Converting Quarterly 2014 Quarter 4 : Page 72

FINISHING Advances in laser micro-perforated flexible packaging for extended product shelf life By John Dillon, vice president-marketing; and Jim Bucklew, senior applications development engineer, Preco, Inc. Abstract The market for prepackaged produce continues to grow at a brisk pace. This growth is a result of a market desire for the convenience of pre-packaged foods that minimize meal preparation time. Packaging technology plays a key role in the ability of food suppliers to offer case-ready products, specifically the ability to offer flexible-packaging films that are tailored to match the vapor transmission rate of the specific food product to maximize its shelf life. A key technology that controls the vapor transmission rate is the use of industrial lasers to micro-perforate the flexible-packaging material. This article investigates the current state-of-the-art and recent improvements in laser micro-perforation of flexible-packaging materials and looks at future technologies and trends that could improve this process. Micro-perforated flexible-packaging film lexible-packaging technology plays a key role in optimizing produce shelf life and in the overall quality of the food product while reducing spoilage in the supply chain. “Basically, the right packaging coupled with the right storage temperature can help create conditions in the packaging that will delay maturation and aging of produce. Therefore, it is possible to increase shelf life and/or to harvest the product later so the product is sold with better quality. Packaging really can make a difference. If both temperature and packaging are optimum, aging of produce can be slowed down more than 800 percent.” [1] With these obvious advantages, it is clear why micro-perforating of flexible packaging in this market has grown. produced, and the film then can be tailored for the product to be packaged. The questions then become, how is the transmission rate altered and what technique provides the highest-quality film for the food supply chain? Table 1 illustrates the difference in micro-perforations required, depending on the product being packaged. Both packages are for 6-oz servings, but melon requires three times the oxygen transmission rate (OTR) versus citrus. This is accomplished by placing four micro-perforations on the lid for the melon and two for the citrus. TABLE 1. Micro-perf variations based on packaged product Product Container ID (in.) Lid area (sq. in.) OTR required OTR for 2-mil permeable PE OTR on lid without perf # of perfs on lid OTR on lid with perf 6 oz Melon 3.8 11.3 1,000 254 28.8 4 958 6 oz Citrus 3.8 11.3 320 254 28.8 2 314 F It should be noted that, in addition to laser micro-perforating, there are two other perforating processes for flexible packaging: Needle and electrostatic perforating. However, as laser micro-perforating technology has advanced, the laser’s ability to produce consistently round holes to an optimized size has become the dominant production process for micro-perforating flexible packaging. As such, this article will focus discussion on laser micro-perforating. Laser micro-perforating Using lasers for micro-perforating various materials has been possible for decades. While not an early application, laser micro-perforating is now a well-established process in the flexible-packaging market (see Figure 1). Laser improvements have been impressive, however, the pulse on-time duration compared to the distance the web travels during this time still needs to be factored into the micro-perforating process. With a stationary web, the laser can be rapidly pulsed (100-µsecond pulse duration) to produce a consistent round hole, Controlling the transmission of oxygen, carbon dioxide, ethylene and water vapors through the flexible package for each specific produce is important, as the optimum storage conditions vary according to the product type, processing and ripening degree, time of harvest and more. Because the transmission rate for the gases and vapors varies, it is not economical or technically feasible to produce a flexible-packaging film for each food product. It is far more economical to produce families of films that can then be laser-altered to yield the desired transmission rate. In this manner, cost-effective lot quantities of film can be 70 • 2014 Quarter 4

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