Milk protein complexes may hold key to WOW emulsions

By Stephen Daniells

- Last updated on GMT

Related tags: Emulsions, Water, Liquid, Emulsion

Using conjugates of caseinates from milk and maltodextrin may improve the stability of double emulsions, and lead to a wider acceptance of the technology in a range of food applications.

Irish researchers report that the formulating water-in-oil-in-water (W/O/W) emulsions with the maltodextrin–sodium caseinate complex produced more stable emulsions than when sodium caseinate was used alone, according to findings published in Food Research International​.

In normal emulsions, the oil is dispersed in water; in W/O/W emulsions, however, the oil droplets are packed out with water, which makes for reduced fat. Despite increasing interest in the development of these emulsions, current application of the technique has been limited due to difficulties with the stability of the internal water droplets. This is linked to thermodynamic stability issues, and their strong tendency for droplet coalescence.

Previously, water-in-oil-in-water emulsions have been investigated for their potential for fat reduction in products like mayo, salad dressings, sauces and dips.

The new study, by Jonathan O’Regan and Daniel Mulvihill from the Department of Food and Nutritional Sciences at University College Cork, looked at the potential of sodium caseinate–maltodextrin conjugates to improve the stability of W/O/W double emulsions. O’Regan and Mulvihill compared conjugates made with two types of maltodextrin – Md40 and Md100 (Grain Processing Corporation, Iowa, USA) – with pure sodium caseinate (Kerry Ingredients).

The emulsions, prepared using a two-step emulsification process, were tested for their ability to encapsulate vitamin B12, and the stability of the emulsion assessed by measuring the level of entrapped Vitamin B12 in the inner aqueous phase.

After storage at 45 °C for seven days, the Cork-based researchers reported that the “conjugate stabilized emulsions were more generally stable than sodium caseinate stabilized emulsions”​. In comparison to NaCN stabilized emulsions, conjugate stabilized emulsions showed improved Vitamin B12 encapsulation efficiency in theinner aqueous phase on emulsion formation and improved encapsulation stability following storage of the emulsions.

The droplets in the conjugate stabilised emulsion tended to not coalesce, as evidenced by less increase in the size of droplets.

Improvements in the inner phase encapsulation efficiency and encapsulation stability of Vitamin B12 were also reported by the researchers.

Indeed, loss of vitamin B12 in the caseinate-only emulsion was almost 40 per cent, compared with 34 and 27 in the Md40 and Md100 conjugate stabilized W/O/W emulsions, repsectivley.

“Overall, these results indicate the potential of sodium caseinate–maltodextrin conjugates to produce more stable double emulsions than sodium caseinate,”​ concluded O’Regan and Mulvihill.

Source: Food Research International
Volume 43, Pages 224–231
“Sodium caseinate–maltodextrin conjugate stabilized double emulsions: Encapsulation and stability”
​Authors: J. O’Regan, D.M. Mulvihill

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