ASSESSING THE PROCESSABILITY OF SUGARCANE VARIETIES
The Sugar Milling Research Institute (SMRI) is developing methods to characterise the processability of sugarcane, particularly pre-release varieties from the South African Sugarcane Research Institute’s (SASRI) breeding programme. The pith/fibre ratio and colour are presently used to characterise the processability of sugarcane; however, further parameters are required to obtain a better understanding of how a particular variety would behave during processing, particularly in the front end of the factory. A number of methods have been investigated; these include the use of a stereomicroscope to identify pith and fibre, an impact test method and a percolation test method. Each method is described and test results obtained on selected varieties are given. The suitability and feasibility of each of the different methods is discussed.
Cane characterisation: the percolation test.
The considerations for selection and release of a c ommercial variety of sugarcane have primarily been limited to agronomic factors. Certai n varieties which have been released have gained the reputation of being problematic in the factory. Since most of the evidence is anecdotal, little progress has been made in deve loping methods to screen for varieties which might cause processing difficulties. Recently , efforts have been made to identify parameters that could be measured to express the pe rformance of a particular variety in a factory. The main weakness to date has been that th e methods are indirect and focus on a small sample of cane stalk. These tests have includ ed microscopic examinations, pithfibre ratios and impact strength tests. Percolation was chosen as a possible test method th at could address this problem. Thishas the advantageof resembling the process to which the cane would be subjected and allows the simultaneous analysis of representative parts o f the single cane stalk and of multiple stalks. It was anticipated that this approach would reduce the in-sample variation that had been observed with other techniques. The disadvanta ge is that percolation velocities under factory conditions and those observed in the percolation test apparatusare not directly comparable. This paper explores the use of percolation rate in a small column as an indicator of the percolation characteristics of selected varieties i n a diffuser. The results were compared with perceived percolation rates of the varieties i n a factory. The variability of results from essentially similar samples was also investiga ted.
Debrisoquine, guanethidine, propranolol and human sleep
Debrisoquine in dosage of 20–60 mg continued for up to 10 days caused suppression of human paradoxical sleep and withdrawal rebound, and also increased intra-sleep restlessness. An overdose of debrisoquine 200 mg caused suppression of paradoxical sleep and a rebound of over 2 weeks duration.Guanethidine 20–40 mg for 21 days did not affect paradoxical sleep but increased intra-sleep restlessness and reduced stages 3 + 4 sleep.Propranolol 120 mg had no discernable effect on sleep and did not prevent actions of dexamphetamine sulphate 10 mg nor of imipramine 75 mg. The findings relate to theories of cerebral noradrenaline in the control of sleep mechanisms.