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UNIT-1:MILK RECEPTION,  STRUCTURE:, ,  MILK COLLECTION,  MILK TRANSPORTATION,  METHODS OF MILK PRESERVATION,  MILK RECEPTION AT DOCK-, , Unloading,weighing,sampling,grading,dumping., ,  MILK CHILLING METHODS AND STOREGE.

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MILK COLLECTION, , , , , , , , Milk production is confined to rural areas while market demand is more in urban and city, areas. Hence, milk is collected from rural milk producers in the milk shed area and, transported to processing and distribution points in towns and cities., A milk shed are is the geographical area from which a city dairy receives its fluid milk, supply., , A) The common systems for collection of milk are as follows:, ,  1. By co-operative organizations: formed by individual or collective milking, societies. This is suitable to the milk producers because no profit making middlemen are, involved in this system.,  2. By contractors: Less return to producers., ,  3. By individual producers: Practical for those situated near processing dairies.

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Cooperative society, , contractor

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 B) Milk collection cum chilling, , centres/depots :, , Milk collection cum chilling centers are normally attached to city dairies., These are to preserve the quality of raw milk supplies, and to provide, easy transport to the processing dairy., Location of milk collection cum chilling centre:, This is guided by,  Adequate milk production,  Adequate (potable) water supply,  Proximity to a good road or railway station,  Electric supply,  Sewage disposal facilities

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Major items of equipment, , , , , , , , , , a. Milk weigh tank/pan and weighing scale, b. Drop (dump) tank with cover, c. Can washer, d. Milk pump (sanitary type), e. Surface/plate cooler, f. Refrigerating unit (of suitable capacity), g. Cold room (of suitable capacity), h. Milk testing unit, etc.

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 Operational procedure:,  Essentially this is the same as a in a small dairy.,  On arrival, the milk is graded for, , acceptance/rejection, weighed, sampled for, testing, cooled and stored at a low temperature, until dispatch to the processing dairy.

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On arrival the milk is Graded for acceptance /rejection

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Milk transportation:,  Under Indian condition , milk has to be regularly, , collected and transported twice a day(morning &, evening)

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Methods of milk transport, Mode, , Optimum, load(KG), , Optimum, distance(KG), , Remarks., , 1.Head load, , 15-25, , 3-4, , Small loads & distances-in hilly areas, , 2.Shouldersling, , Upto40, , 3-6, , Heavier loads but for shorter distance than head load., , 3.Pack animal, , Upto 80, , 6-10, , Ponies, horses and donkeys usually employed, , 4.Bullock cart, , 300-400, , 10-12, , Rather slow, , 5.Tongos, , 250-300, , 12 or more, , Larger quantities transported, faster than head load, should, sling and pack animal, , 6.Bicycle, , 40-or more, , 15 or more, , Quick and handy, easily, , 7.Cycle rickshaw, , 150-200, , 10 or more, , More carrying capacity than bicycle, , 8.Autorickshaw, , 250-500, , 15 or more, , Greater carrying capacity and faster than cycle rickshaw, , 9..Moter truck, , ½-3 tones, , 15 or more, , Increasingly in use with more road building, , 10.Rail wagon, , 11 tons or, more, , 80 or more, , Great scope in future, , 11.Tankers(road rail), , 5 tons or, more, , 80 or more, , Great scope in future

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ROAD, , V/S, , RAILWAYS TRANSPORT, , ROAD, , RAILWAY, , 1.Loading and unloading possible, directly at godown of seller and, buyer., , Cheaper than road over long, distances., , 2.Cheaper than rail over short, distance., , Larger quantity of milk can handled, at a time, , 3.Less time consuming, , Long time consuming

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CAN, , V/S, , CAN, , TANKER TRANSPORT, ,  Handling of small quantities, possible, , TANKERS, ,  Quicker more of transport,  Lower costs,  Better temperature control, ,  Less rick of contamination.,  More time and labour saving.,  Over all savings in detergents, etc.,

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TYPES OF CONTAINERS USED, 1., 2., 3., 4., 5., 6., 7., , Backed earth, Wood or bamboo, Metal(general brass), Galvanized iron(G.I), Second hand tins(mainly vegetable oil or ghee), Tinned iron and aluminium alloy(used by organized dairies), Polypropylene can

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THE PROBLEMS IN RELATION TO MILK COLLECTION AND TRANSPORTATION ARE:, , 1., , 2., 3., 4., 5., , 6., , Milk is liquid , perishable & bulky, Small and scattered production of milk, Tropical climate, Lack of transport facilities., Lack of countrywide organization for milk collection and, transport., Vested interest among milk merchants.

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METHODS OF MILK PRESERVATION,  Milk is highly perishable item.,  The keeping quality of fresh milk is only5-6 hours unless proper steps are, taken to preserve the quality.,  The major cause for spoilage of milk is due to the action of micro organisms, on lactose yielding lactic and other acids, Causing increased acidity of milk.,  The milk with high acidity can’t tolerate heat and so coagulates on heating.,  When the milk acidity reaches 0.6%,milk coagulates at room temperature, with out heating.,  The principle involved in the preservation of milk is only to destroy the micro, organisms or obstructing the microbial growth, so that acidity development, is stopped or slowed down, the various methods are

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METHODS OF MILK PRESERVATION, ,  BY COOLING THE MILK,  BY HEATING, ,  BY ADDITION OF CHEMICALS

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BY COOLING THE MILK, ➢The most of micro organisms present in, milk are mesophillic i.e. They grow well at 20, to 40 c., ➢By cooling the milk to refrigeration, temperature i.e. 5 to 10c, the multiplication, of micro organisms can be restricted., ➢Only psycrophils will grow., So the acidity development is at slower rate., ➢This side table shows that the bacterial, growth factor in the milk at different, temperature., , Temperature, c, , Bacterial growth, factor, , 0, , 1.0, , 5, , 1.05, , 10, , 1.80, , 15, , 10.00, , 20, , 200.00, , 25, , 120000.00

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BY HEATING,  By heating the milk, the micro organisms will be killed., ,  The various micro organisms are destroyed at different, , temperatures.,  Pasteurization temperatures kill cent percent pathogenic micro, organisms and 98-99% of spoilage micro organisms.,  Boiling milk will kill all the micro organisms, except spores.,  The effect of heat is discussed well in unit-3

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BY ADDITION OF CHEMICAL,  Preservatives are the chemicals, which when added to milk at small concentration will, , inhibit the microbial multiplication by interfering the metabolism path way of micro, organisms or by neutralizing the acids produced., ,  The various preservatives are:, 1., Sodium carbonate, 2., Sodium bicarbonate, 3., Formalin/formaldehyde, 4., Boric/benzoic acids, 5., Salicylic acids., 6., Nisin,acidophillin like antibiotics will also inhibits microbial growth, , 7., , Note: LACTOPEROXIDASE/COLD STERILIZATION:- milk contains natural, Lactoperoxidase enzyme. Thiocyanate and hydrogen peroxides are added at, 30:70ppm level to activate the Lactoperoxidase system., , 8., 9., , this system contains 3-components, 1).thiocyanate 2). Hydrogen 3).hydrogen peroxide lactoperoxidase.

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MILK RECEPTION AT DOCK, , , , , , , , , , , , , , The operation of receiving milk may be subdivided into Unloading, Weighing,, Sampling, Grading and Testing., 1) Unloading: The truck carrying the filled milk cans is brought aside to the, unloading platform., The milk cans are then unloaded manually., The milk cans are then assembled for grading in a definite order, according to each, supplier, viz. the contractor or patron., If a milk tanker is used, it is first properly positioned so that pipe fitting connections, can be made conveniently in the Tanker bay., 2) Grading: It is well known that the quality of the finished product depends on, that of the raw material used., This refers to the classification of milk on the basis of its quality, for price-fixation., The milk grader is the key man for the proper selection of milk., The principle of grading is based on organoleptic (sensory) tests such as those for, appearance, smell (odour), and taste., Acidity, sediment test etc. are included under platform tests.

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 Note - The term 'Platform Tests' includes all tests which are performed to check the, quality of the incoming milk, to decide regarding its acceptance/rejection.,  They are performed on each can/tanker of milk with the objective of detecting milk of, inferior or doubtful quality, preventing it from being mixed with high grade milk.,  The technique of grading milk is as follows:, ,  Milk tanker (road/rail): The grading has already been done at the milk, , collection-cum-chilling centre.,  As milk is chilled (< 5°C), it is not possible to detect off-odours.,  The appearance is noted, as testing of raw milk is usually avoided.,  After thoroughly mixing it for 5-10 min, a sample is taken for laboratory testing., , , , Milk can: The main tests applied to each can of milk consist of appearance, smell, , and temperature (touch); other tests such as taste (seldom carried out with raw milk), and sediment might be used to substantiate the initial findings.,  Tests involving time, laboratory facilities and special techniques are done by the quality, control technician, for which a sufficiently large sample is taken., 

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 3) Sampling: While strict precautions regarding sterility of the stirrer,, sampler, container etc. are required for obtaining a bacteriological sample;, dryness and cleanliness of the above equipment should be sufficient for a, chemical sample.,  The first pre-requisite of sampling is thorough mixing of milk.,  This can be done with a plunger or stirrer (agitator), operated manually or, mechanically for milk contained in cans or tankers, as the case maybe. With, the former, a representative sample may,  be taken after dumping the milk in the weigh tank, whereby it gets mixed in, so thoroughly that a representative sample may be taken without further, mixing., , Samples may be individual, composite (mixture of two or more, individual lots of milk), drip (representing the entire day's supply), etc., Samplers may be dipper-tube or proportionate (also known as milk thief),, automatic vacuum, drip etc., 

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 4) Weighing: This is an essential step in accounting for milk, , , , , , , , receipts, disposal and making payments for milk., The milk from cans is dumped into the weigh tank, either manually, or mechanically. The tank is mounted on scales and the scale dial, set at zero when the tank is empty., Automatic printing of the weight is now becoming a practice., The milk in tankers (road or rail) may be measured by volume by, passing it through a flow meter, and its measurement converted, into weight by multiplying volume with density (m = d x v)., In case of road milk tankers weigh bridge can be used to determine, its weight (weight of tanker when full – weight when empty).

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, , PLATFORM TESTS TO BE CONDUCTED FOR MILK, , 1.Appearance: Observing each can of milk for any floating extraneous matter, off colour, or partially, churned milk.,  The milk should be normal in colour, free from churned fat globules and reasonably free from any, floating extraneous material., 2.Smell (Odour): This furnishes an excellent indication of the organoleptic quality of milk that can be, ascertained quickly (in seconds).,  In making the test, the cover of each can is removed, inverted and raised to the nose.,  The headspace in milk can is smelled.,  By replacing the lid and shaking the can vigorously, the test may be repeated. An experienced milk, grader with a 'trained nose' decides the acceptance/rejection of the milk.,  The milk should be free from any off flavours., 3.Temperature: The temperature at which milk is delivered is often an indication of its quality.,  A daily check on the temperature of milk is helpful in keeping check on the quality of milk.,  With practice, the grader can tell with a high degree of accuracy whether the milk is sufficiently cold, by touching the side of the can.,  A temperature of 5°C or below is satisfactory.

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4.Sediment test: It shows the visible foreign matter contained in the milk.,  A low sediment is desirable. Sediment test is performed to judge the cleanliness of, milk.,  There is no correlation between the amount of sediment and the bacteriological quality, of milk.,  Measured quantity of milk is filtered or centrifuged and checked for sediment.,  A good quality milk gives no visible dirt whereas poor quality milk shows dark or, blackish deposits on the filter pad.,  The milk is graded for its quality on the basis of BIS standards., 5.Acidity: ‘Natural’ or 'apparent' acidity of milk is desirable which does not adversely, affects its heat stability.,  However, ‘developed acidity’ (Natural + Developed = Titratable acidity) adversely, affects the quality of milk which cannot be processed in pasteurizer., 6.Lactometer reading: The addition of water to milk results in lowering its density., Hence, this test is applied for detection of adulteration of milk with water.,  The reading for cow and buffalo milk should be about 28 to 30 and 30 to 32, respectively, when measured at 15.5°C.

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5.Dumping,  After the weighing of milk it, , is operated manually to, release each batch of milk in, the dump tank immediately, below.,  The milk is then pumped to a, chillier arte than to storage, tank

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 Quality control tests for milk:, 1., , 2., 3., , 4., 5., 6., , 7., 8., , Clot-on-boiling (COB) To find out the heat stability of milk Applied, as a platform test, Acidity To determine final acceptance/rejection of milk. Applied as a, platform test, Alizarin alcohol To find out the heat stability and pH of milk. Applied, as a platform test, Lactometer To detect adulteration of milk with water Applied as, a platform test, Reassuring Reduction test To find out the bacterial contamination, and growth in milk 2 minutes RRT as a platform test, Direct microscopic count (DMC) To identify the types of microorganisms present in milk. Applied as a Lab. test, Standard plate count(SPC) To find out the bacterial contamination, and growth in milk Applied as a Lab. Test, Fat and SNF To make payment for milk Applied as a Lab. test

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MILK CHILLING METHODS,  Milk contains some micro-organisms when drawn from the udder, their numbers, increase during subsequent handling.,  The common milk organisms grow best between 20 and 40 °C.,  Bacterial growth is invariably accompanied by deterioration in market quality due, to development of off- flavours, acidity etc.,  One method of preserving milk is by prompt cooling to a low temperature., Freshly drawn milk should be promptly cooled/chilled to 5 °C or below and also, held at that temperature till processed.,  Importance of Chilling/ cooling,  DIFINATION: Chilling of milk means rapid cooling of raw milk to sufficiently low, temperature so that the growth of micro-organisms present in milk is checked.,  In chilling process the temperature of milk should be reduced to less than 10, degrees Celsius preferably 3 - 4 degree Celsius.

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IMPORTANCE OF CHILLING,  Chilling of milk means rapid cooling of raw milk to sufficiently low temperature so, , , , , , , that the growth of micro-organisms present in milk is checked., In chilling process the temperature of milk should be reduced to less than 10, degrees Celsius preferably 3 - 4 degree Celsius., Various sources which contribute to the micro flora in milk are containers, udder of, the animal, dust and dirt particles, fodder, leaves, atmospheric air, the milker and, the animal itself., As soon as microorganisms get into the milk, they start growing rapidly because, milk contains all the nutrients required for their growth, and the conditions for their, growth are favourable., If the growth of microorganisms is not checked then their growth will continue and, several biochemical changes will take place in milk. Due to these changes the, quality of milk is adversely affected so much so that sometimes milk becomes unfit, for consumption as fluid milk.

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IMPORTANCE OF CHILLING,  Keeping quality of raw milk is very low as most of the milk is produced in, the rural areas under unhygienic conditions and atmospheric temperature, remains fairly high throughout the year.,  If milk has to be transported to longer distances, considerable time is, involved between production and heating process.,  During this period milk must be protected from spoilage by the action of, microorganisms.,  Chilling is considered necessary soon after the milk is received at the, chilling centers.,  The most effective means of controlling the growth of microorganisms, without affecting the physico-chemical properties and nutritive value of, milk is to chill it.,  Lower temperatures inhibit the growth of most of the microorganisms.,  It is only a means of checking the growth of microorganisms for some, time.

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METHOD OF CHILLING,  1. In can or can immersion method:, , , , , , , The milk is directly poured into cans through a strainer., When the can is full it is gently lowered into a tank of cooling water., , Advantages:, , The milk is cooled and it also stays cool., A much smaller mechanical refrigeration unit is required., ,  2. Surface cooler:, , , , , , This may be plain-conical, spiral or horizontal-tubular in shape., The milk is distributed over the outer surfaces of the cooling tubes from the top and flows, down in a continuous thin stream., The cooling medium mostly chilled water is circulated in the opposite direction through the, inside of the tubes., The cooled milk is received below in a receiving trough from which it is discharged by gravity, or pump., ,  Advantages:,  It transfers heat rapidly and efficiently.,  It is relatively inexpensive and also aerates the milk, thus improving its flavour

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IN CAN MILK CHILLING, , SURFACE MILK CHILLING

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 3. Tubular coolers:,  For continuous cooling, it consists of stainless steel tube about 2.5 to 5.0 cm in diameter, , , , surrounded by a similar tube, forming a concentric cylinder., Several such tubes connected in series to obtain sufficient cooling., The cooling medium flows counter to the milk flow., ,  Advantages:,  • Cooling is quite efficient,  • Not exposed to air-borne contamination,  • No evaporation losses,  4. Plate Cooler:,  To maintain the quality of milk received in the Dairy/Chilling centre, it is chilled to 4°C by, milk chillier.,  The chillier consists of number of thin, flat, grooved, stainless steel plates sealed at the, edges with a gasket and clamped tightly within a press.,  Chilling is done by flowing milk from one side and chilled water from other side of the plates.,  Advantages:,  • Cooling is quick and efficient.,  • Not exposed to air-borne contamination.,  • No evaporation losses.,  • Cleaning and sanitization are easy.

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 5. In tank or bulk tank cooler:, It is used extensively in developed countries.,  These are run by mechanical refrigeration systems.,  These will cool the milk rapid to a low temperature (5 °C or below) and maintain this, temperature during the storage period., , , , , , Advantage:, It helps in collection of produced milk on alternate days.

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MILK STOREGE TANKS, , , , , , , , , 1., 2., 3., 4., , , Raw cooled milk is stored in storage ranks until required for further processing., Modern milk plants hold both raw and pasteurized milk for a much longer period., It allows a more uniform work-day for processing and bottling operations with less dependence on the time, for receiving raw milk., Storage tanks are used for the storage of raw, pasteurized or processed milk in dairy plants., The storage tanks must be designed for ease in sanitation preferably by the circulation-cleaning method., In addition the tank should be insulated or refrigerated, so that they can maintain the required temperature, throughout the holding period agitation should be adequate for homogenous mixing but gentle enough to, prevent churning and incorporation of air., Objects:, To maintain the milk at a low temperature so to prevent any deterioration in quality prior to, processing/product manufacture., To facilitate bulking of raw milk supply, which will ensure uniform composition., To allow for uninterreupted operation during processing and packing, To facilitate standardization of milk., Types of milk storage tanks are insulated or refrigerated tanks, Horizontal or Vertical tanks and, rectangular, cylindrical or oval tanks.

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MILK STOREGE TANKS,  Objects:, 1., , 2., 3., 4., , To maintain the milk at a low temperature so, to prevent any deterioration in quality prior to, processing/product manufacture., To facilitate bulking of raw milk supply, which, will ensure uniform composition., To allow for uninterrupted operation during, processing and packing, To facilitate standardization of milk.

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TYPES OF MILK STORAGE TANKS,  Types of milk storage tanks are insulated or refrigerated tanks,, Horizontal or Vertical tanks and rectangular, cylindrical or oval tanks, silo tanks., , Normally storage tanks are located on an upper floor., The milk is pumped from the receiving room to the floor above. It than, flow by gravity.

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1., , , 2, , , 3., , , 4., , , , , Insulated/refrigerated:, In the former there are 5 to 7.7 cm of insulating material between the, inner and outer lining in the latter, the space between two linings is, used for circulation of the cooling medium., Horizontal or vertical:, While the former requires more floor space and less head space, the, latter requires less floor space and more head space., Rectangular or cylindrical or oval:, Of these, the first suffers from the disadvantages of having dead, corners during agitation while the other two do not., Built for gravity flow, air pressure or vacuum operation:, The first is the most common., However air pressure is sometimes used to evacuate the products., This requires special construction of the storage tank for greater, strength than necessary for normal operations under gravity flow.

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PARTS OF STORAGE TANK, 1., 2., 3., 4., 5., 6., 7., 8., 9., 10., 11., 12., , SIGHT GLASS, LIGHT GLASS AND LAMP, LADDER, MANHOLE, AGITATOR, OUTLET VALVE, INLET, AIR VENT, SAFETY VALVE, LEGS, INDICATING THERMOMETER, VOLUME METER.

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ASSIGNMENT, Name different mode of milk transport?, What is sampling of milk?, What do you mean by plant form test?, What is advantage of lactometer reading?, Name the different parts of storage tank?, Long answers, 1. Explain different modes of milk transport?, 2. Discuss in detail about platform test?, 3. Explain different methods of milk cooling/chilling?, 4. What are the objective of milk storage and briefly write about, type of milk storage tanks?, 1., 2., 3., 4., 5.