Kothakota et al.

Results and Discussion

storage of dried powders. Basically the sticky

behaviour of powder depends on the sugar content

Quality determination

and temperature of the product. The fast removal

In the initial trial dahi as such is directly fed in the

of moisture during spray drying results in either

spray drier and it was observed that some powder

a completely amorphous product or with some

tends to stick inside the main chamber and the

microcrystalline regions dispersed in the amorphous

powder collected in the cyclone shows some

mass. The amorphous form is a non-equilibrium

browning reaction. As the outlet air temperature

meta-stable state. Amorphous products also show

was major parameter affecting number of survivors

high degree of hygroscopicity. The values in Table

in spray drying of plain yoghurt (Kim and Bhowmik,

1 indicate that hygroscopicity of spry dried dahi

1990) the parameters such as feed rate and inlet

powder decreasing by increasing the concentration

temperature are maintained so that the outlet

of maltodextrin up to 17.95(g/100g).Similar results

temperature remains constant i.e.70 o C. On the

of decrease in hygroscopicity of fruit powder with

basis of literature Maltodextrin was incorporated

increase in maltodextrin concentration were also

in various levels as bulking agent to facilitate the

found in acai (Euterpe oleraceae) powder produced

spray drying and to improve the functional and

by spray drying (Tonon, et al., 2008). The drying aids

physicochemical characteristics of spray dried dahi

decreased the powder hygroscopicity, especially

powder.

cashew tree gum (CTG), which also enhanced the

powder flow ability (Germano, et al., 2009).

Moisture content

Solubility index

Regarding the moisture contents of dahi powders,

all specimens had moisture contents below 4% wb.

Solubility of powders can be affected by many

They are close to the moisture contents of dried tea

parameters such as initial compositions of the

powders with the range of 3-5% (Sinija et al. , 2007).

raw material to be spray-dried, the carrier agents,

The results showed that the moisture content of

compressed air flow rates, and low feed rates

spray dried dahi powder by increasing concentration

(Bhandari et al., 1993; Al-Asheh et al., 2003; Goula

of maltodextrin .Similar results were observed in

et al., 2004). The results showed that the solubility

spray dried pineapple juice in which increase in the

index of spray dried dahi powder without addition

maltodextrin concentration resulted in decreases of

of maltodextrin contains 22% and then increasing

the moisture content dried product. This decrease

concentrationofmaltodextrincontentindahipowder

might be attributed to an increase in solids in the feed

which increases the solubility index up to 48%. It

and reduced amount of free water for evaporation

means that the tamarind powder could be dissolved

(Abadio, et al ., 2004).

in water at room temperature without difficulty.

Similar results were observed in spray dried ginger

Hygroscopicity

juice powder in which increase in solubility index

with increase in maltodextrin concentration due to

Hygroscopicity isthe ability of foodpowderto absorb

drying aids of Maltodextrin (Phoungchangdang and

moisture from high relative humidity environment.

Sertwasana, 2010).

In case of fruit powder, glucose and fructose are

responsible for strong interaction with the water

Bulk density

molecule due to polar terminals present in this

molecules (Haugaard, et al., 1978; Slade and Levine,

The bulk density is an important characteristic

1991). It is very important to study this property

for the packaging design and the calculation of

in case of powders as stickiness is a phenomenon

transportation volume.. The results showed that

frequently encountered during production and

the increasing concentration of maltdextrin content

856