eChapters

Cleaning and sanitisation are the two processes employed in dairy industry to ensure hygiene and product safety. The safety of milk and milk products is a very important aspect and every attempt should be made, during processing, to minimize contamination through handling and processing equipments. The accumulated dried milk solids (milk stones) consist largely of calcium phosphate, milk proteins (precipitated, coagulated and baked on by heat) and insoluble calcium salts from water and washing detergents. The surface can also contain biofilms, which are formed by the incorporation of bacteria into the accumulated inorganic and organic materials that attach to most surfaces. With time and in the presence of nutrients, a biofilm and the bacteria within the biofilm will grow and become strongly attached to the surface. The removal of dairy soil, milk stones as well biofilms is the prime objective of the cleaning process. International Dairy Federation (IDF) defines a clean surface as one which is free from residual film or soil that will not contaminate the food products coming in contact with it.

While cleaning refers to the removal of soil from the surface of the equipment, sanitisation implies destruction of all pathogenic and almost all non-pathogenic organisms. Cleaning and sanitisation are complimentary processes. Either of the processes alone will not achieve the desired result, which is to leave the surface as free as possible from soil and viable organisms. In actual practice cleaning and sanitisation overlap to some extent, as during cleaning a high proportion of bacteria are destroyed and others get removed in the detergent solution. Inadequate or faulty cleaning and sanitisation can have serious consequences, as milk is a prefect nutrient in which bacteria can multiply. A thorough understanding of the cleaning methods is, therefore, necessary for economic production of high quality food products.

Packaging is a tool that is used to contain the product, protect the product from environmental hazards and help in marketing the product. Examples of ideal natural packaging systems are that of a banana, orange, coconut and egg, where the packaging is provided by nature. The major step forward in the food processing arena has been the ability to protect and preserve products with packaging and hence ensuring the availability of fresh and processed products out of season and over long distances in various forms. Milk is a highly perishable product and is not uniformly available round the year to the whole country due to geographical and genetic variations. If dairy products are to be available all the year round the country, irrespective of the season and area, it must be presented in packages that are convenient to purchase and use.

Packaging has additional responsibilities of providing convenience, safety and facilitating, besides handling, storage and distribution of products. It should prevent spoilage of food by microbial or insect attack. It also preserves the quality and nutritive value of many foods by the exclusion of oxygen and the control of moisture loss or gain. It increases the shelf-life and ensures longer availability and contributes to the product image through structural and graphic design. Product information is also given out through the medium of labeling, which acts as a tool for marketing and advertising.

Milk, as secreted in the udder of a healthy animal is practically sterile, but during its transit to the processing plant, becomes heavily contaminated with a variety of micro-organisms. These may be responsible for spoilage of milk or for causing diseases in animals and human beings. It thus becomes imperative that adequate heat treatment is given to milk to destroy these micro-organisms, thus increasing the shelf-life of milk as well as making it safe. Varied heat treatments offer the potential of producing different kinds of processed milk to satisfy the needs of the consumer. To cater to the ever-increasing demand of consumers, several varieties of processed milk are available in the market, some of which are discussed below.

5.1. Pasteurised Milk

Pasteurisation was named after the renowned French scientist Louis Pasteur, who discovered that spoilage organisms could be inactivated in wine by applying heat at temperatures below its boiling point. The process was later applied to milk and remains the most important operation in the processing of milk.

It is the process by which every particle of milk is heated to such temperature-time combinations (usually to 63°C for not less than 30 minutes or to 72°C for not less than 15 seconds) and promptly cooled to 4°C or below so as to destroy any harmful bacteria that may be present without affecting flavour and food value. Pasteurisation does not involve the use of any additives. Apart from making milk safe to drink, pasteurisation increases the length of time it can be kept before it spoils. The nutrient losses due to pasteurisation are so small, that they are considered insignificant.

Milk, on reception at the dairy factory is subjected to various unit operations on its way to product manufacture. Processing is applied as a means to convert liquid milk into products or to render the milk (and products) safe from harmful organisms. The basic processing operations to which milk is subjected at processing units have been described in this chapter. The common processing operations employed are depicted in Fig. 4.1. Several of these operations are routine compulsory processes common to all dairies, while certain others are undertaken for specialized purposes in some dairies.

4.1. Filtration and Clarification

At the time of milking various foreign materials such as dirt, feed, manure, dandruff, hair, flies, dust particles, worn out cells, cell debris and many other undesirable substances may find their way into milk. The process of removal of this extraneous matter (solid particles of higher density than that of milk) is called filtration or clarification. This can be achieved either by simple filtration through specially woven filter cloth or continuous process of centrifugal clarification that helps

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.

Milk is the secretion of the mammary glands of animals. For human consumption, milk is that liquid obtained from the cow or the buffalo during the period following at least 72 hours after calving or until the milk is colostrums-free. It is a complex biological fluid consisting of seven main components: water, fat, protein, sugar (lactose), minerals, vitamins and enzymes. Milk is a white opaque fluid in which fat is present as an emulsion, protein and some mineral matters in colloidal suspension and lactose together with some minerals and soluble proteins in true solution. The opacity of milk is due to its content of suspended particles of fat, proteins and certain minerals. The colour varies from white to yellow depending on the carotene content of the fat. Skimmed milk is more transparent with a slightly bluish tinge. Milk of a good flavour has a pleasant, slightly sweet taste, and no odour. It is an excellent source of calcium, phosphorous and riboflavin. Vitamin A and D are currently added to whole milk, partly skimmed and skimmed milk.

1.1. Introduction

The significance of milk as the most wholesome single food available in nature has never been debated. It is as ancient as mankind itself, as it is the substance created to feed the mammalian infant. All species of mammals, from the lowly rat to the mighty whale, produce milk for this purpose. Several centuries ago, perhaps as early as 6000-8000 BC, ancient man learned to domesticate species of animals for obtaining their milk for consumption. These included cows, buffalos, sheep, goats and camels, all of which are still used in various parts of the world for the production of milk for human use (Fig. 1.1 & 1.2).

Abstract

Drying is a widely used method of food preservation. It leads to some structural changes in the dried material resulting in poor quality and rehydration. Freeze drying, though a costly process, reduces water activity without exposing the food material to high temperatures, eventually retains the original quality to a great deal. Moisture in the foods is frozen to ice which is sublimated under low pressure. Low pressure helps to vaporise the ice without transforming it to liquid, hence leaving the food structure porous in nature. The food is claimed to preserve the nutritional, sensory and re-constitutional qualities.

1.1 INTRODUCTION

Most food materials are composed of a very high percentage of water, which can be as high as 95%, and this makes them susceptible to microbial activity. Microbial activity spoils the products, leaving them useless for human consumption. It not only changes their taste and color but it may also develop toxins, thus making them unsafe. There are various methods for preserving food but in order to make them shelf stable, removing water from foods helps keep them from spoiling for a longer period of time.

Abstract

Multiflash drying (MFD) process is based on the application of multiple cycles of heatingvacuum pulse to a solid food. Heat can be provided by convection (from hot air), conduction (by contact with a hot surface), microwaves, or by a combination of these methods. Due to the moderate temperatures applied to the drying food, and the sudden decompression step (vacuum pulse), MFD processes allow obtaining crispyanddried foods with very good nutritional and sensory properties. Vacuum pulses cause food texturization, which depends on the pressure drop rate during decompression. In fact, the dried products are similar to freezedried foods, but with more open structures, which result in higher crispness. The dehydration can be performed in relatively short processing times, when compared with traditional drying processes (e.g. solar drying, airdrying, vacuum drying and freezedrying). The short process time indicates clearly that this class of drying process presents a huge potential to the production of driedandcrisp foods at industrial scale.

Abstract

Drying is one of the most important industrial operations for preservation of food material. Due to the major limitations posed by convective drying methods, there is always a need for novel drying techniques which are technically, economically and environmentally sustainable. Based on the principle of moisture diffusion due to vapor pressure gradient, atmospheric freeze drying (AFD) offers a promising alternative to conventional drying systems. A cold gas with low water vapor pressure is used as drying medium to sublimate moisture directly from the frozen material at atmospheric pressure conditions. As a result the product gets dried at much lower temperature unlike convective drying. Thus, products dried with AFD retain better nutrition, texture and color and the process is also considerably cost effective. Major limitation of the AFD process is longer drying time, which can however be accelerated by using heat pump drying or new ultrasound technology. This chapter focuses on mechanism, benefits, limitations and comparative study of AFD with other drying methods such as hot air drying and vacuum freeze drying. It provides an insight regarding effect of AFD on properties of food material based on various studies reported in literature.

Introduction

The dairy sector is one of the most important food sectors, which introduced the physical, chemical, microbiological and sensorial criteria duringprocessing steps and in the final dairy products. Several agents/ingredients of non-dairy origin are commonly used to maintain the quality of milk and milk products during processing, transportation and storage. In general, such ingredients are known as food additives and it can be antioxidants, coloring agents, flavoring compounds, preservatives(naturals and synthetic),artificialsweeteners, vitamins, minerals, stabilizers, emulsifiers and curing agents. From the safety point of view, some toxic agents can come into contact of dairy products duringmilking, storage or processing; such as fungal toxins, heavy metals, antibiotics or radionuclide’s, etc., which need to be identified and processed accordingly. Although addition of food additives in food/dairy product is controlled under country specific food laws or Codex Alimentarius Commission (CAC), few dairyproducts such as butter and unflavored fermented milk products are highly restricted for food additives.

Introduction

Spectacular accomplishment in every sector has enabled India to be amongtop achieving nations. However, every section of the society is not benefited by these achievements and problem of malnutrition still remains unresolved. Malnutrition is a common problem faced by underdeveloped and developing countries suchas Philippines, Nepal, Sudan,Tanzaniaand Indiasincelongback. Malnutrition includes undernutrition(wasting,stunting,underweight),inadequate vitamins or minerals as well as overweight, obesity and resulting diet-related non communicable diseases(NCDs). As per the latest report of World Health Organization, 52 million children under 5 years of ageare wasted, 17 million are severely wasted and 155 million are stunted, while 41 million are overweight or obese (WHO, 2018). More than 50% women of marriage age are suffering from anemia. If women are malnourished at the time of pregnancyand delivery, the babybornface theproblems such asphysical retardation,sensitive tocommon infections, reduced cognitive abilities, reducedmental development, etc. As per the World Health Organization (WHO) guidelines, starting from the date of conceiving a child, the first 1000 days are a critical window from nutrition point ofview.Unfortunately, inseveral regions of developingcountries includingIndia, neither the mother nor the babyis provided with the right quantity and qualityof food during this window period. Therefore, it is important for the policymakers to identifymalnutrition at an earlystage for timelyplanningand implementation of various intervention strategies at the community, village, and district level. NitiAyog, Government of India (GoI) (previously known as Planning Commission), in an effort to eliminate malnutrition,regularlyplans several short and longtermnutritionalprogrammesand policies.In thischapter,we willdiscuss some of these policies launched since independence and their impact in combatingmalnutrition.

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.

Introduction

Digestion may be defined as the hydrolytic process carried out by various enzymes for breaking down complex food components such as proteins, fats and carbohydrates into simpler molecules like amino acids, fatty acids and monosaccharides, respectively. Whereas, absorption may be defined as the movement ofthese simple soluble digested food componentsalongwithvitamins, minerals and water from gastrointestinal track into the circulatory system.

The process of digestion starts from oral cavity (mouth) and ends at large intestineincluding tongue, teeth, jaws,secretions from salivaryglands (parotids, sub maxillary or submandibular and sublingual glands), pharynx, esophagus, stomach, small intestine and digestive enzymes secreted from pancreas and liver.

Introduction

Nutritive value of any food indicates the calories content as well as quality attributes. Macronutrients such as carbohydrates, fats and proteins provide energy by4-9-4 rule. It meanstheyprovide 4,9 and 4 kcal/genergy, respectively, when oxidized completely. Though micronutrientssuch as vitaminsandminerals do not provide any calories, they are essential for the enzymatic activity and metabolic reactions.

ATP or energy is measured in terms of ‘calories’ or ‘joule’. One calorie is the amount of heat required by 1g of water to increase its temperature from 14.5 to 15.5°C under standard conditions. Nutritive value of any food can be measured on shelf usingcalorimeter, in which food is completelyoxidized under specified conditions and converted into CO₂ and water.

Introduction

Nutrition is the fundamental pillar of life and an essential foundation of human and national development. Rightfrom the earliest stage of human development, the fetal stage, at birth, infancy, childhood, adolescence, adulthood and old age, nutrition forms the basis for survival, performance, mental and physical development & economic and social development.Nutritional deficiencies during pregnancy, fetal and early postnatal life can have a negative impact not only on the subsequent growth and development but can also lead to changes in metabolic regulation and homeostasis.

Introduction

Nutrition, a basic human need, is a critical part of health and development. Nutrition can be defined as the intake of food, deliberated in relation to the body’s dietary needs. On one hand, good nutrition – an adequate, well balanced diet combined with regular physical activity – is a foundation of good health, whereas,poor nutritionleads toreducedproductivity,impairedmental andphysical development, increased susceptibility to disease, and reducedimmunity. According to WHO, under-nutrition, together with vitamin and mineral deficiencies accounts for one-third of all child deaths and impairs healthy development and lifelong productivity. At the same time, sedentary lifestyles, demographic shifts, urbanization and the liberalization of markets have steered the world population to being overweight along with risk of chronic diseases like hypertension, dyslipidemia, type 2 diabetes, coronaryheart disease, stroke, etc.; thus, resulting in a double burden of malnutrition.

To address this dual burden of malnutrition, individuals needaccess to sufficient and good quality food; but focussing solely on food security is unlikely to solve the problem of global malnutrition. The challenges of malnutrition cannot be solvedjustbyincreasingfoodproductioninordertoimprove healthand nutritional status of the population. To resolve such challenges, awareness about food choices for optimal health plays a pivotal role among population.

Human nutrition is the science of understanding food; its component; intake; and how it is related to health, growth, development and diseases. Human nutrition involves the study of ingestion, digestion, absorption and assimilation of the nutrients; their metabolic functions, deficiency or excess disease as well as their regulation through several factors such as choosing particular food components/nutraceuticals or physical activity.

Introduction

The basic physiological structures of mammary glands in all species are almost same and are located externally in order to fulfill the milk requirement of neonates after parturition. The process of secretion of milk from the mammary glands is known as lacto genesis. Milk provides an almost complete nutrition to neonates from birth till weaning period. It is a complex mixture of various constituents like:

Lipids such a striacyl glycerols(TAG),phospholipids,cholesterols and other sterols, free fatty acids and fat-soluble vitamins

Carbohydrates such as lactose, oligosaccharides

Proteins such a scaseins, α-lactalbumin, β-lactoglobulin, immunoglobulin’s, bovine serum albumin, lactoferrin, lysozyme, enzymes, hormones and growth factors

Non-protein nitrogenous compounds like urea, creatine, creatinine, uric acid and amino acids

Major and minor minerals, water-soluble vitamins and cells (leucocytes, macrophages, and epithelial cells).

Introduction

Proteins are the most abundant organic compounds constituting major part of the body. Chemically, proteins are nitrogen containing macromolecules and polymers of L α-amino acids, which serve a wide range of structural and biological functions in animal body. For example, connective tissue made up of collagen, metabolicenzymes, neuro transmitters,signal in gmolecules, structural components of cell membranes and cell organelles, etc. all are chemically proteins.

Before goinginto the details of protein metabolism, first, we need to understand that there are majorly two sources of proteins in our body: dietary protein and body protein. Dietary protein is taken in diet, while body protein indicates the protein and amino acids synthesized in animal body to fulfill the requirements for growth and development. The digestion of proteins will not be discussed here as it has been described in detail in chapter 12. Dietary protein is digested in presence of several enzymes such as trypsin, pepsin, chymotrypsin, aminopeptidases and carboxypeptidases and is converted into mono-, di- and oligopeptides in stomach and small intestine; and finally converted into amino acids. These amino acids are transported to the systemthrough intestinal mucosa via active transport, from where they enter into the cells for further metabolism. Therefore, ‘metabolismof proteins’ is more appropriatelylearnt as ‘metabolism of amino acids’.

Introduction

The diverse cluster of naturally occurring organic compounds including fats, oils, fatty acids, waxes, phospholipids, eicosanoids, terpenes, steroids and fat soluble vitamins that do not prefer to interact with water but soluble in non-polar organic solvents like ether, chloroform, benzene, acetone, are called as lipids. The main functions of lipids in biological system include storage and transport of metabolic fuel, structural component of cell membranes, insulation & protection of vital organs from shock and carrier of fat soluble vitamins. Contradictory to proteins,lipids are not polymers in nature and are hydrophobic due to presence of a long hydrophobic chain. Apart from this, lipids also act as precursor molecules for several pigments, hormones and signaling molecules.