UNIT - IV

AGRO-BASED INDUSTRY

(MILK PRODUCTS AND ITS PROCESSING)

CONTENT

1. Introduction

2. Importance of Processed Milk

3. Milk Quality Test

4. Processing of :

a). Butter

b). Curd

c). Paneer

d). Mattha

e). Cheese

5. Conclusion

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INTRODUCTION

Dairying in India, over the years, has witnessed a sea change from a largely unorganized activity into a blooming organized industry. Dairying in India has traditionally been a small holders’ enterprise. As demand for milk and milk product is increasing rapidly, milk producers are adopting dairy farming on commercial scale to top the market opportunities.

The dairy industry plays an important role in our daily life. Milk and its products are important human food, it is potable, easy to digest and highly nutritive. One of the important factors affecting the total amount of milk produced is utilized is the demand for the various products. In order to prepare such a diversity of products, many different processes have been developed by the industry.

The present study was conducted on a dairy cooperative, Uttaranchal Cooperative Dairy Federation Ltd. (UCDFL) from 20th March to 5th April 2014, which is an apex level state federation of district milk cooperative unions in the state of Uttarakhand. Established in the year 1965, with its head office at Mangal Parao, Haldwani (Nainital) for the successful implementation of the dairy programmes in the state, for the socio-economic upliftment of the poor remote areas by providing them a milk market at reasonable price. UCDFL is also popularly known as “Aanchal dairy”, located in Raipur road, Dehradun district, and the product branding is “Aanchal”.

This study focused mainly on the numerous types of milk products and it’s processing of Aanchal dairy, such as milk, buttermilk (Mattha), butter, cheddar cheese, cottage cheese (Paneer), curd (dahi), and table butter. Each of these has been designed to take advantage of some particular property of milk. They are usually high energy yielding food products. The major protein in milk, accounting for about 80% of the total protein, is called casein.

WHY PROCESS MILK?

There are many reasons to process milk into dairy products, such as the following:

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Many dairy products can be kept longer than fresh milk; therefore the milk does not have to be consumed immediately.

The demand for fresh milk may be limited, and there may be more interest in dairy products.

If the daily amount of fresh milk for sale is limited, it may be more economical to process the milk into less perishable products, store them, and sell them later in greater quantities.

There may be no market for fresh milk close by, and only preserved products can be sold at markets at a greater distance.

Greater financial gain may be obtained.

MILK AND its COMPOSITION

Milk is the primary source of nutrition for neonates before they start digesting other foods. Although milk from several species such as cattle, buffalo, sheep, goat etc., has also studied scientifically for several decades, cow’s milk has proven to have vast benefits to human health and nutrition due to its resemblance to human milk composition (agastonia et al. 2000; lonnerdal and Atkinson 1995).

The major constituent of milk is water, but according to species milk contains varying quantities of lipids, proteins and carbohydrates which are synthesized within the mammary gland.

TABLE 23: MILK COMPOSITION ANALYSIS OF COW, PER 100 GRAMS

Constituents CompositionWater 87.8 gProtein 3.2 gFat 3.9 gCarbohydrate(lactose) 4.8 gCholesterol 14 mgCalcium 120 mgEnergy 66 kcal

Milk is a complex, nutritious product that contains more than 100 substances that are either in solution, suspension or emulsion in water. For example, casein (major protein of milk), the fat and fat soluble vitamins, lactose (milk sugar) and mineral salts. The casein micelles and the fat globules give milk most of its physical characteristics, and give taste and flavor to dairy products such as butter, cheese, yogurt, etc. the composition of milk varies considerably with the breed of cow, stage of lactation, feed, season of the year, and many other factors.

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The composition of milk also varies with different breeds. The breeds have similar lactose level, but milk fat and protein may vary considerably. These differences are partly genetic in origin and partly the results of environmental and physiological factors.

1 PROCESSING OF MILK  "Milk processing" means the handling, preparing, packaging, or processing of milk in any manner in preparation for sale as food. Milk processing does not include milking or producing milk on a dairy farm that is shipped to a milk processing plant for further processing. Milk can be stored longer if it has been processed. Extended storage is possible if you are able to control the growth of micro-organisms. The processing technique used will determine the storage life of the milk and dairy products. Some of the milk processing methods are:-

A. Standardization: Standardization is the process of increasing or decreasing a particular constituent in milk or milk product so that it conforms to the desired industrial or legal standards. Milk may be standardized to Full Cream Milk; Toned milk, Double Toned Milk etc. Full Cream Milk should contain minimum 6.0% fat and 9.0% Solids Not Fat (SNF) while Standardized Milk should contain minimum 4.5% Fat and 8.5% SNF. Toned Milk and Double Toned Milk should contain minimum 3.0% Fat and 8.5% SNF and minimum 1.5% Fat and 9.0% SNF, respectively.

B. Pasteurization: The microorganism that had gained entry into milk may be either pathogenic (disease causing) or spoilage type. Pasteurization is the process of heating milk just enough to kill harmful micro-organisms without destroying flavor and nutritional qualities. Pasteurization may be done by two methods – Low Temperature Long Time (LTLT) or High Temperature Short Time (HTST). Nowadays, the HTST method is mostly used. Milk is heated to either 63-65°C for 20-30 minutes or 72-75°C for 15-30 seconds. Pasteurized milk has a shelf life of 2-3 days, and up to 12 days if kept at 4°C.

>Low pasteurization is used for milk for direct consumption and Cheese. >High pasteurization is used for yoghurt, butter.

C. Cream Separation: In cream separation, fat is removed from the milk by passing it through a cream separator in which it is rotated at a very high speed (around 8000 revolutions per minute) in thin films. Milk cream or fat, being lighter (specific gravity 0.9); remains in the centre while the skimmed milk, being heavier (specific gravity 1.036), goes towards the periphery in the cream separator. The separated cream and milk are collected from different outlets provided in the cream separator.

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D. Homogenization: Homogenization breaks up the oil droplets in milk and prevents the cream from separating out and forming a layer. This is of particular importance for sterilized milk which has a long shelf-life and when the formation of a cream layer is not desired. Additional changes include increased viscosity and a richer taste. Homogenizers are more usually designed for industrial-scale production, but it is possible to purchase smaller versions.

E. Sterilization: Sterilization is a more severe heat treatment designed to destroy all contaminating bacteria. The milk is sterilized at a temperature of 121°C maintained for 15-20 minutes or 150 degree C for 2-3 seconds so that a shelf life of six months of milk at room temperature is ensured.

The pasteurization temperature to be used depends on the product to be made of the milk.

F. Fermentation: Some desirable bacteria convert lactose of milk into lactic acid and some other flavor-producing compounds and are helpful in producing different products like dahi, yoghurt, etc. Conversion of milk into various cultured products by these bacteria is known as fermentation and these products are known as fermented milk products.

MILK QUALITY TEST

Milk testing for quality can be divided into testing for hygiene and for composition. The milk testing equipments should always be cleaned thoroughly after use, for that we can use boiling water for at least one minute, 70% alcohol or keeping the equipment in a flame.Some methods of the test are given below:-

1. Taste, smell, visual observation and temperature:

This is always the first screening of the milk, since it is cheap, quick and does not require any equipment. These tests are also called 'organoleptic tests'. It is also reliable if the person carrying out the tests is experienced. The tester smells the milk, observes the appearance, tastes if necessary, checks the can for cleanliness, looks for sediment, and filters the milk to check its cleanliness. If doubts arise after the examination about the quality of the milk, other tests can be done to determine the quality.

2. Density meter or lactometer test:

With a lactometer the specific density of milk is measured. At 15◦c the normal density of the milk ranges from 1.028 to 1.033 g/ml, whereas water has a density of 1.0 g/ml. So

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when we read the lactometer, we can determine whether water has been added to the milk. It is best to combine the lactometer reading with the fat test. We can use the lactometer reading together with the fat percentage to estimate the Solids Non Fat (SNF) content of the milk. Always read the temperature of the milk first, the lactometer reading varies according to the temperature.

3. Acidity test:

This test measures the lactic acid in the milk. If the acidity is higher than 0.19%, then the milk quality is poor and cannot be processed. If the acidity is lower than normal (e.g. 0.10% lactic acid) then the milk is of poor bacterial quality or sodium hydroxide/bicarbonate might have been added.

For this test we need a white porcelain dish, a 10 ml pipette, a 1 ml pipette, a burette (0.1 ml graduations), a glass rod for stirring, a phenolphthalein indicator solution (0.5% in 50% alcohol) and a 0.1 N Sodium Hydroxide solution. Measure 9 ml of the milk into the dish, add 1 ml of phenolphthalein and from the burette, slowly add the 0.1 N sodium hydroxide solution while mixing continuously, until a faint pink color appears. The more Sodium Hydroxide you have to add before it turns pink, the more acid the milk.

5. Gerber test for fat:

This test is used to determine the fat content of the milk. 10.94 ml. of milk at 20 degrees Celsius is added to a butyrometer together with sulphuric acid and amyl alcohol. After centrifugation, the sample is put in a 65 degrees Celsius water bath and read after 3 minutes. The fat content from this reading should not be less than 3%.

Aanchal Dairy Milk Products

A. Pasteurized package liquid milk:

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Milk is first received in a dump tank from the road milk tankers. It is then chilled to 4◦c. the milk is then pasteurized and cream is separated to get skimmed milk. Milk is then standardized depending on the requirement of toned milk, double toned milk, full cream milk or standard milk. The pasteurized milk is sent for packaging in pouches in the packing machine for various capacities like 500 or 1000 ml pouches. Once packaged, the packet milk is quickly conveyed to a cold storage warehouse and later sent out to the market for sale. The products have sell-by-date printed on the package.

TABLE 24: FAT % & SNF OF VARIOUS FORMS OF MILK Type of Milk

Quantity of Milk

Fat %

SNF(solid non-fat) %

Full cream milk

500/1000 ml

6 9

Standard milk

500/1000 ml

4.5

8.5

Toned milk

500/1000 ml

3 8.5

Double toned milk

200/500/1000 ml

1.5

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1. Butter:

Butter is a fat concentrate which is obtained by churning cream. It is normally obtained from cow's or buffalo's milk. First of all, cream or curd is obtained from the milk and then it is converted into the butter. Butter contains about 80% fat by weight. Some time salt is added in the butter for flavor and carotene as coloring matter.

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TABLE 25: THE COMPOSITION OF BUTTER.

Content %Fat 80Moisture 16.3Curd 0.7Salt 2.6

Flow chart of manufacturing butter:-

Separation of milk Separation of cream Neutralization of cream

Cream Pasteurization of cream

Salt Colour

Cream ripening Churning

Packaging Cutting

Cold storage Marketing

2. Curd or Dahi:

Dahi, Indian curd is a fermented milk product obtained from pasteurized or boiled milk by souring (natural or otherwise), suing a harmless lactic acid or other bacterial cultures. Dahi should have the same minimum percentage of fat and solid-not-fat (SNF) as the milk from which it is prepared.

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Manufacturing Process - Milk of cow is steamed for a minimum of 30 minutes and cooled to a temperature of 43◦c and then incubated with 30% yoghurt starter. It is mixed thoroughly, filled into the glass bottles and sealed with aluminium foil caps and kept it at 42◦c+0.5◦c for 3.5 hours when the coagulum is formed. Then bottles are removed from water and placed into a water bath, having temperature of 30◦c for 30 minutes and transferred to refrigerator for overnight storage.

Flow Chart of manufacturing curd:-

Cow milk

Filtration / clarification

Standardization (Fat: Solids not fat ratio)

Pre-heating (60°)

Homogenization and pasteurization (80-90°C for 15 to 30 min)

Cooling (22 – 25°C)

Inoculation with pure lactic culture (single or mixed mesophilic culture)

Packaging

Incubation (23 – 25°C for 16 to 18 h)

Cooling and storage at 5°C

3. Cottage cheese or Paneer:

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Paneer is an acid-coagulated product of hot milk. It is marble white in appearance with a slight spongy-body and close knit-texture. It offers outstanding non-melt functionality because of its ability to withstand cooking and frying temperature. The Pure Food Act of India requires Paneer to have not more than 70% moisture and not less than 50% fat on a dry matter basis. Skim milk Paneer should not have more than 70% moisture and not more than 13% fat on a dry matter basis.

Manufacturing of Paneer: - Paneer is obtained through heat or acid coagulation of casein component of standardized milk, entrapping through various interactions almost all fat, part of the denatured whey proteins, and colloidal salts as well as part of the soluble milk solids. The typical composition of Paneer is 53-55% moisture, 23-26% fat, 17-18% protein, 2.0-2.5% lactose, and 1.5-2.0% minerals.

Flow Chart of manufacturing Paneer:-

Fresh Cow Milk

Filtration

Standardization (Fat: SNF = 1: 1.65)

Addition of Calcium chloride (0.08 %)

Heated to 90OC (no hold)

Cooled to 85OC

Addition of Citric acid

Solution (1% at 85 OC) Coagulation (pH 5.2-5.3)

Settling of coagulated mass for 5 min

Whey drainage,

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Filled into muslin cloth lined cylindrical hoop

Pressed (2-3 Kg/Cm2 for 10-15 min)

Immersed in chilled water

(4OC for 1-2 h)

Cut into 100g circular (1.5 cm thick and 10 cm diameter)

Experimental sample Control sample Packaging

4. Mattha:

Mattha, also called chaanch is an Indian spiced beverage made of buttermilk. It is thin and more acidic than conventional milk. Plain buttermilk is also called by Mattha. It is generally mixed with mint, roasted cuming seeds, curry leaves. Salt and sugar for flavoring. The sourness or tartness is due to the presence of lactic acid in the milk.

6. Cheese:

Cheese is an economical source of milk protein. It provides a palatable milk product of high

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value which can be kept for a long time. It is rich in calcium, vitamins and is nourishing and is easily digestible food.

Manufacturing of cheese flow chart:-

Milk

Automated Standardization

Concentration (ultra filtration) (15% - 18% total solids)

Cheese making

(Enclosed Automated Vats)

Drainage conveyer (curd and whey separated)

Cheddaring tower

Salting

Block former

Packaging

Ripening (5◦c - 6◦c)

CONCLUSION

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Milk is a highly versatile, perishable raw material that can be manufactured into a wide range of products. The processes that are used can be grouped as fractionation, concentration, and preservation, this classification emphasizes the versatility of milk as a multicomponent raw material, from which components can be selectively concentrated and stabilized.

The processes and products described are only a proportion of that in commercial use today or in development. Sale of ghee, butter, yoghurt and other products have increased in the recent years. Organic milk production has not only improved the economics of milk producers, but is also providing employment to the rural people at the village level.

Milk processing is often more problematic than in temperate climates, owing to higher temperatures and humidity. Consequently, milk spoils at a faster rate, cheese ripens too quickly, and it is often difficult to ensure adequate cooling conditions. The extent of such changes and the consequences for the properties and stability of milk depends on the severity of the treatment, as well as the physiochemical changes that occur during processing.

The dairy industry can meet the needs of the consumers and expand the dairy product market by undertaking new approaches to processing and product development. Control and optimization of production processes are of great importance to the food industry as this may lead to improvement of products and processes, and to cost savings. At present, Aanchal Dairy is providing employment to rural people, eliminating any middle men. To maintain a continuous growth in milk production, it requires the collective effort.

In conclusion, the processing of milk represents perhaps one of the most complex fields in the food science and technology, and whiles many underpinning principles have been characterized, and much research to be done in several areas. Furthermore, safety relevant issues to new formulations and processing conditions for extended shelf-life products will continue to challenge the food and dairy industries.

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