Flexible Packaging Material
Problem Definition
The client was a food company, manufacturing an egg-based dry pasta product packaged in multi-layer polymer pouches. The material being used was a lamination of Polyester (PET) and PVDC (for Oxygen barrier), along with a pattern-applied heat-seal coating. Due to the need for a pattern-applied seal coating and the older form-fill-seal equipment being used, the seal location and quality was inconsistent, often resulting in only partial seals being formed on the finished bags. This structure was not only costly to purchase, but was also costly to run, due to these machine issues and poor seals. There were also a number of customer complaints due to open bag seals upon arrival at retail locations. It was an accepted belief within the company that due to the egg content, the product required an oxygen barrier in the bag material; however, no testing had ever been done to confirm or refute this contention. As a result, the company was using this "high barrier" material and incurring added cost and inefficiency, solely based on the belief that the product required an oxygen barrier.
Consultant Analysis
It was proposed that the existing material, while having an excellent oxygen barrier, provided little protection from oxygen intrusion to the product, due to the poor quality package seals. This was easily demonstrated by performing some flat material and some formed package Gas Transmission tests. The flat material had exceptionally low oxygen transmission rates (<1 cc/m_/day), but the finished package oxygen transmission readings were unable to be measured due to the leaks inherent in the bags. Additionally, the existing material was found to be the limiting factor for both line speed and overall package quality. Therefore, some criteria were established and new material candidates were identified. Marketing wanted to retain the high-gloss, high-clarity look and crisp feel to the bag material, and operations wanted a material that would seal faster and easier on the existing Vertical Form-Fill-Seal (VFFS) machinery. The material also needed good puncture resistance and scratch resistance. Ideally, the new material would not cost any more than the current structure, but it was agreed that a potential increase in material cost could be more than offset by reductions in defects, improvements to product shelf life, and increases in line efficiency.
Actions
Using the existing material to establish a performance baseline, several materials meeting the criteria were identified. Each was evaluated for appearance and "feel", and then sent to the plant for machineability, seal performance, and line speed analysis, while Purchasing determined the actual cost of each. After completing these evaluations, the chosen material was a reverse-printed Oriented Polypropylene (OPP) laminated to an inner OPP layer. The inner layer provided protection for the printing, while also providing some cost advantages and material savings.
Consultant Findings
Once the new material had been selected based on the above criteria, additional bags were run with fresh product, in order to do a comparative shelf-life test vs. the existing bags. Accelerated aging studies were conducted (100F / 90%RH), along with room-temperature aging. Fresh product stored at room temperature in sealed glass jars were used as test controls. This 6-week accelerated shelf-life test confirmed that :
- The new material provided a better overall sealed package than the old material.
- There was no sensory difference between products stored in either material
- Therefore, the contention that an Oxygen barrier was needed to protect the egg-based product was proven to be false.
Given the findings of "no difference" in the product after the accelerated testing, the risk of changing to the new material was determined to be small compared with the benefits, and the decision was made to begin implementation of the OPP / OPP material. The room temperature aging study continued for a full 2 years, which was the claimed shelf-life of the product. The findings after 2 years confirmed the results from the accelerated testing.
Consultant Conclusion
Challenging accepted beliefs can be risky, but when there is a lack of supporting evidence and/or testing, as there was in this case, the challenge is easily justified when based on good principles and educated observation. Here the challenge was extremely successful, and the company benefited on several fronts. They learned their product was not as sensitive as they had believed; they improved their packaging line speed and efficiency, they virtually eliminated customer complaints about open bags at retail, and they actually saved over 10% on incoming material cost in the process.
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