Lactose-Derived Prebiotics

A Process Perspective

Andrés Illanes, Cecilia Guerrero, Carlos Vera, Lorena Wilson, Raúl Conejeros, Felipe Scott

• Publisher: Academic Press
• Year: 2016
• Print ISBN: 9780128027240
• eBook ISBN: 9780128027455
• Topic: Biological Sciences
• Subtopic: Biotechnology
• Index: Biological Sciences

Lactose-Derived Prebiotics: A Process Perspective is the first scientific reference to provide a comprehensive technological overview of the processes to derive oligosaccharides from dairy for use in functional foods. With their combined 90+ years in industry and research, the authors present the functional properties of prebiotics derived from lactose and the production technology required to make them. The book focuses on process engineering and includes an overview of green chemistry processes involving enzyme biocatalysis, providing detailed coverage of the use of whey lactose as raw material for producing oligosaccharides. The book's focus on processes and products allows the reader to understand the constraints and impacts of technology on lactose-derived prebiotics.- Presents the challenges of and opportunities for deriving oligosaccharides from lactose- Details the technologies and methods required to produce lactose-derived prebiotics, including a comparison between chemical and enzymatic synthesis- Discusses the potential use of whey as a raw material for the synthesis of non-digestible lactose-derived oligosaccharides- Provides a process engineer perspective and includes valuable information about kinetics and reactor design for the enzymatic synthesis of lactose-derived oligosaccharides

Chapter 1

Lactose

Production and Upgrading

A. Illanes

Abstract

Whey is a plentiful by-product from cheese manufacture that requires to be dried for further use, which may not be affordable to many producers. Besides, demand fluctuates according to price so that surplus whey is a matter of concern. Developing a platform for lactose upgrading is then a strategic opportunity for whey producers. When whey proteins are recovered, whey permeate is produced and lactose is its major component. Lactose upgrading by using it as raw material for the production of valuables like biofuels, organic acids and other fermentation products, and recombinant proteins and enzymes is then an opportunity for conciliating economic profitability and environmental protection. Among such products lactose-derived nondigestible oligosaccharides stand out as quite promising in terms of added value and increasing demand within the framework of the expansion of the functional food market. This is the core subject of this book, which is covered in depth in the following chapters.

Keywords

β-galactosidase; Bioethanol; Lactose; Lactose hydrolysis; Lactose transgalactosylation; Single-cell protein; Whey; Whey permeate; Whey proteins; Whey upgrade

1.1. Whey as Raw Material for Lactose Production

Milk is not only a basic component of human nutrition but also the raw material for an ever-increasing number of dairy products. It is also a rich source of valuable compounds that are mostly used in foodstuffs but also in nonfood applications. With respect to the latter, applications of casein, whey proteins, lactose, milk fat, and dairy effluents have been thoroughly reviewed by Audic et al. (2003).

Whey (milk whey or cheese whey) is a major by-product from milk processing, being the residual liquid obtained after casein precipitation by the action of acids (Morr and Ha, 1993) or enzymes (Kinsella and Whitehead, 1989). The former, whose pH is 5 or lower, is called acid whey and obtained by direct acidification of milk as in the production of cottage cheese; the latter, whose pH is around 6, is called sweet whey and produced by enzymatic coagulation of milk, as used in the production of most types of cheese. Chymosin is a protease that selectively hydrolyzes the Phe105–Met106 peptide bond of κ-casein triggering its clotting in the presence of calcium ions to yield the curd (Visser et al., 1977). The traditional source of chymosin is calf rennet, obtained as a by-product of veal production. Shortage of rennet as a source of chymosin for cheese making became critical so that now it has been replaced to a considerable extent by recombinant chymosin produced by fermentation with Aspergillus (Ward et al., 1990) and Kluyveromyces (van den Berg et al., 1990) strains used as hosts of the chymosin gene. Recombinant chymosin performance has been further improved in terms of specificity and pH profile by using protein-engineering strategies (Mantafounis and Pitts, 1990).

On a dry basis, cow milk contains approximately 28% protein, mostly casein, 29% fat, 38% lactose, and 5% minerals, while whey contains approximately 12% protein (less than 2% is casein), about 2% fat, approximately 77% lactose, and 8% minerals (Illanes, 2011). Whey, a by-product of cheese and casein production, despite being a rich source of lactose and valuable proteins—β-lactoglobulin, α-lactalbumin, immunoglobulins, and lactoferrin (Bottomley et al., 1990)—has been traditionally considered a nuisance rather than a valuable asset. In this context, companies have sought ways of proper management rather than valorization (Marwaha and Kennedy, 1988). This situation has been changing progressively through the years driven by environmental regulations (whey BOD and COD are around 40,000 and 70,000 ppm, respectively, almost 200-fold higher than common sewage), but also because of the economic revenues that may come from the commercialization of whey as a whole, its components, and those derived by its valorization (Smithers, 2008).

1.1.1. Whey as End Product

Whey containing more than 90% water and readily fermented components is highly perishable, so its supply under sanitary acceptable conditions is cumbersome. Therefore drying is necessary for its long-term utilization. Drying becomes an expensive operation, both in terms of equipment and energy consumption, when so much water is to be removed and, in practice, only medium-to-large cheese factories can withstand it. Liquid whey can be used as a liquid feed supplement in animal farming and as soil fertilizer, but transportation cost is high so in most cases its use is locally circumscribed (González Siso, 1996).

Spray-drying, rendering a stable nonhygroscopic product of quite uniform particle size, is the most appealing operation for dry whey production (Písecký, 2005). The principal market for dry whole whey is animal feeding where it is used mixed with molasses and soya flour (Schingoethe, 1976). Whole whey is also used in the formulation of institutional foods (Jelen, 1979), but its use is restricted because of its high lactose and mineral content, so demineralization is required (González Siso, 1996). Nutritional value of whey is related to its caloric value and also to its protein content although in this case whey protein concentrates or isolates are preferred to whole whey.

World production of whey was estimated close to 200,000,000 tons/year with an annual increase of 2% (Smithers, 2008). However, the market is unstable and international prices suffer high fluctuations encouraging or discouraging whey producers to dry it and put it into the market. Production is big enough to cover all present uses of whey and those to come in the near future, highlighting the strategic value of establishing a platform for whey utilization, as will be analyzed in the next section.

1.1.2. Whey Fractionation

Whey contains valuable components that will acquire commercial significance if separated. Therefore, whey fractionation is a key operation for fully exploiting its potential (Atra et al., 2005). Lactose and proteins represent almost 90% of whey on a dry weight basis and membrane separation (ie, ultrafiltration and diafiltration) is nowadays the technology of choice for their recovery (Pouliot, 2008). Membrane fractionation has the advantages of reduced cost, high throughput, gentleness, and neat separation of salts from the protein fraction (González Siso, 1996). The retentate, called whey protein concentrate (WPC), contains most of the whey proteins, while the permeate contains most of the lactose and mineral salts. Whey permeate is a main source for lactose production, so that it cannot be considered a waste stream, even though in some instances its recovery may not be profitable. The high mineral content of whole whey (close to 10% on a dry basis) may be objectionable for some of their applications, so desalting is necessary, which can be accomplished by membrane separation (nanofiltration) (Yorgun et al., 2008; Cuartas-Uribe et al., 2009), electrodialysis, and ion-exchange (Greiter et al., 2002; Nagarale et al., 2006). A thorough analysis of whey fractionation was presented by Tsakali et al. (2010).

1.1.3. Whey Proteins and Peptides

Whey proteins represent about 20% of the total protein content in milk, and its biological value has been estimated to be 15% higher than egg proteins (Smithers, 2008). Its protein quality score is much higher than casein’s, with a protein efficiency ratio of 3.4 versus 2.8, having a significantly higher proportion of essential amino acids (Evans and Gordon, 1980; Ha and Zemel, 2003). Its lysine content is remarkably high, thus making it a matching complement for lysine-deficient cereals (Delaney, 1976; Ibrahim et al., 2005; Jooyandeh, 2009). Content of sulfur amino acids, methionine and cysteine, is also high (around 20 mg/g), which is important for them being precursors of glutathione (Shoveller et ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Preface
• Chapter 1. Lactose: Production and Upgrading
• Chapter 2. Functional Foods and Feeds: Probiotics, Prebiotics, and Synbiotics
• Chapter 3. Lactose-Derived Nondigestible Oligosaccharides and Other High Added-Value Products
• Chapter 4. Enzymatic Production of Galacto-Oligosaccharides
• Chapter 5. Enzymatic Production of Lactulose
• Chapter 6. Enzymatic Production of Other Lactose-Derived Prebiotic Candidates
• Chapter 7. Technical and Economic Analysis of Industrial Production of Lactose-Derived Prebiotics With Focus on Galacto-Oligosaccharides
• Chapter 8. Future Trends and Concluding Remarks
• Index