Preface

Milk is one of the most nutritious of all foods and is widely consumed worldwide. It is a rich source of nutrients and has several biological properties that modulate the biochemical processes in the human body. Milk and milk products have not only become essential products in diets but have also become a global industry, thus, understanding the science of milk, and the biochemical, nutritional, and physical properties of its components, is important to create the unique diversity of the dairy industry. Dairy science and technology involves understanding the technical and scientific aspects of processing, packaging, distribution, and storage of dairy ingredients all the way from lactating mammals to ready-to-eat products. For example, the application of advanced science and technology in dairy processing has resulted in enhancing the shelf life of products such as yogurt, pasteurized milk, cheese and other fermented milk foods, butter, protein products, milk powders, and milk-based nutritional formulations with enhanced sensory attributes and nutrition values. Dairy science and technology are applied in optimizing processes and innovation to convert milk into value-added products, ensuring consumer well-being and food security for a growing global population. Thus, this book provides different perspectives on science and technology as they relate to dairy processing.

Chapter 1, "From Traditional Bulgarian Diary Products to Functional Foods", discusses the science of the use of specific starter cultures in the fermentation process for the manufacture of high-quality fermented foods at the industrial as well as domestic levels. The history of fermented food production begins with traditional Bulgarian dairy products. Elie Metchnikoff, a Russian-French zoologist working in Bulgaria in 1907, was encouraged by the observation that certain Bulgarians who consumed fermented dairy lived significantly longer and healthier lives. Later, it was reported that the health effects of fermented dairy products are related to the microbial biodiversity of these products. Specific microorganisms, mainly lactic acid bacteria (LAB), are used in the fermentation of milk to develop these fermented products with unique physical and biochemical properties. The chapter also evaluates the various functional characteristics of LAB microbiota in traditional fermented foods and the possibilities of implementing prospective strains in new functional formulas, following traditional recipes.

Chapter 2, "Medicinal Potential of Camel Milk Lactoferrin", examines the chemical components and medicinal value of camel milk. Camel milk is known for possessing properties similar to those of human breast milk. Moreover, camel milk differs from that of other animals such as cows, goats, and sheep by its antimicrobial, anticancer, and immunomodulatory properties that confer its medicinal potential. Camel milk consists of various bioactive peptides, minerals, mono and polyunsaturated fatty acids, and proteins. It is a rich source of the protein lactoferrin. Lactoferrin is an ironcontaining glycoprotein that plays a vital role in the innate immune system of humans and possesses proven cancer-fighting and antimicrobial properties. The global market for camel milk products is predicted to be valued at USD 53.78 million by 2027 with a compound annual growth rate of 6.8% during that period.

Chapter 3, "Milk Borne Brucellosis", is about food safety specifications related to the milk-borne infectious disease, brucellosis. Food products made with milk from domestic animals carry a high risk of contamination by harmful bacteria. Brucellosis is a common milk-borne bacterial infection that can spread from animals to people when raw or unpasteurized milk products are consumed. Brucella abortus and B. melitenses are common milk-borne pathogens of the species. The primary hosts of B. melitenses are goats and sheep, whereas cattle are associated with B. abortus. Brucella is responsible for an acute feverish illness that can eventually progress to a more serious, chronic, incapacitating disease. The control of risk factors and surveillance are thus the cornerstones of brucellosis prevention.

Chapter 4, "Innovative Approach of Cheese Making from Camel Milk: A Review", relays an innovative approach to maximizing the potential of using camel milk as a base for manufacturing cheese. The quality of the cheese product depends on the chemical composition of the milk base used and the technical characteristics of the cheese-making processes. Regarding its chemical composition, camel milk is significantly different from other kinds of milk, such as cow's milk, which is generally used in cheese production. This can lead to inefficiency in the use of the typical technology in the cheese-making process or result in low-quality end products. The chapter reviews recent advancements in making cheeses from camel milk using starter cultures and coagulants along with potential ingredients for the fortification of final products to maximize the possibility of manufacturing cheese from camel milk.

Chapter 5, "Acid-Induced Gelation of Milk: Formation Mechanism, Gel Characterization, and Influence of Different Techniques", discusses the mechanism of acid-induced gelation of milk. The techniques applied in the acid coagulation process determine the structural properties of the final gels. Thus, a better understanding of the mechanism results in desired properties in fermented dairy products. Acidinduced coagulation of milk is a complex process, and the development of the gelled structure involves the reduction of stability of casein micelles, casein aggregation, and the progressive formation of the protein network during acidification and cold storage. Other than the processing techniques of high-pressure treatment, heating, enzymatic treatment, and ultrasonication involved in acid-induced coagulation of milk, the use of polysaccharides as additives can also determine the microstructure and rheological properties of acid gels.

Chapter 6, "Milk Fat Globular Membrane: Composition, Structure, Isolation, Technological Significance and Health Benefits", discusses the details of the composition and structure of milk fat globule membranes as well as their existence and application in various types of milk and milk-based foods. The milk fat globule membrane (MFGM) is a complex and characteristic structure consisting of lipids and proteins that surround fat globules in milk. MFGM can be used in food as an emulsifier and stabilizer with excellent water-holding capacity in dairy products. MFGM has also been identified as a source of various bioactive compounds that have significant functional roles in human health. Moreover, MFGM has been proven to be a functional food and beneficial infant food due to its potential to support cognitive development and reduce risks of infection.

Chapter 7, "Volatile Aromatic Flavor Compounds in Yogurt: A Review", reviews yogurt flavor and the role of chemical compounds in defining the sensory characteristics of yogurt. The sensory quality, including flavor, texture, and other organoleptic properties of yogurt, is reliant primarily on the relative balance of volatile compounds derived from fat, protein, and carbohydrate in the milk base used during the fermentation process. The type and level of compounds derived during fermentation depend on the starter culture, lactic acid bacteria *Lactobacillus acidophilus* and *Streptococcus thermophiles*, both of which are commonly used in the yogurt industry, and the conditions of the fermentation process. It has been reported that more than 100 different volatile compounds have been identified in yogurt, including carbonyl compounds, alcohols, acids, esters, and sulfur-containing compounds. These compounds are a result of the synbiotic activities of the starter culture (*L. acidophilus* and *S.thermophiles*) in addition to the interaction of the nutrients (lipids, proteins). As with many other dairy products, yogurt is prone to deterioration due to the generation of volatile byproducts, resulting in off-flavors that make the product unsatisfactory for consumers.

Chapter 8, "Lactic Acid Bacteria: Review on the Potential Delivery System as an Effective Probiotic", reviews the importance of lactic acid bacteria (LAB) as a probiotic to human health and its metabolic fermentation and antioxidant properties. In addition, the chapter discusses biotechnological methods that improve the survival rate of probiotics during processing, storage, and gastrointestinal transit, such as microbial encapsulation, freeze drying, spray drying, and so on. LABs are essential dairy starter cultures that are used to produce several fermented dairy products, including yogurt and cheese. LABs are generally employed in food processing due to their significant contribution to enhancing the flavor, texture, and quality parameters of food products. Probiotics and postbiotics can also have antioxidant properties that help in preventing disorders linked to oxidative stress. Products with these beneficial organisms are available commercially in forms such as functional foods and beverages and dietary supplements. Since our knowledge of the relationship between diet and health has increased significantly in recent years, and consumers are now much more actively engaged in how food affects health, the market for probiotics is flourishing.

#### **Salam A. Ibrahim**

Food Microbiology and Biotechnology Laboratory, Food and Nutritional Science Program, North Carolina A&T State University, Greensboro, NC, USA
