Capping off milk: fluid closures offer tamper evidence, leak protection

Dairy Foods, Oct, 2002

Milk caps are designed to do two things--keep milk in the container, and keep anything else out. Unfortunately they don't always succeed.

The "leaker" has been a pestilence to processors for as long has milk has been sold in grocery stores. Are there solutions? Certainly. And perhaps more than ever, processors are ready to take advantage of them.

A Brief History of Caps

Since the advent of the plastic milk jug, dairy processors have been looking for a better cap. In the beginning there was the screw cap. It provided a pretty good seal on most containers, but there was a problem. Torquing the caps on the line after filling slowed production. As efficiencies were reached elsewhere in the plant, the bottle cap became the bottleneck and before long, dairy processors and their suppliers were looking for a solution. Enter the snap cap.

The snap cap was a great little innovation for dairy processors. It made for speedier filling and capping, and soon, everyone was looking to use snap caps. But consumers weren't all that crazy about the snap cap. Some say it was a psychological thing. If you can't screw down the cap it just didn't seem like it was closed.

Next stop: the snap screw. Sure enough it didn't take long before someone figured out that you can use a lighter thread so that the process can apply the cap easily and the customer can use it like a screw cap, or like a snap cap.

Only problem with the snap screw? They tend to leak.

The Latest Options

That brings us into the 21st century. And heightened concerns about food safety, are only part of what's driving the on-going quest for closure.

Look around at the way milk is being sold. Many retailers, including the world's largest, Wal-Mart, are selling milk from slide racks that are placed behind the glass doors of a walk-in cooler. The slide racks are angled so that the milk slides to the front each time a package is removed from a facing. That keeps things looking nice and neat for the retailer, but all the weight from the line of bottles exerts great pressure on the front package. So without a strong seal ... the leaker strikes again!

So what's to be done to provide more safety and security? A number of things:

Many processors are adding a foil or foam seal under the cap to provide tamper evidence and leak protection. The snap screw can then be used for resealing. Some retailers are demanding an inner seal. Cap suppliers are ready to provide them.

The return of the screw. At least one major retailer/processor is going back to screw caps. But a new version has multiple thread positions that allow for easy application with non-screw cappers.

Shrink sleeve neckbands. With the proliferation of single serve milk in full-body shrink sleeved bottles, this a handy option.

Better cap seals. Manufacturers of bottle caps and gabletop fitments have a variety of products available to provide single and double layer tamper evidence.