UC Davis

Colostrum is a nutrient-dense secretion produced by the mammary glands for several days after parturition. In the dairy industry, colostrum is often produced surpassing the calf’s needs and is subsequently considered a surplus, representing an opportunity for further utilization. Because of its high protein concentration, which includes immunoglobulins, colostrum has a higher viscosity than mature milk, posing challenges to downstream processing. While excess liquid colostrum can be pasteurized and dried into colostrum powder for both animal-rearing and human consumption, these heat-dependent processing methods reduce the nutritional potential of the bioactive components. Further, colostrum is prone to bacterial contamination due to its high nutrient content, underscoring the importance of proper processing to salvage this valuable resource. While colostrum has long been recognized as essential for the health and development of newborn calves, there has been growing interest in its application to human health. Immunoglobulins have received the most extensive research attention among the components of bovine colostrum. Nevertheless, there are other small bioactive components like oligosaccharides (OS) and peptides that have gained recognition. To date, most commercial processing of bovine colostrum has primarily focused on whole colostrum preservation. However, these existing techniques rarely consider the loss of bioactivity in the whole colostrum or the potential enhancement of bioactivity through purification strategies or alternative processing methods. Therefore, this thesis presents the development of scalable processing strategies to improve the recovery of bioactive OS and peptides for enhanced in vitro biological activity from bovine colostrum and its byproducts.Chapter 1 provides an overview of current commercial-scale processing technologies for bovine colostrum. It also introduces scalable strategies to recover and enrich for various bioactive components. In addition, this chapter delves into the nutrient-rich composition of colostrum, encompassing lipids, protein, carbohydrates, and peptides, to underscore the diversity of components with bioactive potential as well as their human health applications. Chapter 2 evaluates the use of a hollow fiber ultrafiltration membrane to efficiently recover small bioactive components (e.g., OS and peptides) from bovine colostrum whey. Hollow fiber membranes can be utilized in applications with viscous material, like colostrum whey, and are generally operated in the laminar region, thereby reducing energy consumption compared to other configurations. A series of experiments, using sequential design, was utilized to identify the effects of feed flow, transmembrane pressure, and method of diafiltration on the permeate flux and selective permeation of OS and peptides. The goal was to maximize the recovery of OS and peptides while minimizing protein permeation and reducing water use. The optimal filtration conditions were utilized to produce whey permeate with high peptide and OS content for subsequent concentration, fractionation, and characterization of their composition and biological properties in the proceeding chapters (Chapters 3 and 4). Chapter 3 explores the use of pilot-scale nanofiltration membranes as a scalable, environmentally friendly strategy for concentrating small bioactive components, OS and peptides, from the bovine colostrum whey permeate produced by the conditions defined in Chapter 2. A central composite rotatable design (CCRD) was utilized to identify the impact of membrane pore size and material, feed flow, and transmembrane pressure on the permeate flux and recovery of OS and peptides by two nanofiltration membranes. The optimal filtration conditions for each membrane were utilized to concentrate whey permeate, and the efficiency of the filtration was evaluated through resistance calculations and overall retention of the target molecules. The recovered materials (rich pools of OS and peptides) were then evaluated for in vitro prebiotic potential and antioxidant, antihypertensive, and antidiabetic properties. This work provides an efficient and effective method for concentrating small bioactive components from colostrum whey permeate. Furthermore, it demonstrates promising health applications for these compounds when used in combination. The methods optimized for colostrum whey permeate in this work can also be applied to whey permeate derived from mature milk, a substantial stream produced during the whey protein concentration process, commonly disposed of as animal feed. The impact of fractionation by membrane filtration to selectively enrich for OS or peptides from bovine colostrum whey permeate is detailed in Chapter 4. Two tight ultrafiltration membranes were individually optimized by using CCRDs to understand the role of membrane chemistry, pore size, feed flow, and transmembrane pressure, similar to Chapter 3. However, this work focused on developing filtration conditions that could fractionate OS from peptides rather than recovering both components in the same pool as described above. The differences in in vitro prebiotic activity and antioxidant, antihypertensive, and antidiabetic properties of the recovered fractions elucidated the distinct biological role of each component (OS or peptides) and paves the way for future development of commercially scalable technologies to recover OS or peptide fractions for targeted health applications. Chapter 5 explores the use of another industrially viable processing strategy, enzymatic hydrolysis, on bovine colostrum and mature milk protein fractions to generate bioactive peptides. While proteins can be bioactive, the utilization of proteases can generate peptides that may exhibit greater bioactivity. Through a series of sequential experiments, the impact of milking time (colostrum vs. mature milk), substrate (curd vs. whey), enzyme type, and hydrolysis time on degree of hydrolysis and in vitro bioactivity (antihypertensive and antioxidant capabilities) was evaluated. To assess the role of peptide size on bioactivity, select hydrolysates were fractionated using a 3 kDa centrifugal filter and each fraction (permeate and retentate) was re-evaluated for antihypertensive and antioxidant capacity, confirming the distinct impact of peptide size and purity on bioactivity. In this collection of studies, we present the applications of commercially scalable processing approaches to isolate small bioactive components from dairy streams, specifically bovine colostrum and its byproducts. The starting materials utilized in these studies, bovine colostrum and mature milk, possess the same components yet in different proportions. The differences in component concentration, in addition to batch variation, are discussed in Chapters 4 and 5, and confirm the importance of studying different matrices while developing strategies with broad applicability. Additionally, this work underscores the value of harnessing bovine colostrum and developing industrially viable processing strategies to enrich for and utilize individual components for human health benefits, reframing colostrum from an excess stream with limited animal applications to a rich starting material for producing nutraceutical ingredients for human health applications. These insights, along with further investigation into scalable purification and extraction strategies, highlight the opportunities to repurpose food byproducts and industrial streams as alternatives to conventional pharmaceuticals. This approach holds potential to improve human health in an environmentally sustainable manner.