Pectin-stabilised oil bodies to offer pre-emulsified oil

The new study used an electrochemical process to coat the oil bodies with citrus pectin to produce stabilised oil bodies which were stable to freeze-thaw processes and possessed higher stability to environmental stresses, according to research published in the Journal of Agricultural and Food Chemistry .

"These results suggest that pectin-coated oil bodies have similar or improved stability compared to uncoated oil bodies and may provide a new way of creating functional soy products for use in the food and other industries," concluded the researchers.

The research, by scientists at the Biopolymers and Colloids Research Laboratory at the University of Massachusetts, and the University of Nottingham's Division of Food Sciences, represents preliminary investigations into the potential of the oil bodies for food.

"In principle, food manufacturers could benefit from the already existing natural protection of the soybean oil bodies to obtain a product that has improved stability during food processing, storage, transport, and utilisation," wrote the researchers.

"Additional advantages of using natural soybean oil bodies in foods, rather than emulsified bulk soybean oil, are that neither emulsifiers nor homogenisation procedures are required," they added.

However, "the relatively poor physical stability of oil bodies to aggregation would severely limit the range of products in which they could be utilized in the food, health care, and pharmaceutical industries," they added.

But coating the oil bodies with an oppositely charged polysaccharide, like pectin, could stabilise the oil bodies and make them usable by the food industry, state the researchers.

As lead researcher D. Julian McClements explained to FoodNavigator.com the pectin-stabilized soybean oil bodies could be used in a range of foods where emulsions are applied, including salad dressings, beverages, dips, sauces, deserts, and yoghurts.

The scientists coated the oil bodies (1.25 weight per cent oil) with differing concentrations of pectin ranging zero to 0.5 weight per cent.

The pectin-coated oil bodies were subsequently tested to ascertain their stability under the influence of salt (sodium chloride), differing pH (pH 2 to 8), and freeze-thaw cycling (from minus 20 degrees Celsius to plus 40 degrees Celsius).

"At pectin concentrations from 0.04 to 0.1 weight per cent, the mean particle diameter of the oil bodies was relatively small and the oil body suspensions were relatively stable to creaming," reported McClements and co-workers.

"The good stability of the oil body suspensions at intermediate pectin concentrations can be attributed to the ability of the pectin molecules to completely cover the oil body surfaces and form a relatively thick electrically charged coating."

They also report improved stability with respect to pH, and pectin-stablisation could "extend the range of pH values at which [the soybean oil bodies] remain stable to aggregation."

These promising results will be backed up by future studies, and McClements confirmed to this website that study was on-going in this area.

"We are looking at how to make them more stable by cross-linking the adsorbed layers of polysaccharides," he said.

McClements was unable to comment on how long it would be before we could see foods formulated with pectin-stabilized soybean bodies.

"In this study, we used a particular type of citrus pectin to stabilise the oil bodies," stated the researchers.

"It would be useful in future studies to examine the impact of different molecular characteristics of pectin on its ability to stabilise oil bodies.

"In addition, it would be useful to examine the ability of other kinds of charged polysaccharides to stabilise these systems."

No industrial partners are involved in the research yet, he added.

Source: Journal of Agricultural and Food Chemistry Published online ahead of print 27 February 2008 , ASAP Article, doi: 10.1021/jf073060y "Stabilization of Soybean Oil Bodies Using Protective Pectin Coatings Formed by Electrostatic Deposition" Authors: D. Iwanaga, D. Gray, E.A. Decker, J. Weiss, D.J. McClements