The present study was aimed to evaluate the optimum inclusion level of soy milk with mint flavour for value preparation of value added paneer. The paneer products prepared by incorporation of soy milk at 10, 20 and 30 percent levels with mint flavour at2 percent level were tested for microbial and sensory properties. Analysis of the data for total bacterial count and yeast and mould count revealed a significant difference between control and treatment and between treatments whereas non-significant difference was observed in the Coliform counts of the samples. In sensory evaluation, scores with regard to flavour, body and texture, packing and overall acceptability did not differ significantly between control and treatments and between treatments indicating that addition of soy milk at different level did not produce a significant change in the quality of paneer. However, colour and appearance scores of the product differed significantly between control and treatments and within treatments. Based on the results, it was recommended that paneer can be prepared by incorporating 30 per cent soy milk with two per cent mint flavour to reduce the cost of production without altering the overall acceptability of the consumers.
Paneer, an acid coagulation product popular among vegetarians is valued for its nutritional and health benefits. It is prepared by coagulating the casein with the help of citric or lactic or tartaric acid. The quality of paneer is mainly attributed to the higher levels of milk solids and typical textural characters. About 5% of milk produced in India is converted into paneer (Chandan, 2007).Soybeans are the common starting materials in traditional soymilk and tofu manufacture. Addition of soymilk in dairy products with an aim to increase the nutritive value and to reduce the cost of the product has attracted the attention of scientists in different part of the world. Soybean is often called as ‘Golden miracle bean’ as it is the world’s foremost provider of protein and oil and used as health food, feed sources and industrial products. The cultivation of soybeans was first recorded in 283 B.C. in China. From China, soybean cultivation was spread into other Asian countries. Soybean is an excellent source of protein and fat but not readily accepted by consumers due to its beany flavour and presence of indigestible components and anti-nutritional factors. Soybean meal is an excellent source of high quality protein as it contains nearly 480 g/kg of dry matter (DM) (Fan, 1995). Soybean meal is the supplemental protein source most widely used in animal feed. Addition of soy milk in paneer preparation will help to improve its nutritional qualities but also reduce the cost of production. In this view, the present study was undertaken to prepare paneer using cow milk (control) incorporating mint flavour and soy milk at 10, 20 and 30 percent levels.
Materials and Methods
Fresh cow milk used for the preparation of paneer was collected from AAC farm, Arul Anandar College, Karumathur. Food grade soy bean was purchased from Nilgris super market, Madurai. Mint and coagulants – food grade 2% acetic acid purchased from local market.
Preparation of Soymilk
The soy beans of good quality were carefully selected and soaked overnight (12-18 hours), at room temperature in portable water containing 0.5% NaHCO3. After soaking, the seeds were collected by decanting the water and washed again with fresh water. The hulls were removed under running water by manual rubbing. Hundred grams of soaked soybean seeds per litre of water was used for grinding i.e. 1:10 (w/v). The resulting suspension was filtered through a double layered muslin cloth. The muslin cloth was wrapped around the bean pulp and squeezed till the liquid was extracted completely. The filtrate obtained was boiled in water bath at 80°C and cooled under refrigeration for 3 days (Masrath Butool and Shadab Butool, 2005). The flow chart for the preparation of soymilk is shown in the Fig.1.
Soy bean + Sodium bicarbonate
Soaked in water
Raw soy milk
Filtered soy milk
Heat to 800C/ 5 min
Fig.1: Flow chart for the preparation of soymilk
Methods of Manufacture of Paneer
The experimental trials were carried out with one litre of sample for each. A solution of 2 ml mint for flavour and 2 percent acetic acid was used to coagulate the sample. The samples were heated to coagulation temperatures of 80°C. The coagulant was added into soymilk samples slowly with gentle and continuous stirring. After complete coagulation, stirring was stopped and contents were left undisturbed at room temperature of 300C for 15 min. Whey was then removed by straining through a muslin cloth and the coagulum obtained was pressed. After pressing the coagulated mass was removed and soaked in cold water for 30 min. Then it was taken out and the free water on the surface was removed by wrapping paneer blocks on a clean muslin cloth. The method adopted in the preparation of soy paneer is shown in Fig. 2.
Receiving of cow milk and soy milk
Heating (800C/ 5 min)
↓addition on mint flavour
Coagulation with 2 % acetic acid solution at 700C
↓ Draining of whey
Cut into desired size
Immersion of Paneer blocks in chilled water (40C)
Draining of water and wiping the surface
Storage at 40C
Fig.2: Flow diagram for preparation of Soy paneer with a mint flavour
Treatment combination used for preparation of soy milk paneer as detailed blow-
|Trial||Milk Percentage||Percentage of Soy Milk||Mint Flavor (ml)||Acetic Acid Percentage|
TC Control – 1000 ml milk + 0 ml Soy milk + 2 ml mint + 20 ml Acetic acid
T1- 900 ml milk + 100 ml Soy milk + 2 ml mint + 20 ml Acetic acid
T2- 800 ml milk + 200 ml Soy milk + 2 ml mint + 20 ml Acetic acid
T3- 700 ml milk + 300 ml Soy milk + 2 ml mint + 20 ml Acetic acid
Microbial Analysis of Paneer
All the samples were subjected to microbiological analysis for Standard Plate Count (SPC), coliform count and Yeast and Mould Count (YMC).
Preparation of Diluents
Normal saline was used for serial dilution of samples. One gm of paneer sample was transferred aseptically into 9 ml of sterile saline. Serial dilutions were prepared up to10-6dilution factor. One ml of appropriate dilution (10-4 to 10-6) was used for enumeration of bacteria and 10-1dilutions for Coliform count and yeast and mould count.
Preparation of Media
The standard plate count of the samples were analyzed as per the methods followed in IS: 5402 (1969). Plate count agar was used for this purpose. 1 gm of sample of appropriate dilution (10-4 to 10-6) was transferred in duplicate of sterile petridish. Approximately 15-20 ml of the melted agar medium was then poured at 30 to 400C and mixed thoroughly by rotating the Petridis. After solidification invert the plates and incubate at 37°C ± 0.5°C for 24 – 48 hours. The colonies were enumerated with colony counter. Coliform count of the samples were enumerated using dehydrated Violet Red Bile Agar (VRBA) medium and yeast and Mould Count was determined using Potato Dextrose Agar (PDA) medium as per the procedure given in IS: 1224 (part I and II), 1981.
The sensory properties of paneer samples were determined by a panel of judges who were familiar with the product using IS 15346 (2003). The panelists analyzed the samples for flavor, body and texture, color and appearance and package.
The experimental trials were replicated for four times and the observations obtained from all replications were analyzed statistically by using completely randomized design (CRD) as per Panse and Sukhatme (1984).
Result and Discussion
In India quality control with regard to food products is being enforced through various regulatory mechanisms like Prevention of Food Adulteration Act (PFA), Agricultural grading and marketing (AGMARK), fruit products order (FPO). The Bureau of Indian standards (BIS)has launched a HACCP program of certification for the food industry, while efforts are being made to implement HACCP in the organized sector of the food industry, there is a need to implement HACCP in the unorganized sector also, as it accounts for 70-80% of food produced and processed in India. Thus in the context of globalization and post WTO era, the codex Alimentarius commission guidelines on food safety issues such as HACCP should be implemented in India. The code of conduct laid down by BIS should be strictly followed by the paneer manufacturers. Government agencies and NGOs could take initiative in spreading awareness and measures to educate the workers about the manufacturing handling and selling of such products which have a very high risk of getting contaminated during the entire process, and basic training of handling and hygienic practices can be given to the manufacturers and handlers, so that the health of the consumer is not at risk.
Standard Plate Count
Bureau of Indian Standards (BIS, 1983) set limits for microbial count in paneer viz., total plate count<5×10-5/g, yeast and mould count <250/g and coliform count of <90/g. The results of standard plate count (cfu/ gm) of paneer samples were 15.25 × 10-4, 18.5×10-4, 21.25×10-4 and 25.00×10-4for control treatments T1, T2, and T3 respectively. The results of the samples were ranged from 10×10-4to 29 ×10-4. Analysis of data showed significant difference between control and treatments indicating that addition of soy milk at different level produce significant change in the standard plate count due to minimal processing during preparation and contain other ingredients rather than milk. The result of the present investigation was in close resemblance with report of Vishweshwaraiah and Anantakrishnan (1985) suggested that Standard Plate Count (SPC) lesser than 5,000/g and higher than 2 lakhs/g can be termed as ‘Excellent’ and ‘Poor’ quality paneer respectively. In the present investigation even though, significant difference noticed between the control and treatments, the counts of the samples were within the standard of Bureau of Indian Standards (BIS 1983) and fit for consumption.
The presence of Coliform especially the E. coli in the sample is a reflection of poor hygiene and sanitary conditions at different stages of handling (Peter et al. 2015). The range with regard to Coliform count (cfu/gm) of paneer sample was 1 to 05 x 10-1, 03 – 05 x 10-1, 03 – 07 x 10-1, and 03 – 06 x 10-1for control and treatments T1, T2 and T3 respectively. The minimum mean count of 3.25 x 10-1± 0.078 recorded T1 and maximum of 5 x 10-1± 0.050 recorded in T2 and T3. Analysis of data revealed no significant difference noticed in the Coliform counts of the samples. Analysis of the data indicating that addition of soy milk at different level does not produces any significant change in the Coliform count due to strict hygienic condition maintained during preparation of paneer.
Yeast and Mould Count
The statistical analysis of the data revealed significant difference (P<0.05) between control and treatments and within treatments indicating that as replacement level of soy milk increases the yeast and mould growth also increases, may be due to higher moisture retaining capacity of soy milk provide the favourable medium for the growth of yeast and moulds. Comparison of means using critical difference revealed that treatments T1 and T2 were identical. The mean ± SE for yeast and mould for control and treatments T1, T2 and T3 were 20.05 x 10-2± 0.01, 25.25 x 10-2 ± 0.04, 30.00 x 10-2 ± 0.08, 33.00 x 10-2 ± 0.07 respectively. The minimum value of yeast and mould count of 20.05 x 10-2recorded in TC and maximum of 33.00 x 10-2in T4. The occurrence of microbial contamination may be due to lack of knowledge of various practices relevant to paneer production and the possible health hazards may occur if food safety is not followed by the workers and vendors. Bhat et al. (2000) reported that microbial contamination seems to be more effectively controlled by Good Manufacturing Practices (GMP) and hygienic rules as well as HACCP during handling and paneer processing.
Table 1: Microbial and sensory evaluation of paneer
|Standard Plate Count (cfu/gm)||Mean||a||a||b||b||6.601*|
|15.25 X 10-4 ± 0.050||18.50 X 10-4 ± 0.036||21.25 X 10-4 ± 0.032||25.00 X 10-4 ±0.025|
|Range||10 – 23 X10-4||14 – 26 X10-4||15 – 26 X10-4||19 – 29 X10-4|
|Coliform Count(cfu/gm)||Mean||a||a||a||a||2.396 NS|
|3.25 x 10-1± 0.078||5 x 10-1± 0.050||5 x 10-1± 0.046||4.25 x 10-1± 0.045|
|Range||1- 05 x 10-1||03- 07 x10-1||03 – 07 x 10-1||03- 06 x 10-1|
|Yeast And Mould Count (cfu/gm)||Mean||a||b||b||c||25.592**|
|20.05 x 10-2± 0.01||25.25 x 10-2± 0.04||30.00 x 10-2± 0.08||33.00 x 10-2± 0.07|
|Range||11-32 x 10-2||21-36 x 10-2||23-41 x 10-2||25-44 x 10-2|
|Flavour Score||Mean||a||a||a||a||3.612 NS|
|43 ± 0.96||41 ± 0.97||42.8 ± 0.70||45 ± 0.77|
|Range||40 – 46||38 – 44||40 – 45||43 – 47|
|Body and Texture Score||Mean||a||a||a||a||2.457 NS|
|29.3 ± 0.88||29.6 ± 0.88||32 ± 0.96||32 ± 0.97|
|Range||26 – 32||27 – 33||29 – 35||29 – 35|
|Colour and Appearance Score||Mean||a||a||b||b||5.000 *|
|9 ± 0||9 ± 0||8 ± 0.3651||8 ± 0.3651|
|Package Score||Mean||a||a||b||b||5.000 *|
|3 ± 0.37||4 ± 0||4 ± 0||3 ± 0.36|
|Range||02-Apr||02-Apr||02-Apr||2 – 4|
|Overall Acceptability Score||Mean||a||a||a||a||1.890 NS|
|84.34 ± 1.43||83.66 ± 1.62||86.17 ± 1.40||88.0 ± 1.18|
|Range||80 – 90||78 – 89||80 – 90||84 – 91|
* indicating significant difference at 0.05% level, ** indicating significant difference at 1% level, NS – Not significant; Means bearing the common letters as subscript are statistically not significant.
TC Control – 1000 ml milk + 0 ml Soy milk + 2 ml mint + 20 ml acetic acid, T1- 900 ml milk + 100 ml soy milk + 2 ml mint + 20 ml acetic acid, T2- 800 ml milk + 200 ml soy milk + 2 ml mint + 20 ml acetic acid, T3- 700 ml milk + 300 ml soy milk + 2 ml mint + 20 ml acetic acid
Sensory evaluation is an important indicator of potential consumer preferences. The flavour of paneer is a characteristic blend of flavour of heated milk curd and acid. The flavour of high grade paneer should be pleasing mild acid, slight sweet and nutty. The texture of high-grade paneer should be compact (close knit), smooth and velvety. Saidu (2005) reported that soymilk incorporation into numerous foods had been shown to enhance sensory qualities in dairy foods such as yogurt, milk, ice cream, sherbets etc.
The data with regard to flavour score of paneer samples were 43 ± 0.96, 41 ± 0.97, 42.8 ± 0.70 and 45 ± 0.77 for control treatments T1, T2 and T3 respectively. The results of the samples were ranged from 38 to 47 per cent. Analysis of the data revealed no significant difference between control and treatments and between treatments indicating that addition of soy milk at different level does not produce a significant change in the flavour of the paneer. But the flavour score for paneer samples of control and 30 percent replacement with soy milk had highest scores than that of T1 and T2.
The mean ± SE score for body and textural characters of paneer samples were 29.3 ± 0.88, 29.6 ± 0.88, 32 ± 0.96 and 32 ± 0.97 for control treatments T1, T2 and T3 respectively. The results of the samples were ranged from 26 to 35. No significant difference in the body and textural scores of paneer samples were observed, indicating that addition of soy protein at different level does not produce significant change in the body and textural property. Masud et al. (2007) stated that the desirable body of paneer is neither too firm nor too soft. It should be sufficiently firm to hold its shape during cutting/ slicing yet tender enough not to resist crushing during mastication. The data with regard to colour and appearance scores of paneer samples were 9, 9, 8 and 8 for control and treatments T1, T2 and T3 respectively. The results of the samples were ranged between 8 and 9. Analysis of the data revealed significant difference in the score of colour of paneer samples between control and treatments. Comparison of means using critical difference revealed that T1 and T2 were identical. The score for colour decreases as the replacement level increases due to yellow colour of soy milk might be the cause to reduce the consumer attraction.
The score for packing characters of paneer samples were 3, 4, 4 and 4 for control treatments T1, T2 and T3 respectively. Analysis of the data revealed no significant difference in the package scores of paneer samples, indicating that addition of soy protein at different level does not produce significant change in the packaging of the product. The mean with regard to overall acceptability scores of paneer samples were 84.34 ± 1.43, 83.66 ± 1.62, 86.17 ± 1.40 and 88.0 ± 1.18 for control and treatments T1, T2 and T3 respectively. The results of the samples were ranged between 78 and 91. Analysis of the data revealed no significant difference in the score of overall acceptability of paneer samples was observed indicating that addition of soy milk at various level does not produce any change in the overall acceptability of the paneer and soy paneer. EL-Boraey et al. (2015) reported that incorporation of soymilk with buffalo’s or cow’s milk highly improved its sensory evaluation scores. The result of the present investigation was in close agreement with the report of Jeelani Raja et al. (2014).
Based on the results obtained in the present study, it was concluded that the paneer can be prepared by incorporating 30 per cent soy milk with two per cent mint flavour as the microbial and sensory evaluations did not differ significantly from the control and overall acceptability was also at par with control paneer.
Microbial Analysis and Cost of Production of Paneer
Addition of soymilk in dairy products with an aim to increase the nutritive value and to reduce the cost of the product has attracted the attention of scientists. Analysis of the data indicating that addition of soy milk at different level does not produces any significant change in the Coliform count due to strict hygienic condition maintained during preparation of paneer. The variation in total bacterial count and yeast and mould count due to addition of extraneous matter soy milk and the higher moisture retaining capacity of the soy milk provide a favourable medium for the growth microbes. The overall acceptability of the product showed no significant difference between control and treatments and within treatments.