Document Type

Dissertation - Open Access

Award Date

2020

Degree Name

Doctor of Philosophy (PhD)

Department / School

Dairy Science

First Advisor

Lloyd Metzger

Keywords

milk protein concentrate, hydrodynamic cavitation, nanofiltration, plate and frame filtration, functionality

Abstract

It is a common practice in dairy industries to nanofilter milk protein concentrate (MPC) to increase the solids and further drying efficiency. Increasing protein and solids in MPC increases viscosity and resist feed-flow in membrane filtration. Previous research proved that increased temperature and hydrodynamic cavitation (HC) have significantly reduced the viscosity of MPC which can potentially increase the level of solids by reducing concentration polarization during nanofiltration (NF). We utilized plate and frame filtration (PF) as an alternate method to reduce the viscosity of MPC. In first objective, we studied the application of HC or elevated temperature (50˚C) or both to concentrate MPC with 80% protein (MPC80) based on total solids (TS) using NF. Three replicates of MPC80 having 20% TS were concentrated in NF system at 22 and 50˚C. HC did not have a significant impact on average flux but increased the TS significantly. Study showed that increased temperature or its combined action with HC improves NF performance in MPC filtration. In second objective, we studied the functionality of MPC80 powder after spray drying of NF retentates from first objective. Study showed that, higher temperature NF impacted on rennet coagulation time (RCT), wetting time, and heat coagulation time of the powders. Both HC and elevated temperature did not impact on flowability and emulsion capacity whereas HC alone improved dissolution and foaming capacity of the powders. Study showed that NF temperature and HC have important impacts on the functionality of MPC80. In third objective, we studied the application of PF in MPC80 concentration at 22 and 50˚C using flat-sheet ultrafiltration membrane. Average flux, final TS, and total protein to TS ratio were increased significantly at higher temperature PF. Study showed that increased temperature improves PF performance in MPC filtration. In fourth objective, we studied the functionality of MPC powders after spray drying of feed and PF retentates from third objective. Higher temperature PF impacted on RCT, wettability and solubility but improved foaming capacity and emulsion stability of the powders. Study showed that temperature optimization is important for concentrating MPC80 in PF system to maintain its functionality.

Library of Congress Subject Headings

Milk proteins.
Milk -- Composition.
Dairy processing.
Nanofiltration.

Format

application/pdf

Number of Pages

262

Publisher

South Dakota State University

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Rights Statement

In Copyright