Hardening of raw sugar
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The hardening or "caking" of raw sugar exported to countries with colder climates such as the Soviet Union presents a problem in the marketing of Australian raw sugar. Moisture migration, as a result of temperature differentials in raw sugar exposed to sub zero temperatures, has been recognised as the driving mechanism of this caking phenomena. Factories in the Soviet Union do not exclusively process Australian raw sugars and it is claimed that sugars received from their major supplier, Cuba, do not present them with the same handling difficulties. This investigation aimed to elucidate the fundamental mechanisms of raw sugar hardening, in the hope that appropriate measures can be taken to ensure acceptable handling characteristics of Australian raw sugars. Results indicate that the solution to this problem lies in using sugar manufactured to certain specifications, in some ways mirroring the qualitative characteristics of Cuban sugar. The main areas most likely to provide some basis for improvement appear to be ; (i) a higher RS/Ash ratio, greater than 1. Currently Australian raw sugar RS/Ash ratios range 0.6-0.8 units; (ii) higher DI than currently used, greater than 40 units. Australian sugar currently averaging mid 30's to low 40's; (iii) larger crystal mean aperture around 1.0 mm, currently 0.6-0.8mm; (iv) reduced variation of crystal size i.e. lower coefficient of variation; (v) pol in 98.0-98.8 range, especially avoiding higher pol sugars. Results also allow us to identify sugars possibly already manufactured to these specifications, or will allow us to ensure suitable sugars for export are produced.