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Title: Biodeterioration of harvested sugar cane in Jamaica
Author: Tilbury, R. H.
ISNI:       0000 0001 3533 4332
Awarding Body: University of Aston in Birmingham
Current Institution: Aston University
Date of Award: 1970
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The microbiological, physical and chemical changes which occur in stored, harvested sugarcane were studied in Jamaica and the United Kingdom. The degree of deterioration was proportional to time of storage, and was revealed by a statistically significant reduction in sucrose content. Other symptoms included a fall in pH, and increases in reducing sugars, dextran, viscosity, and microbial count. Cut cane was universally infected with Leuconostoc mesenteroides, which reached a maximum count of 107 to 108 organisms per ml. juice within 3 to 4 days of harvest. Counts of other microorganisms were generally insignificant, except for occasional lactobacilli. A new dextran-forming species was named Lactobacillus confusus. Microorganisms isolated from deteriorated cane were screened for their ability to cause deterioration of a sterile, synthetic cane juice. L. mesenteroides strains were the most deteriogenic, but attempts to reproduce the symptoms of "sour" cane by inoculation of this organism into cut cane were only partially successful. L. mesenteroides was present in the soil and the epiphytic flora of the stalk. The principal vector of infection appeared to be the cutters' machete, especially in wet weather. Cane harvested by a chopper machine deteriorated more rapidly than hand-cut whole-stalks. Economic losses due to deterioration of harvested cane were estimated to be 9.2% of the initial recoverable sugar for the 1969 crop at Frome Estate, Jamaica. Dextran content was a useful indicator of cane biodeterioration. The dextran content of mill juices was correlated with rainfall, and significant correlations were obtained between dextran content and viscosity of mill syrups and the amount of sugar lost in final molasses; it also caused the formation of elongated crystals. Attempts to control sour cane by chemical and physical methods were unsuccessful, and it was concluded that the only solution is to mill cane within 24 hours of harvest. A novel method for removal of dextran from mill juices by enzymic treatment with dextranase was developed and patented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral