Cold-set whey protein microgels for the stable immobilization of lipids

Cold-set whey protein microgels containing immobilised lipid phases to modulate matrix digestion and release of a water-soluble bioactive

“…This suggests that the microgels prepared by both the external and internal gelation methods could be likely to remain stable within a food matrix until their ingestion, thereafter the action of GI enzymes could degrade these microgels. These results correlate with the reported results in Egan et al (2013) showing excellent stability of these protein matrices over a range of pH values and temperatures. It is very promising from the perspective of feasibly adding these foodgrade microgels into complex food products.…”

“…In the internal gelation method an insoluble calcium source is mixed into the denatured WPI, and these pre-gel droplets dispersed within an oil phase are gelled upon the addition of an oil soluble acid, which releases the calcium to initiate gelling from within the droplets. These WP microgels are very efficient immobilisers of lipid phases as previously reported by Egan et al (2013), and by Beaulieu et al (2002) for the external gelation method.…”

“…This difference in rates would be expected due to the difference in the size of the microgels prepared from both methods. Microgels prepared by the external gelation method tended to be about 1 mm in diameter, whilst those microgels prepared by the internal gelation method tended to be much smaller at typically 100 mm in diameter (Egan et al, 2013). The greater surface area of the smaller microgels (approximately 10 times smaller) facilitates enzyme activity, leading to faster protein matrix digestion.…”

“…The preparation of emulsions was as detailed in Egan et al (2013). WPI solution (10% w/w of protein content and containing 0.02% sodium azide) with an intrinsic pH of 6.8 was prepared in deionised water at 40 C. The solution was kept stirred gently overnight (at ambient temperature) to ensure complete hydration and swelling of the proteins.…”

“…These ''cold-set'' gels provide the advantage of incorporating sensitive bioactive ingredients at a stage prior to gelling that does not require any further heat treatments. Recent results from our laboratory have shown that WP matrices, produced by two different cold-set gelation methods (an external and an internal method), had good stability in a variety of pH values and temperatures (Egan et al, 2013). The external method involves drop-wise addition of the denatured whey protein isolate (WPI) solution into a CaCl 2 solution to produce microgels.…”