ALFRED W. TURNER and BASILIO A. ROJAS Instituto Tecnol6gico Azucarero Veracruzano, Cosamaloapan, Veracruz, Mexico

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1 DETERORATON OF SUGAR CANE AFTER CUTTNG ALFRED W. TURNER and BASLO A. ROJAS nstituto Tecnol6gico Azucarero Veracruzano, Cosamaloapan, Veracruz, Mexico (Presented by Dr. B. A. Rojas) NTRODUCTON The losses sustained by sugar cane, cut and left in the field a number of days before grinding, are important and particularly so to San Cristobalsugar mill because of the large area of its cane fields (44,000 ha) also because of the method of cane payment established by government decree. This ordains the use of the final average factory yield and the price of sugar set by the government as the bases for calculating the price to be paid the cane growerper ton of cane delivered. ' Under this' system, our 3,500 individual cane farmers, are inclined to aim for a large figure of tons cane delivered, and scant attention to cane quality. n order to improve the quality of cane delivered, discounts are made by mutual approval for below standard cane. The investigations reported here were made to define the range of the discounts. REVEW OF THE LTERATURE A paper by TURNER 1 on the deterioration of unburnt harvested cane with time left open the question whether it is the age of the cane or the temperature which has the most effect. n Australia, WADDELL2 carried out many experiments on loss of monetary value of sugar cane due to deterioration after cutting, not only with unburnt "cane, but also with burnt cane, cut, andleftstanding: Among his reported results we find the rather surprising fact that, under the conditions of his experiments, cane cut unburnt and scattered on a bare field,decreased in value at a faster rate that burnt cane. The aim of our trials, besides that of verifying the greater influence of high,,temperature overage on deterioration of cut canes,wastofind thetrendof the various changes in cut cane with time thatwould permit us to evaluatethe losses and adjust 'the discounts fairly. MATERAL AND METHODS n order to verify whether the temperature,or the age of the canewas the dominating factor in the deterioration of cane cut and left in the field for a few days before grinding, the temperature' as a factor"was eliminated by testmg two lots of canes of different age, at the same time. ' Two commercial ratoon fields planted with CO~213 were' selected; one field, 13 months old and the other 14 arid a half months old. All otherfactors were alike: same number of years in ratoons, same soil series,.same method of cultivation and

2 ALFRED W. TURNER, BASLO A. ROJAS 3 13 fertilization. Sufficient cane was hand-cut from each field to make 16 bundles of 20 whole canes each, tagged, weighed and stored in a bare field on a thin layer of dry trash. The bundles were left forming a windrow, conforming as much as possible to the windrow 'left by a cane cutter. One bundle was ground immediately, from each test, and one bundle on each succeeding 24 hours, after reweighing. The samples were ground in a 3 roll 14" X 9" laboratory mill giving extractions between 65 and 72%. n the laboratory the brix reading was taken by hydrometers standardized at 20 C, and for polarimeter reading Horne's dry-lead method for sucrose analysis was used. The volumetric method of Eynon and Lane was used to determine the percent invert sugars, hence the glucose ratio: ited % reducing sugar X roo % sucrose in juice. n reporting our ordinary juice analyses fr~m grindings in our laboratory mill, we use an empirical formula for yield which we label 'probable rendement', which is in close concurrence with actual factory yield. But when the conditions change drastically fromnormal,our probable rendement figure is unsatisfactory. After careful studies of ten years reports of our factory work the following formula was developed: Factory yield = [(100 - F)/OO] (1.5 S B) F, in which =convertingfactor to change laboratory-mill juice to absolute juice; (100 - F)/OO = change % juice to % cane; 1.5 S B = modified Winter - Carp formula. By the using of this formula, we have taken into consideration the importance of the fibre factor and we find the results approximateclosely to factory yields. When the % extraction of our laboratory mill is reduced for any cause, the converting factor given above must also be reduced. For the second part of the experiment,cane was taken from only one field, variety Pepecuca plant, age 18 months. Aftertaking one17 bundle sample immediately before burning and the second sample in the same locality after burning, the handling, storing and analyzing were as described above for the first part of the trials.. EXPERMENTAL RESULTS n the first pair of experiments with unburnt cane of two distinct ages but under otherwise identical conditions, there was no significantdifference in the various losses directly due to age, and as can. beseen in Fig. all deterioration factors are straight lines. The results of. the second part of the experiment where the same varieties of cane under identical conditions of cultivation and storage were compared for deterioration, burnt and unburnt, are shown in several graphs where the results of the first day ofthe various analyses are given a 100% rating. The rate of increase of the glucose ratio during the 17 days of the experiment's duration, are illustrated in Fig. 2. On the 5th day the glucose ratio for the unburnt cane had increased 155%, over the first daylevel and by using the graph the ratio on any day can be found. Similarly Figs.' 3 and 4 can be used to find glucose % and fibre %cane respectively. The decline of the curve of apparent purities is.shown in Fig. 5. Taking again

3 3 14 AGRCULTURE FBRE GLUCOSE RATO LOSSN WEGHT e X: Days after cutting Fig.. The deterioration of carte after cutting as illustrated by the changes in its chemical composition with time; % 1 (FRST DAY: % ) Fig. 2. live days after cutting, we see that burnt cane retains 85.35% of its original purity, and if the first day was Bz then we have 7.90 purity on the 5th day. Unburnt cane, on the other hand, would retain 9L85% of the originalpurity, and by the sane process its purity on the 5th day would be 75,32~ The consequence of the various.deteriorations on factory yield are shown in Fig. 6. With an original yield of12%, we find that on the 5th day the unburnt cane has and the burnt 9.82 factory yield.

4 ALFRED W.TURNER, BASLO A. ROJAS ~30 (FiRST DAY=100.00"10) ljj ~...J l!l Ofo (FRST DAY=100.00Ofo) ~.150 <3 o!140 ljj 0:: ~ ited Days Fig. 3. The effect of time and pre-harvest burning on the glucose content of cut cane ~ ~ (FRST DAY= "/0) '!! o Days Fig. 5. The effect of time anci pre-harvest burning on the purity of cut cane. Fig. 4. The effect of time and pre-harvest burning on the fibre content of cut cane..,. (FRST DAY=100.00"!o) Q 80...J ljj >= >- 70 0:: 8 U60 t o (!, Days Fig. 6. The effect of time and pre-harvest burning on the factory yield of cut cane. DSCUSSON OF RESULTS t is known that cane varieties respond differently to the various factors influencing deterioration after cutting andtherefore the results presented here can only be held to be true, for the varieties tested. With Co. 213, under our field conditions, at the same temperature, there are no differences in any ofthe component factors of deterioration due to age of the cane cut unburnt..

5 316 AGRCULTURE We want to emphasize that our tests were done simulating actual field practices and conditions, in orderto arrive at the actuallosses in the fields, where theytakeplace. Comparison of the deterioration of unburnt cane from the first part of the experiment with results of the unburnt cane in the second part are not justified.idue to dissimilar factors: variety and temperature. The cooler month of February with variety Co. 213 did not, however, give slower deterioration than variety Pepecuca in the warmer month of April..' Taking into consideration that we have a loss in factory yield of % per day after cutting unburnt cane in the first part of the crop which is! a direct loss for the cane farmer; we have to take into account also the greater difficulties that are presented to.the factory with the increased fibre % cane, also the greater amount of glucose which hamper the sugar making. process. The test carried out in April withpepecuca, burnt and unburnt, plainly show great deterioration of sufficient quantity to warrant the expenditure of a large amount of money to prevent this loss of sugar. CONCLUSON ; Deterioration of unburnt canes, of the variety Co. 213 cut and left under our field conditions from one to S days indicatethat age of cane is not a factor of the deterioration. 2. For each daythatthe caneisleft in the field after cutting it willsufferthe following changes: Fibre percent cane will increase Loss in weight is -'--Percen~ invert sugars increases --Glucose ratio will increase Factory rendement will decrease 3. Plant cane of variety Pepecuca S months old, one set cut before and the other after burning, kept under our field conditions a number of days before grinding, suffered the following changes for each day after cutting: Glucose ratio, increase daily nvert sugar, increase daily Fibre % cane, increase daily Apparent purity, decrease daily Factory rendement, decrease daily Burnt % % % 2 93 % % Unburnt % % 3 71 % 1.63 % % With losses of such magnitude as these studies demonstrate, all endeavours directed to reducing the time lag between cutting and grinding, whether the cane is burnt or unburnt, will result in higher-priced cane for the farmer and better yield for the factories, Factory managers do not hesitate in assigning large sums of money in order to cut down the. sucrose losses in the manufacture of commercial sugars,,but are indifferent to the losses of sugar already made by the cane that do notreach the factory. We demand ofthe geneticists sweeter canes, of agronomy the best.use of -fertilizers, cultivation and irrigation, all for.more sugar production in-the fields, then we lose part of that sugar and continue our demands for better canes.

6 ALFRED W. TURNER, BASLO A. ROJAS SUMMARY The losses in recoverable sugar and the changes in the chemical composition of cane cut and left in the field for several days before grinding as well as the effects of pre-harvest burning have been studied. The financial losses incurred by delayed crushing of the cane are large and the authors concluded that every effort should be made to keep the time between cutting and crushing as short as possible. ' REFERENCES TURNER, A. W., Deterioration of cane quality with time aftercutting at San Cristobal, Veracruz, Mexico. Proc, into Soc. Sug. Cane Tech., 10 : o WADDELL, C. W., Stale cane losses. Proc, Qd Soc. Sug. Cane Tech. : WADDELL, C. W., Stale cane losses. Proc, Qd Soc. Sug. Cane Tech. : APPENDX A SMPLE METHOD FOR. FBRE DETERMNATON Basilio A. Rojas ited The method described departs from those already known in that it is not necessary to wash out sugars from the bagasse. For this reason, the method is quicker than other methods. The procedure is as follows: 1. Take a30 to 50 kg sample ofcane (G). 2. Crush it at least twice with an experimental mill or squeeze out the juice with other devices. 3 Weigh either juice (J) or bagasse (b). ndirectly 'b = C-]. 4. Determine Brixof juiccse B.. 5 Take a well representative subsample of bagasse weighing 0.5 to 1.0 kg (P)' 6. Dry out the subsample of bagasse. The dried bagasse will beof weight P 2 7. Finally, fibre percent cane is: 100 P 2 - PB 100 b F B X PC Demonstration»- By definition -and after drying out Pi we get wherefrom and bu't and so s P = fibre + solids + water, or P =1+ s + a Po =1 + s a 7' 'r - Po = P 2 - s Brix = 100 S = B s+a Ba = Substituting (2) in (4) and the result thus obtained in (3) 100 P 2 - PB 1= B 1 is the content of fibre in the subsample of bagasse. The fibre percent bagasse will be ooflp' The bagasse percent cane is 100 b[c, Therefore the fibre percent cane is the result expressed by formula (). Accuracy The main assumption behind the derivation of formula () is that the juice remaining in bagasse has the same Brix as the juice expressed by the mill. At first sight this assumption cannot hold. However, a difference in both Brixes does not affect appreciably the fibre determination. t can be shown that the accuracy of the method is higher when the percentage of juice extracted from the cane is larger. To show the precision of this method let us consider the following example: the cane sample weighed C = 100 kg. The juice extracted weighed] = 75 kg. So b = 25 kg. The Brix of the juice was B = 20. P = kg and Po = kg. Therefore our estimate of the fibre percent cane will be, using formula (): (2) (3)

7 AGRCULTURE F = 100 X 0.68 ' X 20 X :.?O X ~ = ' Now, suppose that the Brix in the juice left in the bagasse had B less. Then our estimate oif would be 18, that is two points F 100 X 0.68 ' X X25 2 =" ' X 100 t can be seen that the two estimates of fibre are practically the same, and certainly the difference is within the cane sampling error. An adjustment for Brix, according to experience, would reduce the difference. DSCUSSONS H. F., CLEMENTS (Hawaii): The rate of deterioration after burning is determined by the climatic conditions which prevail. n cold weather, deterioration is almost negligible, but in hot weather there is a noticeable deterioration after a day or two. have noticed severe deterioration within 24 hours due to growth of mouldwith cane stacked in the mill yard. A. ]. VLTOS (Trinidad): agree with Dr. Clements about the effect of mould. s there any difference between deterioration of burnt standing cane and burnt cane which is cut and left on the ground? H. EVANS (B. Guiana}: The former deteriorates more quickly.. ]. P. COGNET (S. Africa): The general practice in Natal is to harvestunburntcane but accidental fires are frequent. Burnt cane left standing does not deteriorate rapidly providing weather conditions do not favour, regrowth. ]. L. Du TorT(S. Africa}: n South Africa, we found that () burnt cane left standing deteriorates less than burnt cane cut down, (2) burnt cut cane deteriorates more 'than.unburnt cut cane, (3) there is an apparent.loss of brix with deterioration and a consequentpoor purity.. P. R. TATE (Hawaii): We milled One acre of burnt and unburnt cane, respectively,every second day for a total of 29 days,from a field at 2400 ft elevation during the winter, months. There was no juice deterioration for 19 days and no economical loss until the 29th day, due to additional transportation costs and fuel oil requirements, reduced rate of grind, etc., of unburnt cane.. D. S. HUGHAN (S. Rhodesia): do not agree that deterioration/time relationship gives a straight line. n S. Rhodesia loss in sugar is unimportant on the rst and znd days but is rapid on the 3rd and 4th days. A good means of fibre determination in small samples is required for further work. B. A. ROJAS (Mexico): always found that deterioration vs time gives a straight line relationship. ]. WLSON(S. Africa): s there a varietal effect on the ability of burnt cane to stand over? DR. ROJAS: Yes, would refer to Turner's paperin the Xth Proceedings. J. L. CHALMERS (Australia): n Fiji, burnt cane deteriorates faster whenleft standing than when cut and the rate of deterioration increases rapidly in both cases after the first few days. High temperatures hasten deterioration, and immature canes' deteriorate quicker than mature canes. The effect of delay between burning and crushing differs with different varieties. H. K. STENDER(P; Rico}: agree with Mr. Chalmers statements. DR. CLEMENTS: wish to ask Dr. Evans ifthe different deterioration rate of burnt standing and cut cane is related to high temperatures prevailing in the stacks compared to that the canes encounter when left standing. DR. EVANS:We did not compare canes standing to cut canes instacks but to canes left on the ground by the cutters. The reason for faster deterioration in cane left standing is due to increase in moisture content of the stalks.