Whey protein hydrogels offer encapsulation advantages - study

Writing in the Journal of Food Engineering , Sundaram Gunasekaran and co-workers at the University of Wisconsin-Madison report that whey proteins can form nanoparticles in addition to the hydrogels to encapsulate bioactive compounds, and offer advantages over other encapsulating materials.

"The advantages of using whey protein-based gels as potential devices for controlled release of bioactives is that they are entirely biodegradable and there is no need for any chemical cross-linking agents in their preparation," wrote the authors.

"These are two of the major requirements for wide use of hydrogels not only in the pharmaceutical area but also in many food and bioprocessing applications," they added.

Whey protein is increasingly hitting the mainstream.

It is now on supermarket shelves, and is used extensively in infant formula.

Whey has long been used for its functional properties, but it is also now being added because of nutritional properties.

It is natural, has no E-numbers and can be used by food makers to reformulate their products to take out additives.

A recent survey by Danish 3A Business Consulting on whey and lactose ingredients, suggested that food makers are increasingly viewing whey and lactose products as an ideal means of achieving added value.

As such the global whey protein concentrates and isolates market is estimated at 395,000 MT in 2004 representing a value of just over $1bn.

The US remains the biggest producer at 187,000 MT followed by Europe with 159,000.

Gunasekaran and co-workers used caffeine as a model bioactive, and encapsulated this in a commercial whey protein concentrate (WPC, Davisco Foods International).

The bioactive (15 g) was dissolved in a WPC solution (15 per cent), in order to obtain a 1:20 bioactive/WPC mass ratio.

The hydrogels exhibited a pH-sensitive swelling ability especially at pH above their isoelectric point (the point at which the hydrogels are not electrically charged).

The release of bioactive model compound was also sensitive to changes in pH. "Consistent with the swelling behaviour, the release of encapsulated model drug from the hydrogels was slower when the pH was below isoelectric point (pI) than it was at pH above pI," stated the researchers.

They also report that the swelling and release behaviour could be easily slowed by coating the gels with alginate, a result that could lead to targeted release of bioactives at specific points in the gastrointestinal tract.

More research is needed to further explore the potential of whey protein hydrogels, and whether other bioactives, both lipid and water soluble, could be encapsulated in this way.

The research is in-line with the current trend of food manufacturers to turn to encapsulation technologies as a way of achieving much-needed differentiation and enhancing product value.

Tapping into key and emerging consumer trends with innovative techniques is becoming increasingly important for food manufacturers.

Source: Journal of Food Engineering (Elsevier) Volume 83, Issue 1, Pages 31-40 "Use of whey proteins for encapsulation and controlled delivery applications" Authors: S. Gunasekaran, S. Koa and L. Xiao