The values of pH, aw and WSI of the Gac powers in this study were not significantly affected by inlet air drying temperature and maltodextrin concentration (p>0.05).For pH value,this finding is in agreement with the results of
Who found that pH of the Roselle extract powders does not change with different air drying temperatures. Moreover,aw is one of the most important factors that significantly influence the shelf life of the most important factors that significantly influence the shelf life of powder products.High water activity in products leads to shorter shelf life due to high free water for biochemical degradation. The deterioration of dried powder caused by microorganisms and biochemical reactions can be prevented at aw lower than 0.6
The average aw of powders in this study ranged from 0.38 to 0.54
and can thus be considered to be quite microbiologically stable. Additionally,from the results show in.**, the aw of powders decreased with increasing maltodextrin concentration.The results for aw of the powders were consistent with the findings of the study carried out by**They stated that the water activity of spray-dried water melon powders was not significantly changed by inlet temperatures of between 145°C and 175°C.Further, higher concentration of maltodextrin resulted in decrease in the aw of the powdets