Exopolysaccharides food applications

Xanthan has some unique properties and high activity at low concentrations and is commercially the most important exopolysaccharide. Food products account for approximately 60% of xanthan use, 15% is accounted for by toothpaste, textiles and crop protection products, 10% in the oil industry and the remainder in miscellaneous industrial/consumer applications. 

Fungi and bacteria are sources of polysaccharides and especially of exopolysaccharides which can be produced in culture media on an industrial scale. They are a source of new additives for cosmetic or food applications but also for biological activity. Many of them are now in development a review will be published in the second edition of Reference 12. Many of these polysaccharides are water soluble and able to compete with natural polysaccharides as described before (alginates, carrageenans, galacto- and glucomannans, chitosans, pectins, etc) especially in the domain of food additives. Many books discuss their applications (183-187). 

Commercial applications for polysaccharides include their use as food additives, medicines and industrial products. Although plant polysaccharides (such as starch, agar and alginate) have been exploited commercially for many years, microbial exopolysaccharides have only become widely used over the past few decades. The diversity of polysaccharide structure is far greater in micro-organisms compared to plants and around 20 microbial polysaccharides with market potential have been described. However, microorganisms are still considered to be a rich and as yet underexploited source of exopolysaccharides. 

The method used is governed by the market application of the exopolysaccharide. In general, the food industry has a requirement for a dry powder, whereas for several other applications, such as enhanced oil recovery, a liquid product is required and the ultrafiltration concentrate is preferred. 

For food and pharmaceutical applications, the microbial count must be reduced to less than 10,000 viable cells per g exopolysaccharide. Treatment with propylene oxide gas has been used for reducing the number of viable cells in xanthan powders. The patented process involves propylene oxide treatment for 3 h in a tumbling reactor. There is an initial evacuation step before propylene oxide exposure. After treatment, evacuation and tumbling are alternated and if necessary the reactor is flushed with sterile nitrogen gas to reduce the residual propylene oxide level below the Food and Drug Administration permitted maximum (300 mg kg 1). The treated polysaccharide is then packaged aseptically. 

Exopolysaccharides are used in lotions and gel formation is exploited in encapsulated drugs. The latter application also takes advantage of the mouth feel and flavour neutrality, qualities also vital for the food industry. 

Most polysaccharides used today are of plant origin. However, also bacteria produce polysaccharides. Especially extracellular polysaccharides (eps s) produced by lactic acid bacteria may find application in foods. Lactic acid bacteria are food-grade organisms and the eps s produced offer a wide variety of structures. The presence of eps is considered to contribute greatly to texture and structure of fermented milk products. An exopolysaccharide produced by Lactococcus lactis ssp. cremoris B40 was chosen as a subject of study. The eps was a gift from the Dutch Institute of Dairy Research (NIZO), Ede, the Netherlands. The eps had no gelling properties, could not be precipitated in plates by ethanol or cetylpyridinium chloride and did not show interaction with Congo red. 

Caplice, N. et al. (2015) Sugar-coated exopolysaccharide producing lactic acid bacteria for food and human health applications. Food Fund, 6, 679 -693. Salazar, N., Gueimonde, M.,... 

Harutoshi, T. (2013). Exopolysaccharides of lactic acid bacteria for food and colon health applications. In J. M. Kongo (Ed.), Lactic acid bacteria-R Dforfood, health and livestock purposes. Rijeka, Croatia Intech. ISBN 978-953-51-0955-6. http //dx.doi.org/10.5772/50839. Available fromht //www.intechopen.com/books/lactic-acid-bacteria-r-d-for-food-health-and-hvestock-purposes/exopolysaccharides-of-lactic-acid-bacteria-for-food-and-colon-health-applications. 

Janzen, T., Christiansen, D. (2012). Lactic bacterium with modified galactokinase expression for texturizing food products by overexpression of exopolysaccharide, European Patent Application EP2473058 Al. 

Patel A, Prajapati JB. Food and health applications of exopolysaccharides produced by lactic acid bacteria. Adv Dairy Res 2013 1 107. http //dx.doi.org/10.4172/2329-888X.1000107. 

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