The present invention relates to a process for preparation of fermented okara(soy residue) based idli batter. More particularly the present invention relates to the quick fermentation of idli batter utilizing the soy residue called okara. Idli, is one of the traditional fermented cereal pulse product popular in southern India, and is prepared from rice (Oryza sativd) and black gram (Phaseolus mungo). Black gram can be substituted by other legumes, such as common beans, green gram, red gram etc. Soyabeans are superior to other legumes in its nutritive value, and hence provide idli with higher protein content than idli prepared from the same proportion of black gram. Okara is a soy residue, obtained during the preparation of soymilk. Idli batter is fortified with okara resulting in a protein quality of staple foods through a mutual complementation, contributing towards protein-energy malnutrition. The addition of okara to the idli batter reduced the fermentation time, as a result of an acceleration in fermentation process. Acidification & leavening are the most important changes which occur during fermentation. f The extents of these changes depended on the microflora and the fermenting substrates. The acid and gas required for leavening action are produced by the lactic acid bacteria which increase the batter volume and decrease the batter pH during fermentation causing sour taste in the final product.The changes that occur during fermentation include increase in free sugar, non protein nitrogen, thiamine, nicotinic acid and riboflavine, methionine and total niacin and breakdown of trypsin inhibitor.
Reference may be made to K.H.Steinkraus, A.G.Van veen and D.B.Thiebeau (1967) Food technology21, 916-919, wherein various methods of preparing idli using dehulled soyabeans, common beans substituting black gram dhal was used. The drawback in the described procedure is long fermentation period of batter for about 20-24hrs. Reference may be made to V.D.Nagaraju, B.Manohar (2000) Journal of Food Engineering 43,167-171, wherein the rheology and particle size changes during idli fermentation was reported. The raw material for idli fermentation is only Parboiled rice and decuticled black gram. The drawback is fermentation time is overnight at room temperature. Reference may be made to S.k.Mukherjee, M.N.Albury, C.S.Pederson,A.G.Van veen and K.H.Steinkraus( 1965)Applied Microbiology vol 13, 227-231, wherein they have isolated & identified the microorganism(Leuconostoc mesenteroides) responsible for souring, as well as gas production in the idli batter are isolated and identified. Idli is prepared with blackgram and rice in 1:1 proportion. The drawback is that, they have not described the cereal legume substituted idli.
Reference may be made to Renu Agrawal,E.R.Rati, S.V.N.Vijayendra, M.C.Varadaraj, M.S.Prasad& Krishna Nand (2000) World Journal of Microbiology& Biotechniology 16:687-690 wherein the flavour profile of idli batter prepared from defined microbial starter cultures like Pediococcus and Candida sps is reported. The fermentation period was for of 10 days.
Reference may be made to N.T.Annan,W.A.Plahar,L.Pill&MJakobsen 2005;International Journal of Food sciences and Nutrition 56(5);315-326, wherein the effect of soybean
fortification in Ghanian maize dough fermentation is reported. However time taken to ferment is 72 hrs. There is no mention on the utilization of okara in the preparation of idli. Reference may be made to R.P.Yajurvedi (1980) Indian food Packer34 (6)33-38, wherein, idli is prepared using rice and black gram dhal. The drawback is longer period of fermentation.
Reference may be made to N.Thyagaraja, H.Otani and A.Hosono(1992) Lebensmittel-wissenschaft and Technologic, 25,77-79 wherein microbiological changes during the fermentation of idli. is reported The lactic acid bacteria and non lactic acid bacteria reached maximum at 24hrs and subsequently the numbers reduced with time. However no mention on utilization of okara is reported in the study.
Reference may be made to Chandini.S.Kumar, E.Rati Rao and Jamuna prakash (2005) Journal of Sensory studies20, 397-409 wherein the effect of varietal differences & polishing of rice on quality parameters of idli is reported. The drawback is that the period of fermentation was for 20hrs.
Reference may be made to H.S.R.desikachar, R.Radhakrisna Murthy, G.Rama rao, S.B.Kadkol, M.Srinivasan&V.Subrahmanyan (1960) J.Sci.Indust.Res.,19c,168-172, wherein the changes in the batter during idli fermentation like effect of temperature, microbial growth during fermentation and effect of antibiotics on the fermented batter is reported. The drawback is that the batter was allowed to ferment overnight.
Reference may be made to C.V.Ramakrishnan, L.J.Parekh, P.N.Akolkar, G.S.Rao and S.D. Bhandari (1976) Plant Foods for Man 2, 15-33, wherein dehusked soy dhal and rice were used to prepare idli. The changes during fermentation in volume & pH of the batters from rice & soybean or blackgram and the acceptability of the finished product were found to comparable. The drawback is that the fermentation period was 14 hrs.
The main object of the present invention is to provide a process for preparation of fermented okara based idli batter, which obviates the drawbacks as detailed above.
Another object of the present invention is reduction of fermentation time by accelerating the fermentation process.
Still another object of the present invention is to provide the fortification of soy residue-okara waste to the idli batter fortification, thus enhancing the nutritive value of idli.
Yet another object of the present invention is the improvement in the texture of idli fortified with okara
Accordingly, the present invention provides a process for preparation of fermented okara(soy residue) based idli batter which comprises
a) washing & soaking of dehulled black gram dhal in cold water for 4hrs at room temperature,
b) grinding to a paste in a wet grinder, using cold water,
c) washing of rice soji thoroughly with water, decanting excess water and mixing with the
gram paste as obtained at step (b),
d) obtaining okara from soybean seed by a process as herein described ,
e) grinding of okara with little amount of water & mixing the okara paste with rice soji and
gram paste of step ( c ) to get batter wherein the ratio of rice soji, black gram and okara
is 3.0: 0.5: 0.5-3.0:0.1:0.5,
f) adding 1% salt to the batter obtained at step ( e ) and dispensing it to the commercially
available metallized polyester polyethylene pouches of 20x18 cm & heat sealing in a hand
sealing machine,
g) fermenting the batter at room temperature of 25-30 ° C for 8-10 hours to get desired idli
batter having pH 4.58 , acidity 0.58% and 3.8 % CO 2 .
In an embodiment of present invention the okara used is obtained by a process comprising the steps of
a) cleaning and soaking of Soybeans with water for 12 hrs, till the beans become double the
original size,
b) washing of soaked beans with water to remove the seed coats by rubbing manually with
hands,
c) grinding the beans with 1:8 ratio water in a wet grinder for 2 to 3 minutes to make slurry
to avoid foam formation,
d) filtering the slurry through double layered cheesecloth to yield the residue okara.
e) drying of wet okara at 45°C for 10-12 hrs, to remove the moisture and stored in airtight
containers.
In another embodiment of present invention fermentation time is reduced to 8-10hrs.
In yet another embodiment of the present invention texture of idli improved with okara added to idli batter.
The above process involves cleaning, washing and soaking of dehulled black gram dhal, grinding to a gelatinous paste by adding water. Washing idli soji and draining excess water, mixing with the batter of blackgram dhal. Cleaning and soaking of soybeans, dehulling, grinding to slurry with excess water, filtering to remove okara. Drying of okara and grinding with water and added to the batter. Adding 1% salt and allowing it for fermentation. Preparation of okara; - Soya beans are purchased from a local market. lOOgms of cleaned soyabeans were soaked in 1000ml beaker for 12 hrs in about 800ml tap water. It is drained, rinsed 2 or 3 times in tap water, dehulled and ground with 400ml of water in blender for about 2-
3 min. Additional water was added to obtain 600ml of Soya slurry (i.e. Water to bean ratio is 8:1). The soy slurry was filtered through a cheese cloth to obtain 800ml of soymilk and okara was separated. The wet okara was oven dried for 10-12 hrs and stored in airtight containers. Preparation of idli batter;
Idli sofi(Oryza sativa) and black gram dhal (Phaseolus mungo ) were purchased from a local market in one lot for the entire study. Dhal was cleaned, washed and soaked in tap water for 4 hrs at room temperature. It is ground separately in a blender at high speed to a fine gelatinous texture. The idli soji (Rice grits) was washed, excess water was drained and mixed with black gram dhal batter. Okara was ground with water and mixed with the batter. The control batter is without okara. 1% common salt was added and allowed to ferment for known period of time at room temperature. At the end of the incubation period, the batter appeared risen. The batter was poured over idli pans and steamed Texture analysis:
Texture of idli was analyzed employing texture analyzer TA-Hdi (Stable Microsystems, Surrey.U.K With a cross head speed of 0.5mm/s and with 50% compression for hardness and stickiness parameters. Among the several textural parameters, hardness and stickiness were selected to represent the results because of their repeatability and reasonable variations. Measurements were performed in six replicates and averages were reported in Newtons. Sensory evaluation:
Idli prepared form different batters were subjected to sensory evaluation by the method of Quantitative Descriptive Analysis (QDA), employing a trained panel. During initial session descriptors of the product were obtained by "Free choice profiling". Panelists were asked to describe the samples with as many spontaneous descriptive terms as they found applicable. The common descriptors chosen by more than one third of the panel were used in preparing a score
card consisting of a 15cm scale wherein 1.25 cm was anchored as low and 13.75 cm as high. The panelists were asked to quantify the perceived intensity of attributes by marking a vertical line on the respective scale and writing the code number of the sample. The panelists were also asked to indicate the overall quality of the product on an intensity scale which was anchored at very poor, fair and very good to assess the liking or preference of the product. The scores for all the attributes were tabulated and the mean values were calculated. These mean scores represented the panel's judgement about the sensory quality of the samples. Data was statistically analyzed by Duncan's Multiple Range Test.
TABLE -1 Means scores of Traditional and Okara substituted idli
pH measurement;
pH of the batter was measured using a pH meter
Titrable acidity
10 gms of sample was taken in a 100ml beaker and 20ml of distilled water and 3-4 drops of In an embodimnt of preesent invention the okara used is obtained by a process
Measurement of CO2
Amount of CO2 released by the fermented batter is detected by using CO2 Analyzer (phi Dan sensor, Denmark) In the flowchart accompanying this specification flow chart-1 represents the preparation of idli using okara. Flow chart-2 represents the production of okara using soybean.
Flow chart for idli preparation (Flow Chart Removed)
The following examples are given by way of illustration of the working of the invention in actual practice and should not be construed to limit the scope of the present invention in any way
Example 1 Control idli batter
Rice soji and black gram dhal was taken in the ratio of 3:1. Rice soji was purchased from a local market. 30gms of dehusked split black gram dhal is washed twice with 90ml water and the washings were discarded. Then it is soaked in 120ml water for 4 hrs, at room temperature,then ground in a blender to a fine paste. 90gms of Rice soji is washed in 270ml water, excess water is drained and mixed with dhal batter. The batter is dispensed to the commercially available metallized polyester polyethylene pouches of 20x18 cm & heat sealed in a hand sealing machine (Quick seal, Sevana, India3) and allowed to ferment for 14 hrs at room temperature. Every 2 hrs of fermentation pH, acidity and the percentage of CO2 released was measured. At the end of fermentation, the fermented batter was distributed into hollow depressions in steaming pans and steam cooked.
After 14 hrs of fermentation the pH of batter was 4.51, 0.64% acidity with 19.7%CO2
Example 2
Okara fortified idli batter
Rice soji, black gram dhal and okara were taken in the ratio of 3:0.5:0.5. Okara was obtained during the preparation of soymilk. Whole soybeans were first washed and soaked overnight in distilled water. After decanting the water, the soaked soybeans are dehulled manually and mixed with 8 times the weight of soybean and comminuted in a blender for 3 min. The resultant slurry was then filtered through double-layered cheesecloth to yield soymilk. The remaining residue is called okara. Wet okara is dried at 45°C for 10-12 hrs, to remove the moisture and stored in
airtight containers.
Rice soji was purchased from a local market. 15 gms of dehusked split black gram dhal is washed twice with45ml water and the washings were discarded. Then it is soaked in 60ml water for 4 hrs, at room temperature. It is ground in a blender to a fine paste. 90gms of Rice soji is washed in 270ml water, excess water is drained and mixed with dhal batter. 15 gms of okra was ground to fine paste with little amount of water and added to the batter. It is dispensed to the commercially available metallized polyester polyethylene pouches of 20x18 cm & heat sealed in a hand sealing machine (Quick seal, Sevana, IndiaS). It was allowed to ferment for 10 hrs at room temperature. Every 2 hrs of fermentation pH, acidity and the percentage of COi released was measured. At the end of fermentation, the fermented batter was distributed into hollow depressions in steaming pans and steam cooked. After 10 hrs of fermentation the pH of batter was 4.68, 0.65% acidity with 33.6%CO2.
Example 3 Okara fortified idli batter
Rice soji, black gram dhal and okara were taken in the ratio of 3:0.5:0.5. Okra was obtained during the preparation of soymilk. Whole soybeans were first washed and soaked overnight in distilled water. After decanting the water, the soaked soybeans are dehulled manually and mixed with 6 times the weight of soybean and comminuted in a blender for 3 min. The resultant slurry was then filtered through double-layered cheesecloth to yield soymilk. The remaining residue is called 'okara Wet okra is dried at 45°C for 10-12 hrs, to remove the moisture and stored in airtight containers.
Rice soji was purchased from a local market. 15 gm of dehusked split black gram dhal is washed twice with 45 ml water and the washings were discarded. Then it is soaked in 60ml water for 4 hrs, at room temperature, then ground in a blender to a fine paste. 90gms of Rice soji
is washed in 270ml water, excess water is drained and mixed with dhal batter. 15 gms of okra is grinded with little amount of water and added to the batter. It is dispensed to the commercially available metallized polyester polyethylene pouches of 20x18 cm & heat sealed in a hand sealing machine (Quick seal, Sevana, India3). It was allowed to ferment for 8 hrs at room temperature. . Every 2 hrs of fermentation pH, acidity and the percentage of CO2 released was measured. At the end of fermentation, the fermented batter was distributed into hollow depressions in steaming pans and steam cooked. After 8 hrs fermentation the pH of batter was 4.58, 0.58% acidity, and 3.8%CO2 .
Example 4 Okara fortified idli batter
Rice soji, black gram dhal and okara were taken in the ratio of 3:1:0.5. Okara was obtained during the preparation of soymilk. Whole soybeans were first washed and soaked overnight in distilled water. After decanting the water, the soaked soybeans were dehulled manually and mixed with 8 times the weight of soybean and comminuted in a blender for 3 min. The resultant slurry was then filtered thrugh double-layered cheesecloth to yield soymilk. The remaining residue is called okara. Wet okara is dried at 45°C for 10 - 12 hrs, to remove the moisture and stored in airtight containers.
Rice soji was purchased from a local market .30 gms of dehusked split black gram dhal is washed twice with 90ml water and the washings were discarded. Then it is soaked in 120ml water for 4 hrs, at room temperature. It is ground in a blender to a fine paste. 90 gms ofRice soji is washed in 270ml water; excess water is drained and mixed with dhal batter. 15 gms of okara was ground to fine paste with little amount of water and added to the batter. It is dispensed to the commercially available metallized polyester polyethylene pouches of 20 x 18 cm & heat
sealed in a hand sealing machine (Quick seal, Sevana, India3). It was allowed to ferment for 10 hrs at room temperature. Every 2 hrs of fermentation pH, acidity and the percentage of CO2 released were measure. At the end of fermentation, the fermented batter was distributed into hollow depressions in steaming pans and steam cooked.
After 10 hrs of fermentation the pH of batter waw 4.38. 0.75% acidity with 6.4% CO2. Summary of observations:
Fortification of okra to the idli batter accelerates the production of lactic and acetic acids during fermentation and reduces the fermentation time. The samples were subjected to ph, acidity and COi released during fermentation.
The pH of controlled idli batter after 14 hrs of fermentation was 4.51 and the pH of okara fortified idli batter after 8 and lOhrs of fermentation were 4.58 and 4.68. Similarly the acidity of controlled idli batter after 14 hrs of fermentation was 0.64% and the acidity of okara fortified idli batter after 8 and lOhrs of fermentation were 0.58% and 0.65%.The amount of CO2 released by the controlled idli batter after 14 hrs of fermentation was 19.7% and that of okara fortified idli batter after 8 and l0hrs of fermentation were 3.8% and 33.6%.
Texture analysis;
Hardness measured as the peak force during compression in the first cycle. Hardness of traditional idli was 33.05N & okara substituted 8 hrs idli was 20.8N and okara substituted 10 hrs idli was 24.4N.These values show that the traditional idli offered more resistance to compression than that made from batter with okara. This indicates that okara substituted samples were softer and easy to bite compared to traditional sample. It may be due to partial substitution of black gram and desired level of fermentation of okara containing batter. On the other hand the values
for stickiness were relatively low. The stickiness of traditional idli was 0.13N.S and okara substituted 8hrs idli was 0.14N.S. Sensory evaluation;
The difference in sensory quality of traditional and Okara containing samples were significant in some of the attributes viz sponginess, sticky, beany, salty and overall quality at p<0.05 level. It was also observed that sponginess was significantly lowered in idli made from batter fermented for eight hours. Overall quality scores of 7.96 and 7.84 indicate that idli made from batters fermented for 8 and 10 hours respectively were fairly acceptable. Fermentation of 10 hours resulted in higher sponginess and fluffy texture.
Novelties of the present invention are:
1. Utilization of waste soy residue Okara as a protein source of idli
2. Quickening of fermentation, thus reducing the fermentation time.
3. Improvement of idli texture by fortifying okara
4. Nutritionally better quality idli in okara fortified samples
The main advantages of the present invention are

1) Shorter period for fermentation of batter
2) Enhancement of nutritional value of idli as it is rich in
Protein

3) Improvement in the texture of idli.
4) Soy residue can be dried and stored and used whenever needed.

WE CLAIM:
1. A process for preparation of fermented okara (soy residue) based idli batter which comprises
a) washing & soaking of dehulled black gram dhal in cold water for 4hrs at
room temperature (25-30 ° C ) ,
b) grinding the above black gram to a paste in a wet grinder, using cold water
c) washing of rice soji thoroughly with water, decanting excess water and
mixing with the gram paste as obtained at step (b) ,
d) obtaining okara from soybean seed by a process as herein described ,
e) grinding of okara with little amount of water & mixing the okara paste with
rice soji and gram paste of step ( c ) to get batter wherein the ratio of rice
soji, black gram and okara ranges from 3.0: 0.5: 0.5 - 3.0:0.1:0.5,
f) adding 1% salt to the batter obtained at step ( e ) and dispensing it to the
commercially available metallized polyester polyethylene pouches of 20x18
cm , heat sealing the said pouches in a hand sealing machine ,
g) fermenting the batter at room temperature of 25-30 ° C for 8-10 hours to get
desired idli batter having pH 4.58 , acidity 0.58% and 3.8 % CO 2 .
2. A process as claimed in 1 wherein the batter obtained after 8-10 hours of
fermentation is useful for preparation of superior quality idli having characteristics
such as herein described .
3. A process for preparation of fermented okara (soy residue) based idli batter
substantially as herein described with reference to example no. 2-4.