Aseptic milk processing, filling and packaging in plastic gains commercial acceptance —another milestone for fluid milk containers.

Until recently, the only FDA accepted, commercial, aseptically processed and packaged dairy-based (low-acid) beverages in plastic bottles available for sale at ambient temperature came from Columbus, Ohio-based Ross Products, a division of Abbott Laboratories, for its Similac infant formula and Ensure nutritional drink. A lot has changed in the past few months.

On November 7, 2002, FDA accepted the high-speed, linear filler aseptic (LFA) system installed by Tetra Pak Inc., Vernon Hills, Ill., at Jasper Products LLC, Joplin, Missouri.

“We filed the LFA-20 system on August 22, and it took less than 90 days to receive FDA’s acceptance,” says Jeff Kellar, vice president, plastic packaging systems at Tetra Pak. “We installed the system at Jasper Products a year prior to filing with FDA, and managed to test and prove within the year that it is FDA compliant.”

Tetra Pak, Jasper Products and Dover Brooks, the process authority, worked together to finalize the development and prove the safety and efficacy of the LFA20 low acid filling system according to the regulatory requirements, Kellar said.

FDA’s acceptance letter states that Tetra Pak’s filing is considered to be in compliance with Section 108.35 and Part 113 of Title 21 of the Code of Federal Regulations.

Section 108.35 addresses emergency permits, which includes initial permits, for thermal processing of low-acid foods such as fluid milk, that are packaged in hermetically sealed containers. The CFR says that a commercial processor, when first engaging in the manufacture, processing or packing of thermally processed low-acid foods in hermetically sealed containers, shall, not later than 10 days after first so engaging, register with FDA as a food canning establishment, hence the “initial permit” nature of this regulation. Registration includes name, principal place of business, location of each establishment in which processing takes place, processing method in terms of type of processing equipment employed and list of low-acid foods processed in each such establishment.

“The filing and acceptance is specifically for commercial manufacturing, filling and sterilizing of 32-oz. HDPE (high-density polyethylene) bottles,” says Kellar. “While the system is accepted for its efficacy and safety, each package shape, size and material represents another level of validation and testing to continue to prove the viability of the system. It’s a rigorous process, but Tetra Pak has established the processes to manage all the regulatory requirements efficiently.”

There are three elements to the accepted LFA-20 system, according to Kellar. “There’s the heat processing system, the filler and bottling operation and then downstream, which includes the application of secondary packaging such as labels.”

To assist with all the details regarding thermally processed low-acid foods packaged in hermetically sealed containers, 21CFR113 provides definitions, good manufacturing practices and a description of equipment, procedures, containers, operations and record keeping.

Section 113.3 provides definitions for key terms such as aseptic processing and packaging, which is defined as the filling of a commercially sterilized cooled product into pre-sterilized containers, followed by aseptic hermetic sealing with a pre-sterilized closure in an atmosphere free of microorganisms.

Commercial sterility is defined as a condition that renders a food free of microorganisms capable of reproducing in the food under normal non-refrigerated conditions of storage and distribution, and viable microorganisms (including spores) of public health significance. This condition is achieved either through the application of heat or by the control of water activity and the application of heat.

Hermetically sealed container refers to a container that is designed and intended to be secure against the entry of microorganisms and thereby to maintain the commercial sterility of its contents after processing.

Low-acid foods are any foods, other than alcoholic beverages, with a finished equilibrium pH greater than 4.6 and a water activity greater than 0.85. Fluid milk and soy beverages are low-acid foods.

In essence, the FDA-approved LFA line at Jasper Products is aseptically filling commercially sterile low-acid beverages into commercially sterilized plastic bottles that are hermetically sealed and available for distribution, merchandising and storage at ambient temperature. The first beverage going into the bottles is Soysense™, a line of organic soymilk. It comes in three flavors: Chocolate, Original and Vanilla, and until now, was only sold in aseptic Tetra Briks.

In addition to the LFA20 filling technology, Tetra Pak has developed a critical bottle manufacturing capability at Jasper Products. Using multi-layer extrusion technology, Tetra Pak is able to protect the product after filling with the appropriate barrier technology, and create the optimal bottle designs to maximize the aseptic performance of the package. Tetra Pak’s unique sealed-neck, superior hygiene technology for HDPE bottles protects the interior of the unfilled bottles, maximizes performance in the LFA-20 filler, and insures quality and product safety.

So why go aseptic?

“This is one of the most noteworthy opportunities for milk to compete in the beverage category,” says Kellar. “The real significance of this development is to provide distribution through venues where milk traditionally has not been sold. It also is ideal for a new generation of milk products, such as dairy-based nutritional beverages.”

Dairy-based nutritional beverages are new to consumers, so consumers are open to different packaging and alternate purchase venues. They are not skewed in believing such products, even though they contain milk, must be sold in the dairy case.

“In the United States, consumers are not familiar with shelf-stable milk, although it’s the dominant format for consumers in many other parts of the world,” says Kellar. “In the States, we have grown up with a vast chilled distribution chain, so the presence of the technology has only a minor position in milk. However, today, the fragmentation of the retail channel, the development of new channels and the on-the-go American wanting products to be readily available will vastly increase the relevance and applications for aseptic products in all package formats.

“By adding plastic to the options, we will give consumers a format they know and are familiar with,” Kellar adds. “This will educate them to the benefits of aseptic processing and packaging, which will drive all aseptic package formats.”

Until now, aseptic milk has basically been packaged in foil barrier boxes. Foil pouches and aluminum cans are also an option, but they are not any more desirable than boxes.

“As for the taste implications for aseptically processed milk, any differences that existed when the processing technology was emerging 20 years ago have since been improved,” says Kellar. “In a blind taste panel, consumers cannot tell the difference between aseptically processed and traditionally pasteurized milk.”

Improved technologies have reduced the cooked flavor notes, and plastic approval makes aseptic more desirable to manufacturers and less objectionable by consumers.

“The first evolution of products resulting from this emerging technology is an extension of brands. The technology breaks down barriers for milk, particularly flavored milk, and gets the product into channels where it has always wanted to be,” Kellar adds. “The second evolution of products is still an unknown. Aseptic plastic bottles present an opportunity for the development of new types of dairy-based beverages.”

In addition to opening up new markets, there are significant cost-savings that can be gained in distribution. Shipping costs will be lower as a result of not having to employ refrigerated trucks.

Horizon Organic Dairy Inc., Boulder, Colo., is reaping the benefits of offering consumers an aseptic milk option, even though it is not aseptic plastic, yet. In efforts to get into quick-service beverage environments that traditionally have not wanted to sell milk because of its perishable nature, Horizon uses the Tetra Prisma, an 8-oz, eight-sided foil board container, which comes with a wrapped straw in addition to a pull-tab, to sell regular and flavored milk in places such as Starbucks.

Details of the process

The 3,600 gal. per hour processing system at Jasper Products heats low-acid beverages with super-heated water to 280¿F for at least two seconds. Product is rapidly cooled to 45¿F, homogenized and stored in aseptic silos for filling into sterile bottles. This process is milder than earlier aseptic systems and helps reduce the development of off-flavors. However, the treatment is potent enough to achieve commercial sterility.

Under sterile conditions using a HEPA air filtration system, a blow molder produces bottles with closed tops. Bottles are composed of three HDPE layers. The two exterior layers of ordinary HDPE enclose an interior black light-blocking HDPE layer. Bottles remain sealed until just before filling. This assists with cleanliness and structural integrity.

When it is time for filling, in a clean room that also uses HEPA air filters, bottle tops are cut off and bottles are sterilized with hydrogen peroxide vapor, a step required by FDA for aseptic processing. Upon filling, bottles are quickly hermetically sealed with sterilized foil seals.

“The system at Jasper Products fills about 200 bottles per minute,” says Kellar. “This is about twice the speed of the only other FDA-approved commercial aseptic plastic bottling system.”