Effect of the phosphate/calcium molar ratio on fouling deposits generated by the processing of a whey protein isolate in a plate heat exchanger

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

“…Finally, the sole work that shows, at a pilot scale, the influence of calcium chelators by fixing the amount of protein and Ca 2+ , and changing only the phosphate concentration, is that of Blanpain-Avet et al [22]. They followed the decrease of the fouling deposit mass when phosphate was added in the system.…”

“…More importantly, the two major descriptors used in the industry (namely the pressure drop and the thermal resistance values) were not given and, consequently, it is not possible to compare the dynamic of the evolution of these parameters in respect of deposit mass decrease. Nevertheless, Blanpain-Avet et al [22] were also the first to report electron probe micro analyses (EPMA) of the fouling layer and attempted to provide a molecular scale interpretation of how the structure of the deposit is modified with the increasing calcium chelator concentration.…”

“…The amount of CaCl 2 was targeted to have 100 mg/L of Ca in the final solution as it was established that this level allowed (i) enough fouling of the PHE after two hours (without plugging), and (ii) to compare and to go further than the work of Blanpain-Avet et al [22]. Average total calcium concentration ([Ca]) in WPI solutions was 101.02 ± 2.06 mg/L, determined by atomic absorption spectrometry using a Spectro AA 55B apparatus, (Varian, Palo Alto, CA, USA) as [22].…”

“…Pilot scale fouling experiments were conducted, as previously described [8,22,25], in a plate heat exchanger represented schematically in Figure 1. Fouling installation was divided in two distinct zones: a pre-heating and a heating zone composed of a PHE (VI-CARB, model V7, Alfa-Laval, Saint-Priest, France).…”

“…where ρ is the fouling solution density in kg/m 3 , v is the average fluid velocity in m/s (which is also equal to Q/l•e), Q is the fouling solution flow rate in m 3 /s, l is the plate width in m, µ is the fouling solution viscosity in Pa.s, and D h , in m, is the hydraulic diameter defined by: D h = 2•e as classically encountered in other publications [22,[26][27][28]. The water physical properties at the mean temperature in the PHE were used to calculate Re once the presence of a 0.5 wt% WPI in water does not modify them significantly, as assumed by [22,25,26,29]. Indeed, Petit et al [27] estimated the density of the WPI at 1025 kg/m 3 while the true water density at 20 • C is 996 kg/m 3 , so the approximation of volume additivity due to the 0.5% WPI leads to 996.1 kg/m 3 which is almost the water density.…”