Effect of inlet temperature on physicochemical properties of spray-dried jamun fruit juice powder

• Inlet temperatures have significant effect on physicochemical properties.
• The moisture content of the spray-dried jamun juice powders was not significantly affected by varying inlet temperatures.
• The colour of the spray-dried jamun juice powders was mainly affected by inlet temperatures.
• With increase in inlet temperature, glass transition temperature decreased.

The aim of the present investigation is to study the effect of inlet temperatures on the physicochemical properties of spray-dried jamun juice powder. The inlet temperatures varied from 140 to 160 °C, whereas other parameters like outlet temperature (80 °C), maltodextrin concentration (25%) and feed flow rate (10 mL/min) were kept constant. Moisture content, water activity, bulk density, solubility, hygroscopicity, colour, powder morphology, particle size and glass transition temperatures were analyzed for the powder samples. Higher inlet temperature increased the moisture content of the powder, and led to the formation of larger particles. Powder samples showed water activity values below 0.3, which is good for powder stability. The colour of the jamun juice powder was mainly affected by inlet temperature, leading to the formation of powders that were significantly brighter and less purple as the inlet temperature increased. Glass transition temperature ranged from 55.85 to 71.78 °C. Powders produced at lower inlet temperatures showed smoother particle surfaces, whereas higher inlet temperature showed spherical particles with some shrinkage as analyzed by scanning electron microscope.

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