Preparation of Dahi
Objectives:
To prepare dahi, fermented milk to extent utility of milk.
To study the quality of the product.
Relevant information:
Dahi is a well know fermented milk product consumed throughout India. The conversion of milk into Dahi is an intermediate step in the manufacture of Shrikhand, Makhan and Ghee. There are three types of Dahi –prevalent in the country viz.
1) Sweet, mildly sour dahi
2) Sour dahi and
3) Sweetened dahi (called misti, lal or payodhii).
Dahi has higher nutritive value as compared to milk. It is palatable, digestive, and assimilable than milk. The product has got nutritive and therapeutic value.
Dahi is carbonated to increase its keeping quality up to 15 to 30 days without refrigeration. Thermization is another process in which starter micro-organisms are killed after production of dahi to stop further metabolic degradation of milk constituents. Yoghurt is taken as short of set curd alike to dahi.
Precautions:
Starter culture of dahi must be free from undesirable and harmful bacteria.
Material required:
1. Whole milk preferably homogenized.
2. Mixed starter culture (portion of previous day’s dahi).
3. Dipper type long handled spoon for transfer of culture.
4. Plastic coated cups.
5. Stainless steel pan.
6. Chulah/stove/gas shegadi for heating milk.
7. Thermometer.
8. Incubator.
Procedure:
1. Take one or two liters of milk in the pan.
2. Boil the milk for 5 to 10 minutes.
3. Cool the milk to body/room temperature (35 0 C).
4. Inoculate the milk with mixed culture or previous day’s mild acidic curd at the rate of 0.5 to 1 percent.
5. Mix the milk thoroughly.
6. Fill the milk in plastic cups.
7. Incubate the cups or container at a temperature of 30-35 0 C for 14 to 16 hrs. (Acidity to reach about 0.7 to 1 percent).
10. After incubation the cups or the containers are removed from the incubator and stored at low temperature to check further fermentation reactions.