Journal of Food Processing & Technology

Abstract

Concentration of Apple Juice Using Spinning Disc Reactor Technology

Mahmood Akhtar, Philip Chan, Novi Safriani, Brent Murray and Graham Clayton

The use of spinning disc reactor (SDR) technology for the concentration of apple juice was investigated. The apple juice was passed over the SDR disc spinning at 2000rpm, heated at 90-120°C, and at a flow rate of 7mL s -1 . Experimental results showed that the SDR has no significant detrimental effects on the physicochemical properties and quality of the apple juice after the concentration process, despite using high processing temperatures (90- 120°C). Due to the short residence time of the SDR, the thermally-induced colour change of the concentrates has been minimized. All apple juice concentrate samples exhibited narrow particle size distributions with the average particle size in the range 0.1 to 12μm. The SDR-made reconstituted apple juices are comparable to both the original pure-pressed apple juice sample and the commercial reconstituted product. Volatile components (ester, aldehyde and alcohol) collected during the concentration process were analyzed with GC-MS, and the analysis suggests the formation of new aroma compounds (ethyl acetate, n-butyl alcohol and 2-hexenal) which can be added back to the reconstituted apple juice to enhance its sensory quality.