MANNITOL AND DEXTRAN AS INDICATORS IN ASSESSING POST HARVEST CANE QUALITY UNDER SUB-TROPICAL CONDITIONS

SUGARCANE HARVESTING IN India takes place during temperature extremes which range from 7 to 40 °C. Sugar losses due to the time lag between harvesting and milling are often high leading to low sugar recovery. These losses are caused by sucrose inversion to acid, ethanol and dextran formation in the harvested cane and milled juice. Studies were directed to assess the magnitude of losses in two different climatic conditions in sub-tropical India in harvested cane and in milled juice with reference to the formation of mannitol and dextran. Mannitol formation in the month of December in harvested cane was low, i.e. 1896 ppm/100 brix and increased fourfold after 240 hours of storage. Late in the milling season i.e. in April, the initial mannitol concentration was 10 520 ppm/100 brix and it increased by 5.7 times to 59 215 ppm/100 brix, 240 hours after harvest. Commercial cane sugar (CCS) in the month of December was 67.4/100 brix, which declined to 48.4/100 brix after 240 hours of harvest whereas, in April, the CCS was 71.27/100 brix and it declined to 34.96/100 brix after 240 hours. The dextran level was up by 2.26 times during April as compared to December. This study was further extended to the mill level where mannitol and dextran content in sugarcane showed a progressive increase from field to mill yard and further increased in primary and mixed juice.