Boost for corn fibre gum's emulsifying potential

USDA scientists are continuing to expand the potential of a gum produced from corn fibre to replace gum arabic as emulsifiers in beverages, with a new study pinpointing the emulsifying properties of the gum.

The study, published online in the Journal of Agricultural and Food Chemistry, extends our understanding of the gum, highlighting its potential to eventually replace gum arabic as an emulsifying agent. The supply of gum arabic (E414 in the EU), also known as acacia gum because it comes from Acacia trees in the gum belt of Africa, is variable due to political and climatic factors in the primary producing countries like Sudan and Nigeria and this has led to spikes in the price of the ingredient. Gum arabic, known as the Rolls Royce' of gums, is widely used by the food and beverage industry, and the top producers (mainly Sudan) bring about 50,000 tonnes of the gum to the market each year. Attempts to find an alternative have lead researchers, particularly in the US, to look into the use of corn fibre, a readily available and low valued by-product of corn milling, to produce a gum that could be used as a thickener, adhesive, and stabiliser for food and beverage applications. "This is the first detailed report of the emulsifying behaviour of various fractions of corn fibre gum obtained by hydrophobic interaction chromatography (HIC)," wrote lead author Dr. Madhav Yadav from the USDAs Agricultural Research Service. "These results indicate that all components of corn fibre gum contribute to its strong emulsion-stabilizing capacity." The research builds on previous studies by the same researchers. FoodNavigator.com reported on these earlier findings in October 2006. At the time, Dr. Yadav told this website that the applications for corn fibre gum beyond beverages could possibly include encapsulation of essential oils and fatty acids, glossy coatings and biodegradable edible films, and even as a prebiotics. For the new study, Dr. Yadav and co-workers used the hydrophobic interaction chromatography technique to separate the corn fibre gum into three fractions, all of which consisted of carbohydrates and proteins. The main fraction, representing 65.3 per cent of the total weight of the gum, contained more carbohydrate and less protein and than the whole CFG and other fractions. The second fraction required sodium hydroxide to elute from the chromatography column, and represented only 2.7 per cent of the total gum weight. It contained a higher protein and acidic sugar content and a lower carbohydrate content than the first fraction. Finally, the third fraction required methanol to elute from the column. It represented 11.1 per cent of the total gum weight, and contained more protein, but less acidic sugars and carbohydrates than all of the other fractions. In terms of the emulsifying ability of the total gum and its fractions, Dr. Yadav and co-workers report that the whole corn fibre gum and the main fraction peformed between than the other two fractions. However, the overall best emulsifying ability was possessed by the whole corn fibre gum. "Usually, emulsion stability increases with increasing molecular weight and protein content. Therefore, it is likely that the good emulsifying properties of the main fraction are due to the combination of its high molecular weight and protein content," they wrote. "It is interesting that although the protein content of the last fraction, (lowest molecular weight), is high, it produced the least stable emulsion relative to the other fractions. "Thus, it appears that in addition to protein content a typical corn arabinoxylan structure with high molecular weight may be essential to be a good emulsifier," they added. Interactions between the protein and carbohydrate polymers in the gum and their emulsifying activity will be studied in future work, added Dr. Yadav and co-workers. Bright future? "If corn fibre gum can be produced economically, it has a number of potential industrial applications," wrote the researchers. "It could be utilized as a viscosity modifier, adhesive, thickener, flavour binder, a film former, or an emulsifier." An early rough cost estimation by an ARS cost engineer suggested that, based on the assumed price of the raw materials, the cost would be about $2.00 per pound ($4.40 per kg) for a laboratory preparation. This compares favourably with the time market value of gum arabic, that was between $3.00 and $6.00 per pound ($6.60 to $13.20 per kg), said Dr. Yadav in 2006. But the cost of the individual ingredient may not be the only benefit, he said, because corn fibre gum could reduce or even eliminate the need for weighting agents, such as brominated vegetable oil (BVO), sucrose acetate isobutyrate (SAIB), ester gum, and damar gum, that are used to increase the specific gravity of oil to match aqueous phase density, and therefore stabilise flavour oils and/or clouding oils in the beverages. These additives are not always acceptable to consumers, said Dr. Yadav, with many countries expressing concern about the possibility of bromine storage in the body when BVO is included in food. This, he said, has lead the United States government to impose a limit of BVO to 15 ppm in the finished beverage. "Thus the development of a technology to formulate a physically stable oil/water beverage emulsions without using any weighting agents looks beneficial." Source: Journal of Agricultural and Food Chemistry Published online ahead of print, ASAP Article, doi: 10.1021/jf703672d "Fractionation, Characterization, and Study of the Emulsifying Properties of Corn Fiber Gum" Authors: M.P. Yadav, N. Parris, D.B. Johnston, K.B. Hicks

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