Denaturation Kinetics of Whey Protein Isolate Solutions and Fouling Mass Distribution in a Plate Heat Exchanger

Marwa Khaldi,Pascal Blanpain-Avet,Guillaume Delaplace,Laurent Bouvier,Thierry Six,Thomas Croguennec,Romain Jeantet,Christophe André,Gilles Ronse,Saloua Bornaz

doi:10.1155/2015/139638

Abstract

Few investigations have attempted to connect the mechanism of dairy fouling to the chemical reaction of denaturation (unfolding and aggregation) occurring in the bulk. The objective of this study is to contribute to this aspect in order to propose innovative controls to limit fouling deposit formation. Experimental investigations have been carried out to observe the relationship between the deposit mass distribution generated in plate heat exchangers (PHE) by a whey protein isolate (WPI) mainly composed ofβ-lactoglobulin (β-Lg) and the ratio between the unfolding and aggregation rate constants. Experiments using a PHE were carried out at a pilot scale to identify the deposit distribution of a model fouling solution with different calcium contents. In parallel, laboratory experiments were performed to determine the unfolding/aggregation rate constants. Data analysis showed that (i)β-Lg denaturation is highly dependent on the calcium content, (ii) for each fouling solution, irrespective of the imposed temperature profile, the deposit mass in each channel and the ratio between the unfolding and aggregation rate constants seem to be well correlated. This study demonstrates that both the knowledge of the thermal profile and theβ-Lg denaturation rate constants are required in order to predict accurately the deposit distribution along the PHE.

Highlights

In the dairy industry, heat treatments are carried out in order to ensure food security and to impart several functionalities to milk and its derivatives, like thermal stability, viscosity, or gelation [1,2,3].Fouling deposit formation on heat exchanger surfaces is a major industrial problem of milk processing plants, which involves frequent cleaning of the installations, thereby resulting in excessive rinsing water and harsh chemicals use
Experimental investigations have been carried out to observe the relationship between the deposit mass distribution generated in plate heat exchangers (PHE) by a whey protein isolate (WPI) mainly composed of βlactoglobulin (β-Lg) and the ratio between the unfolding and aggregation rate constants
We propose to partially fill this gap by investigating the chemical reactions of β-Lg denaturation occurring in the bulk, for two WPI model fouling solutions, and their link with the fouling phenomena

Summary

Introduction

Heat treatments are carried out in order to ensure food security and to impart several functionalities to milk and its derivatives, like thermal stability, viscosity, or gelation [1,2,3]. Fouling deposit formation on heat exchanger surfaces is a major industrial problem of milk processing plants, which involves frequent cleaning of the installations, thereby resulting in excessive rinsing water and harsh chemicals use. A number of studies have reported the drastic economic costs of fouling. Fouling and the resulting cleaning of the process equipment account for about 80% of the total production costs [4]. According to Tay and Yang [5], the total heat exchanger fouling costs for highly industrialized countries are about 0.25% of the Gross National Product. In the USA, total fouling costs have been estimated as US $ 7 billion [6]

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