Risvan Kuswurj

Posts Tagged ‘dextran’

Abstract

Sugarcane is a perishable commodity and must be processed into sugar quickly after it is harvested. Post harvest sucrose losses have been reported from many cane producing countries and linked with low sugar recovery and several problems during sugar processing. Bio deterioration is associated with the inordinate delays between harvest to milling of sugarcane and aggravated by many intrinsic and extrinsic factors causing enormous depreciation in cane tonnage as well as sugar recovery. Besides harvest-to-mill delays, other factors such as ambient temperature, humidity, cane variety, period of storage, activities of invertase, maturity status etc. are responsible for decline in sugar recovery. The activity of invertase and proliferation of acid, ethanol and polysaccharides (dextran) producing microbes play a crucial role in the loss of recoverable sugars in cane and milled juice. In addition to loss in sugar recovery, its adverse affects has been noticed in the sugar manufacturing process and sucrose quality. Efforts have been made to reduce loss in tonnage and sucrose using physico-chemical methods. These include spraying of water, bactericidal solution, use of anti-inversion and anti-bacterial formulations and pre-harvest foliar and soil
application of zinc and mangnous compounds. An integrated mill sanitation program and simultaneous use of dextranase could further improve sugar recovery and minimize problems caused by dextran. The possibility of electrolyzed water (EW) fogging to reduce post harvest deterioration in field and mill yard has also been explored. Some of these methods are useful and present larger options for the industry to minimize afterharvest quality losses in the field and milling tandem.

Keywords : Post-harvest deterioration, acid invertase, dextran,
commercial cane sugar, biocides, field control, dextranase

S. Solomon
Sugartech 2009 : 11 (2) : 109 - 123

Abstract

Dextranase only have a small market and low volume sales compared to many other industrial enzymes. Consequently, research and development efforts to engineer properties of dextranase to specific conditions of industrial processes have not occurred and are not expected soon. This book chapter highlights the difficulties associated with the practical application of dextranases, that are sometimes applied to hydrolyze dextran in sugar manufacture when bacterial deterioration of sugarcane or sugarbeet has occurred. Less than optimum application existed because of confusion about where to add the dextranase in the factory/refinery and which commercial dextranase to use. The wide variation in activity of commercially available dextranase in the U.S., and a standardized titration method to measure activities at the factory are discussed. Optimization by applying “concentrated” dextranase as a working solution to heated juice is described. Promising short-term technologies to further improve industrial dextranase applications are discussed, as well as the long-term outlook.

Gillian Eggleston · Adrian Monge · Belisario Montes · David Stewart

Sugar Tech (2009) 11(2) : 135-141

Tebu (Saccharum officinarum) merupakan tanaman penghasil gula yang telah lama dibudidayakan di Indonesia khususnya Pulau Jawa. Tebu merupakan tanaman penghasil gula yang kita konsumsi sehari-hari. Gula yang kita konsumsi diproses dari sukrosa yang terbentuk di batang tebu. Kadar sukrosa yang ada dalam batang tebu bervariasi antara 8 – 13 % pada tebu segar yang mencapai kemasakan optimal.

Sukrosa adalah senyawa disakarida dengan rumus molekul C₁₂H₂₂O₁₁. Sukrosa terbentuk melalui proses fotosintesis yang ada pada tumbuh-tumbuhan. Pada proses tersebut terjadi interaksi antara karbon dioksida dengan air didalam sel yang mengandung klorofil. Bentuk sederhana dari persamaan tersebut adalah :

6 CO₂ + 6 H₂O —–> C₆H₁₂O₆ + 6 O₂

Gula tebu adalah disakarida, gula tersebut dapat dibuat dari gabungan dua gula yang sederhana yaitu glukosa dan fruktosa (monosakarida). Penggabungan dari dobel unit karbon monosakarida menjadi : C₁₂H₂₂O₁₁ yang selanjutnya dinamakan sukrosa atau saccharose.

Selain sukrosa didalam batang tebu terdapat zat-zat lain. Dalam proses produksi gula zat – zat ini harus dihilangkan sehingga dihasilkan gula yang berkualitas. Berikut adalah komponen yang terdapat dalam batang tebu.

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By :
Efraín Rodríguez Jiménez
E–mail: efrain.rodriguez@cigb.edu.cu

ABSTRACT

In sugar production, dextrans are undesirable compounds synthesized by contaminant microorganisms from sucrose, increasing the viscosity of the flow and reducing industrial recovery, bringing about significant losses. The use of the dextranase enzyme is the most efficient method for hydrolyzing the dextrans at sugar mills. Some bacterial strains, filamentous fungi and a small number of yeasts have been shown to produce dextranase. The fungal dextranases showed the highest reaction rate at low Brix, with pH and temperature close to 5.0 and 50 ºC, respectively, that is, conditions existing in juice extraction. Some of these dextranases formulated in enzymatic preparations have been efficiently used for hydrolyzing dextrans in sugar mill juices. In more advanced points of the process, where the dextrans have already caused losses, the conditions of temperature and Brix are high.

However, although the volumes are smaller, the treatment with these enzymes in syrup showed the need to increase the dose, equaling dextranase consumption. Some thermo tolerant bacterial dextranases identified up to now showed a much reduced specific activity that makes their industrial use unfeasible. The fungal dextranases from Chaetomium sp. have shown the best results on dextrans treatment both in juices and syrups. Any attempt to obtain a new natural or recombinant dextranase enzyme, must be comparable with to the Chaetomium enzyme.

Keywords: Dextranase, industrial enzymes, industrial application, dextran

For full article please see links bellow :

http://elfosscientiae.cigb.edu.cu/PDFs/BA/2005/22/1/BA002201RV020-027.pdf