Kothakota et al.
estimated by the method prescribed by (International
m 1 = mass of dish including zinc oxide and dahi
Dairy Federation, 1991). The percent dispersibility
samples, g
was calculated using the following equation
m 2 = mass of dish including zinc oxide and dried
dahi , g
( 100 + 13 ) Sp
V s =
a = mass of lactic acid, g (as obtained in acidity)
13 × Sr
Viscosity
Where, Sp = Total solids in dahi powder (%)
An aliquot of the reconstituted samples prepared by
Sr = Total solids in reconstituted dahi after it passes
the same method applied for color determination was
through the sieve (%)
used to measure the viscosity using a “Brookfield”
digital viscometer with the spindle no 27 (produced
Acidity
by Brookfield Engineering Laboratories, Inc.,
Acidity is defined as percentage of acid present
Middleboro, MA 02346 USA).
in sample, determined as per International Dairy
Federation (1991). 10gms of sample was taken in a
Enumeration of Lactobacilli
conical flask. The volume was made to 30 ml with
(International Dairy Federation, 1988) methods
distilled water. 15 ml of the aliquot was taken and
were used for the enumeration of Lactobacilli.
2-3 drops of phenolphthalein indicator was added.
(International Dairy Federation 1988) methods
Aliquot was titrated against 0.1N sodium hydroxide
were used for the enumeration of Lactobacilli.
solution (NaOH) until the color changed to light pink
Lactobacillus MRS Agar media was prepared by
and noted the titer value, or the ml, or NaOH used.
dissolving the specific quantity of media in distilled
Acidity (% as lactiacid)
water followed by filtration and then filled in conical
flasks. The conical flasks were cotton plugged and
Titrate value × 0.9 × volume made up
wrapped with aluminium foil. Sterilization was
Aliquont taken × weight of sample
done by keeping the conical flasks in autoclave at 15
psi for 15 min. then the media was allowed to cool
Total solids
to 42-43 ºC. Then 1 ml serially diluted dahi sample
Total solids in the dahi include the fat and the non-
was poured in Petri plate with the help of sterilized
fat solids. Total solids in the dahi can be determined
pipettes under laminar airflow bench. The agar media
using hot air oven as per International (Dairy
(10-12 ml) was added in the Petri plates and rotated,
Federation 1991). Taken 2 g of Zinc oxide in a tarred
10 times clockwise and 10 times anticlockwise to
aluminium box and kept the box in hot air oven at
ensure proper mixing and then the media was
a temperature of 102 ± 2 ºC for 1 h. Dish was cooled
allowed to solidify. The agar plates were incubated
in the desiccators. 10 g of dahi was taken in the dish
at 37 ºC for 72 h under anaerobic conditions. After
followed by stirring with glass rod to mix zinc oxide.
incubation, typical colonies of bacteria were counted
The dish was heated on water bath at a temperature
with the help of Quebec colony counter. The counts
of 90 ºC for 30 min. with frequent mixing. Then it
were averaged for three replicates and expressed as
was placed in hot air oven at 102 ± 2°C for 4 h. After
cfu/ml.
cooling in desiccators, the weight of the dish was
taken and the total solids were calculated as:
Sensory evaluation
m 2 - m 1
Apart from the quality determination as previously
Total solids (%) =
× 100 + 0.1a
m 1 - m 0
described, the reconstituted samples were subjected
to the sensory test for appearance, color, aroma,
taste and overall liking perceptions. The sensory was
m 0 = mass of dish including zinc oxide, g
854