ABSTRACT
CONTENTS 4.1 Relationship between Packaging and Product Physiology ........................................... 74
4.1.1 Gas Technology......................................................................................................... 75 4.1.1.1 Oxygen (O2).................................................................................................. 75 4.1.1.2 Carbon Dioxide (CO2) ................................................................................ 76 4.1.1.3 Nitrogen (N2) ............................................................................................... 77 4.1.1.4 Carbon Monoxide (CO) .............................................................................. 77 4.1.1.5 Sulfur Dioxide (SO2) ................................................................................... 77
4.1.2 Fruit and Vegetable Physiology and Deterioration Processes ........................... 77 4.1.3 Resources for Information on Appropriate Target-Modified Atmospheres .... 80 4.1.4 Respiration Rate Quantification.............................................................................. 80
4.2 Polymer Engineering........................................................................................................... 81 4.2.1 Polymers..................................................................................................................... 81 4.2.2 Films and Structures................................................................................................. 82 4.2.3 Perforations................................................................................................................ 83 4.2.4 Gas Flushing .............................................................................................................. 84
4.3 Converting Technology....................................................................................................... 84 4.3.1 Packaging Format ..................................................................................................... 84 4.3.2 Flexible versus Rigid Packaging............................................................................. 85 4.3.3 Packaging Equipment .............................................................................................. 87 4.3.4 Additives .................................................................................................................... 88
4.3.4.1 Antifog .......................................................................................................... 88 4.3.4.2 Slip and Antiblock....................................................................................... 89 4.3.4.3 Antimicrobial Films..................................................................................... 89
4.4 Applications.......................................................................................................................... 90 4.4.1 Microwave and Steam-In......................................................................................... 90 4.4.2 Varietal Blends and Novel Produce Combinations ............................................. 90 4.4.3 Ready Meals .............................................................................................................. 91
4.5 Future Research Directions ................................................................................................ 91 References...................................................................................................................................... 91
Modified atmosphere packaging (MAP) is one of the key technologies associated with the shelf life extension of fresh produce. This chapter will discuss the technology, materials, and applications of MAP. Discussions will include the symbiotic relationship between the
packaging and the produce and the importance of produce physiology when specifying packaging systems. Specific polymers, films, and structures will be analyzed with respect to their individual properties and subsequent impact on MAP. An analysis of packaging types and formats will also be detailed. Additive technologies such as antimists, slip, and antimicrobials, and their impact on the functionality of MAP will be explored. Common reasons for the failure of MAP will also be reviewed. The chapter will conclude with some of the newest emerging MAP technologies, such as microwave steam technology, and multicomponent trays along with topics where additional research is warranted. MAP, when combined with proper postharvest handling procedures and temperature
control management, can have a positive impact on the quality and shelf life of fresh produce. It is important to begin by stating under what conditions MAP would not work. First and foremost, MAP is only effective if there is consistent temperature management throughout the entire life cycle of the produce. This includes processing as well as the entire distribution channel. Lack of temperature control will result in physiological variations of the produce, which will impact the effectiveness of the packaging system. In addition, MAP will never improve the quality of the incoming raw material product. Under ideal circumstances, the best that can be achieved is to maintain the existing quality level throughout the desired shelf life. In real-world applications, often MAP will maintain quality for the majority of the targeted shelf life, but due to parameter variations during distribution, quality will suffer at the very end of the desired shelf life. Since MAP will never improve incoming product quality, the need for optimal postharvest handling procedures is paramount. Postharvest handling will be discussed in detail in other chapters.
