Document Type

Dissertation - Open Access

Award Date

2020

Degree Name

Doctor of Philosophy (PhD)

Department / School

Dairy Science

First Advisor

Sergio Martínez-Monteagudo

Keywords

Byproduct, Dairy, Ice-cream, Valorization, Wastewater, Whey permeate

Abstract

Ever growing demand for dairy products in many countries has led to advancements in the manufacture of such products. Nowadays, revolutionary trends for high-protein dairy foods and drinks products have brought about new challenges from processing requirements and manufacturing aspects. Using different membrane processing has enabled dairy manufacturers to produce different fraction of milk proteins such as micellar caseins, ultra-filtered (UF) milk proteins, whey proteins concentrate (WPC), and micellar casein concentrate (MCC) to meet the nutritional needs with variety of milk product options. However, the installation of new processing lines and establishing further manufacturing steps requires more consumption of water and raises in the generation of waste streams and byproducts. Dairy wastewater is defined as a biomass with high biological oxygen demand (BOD), chemical oxygen demand (COD), nutrients, organic and inorganic materials. Therefore, dairy wastewater requires multifaceted treatment prior disposal into the municipal sewage system to avoid environmental jeopardies. In this research, the valorization of two main biomass streams from dairy manufacturing have been discussed – ice cream wastewater and whey permeate. Ever growing demand for dairy products in many countries has led to advancements in the manufacture of such products. Nowadays, revolutionary trends for high-protein dairy foods and drinks products have brought about new challenges from processing requirements and manufacturing aspects. Using different membrane processing has enabled dairy manufacturers to produce different fraction of milk proteins such as micellar caseins, ultra-filtered (UF) milk proteins, whey proteins concentrate (WPC), and micellar casein concentrate (MCC) to meet the nutritional needs with variety of milk product options. However, the installation of new processing lines and establishing further manufacturing steps requires more consumption of water and raises in the generation of waste streams and byproducts. Dairy wastewater is defined as a biomass with high biological oxygen demand (BOD), chemical oxygen demand (COD), nutrients, organic and inorganic materials. Therefore, dairy wastewater requires multifaceted treatment prior disposal into the municipal sewage system to avoid environmental jeopardies. In this research, the valorization of two main biomass streams from dairy manufacturing have been discussed – ice cream wastewater and whey permeate. been recognized as a promising method for conversion of ice-cream wastewater into valuable chemicals such as surfactants, foaming agents, emulsifiers, and animal feed. Hydrolysis ice-cream wastewater under subcritical treatment (230˚C, 40 bar, and 240 min) reduced its organic materials significantly (87-97 and 25-70% of the BOD and COD, respectively). Moreover, the subcritical process hydrolyzed 38 to 56% of the protein fraction, and the resulting hydrolysates showed antioxidant activity (14-19% of the DPPH) and antihypertension (ACE) activity (60-97%). Additionally, the hydrolysates contained a high ratio of glutamic acid (20-26%) and proline (10-15%), which confirmed the relevant functional properties. Whey is the main byproduct obtained from the manufacture of cheese, yogurt, and milk protein concentrates. After separation of whey proteins through membrane processing, the remained stream is known as whey permeate, and it contains a considerable amount of lactose (75–80% on dry basis). As a feedstock, lactose has the potential to undergo different reactions leading to the formation of value-added compounds. The simultaneous production of lactulose (LAU), lactobionic acid (LBA), and organic acids from sweet and acid whey permeate (SWP and AWP) via catalytic synthesis (5% Ru/C) was studied in a continuous stirred-tank reactor. At selected conditions (60˚C, 60 bar, and 600 rpm), a maximum conversion of lactose (37 and 34%) was obtained after 90 min for SWP and AWP, respectively. The highest yield calculated with respect to the initial concentration of lactose for LAU was 22.98 ± 0.81 and 15.29 ± 0.81% after only 30 min for SWP, and AWP, respectively. For LBA, a maximum yield was found in SWP (5.23%) after 210 min, while about 2.2% was found in AWP. Six major organic acids (gluconic, pyruvic, lactic, formic, acetic, and citric acid) were quantified during the one-pot synthesis of lactose. The synthesis of a pool of molecules through a one-pot approach represents an alternative approach for the utilization of streams of lactose. Upon further separation, organic acids can be used as building blocks of numerous applications in the manufacture of herbicides, bioplastics, and biofertilizers.

Library of Congress Subject Headings

Dairy waste.
Dairy plants -- Waste minimization.
Whey products.
Dairy processing -- By-products.

Format

application/pdf

Number of Pages

181

Publisher

South Dakota State University

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Rights Statement

In Copyright