Diversification of the sugar industry through xanthan gum production

Transcription

1 53 Diversification of the sugar industry through xanthan gum production M. Hamilton 1, G. Dawkins 1, W. Mellowes 2 1. University of the West Indies, Jamaica 2. University of the West Indies, Trinidad & Tobago Abstract The increased cost of sugar production and the decline in the price of sugar and its by-products on the world market have seriously jeopardised the future of sugar production in the Caribbean region. This has stimulated a search for new and innovative ways of revitalizing and diversifying the local sugar industry through value-added products. One such product is xanthan gum. Xanthan gum is produced by fermentation and has numerous applications in food, pharmaceutical and other industries as thickeners, stabilisers, emulsifiers and suspending agents. The demand for xanthan increases by approximately 5-7 % annually, with sales in the food industry, which consumes just over 50% of xanthan produced, reaching US$ million in A novel process has been developed using products of the sugar industry. The process of xanthan production has the advantage of overall cheaper production costs when compared to other established processes, giving the process a competitive edge. The potential returns from xanthan production are also significantly higher when compared to other sugar related products. The development of this process will diversify the sugar industry both in terms of the range of products produced and the markets accessed and should provide significantly increased revenue for the sugar industry. Introduction The sugar industry is one of the largest agricultural industries in the Caribbean and as such is important to the economy of the region. In 2003, member countries of the Sugar Association of the Caribbean exported 417,975 tonnes of sugar earning approximately 235 million pounds from sales to Europe and US$18.5 million from sales to the United States (SAC, 2003). The industry is however under threat from the effect of globalisation, which has resulted in a shift of agricultural production from less competitive to more competitive regions of the world. Caribbean sugar is uncompetitive due to low productivity, absence of economies of scale of production, labour problems, low utilisation of technology, inadequate research and development support. Additionally few value added products and the pace of diversification has been slow (Ahmed, 2001).

2 The Caribbean sugar industry has however, been protected from the full effects of globalisation, by preferential marketing arrangements, under the Sugar Protocol of the Lomé Convention, and the US Sugar Quota system. Unfortunately this agreement recently came under pressure from the World Trade Organization (WTO) and as a result the Cotonou Accord was signed in Under this new agreement protection is guaranteed only until 2008, after which the Caribbean sugar industry will face the full impact of globalisation. The recent increase in the cost of regional sugar production and a fall in cost of sugar and its by-products on the world market, has further exacerbated the problem and has severely jeopardised the viability of the industry. The need to be competitive in a global economy, as well as the requirement for diversification of the local sugar industry, prompted the development of a novel process of xanthan gum production using products of the sugar industry. Structure and applications of xanthan gum Xanthan gum is a high molecular weight exocellular biopolymer produced by Xanthomonas campestris. The polymer backbone is made up of 1,4-linked ß-Dglucose. A trisaccharide branch containing one glucuronic acid unit between two mannose units is linked to every other glucose unit at the C(3) position (Fig. 1). On approximately one half of the terminal mannose residues, a pyruvic acid moiety is joined by a ketal linkage to the O(4) and O(6) positions. Acetate groups are present as substituents at the O(6) position of the nonterminal mannose (Kang et al, 1993) (Fig. 1). Figure 1. Molecular Structure of Xanthan Gum 2

3 Xanthan gum is soluble in hot and cold water with high viscosity at low concentrations (Sanderson, 1981). The gum has high pseudoplatic viscosity and is very resistant to variations in ph, temperature and salt concentration (Rocks, 1971). It has a low caloric value and a high resistance to enzymatic degradation. Xanthan gum is also compatible with all commercial thickeners and stabilisers and has been shown to have synergistic interactions with other gums (Goycoolea et al, 2001, Katsuraya et al, 2003). These unique properties of the gum have allowed it to find numerous applications in the food, pharmaceutical and other industries as a thickener, stabiliser, emulsifier and suspending agent. The gum is currently used in several products such as salad dressings, juices, cake mixes, antacids, cosmetic items such as toothpaste, and hair care products. The versatility of the gum is also shown by the fact that it is utilized in products such as fertilizers and paints, and enhanced oil recovery in drilling operations. Production of xanthan gum Xanthan gum is produced from the fermentation of sugars by Xanthomonas campestris. A new process utilising raw material from the sugar industry as substrates has been developed at the University of the West Indies, Mona. The basic process involves aerobic fermentation for several days followed by cell removal and gum precipitation using ethanol. The gum is then dried and ground to a powder (Figure 2). Figure 2. Basic process for xanthan gum production Demand for xanthan gum The worldwide market for xanthan gum is growing at roughly 5-7 % per year, with over half of the product going into food applications (Chemical Market Reporter, 2001) (Table 1). Global xanthan gum sales in the food industry are US$ million annually, with percent of sales in the US, and percent in Europe. (Krause, 2002). 3

4 Table 1, Xanthan consumption by application Application World consumption Food 55% Pharmaceutical & personal care 5% Industrial (non-oil field) 10% Oil Field 30% Source: Archer Daniels Midland Company The demand for xanthan gum produced from sugar related substrates is expected to increase even further as there is growing concern in the market about genetically modified food ingredients. Xanthan gum, which is currently fermented primarily in corn syrup from genetically modified corn, is attracting negative attention to the point where some producers are making strong efforts to differentiate their xanthan by producing non-genetically modified gum (Ouellette, 2001, Boswell, 2003). Xanthan produced from sugar products would be classified as a non-genetically modified product. With the organic food market growing around 20% in the US and Europe (Ouellette J, 2001) there is an expected increase in the demand for xanthan produced from other raw materials apart from genetically modified corn. Potential benefits of xanthan gum production. Although the use of xanthan gum could have an impact on the petroleum industry in the region and the wider international community, use of the vast quantities required for oil recovery are dependent upon the availability of a source of xanthan which is very cheap. Consequently, international research has been focusing on ways of reducing the costs of production of xanthan gum. This research project has successfully utilised products from the sugar industry, for the production of xanthan gum. The low cost of the raw materials has resulted in relatively low overall production costs. Xanthan gum is currently produced mainly in Europe and North America from corn syrup. The costs of high fructose corn syrup (HFCS-42) was approximately $0.24 /kg in 2000 (USAD, 2004), while molasses on the Jamaican market was $0.05 /kg in 2003 (SIA 2003). In addition to lower raw material costs, significant value is added when xanthan is produced from molasses (Table 2). 4

5 Table 2. Rough cost benefit analysis of xanthan gum production vs alcohol production Price of molasses (local market 1 ) Cost of ethanol (Jamaican market) 2 Cost of xanthan (average international price) 3 $ 50.00/metric tonne $ 0.05 / kg $ 2.50 /L $ 7.83 /kg With Crude Process 1 kg Molasses = 0.32 l Ethanol (99.5%) 4 1 kg Molasses = 0.30 kg Xanthan Value Added $ 0.05 Molasses = $ 0.8 Alcohol $ 0.05 Molasses = $ 2.35 Xanthan 1 The Sugar Industry Authority (Jamaica) (2003) 2 National Rums of Jamaica LTD (2003) 3 Chemical Market Reporter (2002) 4 United States Department of Agriculture (1938) The production of xanthan should therefore provide significantly increased revenue for the sugar industry through the development of this value-added product for export and local use. It will also diversify the sugar industry both in terms of the range of products produced and markets accessed. Local production of xanthan gum should also facilitate the development of the regional manufacturing sector. The gum is currently imported at costs which are often prohibitive to local manufacturers and this places them at a disadvantage with respect to their international counterparts. Lower production cost should ensure a supply of xanthan gum to local manufactures at a reduced cost with a consequent increase in local utilization of xanthan gum and a concomitant increase in product quality. Conclusion The production of the value-added product xanthan gum, from products of the sugar industry would be a timely move which would secure the viability of the regional sugar industry and boost the economics of participating territories. 5

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