Distinction between non-centrifugal cane sugar (native kokuto) and commercial kokuto by chemical composition and color evaluation

黒糖の一次製品と二次製品における化学成分および色調を比較検討した。水分およびショ糖の含量は両製品間に差異はなかった。しかし,還元糖,灰分,有機酸の含量および色調には両製品間に差異が認められたことから識別に有効な因子であると考えられた。これらの差異は,両製品の原料および製糖法の違いによるものと類推された。The non-centrifugal cane sugar manufactured by seven industries in Okinawa was named native Kokuto. Kokuto samples purchased on the local market in Okinawa were named commercial Kokuto, containing raw sugar, molasses and corn syrup as its ingredients. This study is to examine the difference in chemical composition between native and commercial Kokuto and to evaluate their color profiles by Hunter's Lab values. Sucrose and moisture contents in native Kokuto were almost similar to those of commercial one. Ash content in native Kokuto (4.3%) showed six times of commercial one (0.7%). Reducing sugar content in native Kokuto (6.3%) was lower than that in commercial one (14.2%). Aconitic acid is an unique organic acid in sugar cane and Kokuto. Contents of the principal organic acids in native Kokuto were aconitic acid (4.2%) followed by malic acid (7.1%) and showed three to four times of commercial one. Color evaluation of Lab values showed more yellowish-red in commercial Kokuto than in native one. The results suggest that color evaluation and contents of ash, organic acids, and reducing sugar are useful indicators to differentiate between native and commercial Kokuto