The slides describes desirable sensory characteristics, sensory evaluation procedure, score card used and sensorial defects in Dahi (a fermented traditional milk product of Indian subcontinent)

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Introduction
FSSR (2011) Definition of Dahi:
DAHI OR CURD means the product:
Obtained from pasteurized or boiled milk by souring,
natural or otherwise, by a harmless lactic acid or other
bacterial culture.
It may contain added cane sugar
Dahi shall have the same minimum percentage of milk fat
and milk solids-not- fat as the milk from which it is prepared
Milk solids may also be used in preparation of this product.

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Desirable Characteristics of dahi
Colour & Appearance
Cow milk dahi: yellowish creamy-white
Buffalo milk dahi: creamy-white
Free from browning & visible foreign matter
Smooth & glossy surface w/o any free whey on
sides or top
Sometimes, a cream or malai layer on the top is
indication of wholesomeness & purity, hence
considered as a desirable attribute
Desirable Characteristics of dahi
Flavour
A pleasant, sweetish aroma & a clean acid taste are
desirable in dahi
Derived from the overall blend of the delicate
diacetyl aroma & clean acid taste of LA
Skimmed milk dahi lacks the natural rich flavour
and considered as flat
Should not show any sign of bitterness, raw,
yeasty, cheesy, sharp & unclean off-flavours

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Desirable Characteristics of dahi
Body & Texture
Good quality dahi is a weak gel like junket when
made from whole milk
Body: firm, homogenous & free from gas holes/
air bubbles
On cutting it should appear clean/sharp
Graininess/lumpiness, ropy, shrunken, thin &
wheying off should be absent in dahi
Desirable Characteristics of dahi
Acidity
Range 0.75-0.85 % LA is appropriate for good
quality dahi
Excessive acidity imparts too much
sourness/sharp/astringent taste to the product
Low acidity is considered as raw/bland dahi

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Score Card for Dahi
Score Card
Attribute Perfect Score
Container & closure 5
Flavour 45
Body & Texture 30
Acidity 10
Colour & appearance 10
Total 100
Technique for Sensory Evaluation of dahi
i. Dahi is tempered to 10-15°C for proper judging
ii. Condition of the container/package for fullness, cleanliness
& general appearance should be noted
iii. Remove the closure lid & immediately observe the aroma by
inhaling the product
iv. Examine the appearance of dahi for uniformity of colour &
presence of air holes & free whey
v. Place a spoonful of dahi in the mouth. Manipulate it is inside
mouth by tongue and note the tactual properties on the
tongue & between teeth for grittiness
vi.Note whether the acidity level is pleasant & typical to the
product
vii. Mark the score card

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Undesirable Attributes of dahi
Flavour related
1. High acidic: Certain amount of acid needed to coagulate
the proteins & form coagulum typical to dahi. If acid level
too high taste become sharp, harsh & offensive. Caused by:
1. Higherset temperature
2. Slow/insufficient cooling after setting
3. Temperatureabuse during distribution/storage
2. Low acid: Dahi should exhibit an acid taste. Consumers can
easily detect the ‘low-acid’ taste of dahi. Caused by low
culture activity:
1. Residual cleaning/sanitizing compound
2. Antibiotic in the milk supply
3. Result of bacteriophage attack
3. Lacks freshness: Fresh ingredients should be used in dahi
making. Ingredients should be stored at low temperature.
Undesirable Attributes of dahi
Flavour related
4. Insufficient flavour: Absence of typical dahi flavour.
Caused by low citrate level in milk and destruction of
diacetyl. Rapid cooling after setting helps to prevent this
defect.
5. Bitter: Offensive aftertaste sensed at the back sensed at
the of tasting sequence. Caused by:
1. use of poor quality/old milk contaminated with psychrotrophicor
spoilage bacteria
2. starterculture with proteolytic activity
3. finished product being stored too high a temperature
6. Cooked: a slight amount of cooked flavour is desirable.
Gives an aroma like caramelized sugar, butterscotch, egg-
like odour to dahi.

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Undesirable Attributes of dahi
Texture related
1. Wheying off/Syneresis/Free whey: Translucent, greenish-
yellow liquid on the surface & around the sides of the cup:
Causes:
1. Too low pH
2. Disruptionof the coagulum before setting
3. Heat shock of dahi
4. Rough transportationafter setting
5. Freezing/thawing of dahi
2. Gel like/too firm: has the appearance of a formed gel in the cup,
and a very firm set. Using excessive Exo-polysaccharide (EPS)
producing cultures.
3. Weak: appears “runny” or liquid like or no residence time in the
mouth. Caused by:
1. Insufficient heat treatment 2. Dahi SNF too low
Undesirable Attributes of dahi
Texture related
4. Ropiness: placing the bottom of spoon on the top of the dahi
mass, lifting the spoon. Trail of rope >2 inch: ropiness. Causes
of culture contamination or EPS producing strains.
5. Chalky/powdery texture: caused by too much SMP use in dahi
making.