This document provides information on the traditional and industrial methods for producing Dahi (Indian curd) and Misti Dahi (sweetened fermented milk). In the traditional method for Dahi, milk is boiled and cooled then cultured with the previous day's curd and left to ferment overnight. For Misti Dahi, milk is heated for longer with sugar added to produce a caramelized brown color and flavor. Industrially, ingredients are standardized and pasteurized before culturing and packaging under controlled temperature conditions for longer shelf life. Misti Dahi has a higher sugar content which allows for storage of 12 days at refrigeration versus 2 days at room temperature.

1. By
T. Achuharam
B.Tech (Dairy Technology)
College of Food and Dairy Technology
TANUVAS

2. Dhai
Indian curd
Preferred from Buffalo Milk, Cow Milk, Mixed Milk
Part of Daily diet and refreshing beverage
Dahi is the simplest way of preserving milk for human consumption in a tropical condition.
Milk is boiled and cooled, incubated with dahi starter culture, usually left over from the
previous day stocks and incubated undisturbed at ambient temperature for four to six hours
unit it acquires a thick consistency.
Lactic acid bacteria added multiply, grow and produce lactic acid, acetic acid and carbon
dioxide by utilizing lactose present in milk. Some bacteria uses citric acid of milk to produce
certain volatile organic compounds mainly diacetyl, which is mainly responsible for flavour
of dahi.

3.  With the advent of health foods, dahi is valued for controlling the growth
of intestinal bacteria and incurring intestinal diseases like constipation,
diarrhoea and dysentery.
 Dahi is also found effective in lowering blood cholesterol. Dahi is not only
popular for its therapeutic value but its nutritive value is also unique.
 It contains all the nutrients present in milk except a little variation in
lactose content.
 Lactose content of dahi is about 30 % (per cent) lower than milk as
because some portion of lactose is fermented for the formation of lactic acid.
People who has lactose intolerance syndrome can easily digest dahi.
 Dahi has also a special social value as being served and consumed in all
festival and occasions.

4. Classification
I. For direct consumption
II. For churning in to desi butter
According to uses
I. Dhai for direct consumption
II. Dhai for production chakka,shrikand, lassi,and butter milk
III.Dhai for the production of desi butter, ghee.

5. According to consumption
Whole milk dahi
Skim milk dahi
Toned milk dahi
Standardized milk dahi
Dahi from special milk
According to flavour
Sweet dahi (acidity not more than 0.7%)
Sour dahi (acidity not less than 0.7%)
Sweetened dahi
Fruit dahi

6. The following culture shall be used in the preparation of dahi
a. Streptococcus lactis , streptococcus diacetylactis, streptococcus cremoris, single or in
combination with or with out leuconostoc species: and
b. Also as above along with species of lactobacillus such as lactobacillus bulgaricus,
lactobacillus acidophilus and lactobacillus casei and streptococcus thermophiles.
The amount of culture necessary depends mainly on season of the year due to the
variations in ambient temperature.
In summer 1 to 2 per cent and in winter 5 to 10 per cent by volume of culture are
required for optimum coagulation.
Together with culture, 10 to 12% sugar is added for making sweet dahi but no sugar is
required for making sour dahi.
Fruit or flavoured dahi is prepared by using different fruit juice or added flavour
together with culture and sugar.

7. Method of Preparation
In traditional method of dahi preparation, milk is heated intensively to boil for 5 to
10 min and then it is cooled to room temperature. cooled milk is added with previous
day‘s curd or buttermilk, stirred and allowed to set undisturbed usually for overnight.

9. MISTI DAHI
Misti dahi is also known as Misti doi, Payodhi and Lal dahi. It is a
traditional sweetened fermented milk product popular in the eastern part of
India,A good misti dahi has a characteristic brown colour, firm consistency,
smooth texture and caramelized flavour
Buffalo milk is preferred for the preparation of Misti dahi due to high
fat content, which induce a rich creamy product with excellent mouth
feel.
The high protein content of buffalo milk leads to the formation of firm
coagulum which resists whey separation during storage and
transportation

10. Traditional method of Misti dahi preparation
Traditionally, it is prepared by Halwais on a small scale to meet the local demand.
Whole cow milk or buffalo milk or their combination is added with sugar
(upto15% of the milk) and it is heated continuously in an open pan at a simmering
temperature of 68-70°C for 6-7 hours or boiled to reduce the volume to 60-70% of
the original.
Intense heating imparts cooked flavour and brownish colour to the product.
Artificial colour, caramel sugar and/or jaggery are also added based on the
consumer preference. The mix is then cooled to about 40°C and inoculated with the
previous day‘s product
It is then filled into earthen pots of consumer size or bulk size vessels and
incubated overnight at room temperature. After firm setting of curd, it is shifted to a
cooler place or stored under refrigeration temperature.

11. Industrial method of production
In the organized sector, mishti dahi is manufactured employing improve technological process.
For this purpose, milk solids are used from fresh cow/ buffalo milk, cream, skim. Milk powder (SMP), whole
milk powder (WMP), evaporated whole milk, sweetened condensed milk and white butter.
There is a need to select fresh and good quality ingredients in relation to microbial and sensory quality.
The raw material (milk) used for mishti dahi preparation should be fresh, free from off-flavours and has negative
clot-on-boiling test.
The most common sweetening agent used in preparation of mishti dahi is cane sugar. Other sweeteners such as
corn sugar, corn syrup, and also sugar or maltose can be used as sweetening agent.
Some times in preparation of some special varieties of mishti dahi, fresh palm jaggery is used as a sweetener.
Commercially cane sugar of high microbiological quality and free from extraneous matter is used as sweetening
agent.

12. Mishti dahi is coloured and flavoured commonly with caramel.
Caramel is prepared from heating sugar and it is available commercially in a viscous form (76% TS).
Caramel is soluble in water and having a specific gravity of 1.315 to 1.345.
Synthetic flavours like caramel, vanilla, cardamom, rose, pineapple, etc may also be used.
Fruits and dry fruit, nuts may also be used for developing a wide variety of mishti dahi.
The most critical and important step in the manufacture of the mishti dahi is the selection of appropriate
type of starter culture since it affects the flavour, consistency and acidity development in the presence of
sugar and caramel at relatively higher TS levels.
As such starter culture is regarded as heart of mishti dahi preparation.
The optimum activity of the mishti dahi culture is expected in a narrow temperature range of 40-42oC.
Normally a good starter culture with 1.0 % inoculum develops 0.70 percent acidity within 6-8 hours.

13. Industrial method of production
Calculated amount of milk and cream is taken into a multipurpose vat. Skim milk powder is added
through a venturi assembly to increase the level of total solids and sugar is added at the rate of 9 –
10%.
Commercially available Caramel is added normally at the rate of 0.10 to 0.12%. After the mix is
prepared, it is heated to 90°C for 10 min in a vat or plate pasteurizer.
Then the product is cooled to 40 – 42°C and starter culture containing Lactococcus lactis subsp.
lactis and Lactococcus lactis var. diacetilactis is added at the rate of 1% to the mix and mixed
well.
Selection of appropriate type of starter culture is very important and crucial as it affects the flavour,
consistency and acidity development in the presence of sugar and caramel.
After inoculation the product is packed into sanitized polystyrene cups and sealed airtight.
The sealed cups are incubated at 40 – 42°C for about 6 to 8 hours till the acidity develops to about 0.8
% lactic acid.

14. Industrial method of production

15. Sugar controls the acid production of misti dahi because of its effects on osmotic pressure and
improves its acceptability.
Sugar helps in carmalization and development of brown color which is desirable, product should
be stored at 5°C or below.
Higher temperature of storage can lead to defects like whey separation and bitterness. Very low
temperature induces ice-crystals formation which damages the texture.
Chemical composition of misti dahi

16. Shelf Life
Due of high acidity (0.8%) and high sugar level misti dahi has a shelf life of about 12 days at 4°C and
2days at 30°C.
The shelf life mainly depends on post manufacture contamination particularly with yeast and moulds.
Hence attempt should be made not to unduly expose the finished product to atmospheric contamination.
Packaging
Misti dahi is packed in food grade polystyrene and polypropylene cups in 100g, 200g pack sizes. Various
packaging machines of upto 400 cups/min speed are available to package cultured dairy products in
different sizes.
The packaged product should be stored at <5°Cfor extended shelf life.