Operations in milk processing plant

Milk is most valued food and consumed by majority of the population. Processing of milk thus enables us to provide milk with better quality attribute and shelf-life.

1. OPERATIONS IN MILK PROCESSING PLANT: OVERVIEW Nusrat Ali Bhat Chinmai R D astikop

2. MILK PROCESSING Nusrat Ali Bhat Chinmai R D astikop Milk being most value protein food (ideal food) is also highly perishable because it is an excellent medium for growth of micro-organism – particularly bacterial pathogens – that can cause spoilage and disease in consumers. Milk processing plant allows the preservation of milk for days, weeks or months and reduce food-borne illness. The milk processing plant include a range of milk processing equipment to perform or handling the various operations of milk like heat treatments, pasteurization, homogenization and some others. The milk plant include the fluid milk production, cheese production, yoghurt production, ice-cream production to make huge variety of milk products like cheese, butter, cream, skimmed milk, double-toned milk and many more.

3. General Flow-Chart of The Process Nusrat Ali Bhat Chinmai R D astikop Receiving of Milk (Unloading, Grading, Sampling, Weighing & Testing) Pre-heating (35-40°C) Filtration/Clarification Cooling & Storage (5°C or below) Standardization Pasteurization (62.8°C 30min or 72°C 15sec) Bottling & Packaging Homogenization Storage (5°C or below)

4. I. Receiving of Milk Nusrat Ali Bhat Chinmai R D astikop Milk may be delivered to the milk plant in ‘cans’ or ‘tankers’ (Road/Rail). The milk in these containers has to be graded, emptied, measured by weight or volume, sampled and bulked to provide continuity of supply to the pasteurizing equipment. If milk is received from the milk-chilling centers , it has already been graded, weighed, sampled and cooled. Milk reception should be complete within 3-4hours , especially in tropical countries

5. Milk Reception Operations Nusrat Ali Bhat Chinmai R D astikop UNLOADING Milk cans are unloaded manually from truck. If the level of truck is in line with the platform, the unload requires least effort. If the milk tanker is being used, it is first properly positioned so that connections can be made conveniently. 2. GRADING It refers to the classification of milk on the basis of quality for the price fixing purposes. Milk grader is used for proper selection of milk. Principle of grading is based on organoleptic test (smell, taste, appearance & acidity, sediment etc. which are included in P latform test. Unloading Grading Sampling Weighing Testing

6. Nusrat Ali Bhat Chinmai R D astikop PLATFORM TEST It refers to the test which are performed to check the quality of incoming milk on the receiving platform so as to make quick decision regrading it’s acceptance or rejection. Some of the platform tests are : Smell (Odor): This furnishes an excellent indication of organoleptic quality of milk. An experienced milk grader with ‘trained nose’ usually relies to great extent in the acceptance/rejection of the intake milk on odor test alone. Appearance: Milk should be normal in color (Yellowish Creamy – Cow Milk & Creamy White – Buffalo Milk) free from churned fat globule & free from extraneous matter. Temperature: By touching the sides of can milk grader checks the temperature. A temperature 5 ° C or below is satisfactory.

7. Nusrat Ali Bhat Chinmai R D astikop Sediment: It shows the visible foreign matter Acidity: Natural/apparent viscosity does not affect the milk quality but developed acidity adversely affect the quality of milk. Titrable acidity(TA) of milk cannot serve quality of milk today due to the supplier are freely adding neutralizer to milk to reduce its acidity . Lactometer reading: It is mainly used for detection of adulteration of milk with water. It gives the specific gravity of milk. If SNF is high Lactometer reading is more. Other tests are: Alcohol test, Clot on boiling test(COP) & Resazurin Test(RT)

8. 3.SAMPLING Nusrat Ali Bhat Chinmai R D astikop It is very important in any quality testing of food material either milk or any other. PREREQUISTS OF SAMPLING OF MILK Thorough mixing of the milk by using stirrer/agitator in the can/tanker. Representative samples can also be taken during dumping of milk can into weigh tank, whereby milk gets mixed so thoroughly. Collected composite samples were placed in wide narrow mouthed glass bottles with a rubber stopper. Before transferring the sample into bottle first add the preservatives (formalin, mercuric chloride, potassium dichromate) to avoid subsequent contamination of the sample

9. 4 . WEIGHING Nusrat Ali Bhat Chinmai R D astikop This is essential step in accounting for milk receipts and disposal, making payment for milk etc. Milk in cans are measured by ‘weight’. The milk in cans is dumped into the weigh tank & it is mounted on scales & the scale dial is set at zero when the empty tank is on the scale, thus enabling the operator to make a direct reading of the weight of the milk The milk in tanker may be measured by ‘volume’ by passing it through a flowmeter. The measurement converted into weight by multiplying the volume with agreed density. Measurement by milk by weight gives accurate results by avoiding foam unlike in volume method.

10. 5.TESTING Nusrat Ali Bhat Chinmai R D astikop Apart from platform test in order to provide good quality of milk in-terms shelf-life, payment based on fat content etc. milk is tested in laboratory. E.g. Dye reduction test DMC – Direct Microscopic Count SPC – Standard Plate Count Fat/SNF content

11. II. PRE-HEATING Nusrat Ali Bhat Chinmai R D astikop The term pre-heating refers to heating before the operation which follows immediately. The milk is preheated for efficient filtration/clarification. Pre-heating is essential, if incoming milk is cold as otherwise the flow of milk is hampered. As the temperature of milk increases, the viscosity decreases and more efficient filtration/clarification results. The usual temperature is 35-40°C Equipment used may be plate/tubular heater

12. III. FILTRATION/CLARIFICATION Nusrat Ali Bhat Chinmai R D astikop Filtration removes the suspended, foreign particles by straining process . Clarification removes the suspended, foreign particles by centrifugal sedimentation Clarifier removes sediment much more efficiently than filtration & even clarifier remove still finer particles that escape from filter. Removal of clarifier slime does not affect the composition of milk to a significant extent usually it may be 0.01% Bactofugation is the process of removing 99% of the bacteria in the milk by centrifugal force.

13. Nusrat Ali Bhat Chinmai R D astikop Location of clarifier in the processing line Between Type of Clarifier Reception & storage tank Cold Storage tank & pasteurizer Cold Pre-heater & pasteurizer Warm Regeneration & heating section (HTST) Warm Heating section & holding tube (HTST) Warm

14. IV. COOLING & STORAGE Nusrat Ali Bhat Chinmai R D astikop As soon as milk is received from the plant, it is chilled at 5 ° C/below and stored because to prevent deterioration in its bacteriological quality during storage period. Methods of Cooling Surface Cooler Plate Cooler Inter tubular Cooler Jacketed Cooler

15. Nusrat Ali Bhat Chinmai R D astikop Storage of raw as well as pasteurized milk is important. Therefore design of storage tank such a way that it is easily cleanable/ease in sanitation, insulated with refrigerant and adequate agitation for homogenous mixing. The main objective of storage of raw milk is to facilitate bulking of the raw milk supply, which will ensure uniform composition. Storage Tank Horizontal & Vertical Storage Tank

16. V. STANDARDIZATION Nusrat Ali Bhat Chinmai R D astikop It refers to the adjustment of fat content of milk or milk product, by addition of cream or skim milk as appropriate to obtain a desired value to meet legal or other requirements. E.g. Toned Milk – SNF – 8.5% & Fat – 3%

17. VI. PASTEURIZATION Nusrat Ali Bhat Chinmai R D astikop It refers to heating of every particle of the milk to atleast 62.8 ° C for 30min or 72 ° C for 15sec in approved and properly operated equipment (HTST, LTLT). After pasteurization, the milk is immediately cooled to 5°C or below. The main 2 objective of pasteurization of milk are: To render milk safe for human consumption by destruction of cent % pathogenic microbes. To improve the keeping quality of milk by destruction of almost all spoilage organism (85-99%)

18. VII. HOMOGENIZATION Nusrat Ali Bhat Chinmai R D astikop It refers to the process of forcing the milk through a homogenizer with the objective of subdividing the fat globules. The homogenizer may be located immediately after regenerative heating, or between final heating and holding or before regenerative cooling.

19. VIII. COOLING Nusrat Ali Bhat Chinmai R D astikop After homogenization of milk, it is cooled to a low temperature of 5°C or below IX. BOTTLING & PACKING Milk after undergoing number of processing like pasteurization, homogenization etc. is packed in bottles/packets followed by storage. Then stored at low temperature. ( of 5°C or below )

20. Nusrat Ali Bhat Chinmai R D astikop Some Significant benefits of Milk processing Nowadays, the various modern high advanced milk processing machines are beneficial for any milk processing plants. It increases the quality of the products. It reduces the workload of farmers and dependency on workers. It helps for making products faster and easier . The highly advanced machines are easy to clean with less physical effort due to that milk plants always get clean. These advanced machines can be operated 24 hours for making good quality products. It helps to get more output with few workers. It helps to keep product quality maintain . With the help of advanced machines, it is easy to provide low-cost product to the people

21. Nusrat Ali Bhat Chinmai R D astikop THANK YOU