Improved emulsion stability from protein-sugar complex

By Stephen Daniells

- Last updated on GMT

Related tags Emulsion

Linking sodium caseinate (a milk protein) and maltodextrin (a polysaccharide) may improve the stability of liqueur emulsions, suggests new research from Ireland.

The protein-polysaccharide compound, or conjugate, showed only minimal colour development, as well and an improved solubility, say results in the journal Food Chemistry​.

“Their improved emulsifying properties in oil-in-water emulsions and model cream liqueurs, indicates a potential for sodium caseinate-maltodextrin conjugates as speciality functional food ingredients,”​ wrote Jonathan O’Regan and Daniel Mulvihill from the Department of Food and Nutritional Sciences at University College Cork.

Dr Mulvihill told that while a number of research papers have been published on the topic of protein-polysaccharide conjugates, many of these studies focused on the characterization of the conjugates (degree of conjugation) and in some their functional properties.

Sodium caseinate is already extensively used as an emulsifier by the food industry, while maltodextrin is commonly used an a stabiliser.

"The present investigation involved a more extensive study on sodium caseinate-maltodextrin conjugates and their emulsifying properties and the potential application of these conjugates as emulsifiers in model cream liqueurs,”​ said Dr Mulvihill.

Study details

Using a Maillard-type reaction by treatment at 60 degrees Celsius of sodium caseinate (Kerry Ingredients) and maltodextrin (Maltrin040 (Md40) and Maltrin100 (Md100), Grain Processing Corporation) resulted in formation of the conjugates. Only a minimal level of coloured reaction products was produced during this process, noted the researchers.

Emulsifiers work by stabilizing oil suspended in water, and this is achieved electrostatically. Part of the emulsifier is attracted to water, while another part is attracted to the oil. The isoelectric point (pI) is the pH at which the emulsifier has no electrical charge, and therefore in a food with a pH close to the pI the emulsifier can no longer stabilize the emulsion effectively.

According to O’Regan and Mulvihill, when they tested the conjugates at various pH levels, they observed “improved solubility compared to sodium caseinate, particularly around the isoelectric point of the protein”​.

Applying to food systems

The next stage in the process was to test the performance of the conjugates in a model oil-in-water emulsion and in model cream liqueurs.

“The conjugate stabilised oil-in-water emulsions and liqueurs showed improved stability when compared to sodium caseinate stabilised oil-in-water emulsions and liqueurs,”​ report the researchers.

The road ahead

According to Mulvihill, the conjugates are currently not commercially available. The Cork-based researcher added that the work was not done in association or in collaboration with a company.

Dr Mulvihill did confirm that research was ongoing, with additional study in the area of milk protein conjugates currently ongoing within his research group.

“The next stage for these conjugates would be an investigation of possible technologies for a feasible scale up of production of the conjugates and then an evaluation of their use/application in pilot scale food production,”​ he said.

Source: Food Chemistry
Volume 115, Pages 1257-1267
“Preparation, characterisation and selected functional properties of sodium caseinate-maltodextrin conjugates”
Authors: J. O’Regan, D.M. Mulvihill

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