THE EFFECT OF VARIOUS PACKING MATERIALS ON THE KEEPING QUALITY OF STORED PLANTATION WHITE SUGARS

Transcription

1 Processing THE EFFECT OF VAROUS PACKNG MATERALS ON THE KEEPNG QUALTY OF STORED PLANTATON WHTE SUGARS S.G. Gandana ndonesian Sugar Research nstitute, Pasuruan ABSTRACT To investigate whether bags ade of polypropylene or rosella interwoven with polypropylyne bags could be used as alternatives to the rosella bags currently in use', experients have been conducted in warehouses of sugar factories. Sulphitation and carbonatation sugars were packed in rosella, polypropylene and rosellalpolypropylene bags, with and without plastic inner bags stored for a period of tie and analysed periodically. The results indicated that the sugars in the bags with plastic inner bags did not becoe wet after up to nine onths of storage. There was no significant difference aong the three kinds of bag furnished with plastic liners. NTRODUCTON Plantation white sugars are subject to changes resulting fro reactions between the syrup on the sugar and the air, ore particularly the water vapour in the latter; there ay also be changes within the syrup fil, which ay be of purely cheical origin or ay result fro icrobiological processes3. The changes in stored sugar related to oisture in the atosphere are deterined by the relative huidity of the air surrounding the sugar, and by the coposition of the syrup in the sugar. f the vapour pressure in the air, is higher than the static vapour pressure of the syrup the latter will absorb oisture, while in a reverse situation the syrup fil will dry up (Raaiah5). The changes in the syrup fil in a stored sugar are of a very coplex nature; on one side they are purely cheical, on the other hand they are icrobiological reactions. First aong the cheical conversions is the inversion of the sucrose dissolved in the syrup, which results in a lowering of purity; the percentage of invert sugar increases and consequently causes solid sugar to dissolve in the syrup which has becoe unsaturated by this process; in turn this sugar ay becoe inverted. n ndonesia sugar is packed in rosella bags of 100 kg capacity and stacked in warehouses at the sugar factories. To eet the increasing deand for bags, the use of other aterials such as polypropylene and rosella/polypropylene ixture had to be considered (Mochtar4). Keywords: Plantation white sugar, keeping quality, packing aterial

2 1 SMONGAN GBAR GANDANA 743 Experients have been conducted in the warehouses of both sulphitation and carbonatation factories to observe the effect of various packing aterials on the keeping quality of plantation white sugar under storage. MATERALS AND METHODS Saples of sugar fro sulphitation and carbonatation factories were packed in rosella, polypropylene and rosella/polypropylene bags, with and without plastic liners, and stored in the respective sugar factories. Ten bags of each type were used so that, at intervals of 15 to 30 days, saples could be taken one fro each type of bag, without opening the other bags. The capacity of each bag was 15 kg so that by thorough ixing a hoogenous and representative saple could be taken.! The sugar saples were analysed at the nstitute for oisture, colour in solution, ; colour in solid state (so called reission value), reducing sugar content and polari- etric sugar content (% pol). Moisture - Moisture was deterined by oven drying at 105 OC for 3 hours. Colour - Colour in solution was deterined by CUMSA ethod No. 4 (Carpenter2). Colour in solid state - The colour in solid state is also known as "reission value". t was deterined by the ethod of Anantal based on easureents of reflectance at 440 n and 560 n. Reducing sugars - Reducing sugars were deterined by Ofner's ethod. Polarisation - The pol of sugar was deterined on a noral solution tested directly in a 200 tube in a standard optical polariscope at roo teperature. Readings were subsequently corrected to 20 OC. RESULTS AND DSCUSSONS The analytical results for the sugar saples in the various bags are given in Tables, 1 and 111. Moisture - The oisture contents of the saples in the bags without liners did not show any appreciable increase until after four onths when the liit of the water content (0.10%) was reached. After six onths the sugar in the bags without liners was quite clay. The sugar in the bags with plastic inner bags had not becoe "wet" by the end of the tests. t was obvious that the plastic inner bags had excellent waterproofing properties and a positive effect on the keeping quality of the sugar. However during the packing the sugar should have a low teperature, preferably below 38 "C, and a low oisture content, below 0.05%, otherwise caking (ceentation) of the sugar will take place, particularly at relative huidities above 65%. To keep the huidity low the warehouses should be provided with dehuidifiers. Colour in solution - The increases of colour in solution of saples in all six kinds of bag were alost the sae; there was no difference yhich could be related to a particular kind of packing aterial. Reission value - The reission values (the colour in solid state) of the sugars in the bags without liners decreased alost twice as uch as those of the sugars

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5 TABLE ll. Analytical data for plantation white sugar stored in rosellalpolypropylene bags Packing aterial nner bag Rosella interwoven with Polypropylene Dateof analysis X '84 '84 X '84 '85 '85r'85 '85 ' V '85 '85 V '85 No Water content % 0,04 0,08 0,06 0,06 0,08 0,08 0,lO 0,14 0,32 0,40 0,45 Colour (CUMSA units) Colour(Reission 62,3 61,8 62,2 60,5 60,6 58,4 57,2 57,5 56,6 56,O 56,5 Value) Reducingsugars 0,060 0,116 0,098 0,122 0,168 0,196 0,202 0,248 0,590 0,622 0,680 Pol (20 C) 99,88 99,62 99,59 99,51 99,62 99,73 99,8 99,78 99,23 98,64 98,48 Packing aterial nner bag Rosella interwoven with Polypropylene Plastic Date of analysis X '84 X1 '84 X1 '84 1 '85 '8511'85 '85 '85 V '85 '85 '85 Water content % 0,04 0,05 0,04 0,06 0,04 0,06 0,05 0,06 0,05 0,08 0,lO Colour (CUMSA units) Colour(Reission 62,3 61,8 62,2 61,6 60,5 58,8 58,8 59,O 59,6 59,8 58,5 Value) Reducingsugars 0,060 0,062 0,062 0,068 0,074 0,082 0,080 0,090 0,088 0,088 0,090 Pol (20%) 99,88 99,82 99,70 99,66 99,60 99,64 99,56 99,50 99,52 99,48 99,40

6 SMONGAN GBAR GANDANA Reducing sugars - The reducing sugars of the saples in the bags without liners showed faster and higher increases than those in the bags with liners. n the forer bags the reducing sugars increased by 0.6% within six onths while in the latter the increase after six onths was only 0.02%. t was obvious that the plastic inner bag offered positive resistance to the absorption of oisture fro the surroundings. Polarisation - The decreases in pol contents were not very high in any case but the decrease of pol was slightly greater in the bags without liners for unlined bags against 0.45 for those with liners. CONCLUSONS The results of the trials of storing plantation white sugars in warehouses of the sugar factories aking use of various packing aterials showed that there is no difference in the keeping quality of plantation white sugars in rosella, polypropylene or rosella/polypropylene bags. However, the keeping is uch better when the bags are furnished with plastic inner linings. n order to prevent caking or ceenting of the sugar in the bags with plastic liners, the water content of the sugar at packing should be lower than 0.05% and the teperature should be lower than 38 "C. The sugars in the bags with plastic liners did not becoe wet after up to nine onths of storage whereas the sugars in the bags without inner bags becae wet after less than six onths. The trials were done in warehouses where the relative huidity ranged between 60% and 75%. To avoid the absorption of oisture fro the surroundings the relative huidity should be kept as low as possible (below 65%). The installation of dehuidifiers in the sugar warehouses should be considered. REFERENCES 1. Ananta, Tibul(1974). Die Bestiung van Helligheit, Farbsattigung and Reissionswert durch essung der reflexion on Zwei Punkten. Zucker. 27: Carpenter, F.G. (1978). Colour and turbidity Appendix 1, Method 4 (official) for the deterination of colour of sugar in solution. Proc XV Session CUMSA Lic Mayra Lopez Blanco, Mt Flora C. Castillo Perez, Eduardo L. Raos Suarez (1983). Deterination of white sugar in storage. Cuba Azucar Mochtar, M., Gandana, S.G. and Ananta, T. (1983). Preiu and penalty on plantation white sugar quality in ndonesia. Proc. Techn. Meeting BP3G Raaiah, N.A. and Neade, B.. (1968). Studies on the colour proble of white sugars. Proc. X11 Congr. SSCT,