Milk is considered an ideal food for neonates, adolescents, adults and geriatrics and hence every attempt has been made by mankind to preserve this wholesome food by various processing operations. In the recent decade, the focus of attention has been on improving the quality, particularly sensory, nutritional and functional qualities of foods and at the same time, minimizing the processing and post harvest losses through technological and biotechnological interventions. Recent advancements in dairy technology have also offered the opportunity not only to control the existing food processes in better way, but also to adopt entirely novel approaches to quality control and newer product development. Meanwhile, an ever-increasing variety of specialized dairy products from whole and skim milks to creams, cheeses, yoghurts, whey products and specialty powders are opening up tremendous opportunities for growth. In search of efficiency, the dairy industry, a major sector of the food industry at a national level, is constantly seeking to improve the working practices, and the advances in process technology are an integral part of this trend. Growing awareness towards the beneficial role of milk and milk products in maintaining human health has led to the development of a wide range of novel functional foods, health foods, neutraceuticals, mood elevating and refreshing foods. In the advanced countries the dairy industry is rapidly diversifying its product to produce a range of dairy foods that are targeted to reduce the role of medicines in maintaining the human health. In addition, there are also vast opportunities of development of new milk products for improving their functional and nutritional attributes by the use of food biotechnology. Biotechnology may have immense impact in all areas of food processing, starting from raw material production to improving the shelf life, and enhancing the acceptability and nutritive value of foods. Further the knowledge of physicochemical and microbiological characteristics of milk is most important to understand the properties of food, improving its quality and storage stability and controlling its behavior during handling. I found this an excellent textbook on physicochemical and microbiological characteristics of milk, processing and preservation of milk, manufacturing of various dairy products and quality assurance. This book will be very useful to students as well as faculty in the universities and institutes. In addition to enhancing the quality of instruction it will also be of great value to food scientists. Professor (Dr.) Singh is eminently qualified to write the book on Dairy Technology because of his in-depth knowledge, understanding and dedication to the subject of dairy and food science research and education. This book provides comprehensive coverage of all topics related to dairy technology, suitable for students in the discipline of dairy and food science and technology. I congratulate Professor (Dr.) Singh for this accomplishment and wish him all success in his endeavour.

1.1. General Discussion of Milk “The cow is the foster mother of the human race. From the days of the ancient Hindoo to this time have the thoughts of men turned to this kindly and beneficent creature as one of the chief sustaining forces of human life”. William Dempster Hoard (1836-1918) Former Governor, State of Wisconsin, USA (1889-1891) Founder of Hoard’s Dairyman (1885) The oldest written records of the human race are in Sanskrit and are preserved in India. At the time these records began, about 6,000 years ago, milk had already become an important article of food. In fact, so important was the cow to these early people of South and Central Asia that wealth was measured in numbers of cattle, and the cow was in time made a sacred animal and is still so considered in India. According to the best authorities, the domestication of cattle must have occurred somewhere between 6,000 and 10,000 years ago. The cow was worshipped in Babylonia, and in Egypt about 20,000 B.C. Over fifty references to cows and milk are found in Old Testament and the Promised Land was described as “a land flowing with milk and honey”. Milk is the only food of the young mammal during the first period of its life. The substances in milk provide more energy and the building materials necessary for growth. Milk also contains antibodies which protect the young mammal against infection. A calf needs about 1000 litres of milk for growth, and that is the quantity which the primitive cow produces for each calf. There has been an enormous changes since man took the cow into his service. Selective breeding has resulted in dairy cows which yield more than 5,000 litres of milk per calf, i.e. five times as much as the primitive cow. Some cows can yield 10,000 litres or more.

“Tell me what you eat and I will tell you what you are. The destiny of people depends on the nature of its diet.” A. Brillat-Savarin Milk is the only product which is considered nature’s almost perfect food. It is treasure house of unlimited nutrients. It is considered best and ideal food by virtue of possessing almost all the nutritional factors, viz., fats, proteins, carbohydrates, minerals and vitamins. They are not only of higher quality but are present in milk in such form and proportion that their digestion and assimilation in the body is very efficient. Milk also plays a supplementary role in our nutrition. If it is included in our diet it enhances digestion and assimilation of nutrients of other food products. This is the reason that it is kept in high esteem as a food and is called the nectar for living beings. Milk is the first taste of food for whole mankind. It establishes the mother-infant bond and is a life promoter. Of the many fluids that biology offers milk is perhaps the most versatile in terms of its use– as food, as a growth stimulant and as a defense package to the user. To the infant mammal – be it a mouse, calf or a human child, mother’s milk is more than a source of energy and nutrients. It contains a wide variety of substances that defend the growing infant against infections. Milk, a perfect blend of nutrition and palatability, plays an important role in preserving mental and physical health. Milk has long been recognized as the most wholesome and complete single food available in nature for health and as a medicine, both preventive as well as curative. Ancient chronicles as recorded in the Upnishads, Puranas and Vedas extol the beneficial and therapeutic properties of milk and milk products. It has been stated that cow milk, dahi and ghee impart knowledge and radiance, cure heart trouble and anaemia besides other bodily diseases.

Milk is a complex colloidal dispersion, the physical and physicochemical properties of which depend on intrinsic compositional and structural factors, extrinsic factors such as temperature, and post-milking treatment. There is no clear dividing line between physical properties and physicochemical properties. However, physical properties may be thought of as the measure of the bulk behaviour of milk and of how milk interacts with energy, while physicochemical properties are measures of how bulk behaviour and energy interactions depend on the constituent colloidal particles, molecules, atoms and ions in milk. Knowledge of physical properties is of importance particularly in the technological and engineering design and control of milk processes and processing equipment. Knowledge of physicochemical properties provides the basis for the design of modern methods of milk analysis, determination of milk microstructures and elucidation of the complex chemical reactions that occur in milk. In the dairy industry measurements of the physical properties of milk and milk products are made to secure data necessary for the design of dairy equipment (e.g., heat conductivity and viscosity) to determine the concentration of a component (e.g., specific gravity to estimate solids-not-fat or freezing point to determine added water), or to assess the extent of a physical or chemical change (e.g., titratable acidity to follow bacterial action or viscosity to assess aggregation of protein micelles or fat globules). The great advantage of physical measurements for such purposes is their speed and simplicity as well as their potentialities for automation. Use of physical property to measure concentrations or changes in degree of dispersion demands knowledge of the contribution of the several components to that property. Furthermore, the natural range of variation of the property in milks or products is of major interest. The precision and suitability of possible methods of measurement are also of prime importance.

Microorganism is a collective term for all living organisms, which are not visible to the eye, and occupy an intermediate position between the vegetable and animal kingdoms. They are found every where in the atmosphere, in water and in the soil and, as they break down organic materials, they play a very important role in the cycle of the nature. There are thousands of species which are important to the life and economic structure of the human race. For example, certain species form simple chemical elements during the break down of dead organic material which plants can use again. They increase soil fertility and crop production which results in more food. Other species are present, and essential, in animal intestines, helping in the digestion of food. Some microorganisms are used in many food processes, e.g. dahi, yoghurt, cheese, pickles, beer and wine as well as in the acid production to preserve foods. There are microorganisms that produce toxic substances which kill other organisms, e.g. the mould penicillium which produces the substance penicillin. Many microorganisms cause diseases in animals and plants with a subsequent reduction in the nation’s food supply, whereas others cause food deterioration such as mouldy foods, tainted foods, etc.

Milk is a highly perishable commodity. The shelf life of raw milk is in hours. In order to harness its full potential for the well being of the humanity, it is essential to extend its shelf life not only in days but also in months and years. This can be achieved by judicious application of processing and preservation technologies. Preservation is any purposeful treatment or processing of a food which prevents spoilage and extends the shelf life of raw material to a longer than its natural keeping quality. During storage and distribution foods are exposed to a wide range of environmental conditions. Environmental factors such as temperature, humidity, oxygen and light can trigger several reactions that may lead to food deterioration. As a result foods may be altered to such an extent that they are either rejected by the consumer or are harmful to the person consuming them. It is, therefore, essential that the good knowledge of different reactions that cause food deterioration is gained prior to understanding the principles of food preservation. The deterioration in foods may be caused either due to internal or external chemical or microbial reactions occurring in milk. The changes may be either latent to senses of consumer, or they may be discernible by the human senses. The consumer cannot perceive latent changes visually, olfactorily or otherwise, and laboratory measurements are the only method to detect them. Still the nutritional value of such materials may be seriously impaired. Such changes include fermentation, oxidation of lipids, loss of vitamins and changes in the contents and composition of nitrogenous substances. Non-microbial changes in foods, perceptible to human senses, may often lead to serious deterioration noticeable to the average consumer. These include discolouration and changes in odor, taste and consistency. Microbial changes may result in alteration of original properties of milk making it unfit for further processing, deterioration in flavour quality, loss of nutrients and toxin production.

Membrane technology is a proven separation method used on the molecular and ionic levels. Since the beginning of the 1970s, this technique has been adopted by the dairy industry. Membrane separation is widely used in dairy processing plants to perform an ever-increasing range of duties, e.g. pre-concentration, partial demineralization, protein separation, bacteria removal, brine clarification and waste water recycling. Representing one of the great technological developments occurring within the dairy industry during the second half of the twentieth century, progress was driven initially by the transfer of know-how gleaned from the application of cellulose acetate-based reverse osmosis (RO) and ultrafiltration (UF) membranes in other industrial sectors to whey processing. Later, new membrane materials and engineering designs were built on this initial achievement and opened up further opportunities for the application of the full spectrum of membrane separation systems that also includes Nan filtration (NF) and cross-flow microfiltration The integration of these unit operations into traditional dairy processes has led to the development of innovative ingredients as well as improvements in yield, efficiency and product quality. R & D work indicates potential RO application for concentration of milk for products like khoa, condensed and dried milk products and of UF application for the manufacture of shrikhand, paneer, chana and cheese. Application of these processes permits higher energy saving, higher yields and superior product quality compared to traditional processes of thermal evaporation.

Packaging means a coordinated system of preparation of goods for distribution, storage, merchandizing and shipment at optimum cost compatible with the requirements of the product. It also includes the art, science and technique used, preparatory to and during transportations and selling of goods and technical methods and work processes related to the above preparations. The broad range of dairy products necessitates that packaging equipment and materials encompass nearly all types from flexible to rigid and from high to low barrier. The general types of packaging and equipment are discussed below with a focus on fluid products but it must be recognized that other dairy products such as cheese have their own particular packaging requirements and technologies. Role of packaging in distribution and sale: The essence of what makes milk and dairy products important source of human nutrition also causes rapid deterioration and high perishability. The major role of dairy packaging is to retard the deterioration by preventing microbial recontamination and excessive chemical deterioration. Fluid products are especially susceptible to microbial, enzymatic and chemical degradation. In addition to retarding quality loss, packaging must provide containment, facilitate use, identify products, communicate, and appeal to consumers, all with maximum production efficiency. The large volumes and low unit value means that these functions must be met with minimal economic cost and environmental impact. Because food packaging is generally highly regulated, legal requirements must also be understood and met.

When natural constituents of whole milk are altered by addition, removal, exchange and / or treatment, the resultant milk is designated as special milk. Recent years have witnessed a large increase in market penetration of special milks into the total fluid milk market. In many countries, now a large portion of fluid milk is consumed in the form of special milks. Manufacturers of special milks offer numerous advantages that are broadly related to dietary, cost and scarcity aspects. Special milks provide an avenue to diversify the milk with variety of flavours and other characteristics. Milk is considered as nature’s almost perfect food. However, milk in its natural form is not considered suitable for many more healthy people who do not like the taste of milk as such. All these problems can be overcome by manufacturing special milks such as dietetic milks, low fat milks, flavoured milks, etc. Butterfat is the most expensive constituent of milk. Therefore, the cost of buffalo whole milk is very high and many people particularly the weaker section of our society cannot afford to buy it. Consequently, manufacture of low priced toned milk was introduced in many markets. This also enabled the dairy plants to meet the ever increasing demand of milk, particularly during lean season. Replacement of butterfat by vegetable fat could also help in reducing the cost of milk Due to seasonal fluctuation in milk production, there is acute shortage of milk during the lean period in our country. In certain parts of the world fresh milk is not produced at all. Manufacture of reconstituted and recombined milk from anhydrous milk solids can overcome such whole milk shortage. These anhydrous milk solids could either be prepared from the domestic seasonal surplus or marketed from those countries that have surplus milk production. The machinery and manpower of a market milk plant can be fully utilized all the year round by such diversifications.