Sweet sorghum was kindly provided by the Kyusyu Okinawa Agricultural Research Center. The stems were squeezed after the leaves and husks were stripped, and the fresh juice was stored at −20 ◦C. The pH of the juice was 5.18 ± 0.15, and the juice consisted of the following sugar content: glucose, 55.7 ± 2.8 g/L; fructose, 40.1 ± 5.5 g/L; and sucrose, 19.9 ± 3.6 g/L.