Vacuum Durable Freshness-Keeping Packaging for Chinese Chives

Abstract

Airtight packages, such as freshness-keeping packaging for vegetables, can easily explode in the vacuum pre-cooler by rapid gas expansion under decompression. Therefore, we developed packaging with degassing holes to maintain high airtightness during the distribution process. Packages were manufactured using an automatic reverse pillow packing apparatus with 20-25 μm oriented polypropylene film (OPP). It is important that the expanded gas in the package be exhausted outside immediately. Therefore, we made flat and wide ventilation holes in the center seal area of the pillow film package, allowing any expanded gas to be exhausted immediately and preventing the packaging from exploding. As for the heat sealer of the packer, two grooves of 6∼10 mm are imprinted with a circumference of 350 mm. There are two vents on a standard 520 mm long type film package. The vent holes are made on the center seal area. Therefore, the top seal of both ends create a seat folding. This structure and moisture of the package increase airtightness of the package. In a storage test at 20°C using Chinese chives, the gas density of the package showed low oxygen and a high carbon dioxide concentration on the second day. Product freshness was improved in comparison to the previous open-type package of Oita Prefecture at 20°C stored for at least 3 days.