The ability of whey protein isolate (WPI) microgels to stabilise foams was investigated and compared with native WPI foams. Cold-set gelation was used to prepare the microgels, whereby WPI was heat-denatured, cooled then calcium chloride (CaCl2) added to induce gelation. The effect of CaCl2 concentration and cross-linking time on microgel formation was studied. The microgels were characterised by particle size, rheological properties and on their foam ability. Mechanical whipping was used to prepare the foams which were assessed based on overrun and stability. Higher concentrations of CaCl2 led to the formation of smaller microgel particles and a decrease in the viscosity of the microgel sol. Higher CaCl2 concentration resulted in higher overrun values in the foams, possibly due to lower viscosity. Allowing the microgels to cross-link for 24h resulted in considerably higher G' and G'' values compared to those cross-linked for 0h, indicating more solid-like behaviour. This suggested that the microgels were more structured compared to those cross-linked for 0h. Whipping the microgels immediately after CaCl2 addition (0h cross-linking) resulted in foam overrun double that of foams produced after 24h cross-linking. However, native WPI foams had higher overrun values compared to the microgel foams but they were found to drain within the 60-minute test period. In contrast, the microgel foams had no drainage and in fact remained stable for a prolonged period of >12 months. This demonstrates that WPI microgels can be used as a novel functional application for creating ultra-stable foams by controlling particle size, CaCl2 concentration and rheological properties. The unique properties of microgel stabilised foams have much to offer in developing the science of food structuring and formulating novel structures for the food industry.
|Original language||English (Ireland)|
|Title of host publication||48th Annual Food Science and Technology Conference|
|Publication status||Published - 16 Dec 2019|
- whey protein