# AN ANALYSIS OF THE JAVA RATIO - · PDF file39 AN ANALYSIS OF THE JAVA RATIO by J. Antonowitz...

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AN ANALYSIS OF THE JAVA RATIOby J. Antonowitz

The Java Ratio is a factor obtained by dividingan average sucrose per cent cane value by an averagesucrose per cent first expressed juice value andmultiplying the result by 100, i.e.

Sucrose per cent Cane X 100Sucrose per cent First Expressed Juice 1

On the basis of this definition, it is assumed thatif a Java Ratio calculated from data extracted fromthe calculated analysis of a specific quantity ofcane-the tons of cane crushed during one week-beapplied to the sucrose per cent First Expressed Juicedetermination from each and every individual consignment of cane crushed during that week, it willgive an equitable estimate of the sucrose per centcane of any individual 'consignment sampled duringthat week.

If during any given weekly period, individualJava Ratio's were determined specifically for eachconsignment of cane crushed, the average or meanof this collection of Java Ratio's would coincidewith the calculated value for that week. If we ignoredthe weekly Java Ratio determination and calculated the weekly value as the mean of a very largenumber of determinations (done during that week)we should be correct in assuming that as the meanwas calculated from a very large sample (a greatnumber of determinations) the accuracy of the meandetermination was beyond doubt. This would beperfectly true only if the Java Ratio was such astatistic that, if a number of such statistics can beobtained and compared, the discrepancies amongthem will grow less and less as the samples fromwhich they are drawn are made larger and larger;that is, as the samples are made larger and largerwithout limit, the statistic will tend to be a fixedvalue characteristic of the population sampled, andis therefore expressible in terms of the parametersof the population.

It is just here that the concept that the Java Ratiois a suitable factor to use for calculating the sucroseper cent cane from the sucrose per cent First Expressed Juice breaks down. The Java Ratio calculated for the week's crush is virtually the summationof a large number of actual and widely divergentvalues influenced by many factors and can in noway whatever be considered to be a fixed valuecharacteristic of the population sampled. To repeat,the mean Java Ratio for a week's crush can onlybe equated to the one parametric function, i.e.,to that particular week's crush, and not to anyparticular cane consignment which was crushedduring that week.

Compare the expression-

Sucrose per cent Cane = Java RatioSucrose per cent 1st Exp. Juice 100

with the mathematical function-

Circumference of circleDiam. of Circle =17

both appear to be identical in form. Given 17 it ispossible to calculate the diameter or the circumference of any circle if either dimension is given.

When calculating the relationship of the diameterto the circumference for an infinite number of circles,the greater the number of calculations made, thecloser to the real value 17 is the calculated ratio. Incontrast, when calculating the Java' Ratio for afixed crushing period (or a fixed quantity of cane),even if an infinite number of Java Ratio determinations could be made over that period, their meanvalue could only approach the particular value forthat particular cane crushing period or quantity.That is, the Java Ratio is a value specific to a givenset of circumstances and not a general abstractedvalue and thus cannot be considered to be a consistent statistic.

A wide deviation from the mean value in anyparticular determination in a series of determinationswould not necessarily imply an error in determination but would merely emphasise that the JavaRatio is a continuously variable function operatingbetween limits which are determined quite arbitrarially by chance circumstances.

These chance circumstances are, bad topping ofcane, high or low fibre content, complete or incomplete trashing, state of cleanliness of the cane or themilling train, vagaries in the milling performance,rain, state of maturity of the cane, inadvertantdilution or decomposition of the juice sample, etc.

Any method of analysis for the evaluation of canethus based on an arbitrarially variable function canonly be justified in the absence of a more rationalmethod for the sucrose per cent cane determination.

The actual sucrose content of a cane consignmentis a value characteristic of the consignment of caneas such and of nothing else. The ratio sucrose percent cane is of course influenced by the cleanlinessor otherwise of the cane, and the state of maturityof the cane. The ratio-

Wt. of Sucrose in Cane X 100Wt. of Cane

must therefore give the proper evaluation of a consignment of cane because any extraneous matter isweighed as cane, consequently to be certain thathe receives the maximum possible sucrose per centcane values for his product, the supplier must ensurethat all extraneous matter which contains no sucrosebe removed from his cane. If the supplier actuallywas credited with a true direct analysis of the sucrosecontent of his cane, he would see the real significancewhich cleanliness plays in getting high returns, andnot take advantage of the fact that an analysisbased on a common Java Ratio places a premiumon dirty and high fibre cane at the expense of thesupplier of clean low fibre cane.In contrast the ratio

Sucrose per cent Cane X 100Suc. per cent 1st Exp. Juice 1

varies in the total sucrose content of the cane asdetermined by the Miller, and the factors whichinfluence the sucrose content of the First ExpressedJuice. (Degree of crushing and/or cleanliness ordilution of First Expressed Juice.)

This means that the above ratio is a combinationof the characteristics of the particular consignmentof. cane being crushed at that time and the processof crushing to which it is being subjected and willthus vary accordingly.

The degree of the variation of the Java Ratioin relation to the richness of the 1st Expressed Juicecan be gathered from a glance at Table 3 of theS.A.S.T.A. publication prepared by W. O. Christianson in 1952 entitled "Cane Testing with particularreference to the use of the Java Ratio in Natal."This table shows the effect of double crushing onthe richness of the expressed juice, and reference ismade to a "Report of Cane Testing Investigationcarried out at Gledhow in 1935 (page 13)." TheReport shows Java Ratio figures for the total juiceexpressed, not First Expressed Juice (which isobligatory for cane evaluation). These Ratioscalculated on Total Juice expressed are much higherthan the First Expressed Juice Ratios. Here isvery conclusive evidence that the Java Ratio is nota characteristic of the cane as is the true Sucroseper cent cane ratio, but a combined characteristicof the cane and the crushing process to which it hasbeen subjected. Because the milling process assuch can have no significance whatever to the supplier of cane, no legitimate reason can be sustainedfor tying the evaluation of any consignment of caneto the milling process.

A statistical examination of the accuracy of theapplication of an average Java Ratio to a whole

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series of tests is made in the above-mentioned paperon Table I. In the discussion which follows it waspointed out that no test was more than 1.6 per centsucrose in cane out. This appears to be a relativelysmall error but is it in fact so small? Basing thecalculation on the assumption that the sucrosecontent of the cane is 14 per cent, an error of ±1.6per cent in Sucrose per cent Cane determinationwould indicate an over or an underestimate of11.42 per cent. That is, the supplier of 100tons of sucrose on this basis would be creditedwith either 111.42 tons of sucrose or 88.58 tons ofsucrose, depending upon his good fortune or otherwise. Basing the calculation on the number of testsnot more than 1.0 per cent sucrose in cane out, itwould be evident that 5 out of every 100 suppliersof sucrose would be allocated either 107.14or 92.86tons of sucrose for every 100 tons of sucrose sent in.

The only factor in favour of the Java Ratio as ameans of cane evaluation is its convenience, i.e. itenables relatively unskilled persons to be employedin the analysis of the juices, while the direct determination of sucrose per cent cane requires skilledpersonnel which at present are unobtainable. Thescarcity of skilled personnel can readily be explainedby an almost complete lack of demand for theirservices. This demand, of course, cannot exist unlessthere is an awareness or an appreciation of the factthat skilled personnel are an undoubted asset.

The use of unskilled personnel for such an important function as an analysis of cane for evaluationpurposes is not justified.

Dr. Van der Pol (in the Chair) said that the JavaRatio method for testing cane had been discussedoften before. As pointed out by the author of thepaper it was subject to grave errors. Recently theSugar Milling Research Institute had experimentedon the direct testing of cane with a view to avoidingthe errors inherent in the Java Ratio method.

Mr. Rault: The paper was on a topical subject,much discussed at the present time. The Java Ratiowas a comparatively simple method which had serveda useful purpose, but had its limitations when dealingwith new conditions created by the nature of thecane supplied which was a mixture of genuine stalksand extraneous fibrous matter.

The Java Ratio method could only be supersededby a practical method ensuring the collection of atruly representative sample of the mixture of stalksand foreign matter for testing purposes, providedthis testing did not entail a large increase in labour,staff, equipment and .time. Perhaps the delegatesfrom Mauritius and Reunion could inform us on theirexperience in collecting a representative sample.

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Mr. Antonowitz said that the amount of crushingto which the cane was subjected affected the JavaRatio and this was also changed by the mud on thecane after floods.' "

Mr. Christianson stated that the errors due to theJava Ratio method had been fully realised for verymany years. Some thirty years ago experiments hadbeen started on the determination of fibre in caneconsignments, but in spite of all past experimentationa suitable method for this test had not yet beenfound, and this determination remained the crux ofthe whole matter. If one could successfully test caneconsignments for fibre content the inaccuracies inour present Java Ratio method would disappear. Upuntil now, however. the Java Ratio method was thebest we had for the determination of sucrose in caneconsignments. Paying for cane on a purely weightbasis or on an average sucrose per cent cane figurewould lead to still greater anomalies.

He questioned the author's statement that crushing conditions affected the Java Ratio. Repeatedcarefully controlled experiments had shewn thatvarying the pressure exerted t>y. the crusher had noeffect whatsoever on the polarisation of the firstexpressed juice.

The (:hairman pointed out that the Sugar MillingResearch Institute were now trying out the effect ofincreasing pressures on polarisation of the expressedjuice.

Dr. Rossouw said that the question of Java Ratiowas a thing that affected his officequite considerably.Planters complained when cane. was sent from onemill to another. Tests were different and they cornplained that there must be something wrong withthe testing. Much work done on the subject had notbeen published. .

Mr. Antonowitz said that it was important thatwork which had been done by various committeeson this subject should be more widely published.

Mr. Scott said that from an engineer's point of viewif everybody would clean their cane we would notget any more arguments about the Java Ratio. With

any other food products, the product was graded,but not so with sugarcane. .

Mr.Pc:mgnet said that he was concerned as afarmer with the possibility that tests were notcarried out accurately in certain mills.

Dr. Van der Pol said that the sampling error wouldenter into any method of testing cane.

Mr. Hugot said that it was obvious that fibre hasa big effect on the Java Ratio. The difficulty was tomake a determination of the fibre. However, howdifficult, it would be better to try and get a determination of fibre. In Reunion he had growers whosupplied two varieties of very different fibre, onehigh, one low, so an attempt was made to make thedetermination of fibre although it was not quitesatisfactory. In Reunion factory efficiency was takeninto account as well as the effect of crushing. Hefound that when three tons was passed through themill when the normal quantity was ten' tons thelower amount seemed to yield a higher quality juice.than in the case of the ten tons. The cane wasvalued at the extractable sucrose and the factoryefficiency affected this greatly. This was by agreement between the factory and the growers. He saidthat although they were not satisfied with the determination of fibre they still felt that it was better totake it into account. He said that a minimum ofabout forty tests were made on each planter's canefor fibre but normally the number of tests made wasbetween fifty and eighty.

Mr. Antonowitz said that the factory at which hewas the cane was valuated withthe aid of the S.].M.formula to assess the available sugar. Due to thelarge amount of mud on the cane from the flats thegrowers got such a low purity of crusher juice theywere allocated much less sugar than they wereentitled to. This defect was mitigated somewhat bythe use of refractrornetric purities when necessary.

The Chairman said that we were all agreed thatJava Ratio was not the best method but as yet inSouth Africa we had not been able to improve on it.He hoped that in the near future they would findsomething more suitable for Natal.