Influence of calcium-binding salts on heat stability and fouling of whey protein isolate dispersions

Abstract

The effect of the calcium-binding salts (CBS), trisodium citrate (TSC), tripotassium citrate (TPC) and disodium hydrogen phosphate (DSHP) at concentrations of 1-45 mM on the heat stability and fouling of whey protein isolate (WPI) dispersions (3%, w/v, protein) was investigated. The WPI dispersions were assessed for heat stability in an oil bath at 95 °C for 30 min, viscosity changes during simulated high-temperature short-time (HTST) and fouling

Calcium Chelation by Phosphate Ions and Its Influence on Fouling Mechanisms of Whey Protein Solutions in a Plate Heat Exchanger

“…The decrease of the total deposit mass after adding calcium chelators to the 0.5% (w/v) WPI solutions is in agreement with the work of Hebishy et al [13]. These authors reported that, in a laboratory scale fouling ring, the fouling potential of a WPI solution at a concentration of 3.0% (w/v) was prevented with trisodium citrate, tripotassium citrate, or disodium hydrogen phosphate.…”

“…Moreover, the shape of mass distribution clearly changed, as no plateau value for deposit mass is clearly identified, as it was the case when P concentration is inferior to 10 mg/L. The reduction of the fouling in the first channels when the added P concentration increased is in agreement with the literature, because, as was reported, in lab scale, the calciumbinding agents increase the heat stability of the WPI solutions and, consequently, reduce protein aggregation [11,[13][14][15]. This is due to the presence of phosphate, which reduces the amount of free calcium limiting the deposition of protein on the surface of the heat exchanger, delaying its appearance at higher temperature.…”

“…In fact, to obtain almost the same fouling mass reduction, 50 mg/L of added P are necessary for the solution having a Ca/β-lg molar ratio of 17, while 20 mg/L of added P are needed for the solution with Ca/β-lg molar ratio of 15. Without added P, the total fouling mass was 120 g for WPI solution with Ca/β-lg molar ratio of 10, almost half of the total mass observed for Ca/β-lg molar ratio of 15 (220 g) while for Ca/β-lg molar ratio of 17, this value was equal to 240 g. These results highlighted again that, in absence of P, a change in Ca content impacts strongly fouling mechanism of WPI solutions as previously mentioned in literature [8][9][10][11][12][13].…”

“…As a consequence, fouling deposit at the surface of the exchanger plates can be considered, resulting from protein heat-unfolding and their aggregation by disulfide interchange reactions (-SH/SS), hydrophobic interactions, but also electrostatic shielding [9], and perhaps specific interaction between unfolded protein and ionic calcium (Ca 2+ ), as indicated recently by Peixoto et al [10]. To sum up, heating whey protein isolate (WPI) in the presence of calcium promotes a molecular link of unfolded proteins and allows the formation of protein-Ca 2+ -protein bridges, which facilitate the deposit build-up [11][12][13].…”

“…Hebishy et al [13] observed on a lab-scale fouling ring that trisodium citrate (TSC), tripotassium citrate (TPC) and disodium hydrogen phosphate (DSHP) addition improves heat transfer during thermal processing. Decreasing the ionic calcium (Ca 2+ ) concentration resulted in a decrease of the final solution viscosity and fouling after heat treatment at 95 • C for 2 min.…”