LPT 311: Milk and Milk Products Technology (1+1)

JUDGING OF DAHI

It is done to find whether the dahi offered for sale possess desirable characters for direct consumption.

Procedure

• If the container is taken from cold storage, it is allowed to warm slightly without opening the lid. Examine for the firmness of body, separation of whey at the bottom, middle or top, presence of gas bubbles and change in colour. Open the lid and immediately examine the contents for flavour, odour, etc.
• Desirable characters of market quality of dahi includes colour, appearance, flavour, body and texture and acidity.While examining the body and texture following defects have to be noted.
• Watery consistency: Due to low solids or due to poor quality of milk. Too high or insufficient heat treatment can also cause this defect.
• Hard and lumpy curd: This is due to over ripening especially at high temperature and this defect is usually found along with same amount of whey formation.
• Wheying off: Wheying off in dahi may be due to low solid content or due to deliberate dilution with milk. Higher acidity also causes these defects. Disturbances or vibrations at the time of curd setting also result in whey formation.
• Ropiness: Ropiness due to faulty fermentation resulting in low acid production and sweet curdling due to certain microbes.
• Common flavour defects are,
• Bitter and cheasy: due to peptonising proteolytic organisms.
• Cooked defect: due to overheating
• Flat: due to low acid and diacetyl production
• Rancid: due to lipolytic organisms
• Fruity and alcoholic: due to yeast and molds
• Malty defect: due to S. lactis var. maltigenes