Dairy Process Engineering

Module 5. Packaging machines for milk & milk products

Lesson 25
PACKAGING MACHINES FOR MILK PRODUCTS

Introduction

The wide varieties of milk products packaging makes the choice of packing machines. The requirement of each product is different,as well as the size and shape. Some of them are to be stored at low temperatures, while others are kept in ambient temperatures. The packing material also different, and the information to be given on packages may be a legal requirement in most of the cases. Some products are further processed while in the packaging itself, like sterilization, curd setting etc. The packaging machine working principle will also depend on the physical nature of the product, like liquid, solid, semi solid.

Cheese Packing

Specific applications

When packaging food products those are sensitive to spoilage or loss of freshness,it is important to seal the product in containers that allow a tight seal. Itis typical to evacuate the chamber to a target vacuum level, thus removing air and oxygen. Higher vacuum levels remove more air, but require larger vacuum systems, higher attainable vacuum levels, and more time for the evacuation process. The target vacuum level is a function of the product being packaged and is determined by the packager and/or government regulations. Speed is an important factor in many packaging operations, and machine manufacturer are often rated on how many packs per hour their machine can perform, while meeting a set of specifications. Higher speed usually means higher vacuum system capacities, and/or a secondary vacuum system to “pre-evacuate” the vacuum packaging chamber. Sometimes, purge gases are introduced during the packaging operation to help displace air and oxygen, retard spoilage, and further enhance shelf life and appearance. Appearance is vitally important in the packaging industry.

Machine Types

Chamber packaging machines

Chamber machines are typically used to seal meats and cheeses in film pouches. In appearance, they have a base and a swinging top cover (sort of like a Xerox machine). The product is placed into the machine, and the swing lid is closed.Where the lid and top of the machine meet, a seal is formed. At this point vacuum evacuation begins and the rest of the sealing process occurs under vacuum. When the lid is lifted, the product is fully packaged and ready to remove.

Small chamber machine (desk model)

Chamber up to 50 liters, rotary vane pump 3 to 25 m3/hr.

Double chamber (mobile)

Two chambers, each up to 150 liters, rotary vane pump 40 to 300 m3/hr

Big chamber machine (non nobile)

Chamber up to 400 liters, pump combination rotary vane pump 340 to 1000

m3/hr.Booster pumps 500 to 2000 m3/hr

Rotating chamber machine (non mobile)

Multiple rotating chambers (step evacuation) rotary vane pump160 to 630

m3/hr

Multiple rotating chambers (step evacuation) rotary vane pump 160 to 630

m3/hr and booster pump 500 to 2000 m3/hr

Tray sealing machine

With Tray type machines, the user purchases a tray (Styrofoam, plastic,etc), loads the product onto the trays and places them into the machine. At this point the chamber is evacuated to achieve a “skin pack”. These machines are typically used by small packagers.

Inert gas-flushed packaging (snorkel machines)

MAP(Modified Atmosphere Packaging) involves packaging the food product in an gas atmosphere other than standard room air to achieve specific goals not otherwise possible. Common atmospheres include:

Nitrogen

80% Nitrogen- 20% CO₂ mixture

Saturated oxygen greater then 80%.

The machine pulls a vacuum and reduces oxygen content down to 0.3 to 1% to remove Anabolic Bacteria. When this occurs, meat becomes purple. Back flushing with the appropriate gas maintains product color for an attractive and appetizing appearance. All machines that use a chamber can be fitted with gas flush option, and approximately 25% of machines on the market do so.

Fig. 25.1 Different types of cheeses

Fig. 25.2 Different types of wrapped cheeses

Fig. 25.3 Cheeses packing machine

Chamber Packaging Machines

Small Chamber

Packaging Machines

(desktop and portable)

Fig. 25.4 Chamber packing machine (small size)

Mid Size Chamber

Packaging Machines

For higher production rates

Fig. 25.5 Chamber packing machine (medium size)

Large,fully Automatic

Chamber Packaging

Machines for High

Fig. 25.6 Chamber packing machine (large size, automatic)

Fig. 25.7 High speed rotary chamber machine

Vacuum Packaging

Key factors in vacuum packaging of food products include consistent vacuum levels, fast pump down times and low maintenance. Rietschle pumps are capable of operating cooler than our competition’s models, due to our superior design. Cooler operation contributes to reduced oil breakdown, less oil misting, reduced maintenance and better pump life. Bush claims our cooler operation is a disadvantage, saying that we will condense water vapor inside the pump. That is pure marketing spin on their part. All our oil-lubricated rotary vane pumps come with adjustable gas ballast valves that eliminate the likelihood of any condensation in the pump. It is anon-issue. General Volume and Pressure Requirements: 5 to 1535 CFM, usually at1 Torr Pumps are usually rated @ 1 Torr when purchased. After use, and due to pressure drop for piping lines, 2 to 3 Torr will still produce a good pack.Often, end users cannot reach 2 to 3 Torr even after the OEM service tech visits, and they may believe their pump is undersized for machine. Offer to work on these projects if ROI is good. Many user customers can speed up cycle time for their machines by putting a larger volume pump on the machine. Our VC Product line, with it’s many sizes and increased volume for same HP, is perfect for this purpose. Some users have old, worn, or undersized pumps that cannot attain the ultimate required vacuum or have cycle times that are longer than standard. Look for these opportunities to sell new pumps with more CFM per HP than our competitors. Busch parts prices are higher than ours and in some cases, double! Busch does not include some parts in their standard rebuild kits and these required parts must be purchased as adders. This can be a Rietschle advantage, especially if the customer is feeling he has been gouged. (You might even want to suggest this). Some customers buy “pirate” non-OEM parts from other sources, but they can have genuine Rietschle parts at a reasonable price.Busch requires serial numbers before they will sell any parts; this is an inconvenience to most users. We will provide test units with special terms for large projects. Please inquire with the Rietschle Inc. Sales Department for assistance, terms & conditions.