Colloides Naturels International
BP 4151, F-76723 Rouen cedex, France
BP 4151, F-76723 Rouen cedex, France
1. Introduction
Modern way of life has favoured the expression of several diseases which are nowadays recognised as being connected with food uses. Avoiding intestinal transit disturbance such as constipation or preventing more serious affections such as cancer or cardio-vascular diseases thus become one of the main preoccupations of consumers: there is an explosion of consumer interest in the health enhancing role of so-called functional foods which provide additional health benefits beyond basic nutritional needs.
While the overall benefits likely depend on the entire diet, the role of dietary fibre is largely recognised and its incorporation into diets lacking crude vegetable ingredients is both welcome by consumers and nutritionists. Dietary fibre (DF) is a general term covering a wide variety of substances which are not digested in the upper part of the human digestive tract. Several national institutes and the Association of Official Analytical Chemists (AOAC), have retained the following definition for dietary fibre: "the remnants of plant cells resistant o hydrolysis by the alimentary enzymes of man. It is composed of cellulose, hemicellulose, oligo-saccharides, pectin, gums, waxes and lignin" (Trowell and Burkitt, 1986).
Thanks to its excellent nutritional properties, its high technological compatibility and its image of authenticity and naturally, FIBREGUM is one of the most widely used fibre supplement.
2. Nutritional properties
Acacia hum, also known as gum arabic, is being used in human diets for more than 5,000 years. It is still largely used near by its production zones by local populations, for example in black Africa to stop children diarrhoea or in India to prevent constipation of pregnant women. More recently, acacia gum has been used at industrial scale as a low-calorie bulking agent in meal substitutes and for its specific fibre properties in some medical foods such as enteral products. Indeed, FIBREGUM is an acacia gum which typically doses 85% (90-95% on dry basis) dietary fibre by the AGAC method and more than 70% by the Englyst method, both methods being used as reference by most national regulations.
Like oligosaccharides, because of its very low viscosity, FIBREGUM does not play much mechanical role in the upper intestinal tract. However, as compared with low molecular weight DF such as oligosaccharides, FIBREGUM differentiates by its absence of effect on the osmotic pressure in the small intestine. It therefore does not provoke excessive laxative effects.
All of the beneficial effects of FIBREGUM result from its fermentation by the microbial flora living in the large bowel: the fibre fraction of FIBREGUM is an extra carbon source permitting a significant increase of the number of bacterial leaving cells. The associated increase of the stool volume and stool humidity explains the effects on transit, namely reduction of constipation problems. The increase in cell number is also associated with an increase of the fermentation activity which leads to the production of short chain fatty acids such as acetic, butyric or propionic acids. These acids slightly decrease the colonic pH, probably explaining the experimentally observed stimulation of Lactobacillus and Bifidobacterium species, the so-called bifidogenic or prebiotic activity. Short chain fatty acids are known to play systemic functions. For example, in liver, short chain fatty acids may modulate the cholesterol catabolism. In the colonic tissues they contribute inhibition of colon carcinogenesis. It is interesting to note that, thanks to its extreme complexity and molecular compacity, FIBREGUM is fermented very slowly, avoiding sudden release of fermentation gas and the subsequent flatulent or bloating effects. Also, slow fermentation makes sure that it is still active in the terminal region of colon, where most colon cancers occur.
3. Technological compatibility
Among the various sources of dietary fibre, one may differentiate soluble from insoluble fibres. Because of their specific mouthfeel, insoluble fibres such as bran remain used in few specific food products such as bread, biscuits or cereal breakfast. In other foodstuffs such as drinks or dairy products, soluble fibres are preferred because they do not exhibit sandy textures. However, most polysaccharides exhibit rheological behaviour that justify their uses as food additives for making gels or increasing viscosity, at dosages far below the minimum required to allow a nutritional claim. Thus, among soluble dietary fibre sources, one may further differentiate oligosaccharides (low molecular weight) from long-chain polysaccharides. Oligo-saccharides or partially hydrolysed polysaccharides have mainly been developed to overcome this limitation. FIBREGUM is again completely different because, thanks to its highly branched chemical structure, it associates high molecular weight (over one million Dalton) with low viscosity. The addition of FIBREGUM far above 1%, thus does not disturb the texture of the finish products. In addition, FIBREGUM has no smell and no taste. It is totally bland. Numerous food products are slightly acidic (pH between 3 and 5). In such conditions, most polysaccharides are very sensitive to heat treatment or long term storage, resulting to a significant loss of the DF content. Again, FIBREGUM differentiates from the other DF sources it by its excellent heat resistance in acidic conditions. Indeed, most fruit beverages enriched with dietary fibre presently available on the market contains Acacia gum as a source of DF.
Another advantage of FIBREGUM as compared to more simple polysaccharides is its resistance to fermentation by bacteria. This topic is important from a nutritional point of view because it leads to a soft" fermentation without uncomfortable side-effects but it is also important for technological reasons. Indeed, DF can be added to foods containing living cells such lactic acid bacteria in dairy products (potentially promoted as probiotics) and the use of FIBREGUM insures that no dosable DF has been consumed before the end of the storage period.
Even not for texture control, acacia gum is largely used by the food industry for its emulsifying, film-forming or encapsulating properties. FIBREGUM can thus play two simultaneous functionalities, one being nutritional, the other technological.
4. Conclusion
Intrinsic characteristics of FIBREGUM, both from the nutritional and technological point of view, make of it a very good candidate for the fibre enrichment and is already largely used as such in numerous different food products (enteral nutrition, instant plant infusions, fruit purees and beverages, extruded breakfasts, dairy desserts?) in different countries of the five continents. FIBREGUM also benefits from the safe and natural image of acacia gum. Being not modified by chemical or enzymatic treatments, it is also available in a commercial version (BIOGUM) being certified "organic" according to the specific EU regulation (re. 209 1/92).
Literature
Street C.A. & Anderson D.M.W, (1983), Refinement of structures previously proposed for gum arabic or other acacia gum exsudates, Talanta, 30, 887-893.
Wyatt TM., Bayliss C.E. & Holcroft J.D., (1986), A change in human faecal flora in response to inclusion of gum arabic in the diet, Br. J. Nutr., 55, 261-266.
For more details
Kravtchenko T.P. (1998), Acacia gum -a natural soluble dietary fibre, in "Functional foods, the consumer, the products and the evidence' M.J. Sadler & M. Saltmarsh eds, The Royal Society of Chemistry, pp. 38-46.
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