also contributed to
firming up of coagulum to the desired level. The
water absorbing capacity of the coconut powder has
also been reported (www.Tiana.com). However,
addition of 7% powder probably interfered in the
uniformity of the coagulum resulting in breaking up
of the coagulum. This is the reason why 7% coconut
powder added cake scored less for body and texture
attribute. This trend was also reflected in overall
acceptance scores which were 7.6, 7.3 and 7.0 for 3,
5 and 7% coconut powder levels, respectively.
Increasing the powder level from 3 to 5% did not
have effect on the overall acceptance (P>0.05), but
addition of 7% of coconut powder significantly
reduced the score. Hence, the lowest level of coconut
powder was used for all the trials.
Microwave processing: After arriving at optimum
milk concentration, sugar and coconut powder levels
to be used for the cake preparation, intensity of
microwave
processing
was
optimized.
The
concentrated milk was added with sugar (25%) and
coconut powder (3%), mixed well and processed for
the cake preparation as described earlier. The rennet
coagulum formed in the plastic container was
subjected to microwave processing. The duration of
microwave processing was kept at 5 min, but the
intensity of microwave was altered to three levels,
viz. power level 1, 2 and 3. The intensity of the
microwave was kept within power level 3, because
beyond this it was observed that the coagulum rose
up and spilled out of the container. Hence,
microwave application was limited to the point where
the contents did not spill out of the container. After
microwave processing, the cake was cooled in fridge
and evaluated for sensory acceptance. The sensory
scores as affected by the intensity of microwave are
presented in Table-3 along with analysis of variance
and CD values.
The appearance and colour scores were 7.3, 7.4 and
7.3, and the flavour scores were 7.2, 7.4 and 7.2,
respectively for the cake prepared at power 1, 2 and
3 levels of microwave. From the Table, it may
discerned that all the above scores were statistically
not significant indicating that microwave power range
used had little effect on the appearance and flavour
of the cake. This is because microwaves penetrate
into the product and cause vibration of water
molecules generating frictional heat (Gonzalez-
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
Thomas and Gostell, 2006) causing instant heating of
the product. This means that the product was not
much exposed to high heat, so little heat induced
changes may be expected. In conventional heating of
conduction and convection, chemical reactions are
induced by high heat intensity leading to physicochemical changes including colour and flavour in the
product. Thus, it may be deduced that the heat
intensity used in the present study did not induce
much changes in colour and flavour of the product as
reflected by the non-significant sensory scores.
However, microwave heating intensity did show
some effect on the body and texture of the product.
It was observed that during heating the rennet
coagulum attained flowable consistency and resulted
in whey separation, but during subsequent cooling
the whey was reabsorbed by the coagulum network
completing the texturisation process. The scores for
body and texture attribute were 7.2, 7.5 and 7.2,
respectively for the power intensities 1, 2 and 3. At
power level 1, the cake was softer, but at power 3
level, the cake was slightly firm and there was risk of
product overflowing from the container. At power
level of 2, the rennet coagulum could be safely
processed without the risk of overflowing, and it
yielded a good, soft coagulum earning a score of 7.5
which was significantly higher than the other power
level scores (P<0.05). These aspects were not taken
into consideration by judges while scoring the
product for overall acceptance for which the scores
were 7.3, 7.4 and 7.2, respectively for the three
power microwave power levels employed. This is the
reason why there was no statistically significant
difference between the overall acceptance scores.
Since power 1 yielded softer coagulum and the cake
to be developed was envisaged to have soft body, it
was decided to use low power level (1) of microwave
processing.
Rennet level: Quantity of rennet used plays an
important role in determining the texture of the
rennet coagulum. This aspect was extensively
studied and reported in varieties of cheeses. In the
present study, since the coagulation is basically a
rennet coagulation, the quantity of rennet plays an
important role to get desired body and texture.
Hence, to study this effect, three rennet levels were
used namely 0.01, 0.02 and 0.03% per batch. The
required quantity of Meito rennet was weighed,
dissolved in minimum amount of distilled water and
added to the mixture of concentrated milk, sugar,
coconut powder and cardamom powder taken in
microwavable container. Then the mixture was
microwave processed at power level 1 and further
process continued. The cake was subjected to
sensory evaluation using a nine-point Hedonic scale
and the scores for various sensory attributes are
presented in Fig.2.
The color and appearance scores of the cake were
7.2, 7.6 and 7.3 for 0.01, 0.02 and 0.03% rennet
levels, respectively. There was no significant
difference between 0.01 and 0.03% levels (P>0.05),
but 0.02 % rennet level obtained higher appearance
150
score (7.6), which could be attributed to more
uniform appearance. As regards flavor, the scores
were 7.2, 7.6 and 7.4, respectively for the three
rennet levels used. Again uniformly soft body and
texture might have received higher flavor score. It is
known that texture and flavor have a correlation
between them (Morin et al., 2008). The body and
texture scores of the cake were 7.0, 7.5 and 7.2,
respectively for the three rennet levels. At low rennet
level, the coagulum was very soft, whereas at
0.02%, optimally soft coagulum was obtained. At
higher level of rennet, there was slight increase in
whey separation, which might be because of higher
proteolysis. It is known that rennet which is a
mixture of rennin like proteases breaks k-casein
exposing α- and β-caseins to calcium precipitation
(Choi et al., 2007). Higher the rennet quantity used,
more extensive is the break down of the casein, and
more calcium sensitive caseins are exposed.
However, higher rennet quantity leads to more
proteolysis which has detrimental effect on the
texture of rennet coagulum. During heating of the
rennet coagulum, the curd network shrinks and the
whey entrapped in the gel is released leading to
syneresis. In RCMC, the whey was released during
heating process, but during subsequent cooling step,
it was reabsorbed by the coagulum leaving behind
little syneresis in the final product. The overall
acceptance scores were 7.2, 7.6 and 7.3 for the
rennet levels 0.02, 0.03 and 0.04%, respectively.
The rennet level of 0.02% coagulum cake obtained
significantly higher score for overall acceptance (7.6)
(P<0.05), hence it was recommended to use 0.02%
rennet per batch.
Renneting time: Since the duration of rennet action
also affects the quality of rennet coagulum, it was
decided to study the effect of duration of rennet
action. Three durations were tried namely 1, 2 and 3
hr and their effect on the cake quality was studied.
The sensory scores are presented in Fig.3.
The results indicated that renneting time had no much
effect on the cake quality. The color and appearance
scores were 7.5, 7.5 and 7.3 for the durations of 1, 2
and 3 hours, respectively. These scores did not differ
statistically (P>0.05) indicating that renneting time
had no influence on the appearance. Similarly, there
was no effect on the flavor of the cake, the scores
being 7.5, 7.3 and 7.3 for the durations,
respectively. These results indicated that at 0.02g
rennet level used, the duration had little influence on
the appearance and flavor. The body and texture
scores were 7.7, 7.5 and 7.2, respectively for the
durations. These scores indicated that one hour
duration was enough to get a good quality coagulum.
Increasing renneting time to 2 hours decreased the
score to 7.5, but it was not statistically different from
the one hour duration one. However, when rennet
action was allowed for 3 hours, the body and texture
score reduced to 7.2 which was statistically less than
the first one. Probably, slightly more proteolysis took
place during 3 hour incubation period which might
have affected the body of the coagulum resulting in
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
lower score. The overall acceptance scores were 7.5,
7.5 and 7.3, respectively. It could be observed from
these scores that there was little difference in the
overall quality of the RCMC prepared with three
durations, hence one hour duration of renneting
time, which was least among the durations tried, was
recommended.
Standardized process
The standardized process of RCMC manufacture is
summarized in the flow diagram (Fig. 4) and the
ingredients required are shown in Table-4. Apart
from those listed in the table, ingredients such as
nuts, saffron, nutmeg etc. can also be used
depending on the preferences of the consumer
population. The final product is suggested to be sold
in microwavable container itself or the cake can be
prepared in a big container (ex: 1000 ml capacity)
and cut into required weight before packaging in
LDPE or coextruded film.
Physico-Chemical And Microbiological
Characteristics Of Rcmc
The compositional parameters were analyzed by
standard methods and listed in Table - 5. From the
table it is evident that RCMC is a good source of
protein, fat, calcium and phosphorus.
Storage stability of RCMC: The RCMC prepared was
kept in the plastic containers and stored at
refrigerated conditions (<10oC). The product was
observed to keep well for about two weeks. The
water activity of the product was 0.92. The samples
were organoleptically evaluated for the storage
stability at refrigerated temperature (<10oC). The
results are provided in the Table -6. The results show
slight decrease in the sensory scores till 14th day of
storage. On the final day of storage dullness in the
appearance and slight colour changes were observed.
Conclusion
It has been concluded that a rennet coagulated milk
cake of acceptable quality and resembling colostrum
cake can be prepared by microwave in-package
processing of rennet coagulum of concentrated milk
added with sugar, coconut powder, and cardamom
powder. The product is rich in proteins, fat and
calcium and has a shelf life of two weeks at
refrigerated temperature. The cake has to be stored
in refrigerated conditions and served cold.
Amerine, M. A., Pangborn, R. M. and Roessler, E.
(1965) “Principles of Sensory evaluation of food”.
Academic Press, New York.
Bhasin, N.R. (2013) Second white revolution. Indian
Dairyman, 65(10):14-17.
BIS (1977) “Determination of Fat by Gerber methodmilk” (First version), 1224,Part I. Bureau of Indian
Standards, Manak Bhavan, New Delhi.
BIS (1981) SP: 18 (Part XI): “Hand Book of Food
Analysis”, part XI, Dairy Products. Bureau of Indian
Standards, Manak Bhavan, New Delhi.
Chamolea, F.D., Coulon, M.G. and Ghoul, M. (2001)
Water activity decreases using of high sugar. Journal
of Molecular Catalysis, 11:949-954.
Choi, J., Horne, D.S. and Lucey, J.A. (2007) Rennet
coagulum breaks the protein particles. Journal of
Dairy Science, 90: 2612-2623.
Christopher, Srinivasa N, Bhat and Strephane Bernet
(2004) “Total ash method” Journal of Food
Chemistry, Vol. No. 48, 457-464.
Decareu R.U. and Peterson (1986) “Microwaves in the
food processing industry”, 2nd Edition, Academic
Press, New York, p. 49.
Gastaldi, E., Trial, N., Guileume, N., Be Contrad, E.
and Cug, J.C. (2003) Heat treatment in milk. Journal
of Dairy Science, 86: 704-711.
Gonzalez-Thomas and Gostell, E. (2006) Microwave
treatment. Journal of Dairy Science, 85: 45114519.
John
Blamire
(2003)
[email protected]
“Kjeldahl
Method”.
McCormick, P.G. (1973) Calcium determination by
EDTA method. Journal of Chemical Education, 54:
484-489.
Morin, P., Pouliot, Y. and Britten, M. (2008) Texture
and flavour correlated between them. Journal of
Dairy Science, 91:871-882.
Powell. T., Gaines, Joe W.W. and Joseph F.M. (1989)
Phosphorus by ash method. Journal of Food Science
and Agriculture, 79: 207-213.
Rao, K.V.S.S. (1991) “A process for manufacture of
paneer”. Ph.D. Thesis submitted to National dairy
research Institute, Karnal.
Sundarraj, N., Nagaraju, S., Venkataramu, M.N. and
Jagannath, M.K. (1972) “Design and analysis of field
experiments”, University of Agricultural Sciences,
Bangalore.
www.tradekey.com
References
Abu jdayil, Azzam, M.O.J. and Almalah, K.I.M. (2001)
Viscosity. Carbohydrate polymers, 64:207-215.
151
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
Fig.1: Effect of sugar level on the sensory score of RCMC
(Note: CA=Colour and appearance; BT=Body and texture; OA=Overall acceptance)
Sensory score
8
7.5
7
6.5
6
5.5
CA
Flavour
15% sugar
BT
OA
20% sugar
25% sugar
(Statistical significance: CA-P>0.05); Fl, BT & OA- P<0.05)
Fig.2: Effect of rennet level on the sensory score of RCMC
Note: CA=Color and appearance; BT=Body and texture; OA=Overall acceptance)
Sensory score
8
7.5
7
6.5
6
5.5
CA
Flavour
1 hr
2 hr
BT
OA
3 hr
(Statistical significance: CA,Fl, BT & OA- P<0.05)
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
Fig.3: Effect of renneting time on the sensory score of RCMC
(Note: CA=Color and appearance; BT=Body and texture; OA=Overall acceptance)
Sensory score
8
7.5
7
6.5
6
5.5
CA
0.01%
Flavour
0.02%
BT
OA
0.03%
(Statistical significance: CA & Fl-P>0.05); BT & OA- P<0.05)
Fig. 4: Standardized method of preparation of rennet coagulated milk cake (RCMC)
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TECHNOLOGY OF RENNET COAGULATED MILK CAKE
1000gm milk in open pan
Concentrated to 330gm
(~ 3x)
Concentrated milk taken in microwavable container (100g)
Adding coconut powder (3gm)
sugar (25gm) and
cardamom powder (0.15gm)
Adding of rennet (0.02gm)
Allowed for 1 hr for rennet action
at ambient temperature (~ 280C)
Microwave heating
(power two for 5 min)
Cooling to ambient temperature
Transferred to fridge for cooling overnight
Rennet Coagulated Milk Cake
Table-1
Effect of milk concentration on the sensory score of RCMC
Sensory attribute#
2-times concentration
3-times concentration
4-times concentration
CD05
7.3a
7.6b
7.4a
0.16
7.3
a
b
7.2a
0.34
Body & texture
6.0
a
c
b
0.43
Overall acceptance
7.1a
7.2a
0.36
Appearance & colour
Flavour
7.7
7.4
6.5
7.7 b
Note: RCMC = Rennet coagulated milk cake; # = Score on nine-point Hedonic scale; Mean values with different
superscripts in a row are significantly different
Table-2
Effect of coconut powder level on the sensory score of RCMC
Sensory attribute#
3g
20 g
25 g
CD0.05
Appearance & colour
7.7b
7.5ab
7.2a
0.39
Flavour
7.5b
7.3ab
7.2a
0.28
Body & texture
7.5b
7.1ab
6.8a
0.41
Overall acceptance
7.6b
7.3ab
7.0a
Note: RCMC = Rennet coagulated milk cake; # = Score on nine-point Hedonic scale;
different superscripts in a row are significantly different at P<0.05
0.55
Mean values with
Table-3
Effect of microwave power level on the sensory score of RCMC
Sensory attribute#
Power 1
Power 2
Power 3
CD0.05
Appearance & colour
7.3a
7.4a
7.3a
Flavour
7.2a
7.4a
7.2a
-
Body & texture
7.2a
7.5b
7.2a
0.23
Overall acceptance
7.3a
7.4a
7.2a
-
-
#
Note: RCMC = Rennet coagulated milk cake; = Score on nine-point Hedonic scale; Mean values with different
superscripts in a row are significantly different at P<0.05
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Table-4
Ingredients required for 100g batch of RCMC
Ingredients
Quantity
Milk
300 ml
Sugar
25g
Coconut powder
3g
Cardamom powder
0.15g
Rennet powder
0.02g
Table-5
Physico-chemical characteristics of CMC
Compositional parameter
Percentage
pH / Acidity (% lactic acid)
5.46/0.231
Water activity
0.92
Ash
1.7
Protein
8.2
Fat
8.5
SNF
38
Sucrose
18.2
Lactose
9.7
Calcium
412.8
Phosphorus
76
Table-6
Organoleptic evaluation of the RCMC during refrigerated storage (<10 oC)
0th Day
4th Day
8th Day
Appearance & colour
7.5
7.5
7.5
7.3
7.1
Flavour
7.6
7.5
7.4
7.3
7.2
Body & texture
7.7
7.6
7.5
7.4
7.3
Overall acceptance
7.5
7.5
7.4
7-3
7.2
Sensory attribute
155
12th Day
14thDay
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