Whey encapsulation highlights 2007

By Stephen Daniells

- Last updated on GMT

Whey protein is increasingly hitting the mainstream. This year saw
numerous studies published exploring the potential of the
ingredient to encapsulate value-added ingredients. Here,
FoodNavigator reviews the progress from 2007.

3D hydrogels ​ In August, Sundaram Gunasekaran and co-workers at the University of Wisconsin-Madison reported that whey proteins hydrogels have the potential to encapsulate sensitive ingredients, suggests a new study. The hydrogels, described as 3D networks with the ability retain water in it structure when dissolved, 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. Gunasekaran and co-workers also report that these factors 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. "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 in the Journal of Food Engineering."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. (Journal of Food Engineering​, Vol. 83, pp. 31-40, S. Gunasekaran et al.) Protecting probiotics ​ Back at the turn of the year, researchers from Laval University and the Food Research and Development Center Agriculture and Agri-food Canada reported the potential of probiotics encapsulation in whey protein gel particles to protect the strains during processing and storage, as well as extending the food applications of the bacteria to biscuits, vegetable and frozen cranberry juice. Co-author of the study, Claude Champagne told FoodNavigator.com that the protein-based technique can provide an alternative to microencapsulation (ME) with alginate-type gels or spray-coating with fats, the two most widely-used probiotic encapsulation methods. "It can be expected that the protein matrix would have different cell release properties than the other ME methods (polymer or fat based),"​ said Champagne. "Thus, applications can extend to other foods for protection during processing as well as stability during storage but also in nutraceuticals for protection and cell release in the GI tract." ​ The best results were obtained when the entrapped probiotics were added to vegetable juice, said the researchers, with 33.4 per cent of the cells still viable after a two-week storage period, compared to only 6.6 per cent of non-encapsulated cells. The strains faired less well in the biscuits, with only four per cent of the ME cells were viable in the biscuits after 24 hours storage at 23 degrees. Interestingly, the authors stated it was the first report on the addition of ME probiotics to biscuits, highlighting the potential of additional studies to optimise the process. "We were the first to apply the technique to probiotics and it has subsequently been picked up. Please note that we did not invent the whey gelation process, but we were the first to apply it to probiotics,"​ said Champagne. (Journal of Food Science​, Vol. 72, pp. M31-M37, A.A. Reid et al.) Colloidosomes ​ In February, scientists from the University of Massachusetts reported results from their ongoing study of the potential of "colloidosomes", novel oil-on-oil particles in an aqueous emulsion, as encapsulators for food. The innovative technology uses electrostatic layer-by-layer (LbL) deposition to put small oil droplets around a larger oil droplet and dispersed in an aqueous phase. Such a technology may have important implications by reducing an emulsion's susceptibility to gravitational separation, to develop novel controlled or triggered release systems, or to compartmentalize active agents. And the researchers, led by Professor D. Julian McClements, report that the colloidosomes can be produced entirely from food-grade components, including whey protein, indicating the potential to apply them to beverages and foods. Talking exclusively to FoodNavigator.com, McClements said that the technique, despite being confined to the laboratory at the moment, should be economically feasible for widespread food industry applications. "It is based on food grade ingredients, and is simple to implement using existing technology (just pH adjustment and mixing) - so should be feasible,"​ he said. The researchers prepared the colloidosomes by mixing an oil-in-water emulsion containing large anionic (negatively charged) droplets of pectin-coated beta-lactoglobulin (whey protein) with corn oil with another oil-in-water containing small cationic (positively charged) beta-lactoglobulin with corn oil. By maintaining the pH of the solutions around pH4.0, the pectin will adsorb to the whey protein particles. And with increasing pectin concentrations, the charge of the droplets changed from positive to negative. The average particle size was also affected by increasing pectin concentrations, with concentrations above 0.05 to 0.1 weight per cent giving particles about one micrometre, with no evidence of creaming. Challenges remain to further optimize the technology, said McClements, with the most pressing being to make a stable colloidosome, without getting bridging flocculation. (Food Hydrocolloids​, Vol. 21, pp. 516-526, Y-S. Gu et al.) Whey 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.

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