To better handle variable temperature regimes in produce distribution, a master packaging system consisting of a double-layered gas barrier has been applied to fresh king oyster mushrooms. A secondary master package wrapping four individual 350 g packages was designed to be dismantled when moved to the 10℃ retail display from the presale storage at 0℃. Different numbers of microperforations (10, 15 and 20) were tested on the inner individual packages as a control variable to create and maintain beneficial modified atmospheric conditions around the mushrooms. The microperforated individual packages could all attain an effective range of modified atmosphere during the two stages of storage at 0 and 10℃ while the package with 15 microperforations best reached the desired modified atmosphere of 1 − 3% O 2 and 10 − 15% CO 2 . The individual packages in the master packaging system had better preservation in quality attributes, such as weight loss, mold/yeast count and texture retention, compared with the control perforated packages of a normal atmosphere.Keywords: modified atmosphere packaging, microperforation, temperature change, distribution, quality *To whom correspondence should be addressed. E-mail: dongsun@kyungnam.ac.kr
IntroductionFresh mushrooms have high respiration rates and are very perishable, which limits their shelf life (Cliffe-Byrnes and O'Beirne, 2007). Modified atmosphere packaging (MAP) at a chilled temperature effectively preserves the quality and freshness of mushrooms (Roy et al., 1995;Kim et al., 2006;Li et al., 2007). However, the high respiration rate excludes most polymeric films from direct simple use in the MAP bags of fresh mushrooms because of the anoxic conditions developed inside the package. Microperforations or highly permeable windows have been applied to match the high respiration of the mushrooms and thus create a beneficial modified atmosphere (Li et al., 2007;Sandhya, 2010). Particularly, a high temperature exposure with temperature abuse in the product distribution chain may induce an imbalance between the produce respiration and the package's gas permeation. Unlike the produce storage warehouse and the transportation vehicle that are well controlled at low temperature, the display cabinets in retail markets have a wide variation of temperatures around 10℃. To resolve the temperature-variant regimes in produce distribution, the concept of a master packaging consisting of double layers of a gas barrier has been proposed and introduced for fresh fruit packaging (Jeong et al., 2011). The master packaging system consisting of a liner bag as a secondary package (master package) and the primary individual packages contained within it creates the desired modified atmosphere (MA) for the fruit during transportation and wholesale distribution at low temperatures. At the higher temperature retail level, the outer layer of the master package is dismantled to expose the individual packages to an ambient atmosphere, providing higher gas permeation to match the increased mushroom respirat...