Powderization is a promising way to enhance the usability of fruits. Persimmon is one of the most popular fruits in Korea, but its usability is quite limited due to its high moisture content and seasonal availability. The objective of this study is to powderize a persimmon extract by spray drying and to examine the effects of resistant maltodextrin (RMD) and its mixtures with gum arabic (GA) as biopolymeric drying aids on the yield, moisture content, and water activity of resulting persimmon powder. Maltodextrin (MD) and its mixtures with GA were also used for comparison purpose. The feed solutions for spray drying were prepared by adding RMD, MD, GA or their mixtures (RMD:GA=9:1, 8:2, 7:3, 6:4, and 5:5; MD:GA=5:5 and 1.7:8.3) to persimmon extract at a concentration of 30% (w/w) (40% (w/w) total solid). The inlet temperature, air flow rate, atomizing pressure, and feeding rate for spray drying were set as 140 °C, 0.40 m3/min, 100 kPa, and 270 mL/h, respectively. Among the three biopolymers, the highest drying yield (51%) was obtained when RMD was added, followed by GA-added (34%) and MD-added (21%) powders. However, the RMD-added powder was sticky and caused bag filter blockage. Among the biopolymer mixtures, the highest yield (56%) was obtained when the RMD–GA mixture (7:3) was added, and no serious powder stickiness was visually observed. The powder prepared with RMD or MD only yielded very low values of moisture content (1.5-2.0%) and water activity (0.09-0.10), and the values increased when GA was added together. This study demonstrated that the RMD–GA mixture is an effective drying aid for the spray drying of persimmon extract, which is highly sticky and not able to be spray-dried alone.

ABSTRACT
INTRODUCTION
MATERIALS & METHODS
RESULTS & DISCUSSION
CONCLUSIONS
REFEREMCES

• Minjeong Lee(Food Technology Major, Graduate School of International Agricultural Technology, Seoul National University)
• Donghwa Chung(Food Technology Major, Graduate School of International Agricultural Technology, Seoul National University/Institutes of Green Bio Science and Technology, Seoul National University)