Characteristics of spray dried dahi powder

which increases bulk density may be due to the

by clump formation and is improved when the

reduction in particle size or decrease in moisture

sinkability is high. The values in Table 2 indicate that

content or increase in feed concentration. The bulk

dispersibility of spry dried dahi powder without

density of dahi powder was in agreement with

addition of maltodextrin contains (96%) and then

those of orange powder produced by (Chegini and

increasing concentration of maltodextrin content in

Ghobadian 2005) ranging from 0.41 to 0.85 g/ml

dahi powder which increases the dispersibility (98%).

.Similar results were observed in increases in bulk

These results are in conformation with the research

density with increase in maltodextrin was observed

of previous workers (Figueroa et al., 2002).wherein

in case of spray dried pineapple (Ananas comosus)

they stated that the addition of hydrocolloids such

juice powder due to the lower moisture content of

has (carrageenan, xanthan gum, gellan) to the spray

the products and decrease in void spaces (Abadio et

dried yoghurt the dispersibility will be increases.

al., 2004).(Goula and Adamopoulos ,2004) found a

correlation between an increase in particle size and

Colour

a decrease in bulk density for spray dried tomato

Regarding the color, it appeared that the lightness,

paste. (Banat et al ., 2002) found bulk density to

redness and yellowness of the solutions of spry

increase with increased feed concentration due to the

dried dahi powder were significantly different

formation of heavy, solid spheres with high density .

from the fresh dahi for almost all cases. In general,

Table 1. Moisture content, solubility index, Hygroscopicity and Bulk Density of the spray dried dahi powder

Outlet air temperature

MD content

Moisture

Solubility index

Bulk Density

Hygroscopicity (g/100g)

( o C)/blower speed (rpm)

(%)

content (%)

(%)

(g/cm 3 )

0

8.2 ± .1

22.0 ± .1

33.9 ±.3

0.444 ±.2

5

5.0 ± .2

29.7 ±.3

21.0 ±.5

0.571 ±.4

70 o C /2200

7.5

4.2 ± .1

33.4 ± .3

19.5 ±.4

0.625 ±.3

10

3.8 ± .3

38.5 ±.1

18.8 ±.3

0.666 ±.5

12.5

3.2 ±. 3

47.2 ±. 3

17.9 ±.1

0.714 ±.3

Note: rpm = rotation per minute. MD= maltdextrin

Moisture content, solubility index, bulk density and Hygroscopicity values are mean ± standard deviation.

Dispersibility

the solutions had the more lightness than the fresh

As metioned earlier the spray dried dahi powders

sample but the redness and yellowness were lower.

were reconstituted with distilled water with

The cause of the more lightness was due to the

proportion 37 g of powder per 100 g of distilled water

effect of the maltodextrin. Because of white color

in order to make the solutions that were similar to

of maltodextrin a greater lightness of powders,

the fresh dahi. The results of dispersibility, color

represented by a higher L* value, was obtained at

and pH determination for the solutions comparing

higher concentrations of maltodextrin. The powder

to the fresh dahi are illustrated in Table 2. The term

without addition of maltodextrin was more redness

dispersibility refers to the dispersion of agglomerates

and yellowness due to non-enzymatic browning

with little stirring. “Dispersibility” describes the ease

reactions occurring during the spray drying. But this

with which the powder may be distributed as single

effect can be reduced by addition of maltodextrin.

particles over the surface and throughout the bulk

Similar results were also found in spray dried sweet

of the reconstituting water. Dispersibility is reduced

potato powders (Grabowski et al., 2006) and in

pineapple juice powders (Abadio et al., 2004).

857