A Noninvasive Study of Milk Cleaning Processes: Calcium Phosphate Removal

Abstract

High temperature, high pH milk processing results in the formation of mineral rich deposits that are > 70% mineral and < 30% protein by weight. This research investigates the removal of P32 labeled mixtures of calcium phosphate dihydrate (brushite, CaHPO4–2H2O) and hydroxyapatite (Ca5(PO4)3OH) from stainless steel tubes using a solid scintillation technique. Experiments were performed at pH values ranging from 2.86–7.82 and flow rates from 3.8–11.4 L/min. Previous cleaning models are reviewed and a mass transfer model is proposed which, when compared to the experimental results suggests that film removal is due to both dissolution and mechanical effects due to shear stress. A modified first order model is presented which incorporates the effects of the solvent flow rate and pH on decontamination rates. This first order model is in agreement with the experimental results over the range of pH and flow rates investigated.

Effect of Poly(aspartic acid) on the Removal Rates of Brushite Deposits from Stainless Steel Tubing in Turbulent Flow

“…However, the actual force exerted on particles protruding from the film might exhibit a more pronounced velocity dependence because lift forces due to turbulent bursts close to a solid surface have been determined to be proportional to the third power of the average velocity . In a previous work, we determined that removal rates of DCPD deposits from pipe walls in turbulent flow over a wide range of pHs (2−10), in the absence of sequestering agents, followed a scaling J ∝ v 2.6 , which suggests that shear forces were the most important mechanism for deposit removal.…”

“…For this reason, the main objective of this work is to determine the mechanisms by which PASP affects deposit removal of pure DCPD films at various pHs and fluid velocities. This work uses a solid scintillation technique applied in previous research by our group ,− to experimentally study the removal of DCPD deposits from stainless steel pipes under turbulent flow conditions in the presence of PASP. By comparing DCPD deposit removal in the presence and absence of PASP, we establish how the sequestrant affects the shear-controlled cleaning rate.…”

Effectiveness of Rinse Water during In‐Place Cleaning of Stainless Steel Pipe Lines

“…It has been widely agreed that both physical and chemical forces are involved in controlling the rate and the extent of cleaning, thus any parameters impacting the flow characteristics or dissolution of deposit will impact cleaning (Grant and others ; Fryer and others ; Weidemann and others ). Increasing temperature can improve cleaning to a certain extent, however, the relationship between temperature and rinse effectiveness is not linear.…”

Use of Sodium Polyaspartate for the Removal of Hydroxyapatite/Brushite Deposits from Stainless Steel Tubing

“…This technique involves the use of an experimental flow system equipped with solid scintillation detection equipment. We have used this system previously to study the removal of both mineral (e.g., calcium phosphate) and oil contaminants from stainless steel tubes (Yan et al, 1997;Grant et al, 1996Grant et al, , 1997.…”