eChapters

Abstract

Hot air circulation is the most common industrial method of drying foods which has its own inherited disadvantages. Microwave drying can be an alternative method for removing moisture from foods and there has been a surge of interest in the application of microwave to process the foods, in past few years. The reason being that there is worldwide energy crisis and the growing acceptance and familiarity with domestic microwave ovens. It is well known that conventional means of heat processing irreversibly alter the flavor, colour, and texture of many foods. From the point of flavor alone, it is desirable to improve our present methods of processing foods. Some improvements have been made in this direction with a number of food products by use of high-temperature short- time processing.

Food adulteration is a global issue, and because there are insufficient regulations and oversight, developing nations are more vulnerable to it. But in many nations, food adulteration has gone unnoticed. Contrary to popular assumption, milk adulterants can, regrettably, present major health risks that result in fatal diseases. Modern milk adulteration involves increasingly complex techniques, necessitating state- of- the- art research to identify the adulterants. Because milk contains so many nutrients that are needed by both adults and infants, it is referred to as the ideal food. In terms of protein, fat, carbohydrates, vitamins, and minerals, it is among the best sources. Regretfully, milk adulteration is a very common problem worldwide. Potential causes could be the gap between supply and demand, the perishable nature of milk, the low purchasing power of the consumer, and the absence of appropriate detection tests. Because there is insufficient oversight and inadequate law enforcement, the situation is substantially worse in developing and underdeveloped nations. While quantitative detections of adulterants in milk are varied and complex, qualitative detections can be carried out simply using chemical reactions. The type of quantitative detection methods used depends on the milk’s adulterants.

Typical Adulterants in Milk

The addition of vegetable protein, milk from different species, whey addition, and watering are the main adulterants in milk that are known to be economically motivated. There is no serious health risk associated with these adulterations. Some adulterants, though, are too dangerous to ignore. Urea, formalin, detergents, ammonium sulfate, boric acid, caustic soda, benzoic acid, salicylic acid, hydrogen peroxide, sugars, and melamine are a few of the main adulterants in milk that have been shown to have serious negative health effects.

    1.    As per FSSAI, 2011 regulations, what is the fat and SNF content in buffalo milk
        a)    5 & 9    b)    6 & 8
        c)    6 & 9    d)    None
    2.    As per FSSAI, 2011 regulations, what is the fat and SNF content in  cow milk
        a)    4 & 9    b)    4 & 8.5
        c)    6 & 9    d)    None
    3.    As per FSSAI, 2011 regulations, what is the fat and SNF content in  standardized milk
        a)    4 & 9    b)    4.5 & 8.5
        c)    6 & 9    d)    None

Importance

The dairy products, which have originated in India, are called indigenous dairy products. The products can be broadly classified in to khoa based and channa based. The importance of the dairy products were known to Indians since time immemorial or it could be roughly estimated to be around five thousand years ago and the development could be considered as an art.

Introduction

There has been a considerable progress in the overall production in the dairy sector. Without a proper marketing, the country would not attain the expected rate of growth in dairy farming. Marketing is a flow of goods and services from producer to consumer and users. In this process the activities include moving the goods from the point of production to the point of consumption. The activities like creation of time, place, form and utility are involved. According to Philip Kotler, marketing as a human activity directed at satisfying the needs and wants through exchange process. The performance of the trade activities involved in the f low of goods and services affect the marketing efficiency and producers share in the consumer rupee. A marketing system consists of different milk marketing channels. That marketing channel is considered good in which producer get the highest share in consumer rupee and consumer share is highest in producers rupee. The interest of the Producer is to get the highest possible returns from their milk. Between them, there are marketing intermediaries or middlemen who perform various marketing functions like transporting and retailing. All the intermediaries/ middlemen are also interested to make highest profit from the milk business. The present lesson provides information on the economic aspect of marketing of milk and milk products through a empirical study conducted in Rajasthan state.

The significance of milk in human nutrition is now well established as it is considered as the best, ideal and complete food for all age groups. However, in spite of being so, milk can also serve as a potential vehicle for transmission of some diseases under certain circumstances. Moreover, by virtue of possessing almost all the essential nutritional factors, milk can also serve as an excellent culture and protective medium for certain microorganisms, which may include potential pathogens capable of causing serious health problems to the consumers. In this way, milk may serve not only as a vehicle of transmission of disease causing organisms, but it can also allow these pathogens to grow, multiply and produce certain toxic metabolites, thereby making itself an extremely vulnerable commodity from public health point of view.

Carbohydrates are polyhydroxy derivatives of aldehydes or ketones and undergo all the organic reactions common to the carbonyl groups and hydroxyl groups. The principal milk carbohydrate is lactose. It is a disaccharide. Hydrolysis of lactose with enzyme β-galactosidase yields glucose and galactose.

Lactose is the major carbohydrate present in all types of milk. The first record of isolation of lactose was in 1663, by Bartolettus by evaporation of whey. Milk contains only trace amounts of other sugars, including glucose, fructose, glucosamine, galactosamine, neuraminic acid, and neutral and acidic oligosaccharides.

Lactose plays a significant role in milk and milk products that are

• It plays a major role in the production of fermented dairy products.

• It contributes to the nutritive value of milk and milk products

• It affects the texture of certain concentrated and frozen products;

• It is involved in heat-induced changes in the color and flavor of highly heated milk products.

Status of Lactose

Lactose content varies extensively in the milk of different species. Breed of animal, individuality factors, udder infection, and especially the stage of lactation regulates the lactose content in milk. The lactose concentration in milk decreases gradually and significantly during lactation; this behavior contrasts with the lactational trends for lipids and proteins, which, after a decrease during early lactation, increase significantly during the second half of lactation. Lactose synthesis is hampered during mastitis. Lactose, along with sodium, potassium, and chloride ions, plays the principal role in controlling the osmotic pressure of the mammary system. Thus, any change in lactose content is compensated by a change in the soluble salt constituents. The osmotic relationship between lactose and soluble salts during the secretion of milk partly explains the presence of high lactose in milk with a reduced ash content and vice versa (Table 1).

Types of Enazymes in milk

1. Endogenous and 2. Exogenous.

Three sources of enzyme in milk:

1. The blood via defective mammary cells.

2. Secretory cell cytoplasm. Some of which are occasionally entrapped with fat globules by the encircling MFGM.

3. The outer layer of MFGM is probably the principal source of endogenous enzymes in milk. The outer layer of MFGM is derived from the apical membrane of the secretory cell which in turn originates from the Golgi membrane and acts as the principal source of enzyme in milk.

General Characteristics of Milk Enzymes

1. Deteriorative character e.g. lipase (commercially most important enzyme in milk), proteinase, acid phosphatase, xanthine oxidase.

2. Preservative enzymes. e.g. superoxide dismutase, sulfhydryl oxidase.

3. As an indicator of the thermal treatment history of milk. Related enzymes are alkaline phosphatase, ϒ glutamyl transpeptidase, and lactoperoxidase.

4. Mastitis infection indicator. Related enzymes are catalase, n-Acetyl-β D-glucosaminidase, and acid phosphatase.

5. Antimicrobial activity.

6. Commercial source of ribonuclease and lactoperoxidase

Common Milk Enzymes and their Role in Dairy Industry

Homogenization is now a widely used industrial process in dairy production, essential for stabilizing milk and other liquid dairy products. Its main purpose is to prevent fat from separating out of the milk, ensuring a smooth, consistent, and uniform product. Milk is a complex emulsion comprising water, fat, proteins, carbohydrates, minerals, and vitamins. Among these constituents, fat plays a critical role in determining the texture, flavor, and overall sensory quality of milk and dairy products. In its natural state, milk fat exists in the form of globules of varying sizes, surrounded by a thin membrane that stabilizes them in the aqueous phase. These fat globules typically range in size from 2 to 10 μm and have a lower density than the surrounding water-based phase of milk. This difference in density causes the fat globules to rise and form a cream layer when milk is left undisturbed, leading to an uneven texture and separation during storage.
Homogenization is a mechanical process applied to milk to modify fat globules by forcing the milk under high pressure through a tiny orifice. This reduces the average size of the fat globules while increasing their number and surface area. Practically, this greatly minimizes the tendency of fat globules to rise and form a cream layer. The enhanced stability of homogenized milk is due to three key factors: the reduction in the average diameter of fat globules, as described by Stokes’ Law, which slows their upward movement; the uniformity in size distribution, which ensures globules rise at similar speeds, preventing clustering; and the increased density of fat globules caused by the adsorption of a protein membrane, bringing their density closer to that of the surrounding liquid. Additionally, heat pasteurization complements homogenization by breaking down the cryo-globulin complex, which otherwise promotes clustering and cream formation.
The smaller and uniformly dispersed fat globules create a smoother, creamier texture and enhance the mouthfeel. This process also contributes to the visual appeal of milk, making it appear whiter and more uniform. Homogenization is, therefore, an essential step in modern dairy processing, ensuring the stability, quality, and consistency of milk and other dairy products, while addressing the challenges posed by the inherent properties of milk fat and its lower density.

The first use of milk in a solid chocolate product is commonly attributed to Daniel Peter in 1875. Milk chocolate is the most popular type of chocolate, and milk ingredients are critical in delivering the highly desired properties and taste profile to consumers. Milk ingredients also have a significant effect on chocolate processing.

Milk is one of the most complex raw materials used by the food industry. A typical bovine whole milk has a solids content of about 13.5%, comprising about 3.4% protein, 4.6% fat, 4.7% lactose and 0.7% minerals.

Milk proteins can be classified as either caseins or whey proteins - typically found in milk

Introduction

There are manypeople all over the world who have a certain level of sensitivity or intolerance towards milk and milk products. The reactions to milk which involve the immune systemare termed as milkallergy, whereas, difficulty in the digestion of the milk and milk products is known as milk intolerance. Milk intolerance occurs due to malabsorption of milk sugar (lactose) in intestine, a condition in which lactose is not digested into its monomers (galactose and glucose) due to lower activity or insufficiency of lactase enzyme. Inability to digest lactose, which is a disaccharide present only in milk, is specifically known as lactose intolerance. However, hypersensitivity involves the adverse immune reaction(allergic reaction) inthe body causeddue to the ingestion of milk proteins. Milk and milk products are major source of basic as well as essential nutrients and cannot be skipped from the diet of the individual. It is a rich source of calcium,which is essential for the growth and reformationof bones. The decline in calcium may lead to thin, fragile bones that break easily, a condition called osteomalacia or osteoporosis in women. Thus, it is a matter of concern for both children andadults whoare allergic or intolerant towards milk and milk products and not getting enough calcium and other nutrients in diet. This chapter would provide more insight about milk intolerance and milk allergy/hypersensitivity and how to deal with it.

India

Milk legislation and regulations are designed to prevent fraud and adulteration. But they now cover many factors that affect sanitation and public health. Milk generally is classified into grades according to the care with which it is produced.

Milk lipids or milk fats exist as an emulsion of small spherical droplets called milk fat globules. These globules are very small in size but very large in number. The diameter of the milk fat globules ranges between 0.1 and 22 µm and the number varies between 1.5 and 3.0 billion globules/mL. The average size of milk fat globules ranges from 2 to 5 µm. The average fat globule size in cow and buffalo milk are 3.4 and 4.5 µm, respectively. The surface of the milk fat globules is coated with an adsorbed layer of material known as the milk fat globule membrane (MFGM). MFGM contains phospholipids and proteins in a complex form. MFGM has two main functions (a) fat globule stabilization and (b) preservation of the fat globule’s identity.

General Composition

Triacylglycerols (triglycerides) represent 97–98% of the total lipids in the milk of most species. The diglycerides probably represent incompletely synthesized lipids in most cases. Although phospholipids represent less than 1% of total lipids, they play an important role in being present mainly in the MFGM and other membranous material in milk. The principal phospholipids are phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin. Trace amounts of other polar lipids, including ceramides, cerebrosides, and gangliosides, are also present. Phospholipids represent a considerable percentage of the total lipid of buttermilk and skim milk reflecting the presence of proportionately larger amounts of membrane material in these products.

The primary objective of dairy plant hygiene is to ensure the consistent daily turn-out of safe and clean products which comply with pure-food and public health laws. A secondary and commercially important aim is to preserve the keeping quality of dairy products and so enhance consumer confidence in them. An integral part of a dairy is the quality control laboratory. Continuous testing is necessary for many purposes, including equipment hygiene. Bacteriological standards of dairy products can be maintained only if the raw product is of good bacteriological quality and is protected against contamination from the equipment with which it comes in contact during all stages of processing. 
Many factors may influence the maintenance of dairy equipment in a hygienic condition; the most important are the dairy buildings, the materials and construction of the equipment, personnel, water supply, cleaning procedures, and laboratory control. It is quite impossible to place these points in order of importance, efficient control of dairy plant hygiene being dependent on proper attention to all factors.

Milk production in India is a subsidiary activity of agriculture in contrast to the organized dairy sector in the western countries. Farmers and landless labour maintain one to five milch animals. As a result, small quantities of milk are produced in a scattered manner. Due to this reason, milk procurement models from western countries, such as bulk cooling and bulk transportation are not applicable under Indian conditions. Collection of small amounts of milk is scattered over long distances and, therefore, poses a formidable challenge in maintaining the quality attributes and keeping costs down.

3.1. Rural Milk Collection

A systematic approach to rural milk collection suitable for the tropical climate and techno-economic conditions prevailing in India has been developed, based on the indigenous experience gained over the past few decades. In the first phase, extensive surveys are undertaken in the milkshed areas, where the milk plant is to be established. The second phase involves ‘route planning’ taking into account, availability of quantities of milk, access to roads for plying vehicles and distance from the site of dairy plant. Then zones are identified, representing equal costs of collection and transportation. In the third phase, planning is done for locating the primary collection centres as well as chilling centres, where, milk can be cooled to 4ºC before transporting to the milk plant. Milk may be collected from individual producers either by the contractor or by forming village level cooperative societies.

Bovine milk contains an average of 3.5% protein. The concentration of protein changes significantly during lactation. The first few days of lactation exhibit the main change in protein concentration. The main changes occur in whey protein fraction.

Distribution of Protein in Milk

80% casein and 20% whey protein (β lactoglobulin- 10%, α- lactalbumin- 5%, serum albumin, and immunoglobulin- 5%).

Fractionation of Milk Proteins Fractionation of milk protein is mainly done by acidification at pH 4.6 around 30 °C.

Almost 80% of the bovine milk protein precipitates at pH4.6, and this fraction yielded by precipitation is called casein.

The remaining soluble part of the protein is referred to as whey protein/serum protein/ non- casein protein. Wide variation is observed in the casein- whey protein ratio in different types of milk(protein synthesis is independent of animal diet)

Significant Difference Between Casein and Whey Protein

1. Casein precipitates at pH 4.6 but does not precipitate whey protein at that pH. This property of milk protein is commercially exploited for the preparation of industrial casein and certain varieties of cheese.

2. Chymosin or other proteolytic enzymes produce specific changes in casein resulting in coagulation in the presence of calcium. Whey protein does not undergo this type of coagulation.

3. Casein is very stable to high temperatures. They can withstand heating up to 140 °C for 20 minutes but whey protein is relatively heat labile. They are completely denatured by heating at 90 °C for 10 min.

4. Casein is a phosphoprotein containing an average of 0.85% phosphorous while whey protein does not contain any phosphorous. The phosphate of casein is an important contributor to remarkably high heat stability and calcium- induced coagulation of rennet- altered casein.

5. Casein contains very low sulfur (0.8%) whereas whey protein is relatively rich in sulfur (1%). The principle casein contains only methionine but whey protein contains a significant amount of cystine, cysteine, and methionine. These sulfur- containing amino acids are responsible for many changes in milk on heating.

6. Casein is synthesized only in the mammary gland and no other sources in nature. Some of the whey proteins β lactoglobulin, and α- lactalbumin are synthesized in the mammary gland but bovine serum albumin and immunoglobulin are not synthesized in the mammary gland but derived from blood.

7. The whey protein is dispersed in solution and has a simple quaternary structure. Casein has a complex quaternary structure and exists in milk as large colloidal aggregates.

The salts of the milk include those constituents that are present as ions or in equilibrium with ions. The main salts of milk are phosphates, citrates, chlorides, sulfates, carbonates, and bicarbonates of sodium, potassium, calcium, and magnesium. Approximately 20 other elements are found in milk in trace quantities including copper, iron, lead, boron, manganese, zinc, iodine, etc. These ions are more or less associated with themselves and with proteins. Some metals act as catalysts in the oxidation of milk fat leading to oxidative rancidity and certain metals like Ca, P, Mg, Mo, Co, Fe, etc. are components of metalloproteins such as lactoferrin, lactoperoxidase, xanthine oxidase, and parts of phospholipids.

Distribution of Salts Between Casein Micelles and Serum

The phosphorus is present as orthophosphate, but part of it is bound to organic components like serine and threonine residues of casein, molecules of hexoses and glycerol, phospholipids, etc. Phosphorus is also found in the hydroxyapatite structure of the colloidal calcium phosphate in the micellar structure of casein. The sulfur content of milk is about 0.36 g/kg, but most of it is in the amino acid residues methionine and cysteine of the proteins. About 10% is present as inorganic sulfate.

Physical Equilibria Among Salts

Milk contains several elements but all of them are not entirely in a soluble state. Some minerals exist in colloidal and ionic states at the normal pH of milk. The compounds that are in soluble condition play an important role in keeping various milk constituents in stable condition. A balance exists between the components that are in a soluble state and those which are in colloidal state.

12.1. Introduction

Milking is the crucial operation in a dairy farm, as milk is the main source of revenue of a dairy farm. Milking is a labour intensive operation. About 50-60 percent of the total time of farm operation is required for milking and allied activities. Milking is an art which requires skill, patience, efficiency and experience. It should be handled quietly, quickly, gently, cleanly and completely, by avoiding any type of pain, annoyance or inconvenience to the animals. Possession of high yielding animals or good managemental conditions will not generate profit if the milking operation is inefficient.

Letting the cow to release its milk so the dairy farmer can extract it for personal use or to sell is the procedure of milking. Consequently, it is not totally a natural process. The natural process must be manipulated by the dairy farmer to his advantage. Therefore, in order to control the natural process, one must first understand it. The process of producing milk from blood-derived basic materials by alveolar cells and storing it in the alveolar cavity is known as milk secretion. Only when the alveolar cavity is full and the pressure on the alveolar cells prevents further secretion does this continuous process come to an end.

Milk

Importance

Milk contains approximately 86% water, 4.7% sugar (lactose), 4.1% fat, 4.2% protein and 1% minerals. It supports the growth of micro-organisms and thus is prone to contamination. The purpose of milking a dairy cow is to obtain milk that is fit for human consumption. Milk from the udder of a healthy cow contains very few bacteria and to ensure that it remains fresh for long it should be handled under conditions of good hygiene. Unclean milk can be a source of disease to the consumer, rejected at the market and so is a loss to the farmer, does not keep for long and is not good for processing.