Milk Processing and Packaging

Milk is normal mammary secretion of a healthy animal. Hence, animal health is an important aspect in the production of clean milk. Good hygiene and sanitation practices would keep it free from bacterial contamination. Thus, both these aspects discussed mainly from the point of clean milk production. If raw milk is brought to dairy plant by a producer, then it shall be ensure that he brings it within shortest possible time of milking and it should be cooled as soon as practicable to a temperature of 4°C or lower and maintained at the temperature until processed.

Necessary steps to be taken care for Clean Milk Production:

1. Cattle
   • Give sufficient quantity of feed and drinking water to milch animal prior to milking
   • Remove accumulate cow dung
   • Milch animal shall be batched and if bath is not possible dry cleaning by broom/duster should be done
   • Maintain milch animal clean and healthy
   • In case animal under treatment, discard the milk during withdrawal period of the treatment
   • Clean the udder and teats of milch animal by clean water and wipe using a dry & clean cloth
   • Teats should be cleaned after sucking, if cattle is letting down the milk by calf sucking
   • It is good to keep the animals standing for at least half an hour after milking. Feed may be provided to encourage this
2. Cattle Shed
   • Clean the cattle shed floor either by washing with water or dry cleaning 10-15 minutes before milking
   • The floor should not be slippery. It should be firm and dry so as to provide a proper foothold to the animal while rising or standing.
3. Utensils
   • Clean thoroughly the milk collection vessel preferably with detergent and hot water etc. and keep it inverted to dry before milking.
   • Avoid use of measures, tumbler etc. in the milking vessel for removing or to transfer milk from milking pail.
   • The utensils and the storage vessels should be of SS 304 construction and free from sharp edges.
   • A suitable size lid should be always be used to cover the utensils and the vessel.
   • They should be cleaned and sanitized before and after their use and kept dry.
   • They should be exclusively used for milking.
   • The milk should be filtered before pouring into the vessel.
   • The utensils should be the same in which the milking is done to avoid contaminations due to multiplicity of vessel etc.
4. Milk Handler
   • Milker should wash his/her hands with soap to make them clean and germ free.
   • Milker should wear clean cloths
   • Milker should avoid contact between milk and his body parts, cloths and other belongings.
   • Chewing and spitting with tobacco and smoking should be avoided during milking.
   • Sneezing/coughing towards udder/vessel during milking should be avoided
   • Milker should not be suffering from any respiratory ailment disease.
   • Milker should not have any open sores or cuts.
5. Miscellaneous:
   • Use separate vessel for washing of udder and teats & for milking
   • Discard the initial milk from all the four teats to minimize the bacterial load
   • Flies, hay, husk, dry cow dung cake or other extraneous matter should not get into milking vessel.
   • After milking rinsing of teats in a disinfective solution (with water, iodophor etc.) shall be done to avoid post milking infection.

Delivery of Milk to Cooperative Society/Milk Collection Centre:

The major operations of a Cooperative Society are hygienic Milk Collection and providing input services

• Milk collection involves reception, testing, local and sample milk sale, dispatch of milk to the Milk Union, payment and accounts keeping
• Input services include animal health coverage, artificial insemination, supply of cattle feed, mineral mixture and other feed supplement, fodder seeds, providing extension services to producer members including propagation of clean milk production practices.
• Milk should be carried in SS utensils/SS Cans.
• Milk should be brought to DCS/MCC as quickly as possible after milking to avoid multiplication of harmful bacteria.

Cleaning Procedure:

Tanks may be cleaned manually or with CIP. A typical example of cleaning cycle for bulk milk tanks is provided below:

Manual cleaning of Bulk Milk Tanks

• Pre-rinse

Rinse the tank manually and flush pipeline with lukewarm (38-43°C) water immediately after use to remove remaining milk residues.

• • Disassemble all parts that must be hand-washed. Before carrying out routine cleaning of the tank, the thermometer probe and dipstick should also be removed and put aside carefully.
• Detergent Wash

Alkaline cleaning solution (0.5-0.75%) (Usually containing basic alkali, phosphates, wetting agent, and chelating agent) or as specified in manufacturer’s recommendations and based on water quality tests.

• All detachable parts like tank covers, gaskets, calibration rod etc. should be cleaned manually after disassembling.
• For hand washing of disassembled parts:
  • Soak all parts at 49-57°C for at least 5 minutes
  • Brush all parts thoroughly
  • Drain

CIP of Bulk Milk Tanks:

• Pre-rinse

Rinse the tank manually and flush pipeline with lukewarm (38-43°C) water immediately after use to remove remaining milk residues.

• Detergent Wash

• • Start with detergent solution (0.8 – 1.0%) and circulate it at 77°C for 6-10 min.
  • Brush all parts, including outside of tank and outlet valve, not designed for cleaning by circulation of cleaning solution.
  • Drain
  • Clean the outlet connection and outlet valve manually
• Rinse
  • Risen of the detergent solution with tap water before the acid rinse, if required
  • Rinse tank thoroughly (Inside and outside)
  • Rinse tank outlet valve
• Acid-Rinse (Occasional)
  • Occasionally, rinsing with an appropriate acid (nitric acid) solution (55°C-60°C) is required to remove inorganic soils that build over a period of time.
  • Circulate for 2-3 minutes and drain
  • Visually inspect line, receiver jar, etc., for proper cleaning

Check points to follow in CIP

• Check that all solutions drain completely between cycles
• Check that the pump has sufficient pressure to reach all areas
• Consider an acid wash if no softener is being used in hard water
• Check outlet valve, gasket and manhole area for cleanliness
• Check inter area to cooler and inlet pipe
• The outside of the bulk milk cooler needs to be kept clean at all times

Milk Transportation from DCS to Dairy Plant:

Milk from Dairy Cooperative Society (DCS)/Milk Collection Centre is transferred to Dairy plant through Cans/Road Milk Tankers.

Milk Reception at Dairy:

Dairies have reception bays most commonly known as Raw Milk Reception Dock to receive the milk brought from Dairy Cooperative Societies / Farms in cans as well as milk tankers. The first thing done at reception is determine the quality of milk. The quality is recorded and entered into the weighing system that the Dairy uses to weight the gross and net weight.

Steps of Can reception:

• The Can arrive from the lorry on a conveyor. Each can is subjected to rapid sensory evaluation and some preliminary tests to decide the acceptance or rejection of the milk.
• In automatic Can reception, the lids are automatically removed and emptied into a weighing bowl, which indicates the quantity.
• Cans are also unloaded manually and placed on the conveyors for emptying it.
• Drip saver is provided to collect milk which is left while dumping into the weighing bowl.
• The weighing in system is programmed so that the operator enters the society identification on a keyboard before weighing all the Cans from that route.
• The weighing balance must be well maintained and checked every day to ensure accuracy. Periodic calibration needs to be carried out by external agency.
• From weighing-in, the raw milk is pumped to storage tanks through in-line filter and milk chiller.

Can Washer

The empty Cans are conveyed to Can washer, where they are washed with water and detergent to remove all traces of milk.

Two types of Can Washers are used in Dairy Industry:

1. Rotary Can Washer
2. Straight through Can Washer

These are semi-automatic or automatic Can washing machine, in which Cans are rinsed, cleaned and sterilized very effectively.

Tanker Reception

Tankers arriving at the Dairy drive straight into a reception bay, often large enough to accommodate several vehicles.

The milk is measured either by volume or by weight.

• Measuring by volume

This method uses a mass flow meter. To avoid error in the reading of mass flow meter, a deaerator which eliminates the air in the milk being unloaded from the tanker is installed.

• Measuring by weight

Bulk-collected milk can be weighed in as following procedure:

• By weighing the tanker before and after unloading and then subtracting the empty tanker weight from the gross weighment value.

The tanker is driven onto a weighbridge at the Dairy. Operation may be manual or automatic.

• If manual, operator records the weight against the driver’s code number
• If automatic, the necessary data are recorded when the driver places a card in a card scanner

Process of Milk Reception and Processing:

Chilling of Incoming Milk:

Normally a temperature increases to slightly above 4°C is unavoidable during transportation. The milk is therefore usually cooled to below 4°C in a plate heat exchanger before being stored in a silo tank to await processing.

Raw Milk Storage:

• The untreated chilled raw milk as received at RMRD is stored in large vertical tanks or silos which have capacities ranging from 50 KL to 150 KL.
• Smaller tanks can be located indoors while the larger capacity tanks are placed outdoors to reduce building costs.
• Material of construction (MOC) of silos is SS-304 and they are insulated with EPS or polyurethane form sheets of sufficient thickness to prevent temperature rise.
• The outer cladding is also of SS-304 sheet in modern silos.
• The inner tank is of stainless steel with minimum 150 grit finish.
• There is an agitator mounted on top or inclined near the bottom of the silos for agitating the milk to keep it homogenous and also to cool it uniformly.
• The agitator with mechanical seal that prevents oil from dropping and also to avoid leaking into the milk inside the silo.

Clarifier

Function of Clarifier

• Remove undesirable milk solids like dirt, dust, hay, manure, bacteria, somatic cells and pulverized hair by the application of Centrifugal force.
• Remove bacterial spores present in milk by the application of centrifugal force
• 2-stage Bactofugation can remove 99.9% bacterial spores and 90.0% bacteria from milk.

Cream Separator

Centrifugal equipment that separates milk into cream and skimmed milk.

Milk Standardization:

The separated cream and skim milk are remixed in certain proportion to make standardized milk as per further process/market requirement. Different types of milk like Toned, Double Toned, Standardized, Full Cream etc. have different standards of Fat & SNF as prescribed by the FSSAI. For certain specific products, even protein content may be adjusted.

Homogenizer:

Homogenization is the process of reducing the fat globule size below 2 microns so that they float suspended evenly throughout the entire milk solution.

Homogenization is done in two stages:

In 1^st Stage: Milk is passed through small openings with applied pressure of 2500 PSI followed by 500 PSI in 2^nd stage to prevent fat globule clumps.

Pasteurizer:

Pasteurization is a process that kills pathogens in milk. Pasteurizer is the equipment used for HTST pasteurization.

This is achieved by heating the milk in the pasteurizer to a temperature of minimum 72°C., holding it at the temperature for 15 seconds and then rapidly cooling it below 4°C.

Milk Packaging:

Processed Milk is pumped to the packaging plant where milk is packed in various sizes for final distribution to the end user.

Modern trend is to use mechanical pouch packing machines instead of pneumatic type packaging machines.

Crating and dispatch:

Poly packs are arranged in plastic crates systematically and loaded on to trucks for dispatch to different milk sales outlets.

Crate Washer

Effective cleaning of crates before transport of milk pouches at Dairy plant level decreases contamination. This could also lead to improvements in product quality, transportation and storage. Clean crate meets the hygiene requirement of your customers. To achieve that, you need high quality at flexible crate washers.

A typical crate washer consists of a washing section(s) and a rising section. In these sections, the nozzles that are mounted on the spraying racks will produce the Mechanical Action of the Temperature Controlled and Chemical Dosed Water. Each washing section has its own reservoir for reuse of washing water and for the rising section, fresh water will be used. A transport chain or transport belt will be used to transport the crates through the machine with a certain speed to meet the washing time for a certain crate/pollution.

Packaging requirements for Milk and Milk Products:

• The rooms for storing packaging material shall be free from vermin and from dust which could constitute an unacceptable risk of contamination of the product and shall be separated from rooms containing substances which might contaminate the product. Packaging material shall not be place directly at the floor.
• Packaging shall be done without delay and shall be handled by separate group of staff having experienced in product packaging.
• Bottling or filling of containers with heat-treated milk and milk product shall be carried out mechanically and the sealing of the containers shall be carried out automatically.
• Wrapping or packaging may not be re-used for dairy products, except where the containers are of a type, which may be re-used after thorough cleaning and disinfecting.
• Sealing can be carried out in the establishment in which the last heat-treatment of drinking milk or liquid milk-based products has been carried out, immediately after filling, by means of a sealing device which ensures that the milk is protected from any adverse effect of external origin on its characteristic. The sealing device shall be so designed that once the container has been opened, the evidence of opening remains clear and easy to check.

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