Dairy Pasteurization Process

About Pasteurization Process for Dairy products, Its very helpful knowing about Pasteurization

1. Pasteurization Presenting by: Yousuf Khan Durrani

2. What is Pasteurization Pasteurization is the process of heating a liquid below the boiling point to destroy microorganisms. In general, the process of heating of each and every particle of milk at a particular temperature for defined time.

3. About the scientist Louis Pasteur  (December 27, 1822 – September 28, 1895) Was born in Dole, France. Was a French biologist, microbiologist and chemist.   He was well known for his discoveries of the principles of  vaccination ,  microbial fermentation  and  pasteurization . He is remembered for his remarkable breakthrough in the causes and prevention of  diseases . His discoveries have saved many lives ever since .

4. History of Pasteurization In 1860s French wine industry was in trouble due to wine spoilage. At that time Pasteur was working at the University of Lille. Pasteur examined spoiled wine under microscope. He finally reached that conclusion of Microorganisms similar to the bacteria responsible for lactic acid and acetic acid fermentations. Pasteur then discovered that a brief heating at 55-60°C would destroy these microorganisms and can preserve wine for long periods. In 1886 German chemist F. Soxhlet adapted the technique for preserving milk and reduce milk transmissible diseases.

5. Modes of Pasteurization On the basis of Temperature and Time combination following are the types of Pasteurization Types of Pasteurization Time Temperature Low Temperature Long Time (LTLT) : Vat Pasteurization 30 min 63°C High temperature Short Time (HTST) : Flash Pasteurization 15 sec 72 °C Higher-Heat Shorter Time (HHST) 1 sec 89 °C Higher-Heat Shorter Time (HHST) 0.5 sec 90 °C Higher-Heat Shorter Time (HHST) 0.1 sec 94 °C Higher-Heat Shorter Time (HHST) 0.05 sec 96 °C Higher-Heat Shorter Time (HHST) 0.01 sec 100 °C Ultra Pasteurization (UP) 2 sec 138 °C

6. Purpose of Pasteurization To increase Milk safety by: Pathogen destruction Maintain originality of Milk. To increase Life of Milk by: Almost kills all microbiological spoilage microbial agents. Deactivates enzymatic activity which affect quality and shelf life of product.

7. Pasteurization techniques using in Dandy In Dandy we are using modified HTST pasteurization technique having following combinations: 80°C to 85°C for 30 Seconds: For ice cream products. 90°C to 95°C for 30 Seconds: Stirred yoghurts. 90°C to 95°C for 320 Seconds: For fermented dairy products 90°C to 95°C for 30 Seconds: For juices, nectars, fruit drinks and flavored drinks.

8. Pasteurizers Using in Dandy On the basis of structure and design we are using two types of Pasteurizers in our facility: 1 . Tubular pasteurizer: The Tubular Pasteurizer can be used for juices, soft drinks, tea and coffee drinks, and water. In Dandy we are using for Juices, fruit drinks and Sugar based drinks. Occasionally for Low viscous milk product. 2 . Plate heat exchanger pasteurizer : In Dandy we are using this type of Pasteurizer for Milk and Milk products. Fermented dairy products, and Ice cream mixes.

9. Stages of Pasteurization (PHE) Following are the stages involved in-process of pasteurization: Float Controlled Balance tank Feed pump Regenerative heating (R1 & R2) Homogenization Heating Flow diversion valve (FDV) Holding Regenerative cooling (R2 & R1) Cooling by chilled water or brine

10. 1. Float controlled balance tank (FCBT): Maintains a constant flow of milk for feeding the pump. also receives milk diverted by FDV (if diverted). Float in tank maintain level of balance tank and prevents overflow of milk.

11. 2. Pump Centrifugal pump with a flow control device to ensure constant output, after FCBT is used. Rotary positive pump can be used between the regeneration and heating sections. Is used to maintain constant flow of milk throughout process.

12. 3. Regenerative heating (R1 & R2) To partially heat raw chilled incoming milk. Incoming milk partially and indirectly heated by the heated outgoing milk (milk-to-milk regeneration). This adds to the economy of the HTST process, as the incoming milk requires less heating by hot water to raise its temperature to pasteurization temperature in the heating section.

13. 4. Homogenization Homogenization  is an entirely separate process that occurs during pasteurization in most cases. The  purpose  of  homogenization  is to break down fat molecules in  milk  so that they resist separation. Without  homogenization , fat molecules in  milk  will rise to the top and form a layer of cream.

14. 5. Heating The preheated milk from regeneration section passes through heating section of HTST. Where it is heated to 72°C or more with the help of hot water from hot well. Thereafter, the heated milk enters into the holding section via FDV (plates/tube).

15. 6. Flow Diversion Valve This diverts the milk before holding section. If the milk is not properly heated at specified temperature. Automatically diverted by the FDV back to the Float Controlled Balance Tank (FCBT) for reprocessing. It is usually operated by air pressure working against a strong spring. Very helpful to insure proper pasteurization

16. 7. Holding The holding tube ensures that the milk is held for a specified time, not less than 15s. at the pasteurization temperature of 72°C or more. Designed to get specified time as per the flow of product in system.

17. 8. Regenerative cooling (R2 & R1) The pasteurized hot outgoing milk is partially and indirectly cooled by the incoming cold milk (milk-to-milk regeneration). This again adds to the economy of the HTST process. In fact, when pre-cooled (raw) milk is received, regeneration efficiency is 90% and above which obviates cooling using well water altogether .

18. 9. Cooling The partially chilled milk from regeneration section passes through chilling section of HTST. Where it is chilled to 10°C or less with the help of chilled water IBT. Thereafter, the chilled milk passes to storage tanks.

19. External requirements for Pasteurization: Following are the direct or indirect requirements for the pasteurization: Filters Control panel Automatic control devices Steam pressure controller Water temperature controller Milk temperature recorder Hot water and Chilled water

20. Effect of Pasteurization: Bactericidal effect : All of the pathogens are inhibited : Mycobacterium tuberculosis ( 63°C 30 min) Coxiella burnetti (72 °C 15 sec) Reduction of creamy layer Inactivation of phosphatase enzyme of the cream layer P asteurization has a small effect on the vitamins naturally found in milk. Whiteness of raw milk & pasteurized milk differs Fruit juices – Main problem is color deterioration by enzymic browning (poly phenol oxidase ). This browning reaction promoted by the presence of oxygen. In fruit juice industries, fruits are involve to de- aerated prior to pasteurization process. There for retain natural fruit color.

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