"Covalent proteinpolysaccharide complexes of mixtures of whey protein and maltodextrin have functional properties that offer substantial potential for use as cheap and effective food ingredients," said researchers Mahmood Akhtar and Eric Dickinson from the Procter Department of Food Science at the University of Leeds.
The complexes, produced using a moderately short dry-heating treatment, could offer an effective alternative to gum arabic, said the researchers.
"A major potential application of this type of proteinpolysaccharide complex is in the stabilisation of citrus oil emulsions as an alternative to gum arabic," they wrote in the journal Food Hydrocolloids.
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 to look into alternatives that could be used as a thickener, adhesive, and stabiliser for food and beverage applications.
The study, funded by Uniqema (ICI), suggests that complexes of maltodextrin (MD) with whey protein (WP) isolate could be one such alternative.
Akhtar and Dickinson achieved coupling of whey protein (BiPro, obtained from Davisco Foods International) to the maltodextrin polysaccharide (Roquette, UK) by a dry-heat treatment for two hours that led to covalent bonds forming between the protein and polysaccharide. Such coupling, said the researchers, gave a "very substantial enhancement in the protein emulsifying behaviour under both acidic and neutral conditions."
The maltodextrin with a dextrose equivalent (DE) of 19 was found to produce fine emulsion droplets ranging from 0.5 to 1.0 micrometres with both triglyceride oil or orange oil.
The cost-efficient potential of the complexes were highlighted by the observation that the optimised WP-MD19 complex produced stable emulsions at only a two per cent emulsifier content, compared to the 20 to 30 per cent equivalent conted required by gum arabic.
The researchers also reported that this physical stability of the emulsion was preserved in when food colourings were added, before and after dilution.
"In addition to the extended shelf-life of the concentrates, it has been shown that these systems can be successfully diluted with carbonated sugar syrup to produce stable dilute coloured emulsions, with direct relevance for commercial soft drink applications," concluded the researchers.
The study is published on-line ahead of print (17 August) in the Elsevier journal Food Hydrocolloids (doi:10.1016/j.foodhyd.2005.07.014).