Document Type

Dissertation - Open Access

Award Date

2021

Degree Name

Doctor of Philosophy (PhD)

Department / School

Dairy Science

First Advisor

Sanjeev Anand

Second Advisor

Sergio Martinez Monteagudo

Abstract

Phospholipids (PLs) found in milk are of great interest due to their health and nutritional benefits associated with their consumption. By-products generated during the manufacture of dairy products represent a source of PLs with potential for value-added opportunities. Currently, the extraction of PLs from by-products results in overall lowefficiencies, and it involves subsequent solvent separation and lipid recovery. This dissertation studied the extraction of milk PLs from by-product streams with a tertiary anime (N, N-dimethyl cyclohexylamine, CyNMe2) as a switchable hydrophilicity solvent. This type of solvents can be reversibly switched between a hydrophobic and hydrophilic form in the presence or absence of CO2. Different dairy by-products streams, including buttermilk (BM), beta-serum (BS), concentrate buttermilk (CBM), and raw cream (RC) was used to evaluate the feasibility of CyNMe2. The extraction efficiency of CyNMe2 ranged from 0.33-99%, depending on the type of byproduct. Remarkably, CyNMe2 extracted up to 99% of the PLs directly from buttermilk. The extraction of PLs from BS was further studied using ultrasound prior to CyNMe2 extraction. Overall, higher levels of acoustic intensity (44.56 ± 3.47 W cm-2) prior to CyNMe2 extraction recovered 69.07 ± 0.11% of PLs, 10-fold higher than the samples without ultrasound pretreatment. The recovered fraction of PLs mainly comprised of phosphatidylinositol (32%), phosphatidylethanolamine (30%), and sphingomyelin 37%). The effect of the extraction temperature (25, 40, and 60oC), time (3, 10, and 18 h) and solvent ratio (3/1, 10/1, and 18/1 mL) was also studied. The highest yield obtained was 29.29 ± 0.06% of PLs at 60 oC, at minimized solvent ratio and time (3/1 mL and 3 h, respectively). At these conditions, the fraction of PLs recovered was phosphatidylinositol (59%) and phosphatidylethanolamine (35%). Insights into the extraction mechanism of the CyNMe2 was studied through various analytical measurements, such as analysis of protein-profile, particle size, zeta potential, and microstructure, Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscopy (SEM). CyNMe2 seems to disrupt the protein-membrane through ion pair formation, releasing the PLs into the aqueous medium. Throughout this thesis, CyNMe2 shows to be an effective way to concentrate PLs from by-products.

Library of Congress Subject Headings

Phospholipids.
Milk.
Dairying -- By-products.
Extraction (Chemistry)

Number of Pages

20

Publisher

South Dakota State University

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Rights Statement

In Copyright