STATE-OF-THE-ART OPERATIONS Innovations in Modified Atmoshpere Packaging BY H. LOUIS COOPERHOUSE odified atmosphere packaged that this technology is utilized effectively elevated levels of CO2. Accordingly, the M(MAP) products can be found in and safely. predominating flora of products stored almost every aisle of the supermarket in modified atmospheres consists of today. Billions of packages of refrigerat- PROCESS OVERVIEW these organisms, which develop more ed, frozen and shelf stable foods are sold In the MAP process, product is pack- slowly than pseudomonads and related worldwide every year that are packaged aged in an atmosphere that is different gram-negative bacteria. with this proven technology. This array from that of air, which normally contains Optimal gas mixtures vary widely by of food products includes potato chips 78.08% nitrogen, 20.96% oxygen and product category and can vary dramati- and other snack foods; case-ready fresh 0.03% carbon dioxide. MAP helps to cally within a product category. In the meats; fresh produce; hot dogs and other delay the onset of product degradation, case of produce, this variability is prima- processed meat products; pizza dough typically by reducing the amount of oxy- rily due to respiratory requirements. and other bread and bakery products; gen exposed to the product during its Potatoes, radishes and tomatoes are gen- and items as diverse as coffee, fresh pasta shelf life. In high-moisture products, erally considered low respirers, while and cheese. MAP is a preservation tech- such as cooked entrees and fresh-cut pro- asparagus, broccoli and mushrooms are nique that prolongs product shelf life, duce, MAP delays microbial and sensory considered heavy respirers. Once com- which directly and positively impacts the spoilage. In high-fat products, MAP modities are cut and handled, product profitability and marketability of a food delays rancidity and preserves the smell, deterioration accelerates as the respira- business. taste, texture and appearance. MAP also tion rate is increased, the tissue becomes Consumers today demand products helps to delay enzymatic browning in more susceptible to oxidative discol- that are convenient to purchase, conven- produce and staling in bakery products. oration, and microbial growth is ient to prepare and convenient to eat. Modified atmosphere packaging is a enhanced. With produce, it is critical to They also seek products that are visually process in which the composition of match the oxygen transmission rate appealing, great tasting, flavorful, fully gases in a package of known permeability (OTR) of the packaging material with the prepared, varied, nutritious and “fresh.” is altered after the food is filled, but respiration rate of the product. Industry sectors showing some of the before the package is sealed. Frequently, greatest growth today, whose products MAP is a two-stage process. It begins PROLIFERATION OF MAP IN EMERGING represent these desired consumer attrib- when a vacuum is first pulled on the GROWTH CATEGORIES utes, include the fresh-cut produce, product so that as much oxygen can be Whereas the application of MAP has value-added dairy and refrigerated sand- removed from the system as possible. reached maturity in certain categories, wich categories. For each of these cate- This is followed by a “backflush” of nitro- such as snacks, coffee and processed gories, modified atmosphere packaging gen and/or carbon dioxide and/or other meats, it is becoming increasingly uti- happens to be a principal technology gases. lized in refrigerated, prepared conven- that is applied for shelf-life extension. Nitrogen typically is used as a sterile ience foods that meet consumer desires An interesting and important observa- filler gas to dilute the concentration of for convenience, quality, variety and tion is the fact that, atypical of processed oxygen and carbon dioxide in the pack- health. This is particularly the case with meats, snack foods and other categories age, thereby reducing the onset of oxida- several categories that are growing that helped develop the MAP category, tion while also helping to ensure package extremely rapidly, such as fresh-cut pro- today’s user of MAP technology is much stability. Carbon dioxide has bacteriosta- duce, value-added dairy products and more likely to be a smaller company. The tic and fungistatic properties and its prepackaged sandwiches. Although MAP number of companies that are utilizing effectiveness is in part due to its ability to is a preservation technology, it is “invisi- MAP technology is increasing every year; penetrate the cellular membrane. This ble” to the consumer, since the indica- however, more and more of these com- penetration causes intracellular pH tion of its presence on product labeling is panies are relatively small and lack the changes and disrupts internal enzymatic not typically required. Therefore, it is infrastructure and corresponding sophis- equilibrium. The gas selectively inhibits especially applicable to products that are tication that is present in larger compa- the growth of gram-negative bacteria, designed to be “natural” or reduced in nies. Consequently, it is imperative that such as pseudomonads and other related preservatives. food safety organizations, industry trade psychrotrophs, which otherwise grow Although the application of MAP in associations, gas and equipment suppli- rapidly and produce off-odors and off- the fresh-cut produce category was virtu- ers, and other allied groups organize to flavor. Lactic acid bacteria, such as strep- ally non-existent some 15 to 20 years ago, provide the education that is needed, so tococci and lactobacilli, are less affected by this category represents the fastest grow- 5 F OOD S AFETY M AGAZINE ing segment in which MAP technology is packaged or integrated into the product organoleptically detectable. Reduced being applied. The initial application for and combined at store, on the go, or at oxygen packaging contributes to the MAP in the value-added produce seg- home. As a result, salads that have potential of botulism (caused by ment was the foodservice market, in become quite popular in restaurants, Clostridium botulinum) and other which precut lettuce was sold to salad such as chicken Caesar salad, chef salad, pathogens by providing greater time and bars and to the quick-service restaurant and Cobb salad, are now appearing for opportunity for outgrowth. industry. This was followed by prepack- the first time in the retail marketplace. The U.S. Food and Drug aged iceberg lettuce salads that were Administration (FDA) has been working developed for the retail market, which FOOD SAFETY CONCERNS in concert with the Institute of Food subsequently evolved such that a wide MAP is not by any means a “magic Te chnologists (IFT) and recently pub- variety of lettuces, cabbages, carrots and bullet” that will individually provide for lished a report entitled, “Analysis and other vegetables are marketed with MAP product safety and shelf-life extension. In Evaluation of Preventive Control technology today. fact, because MAP results in a dramatic Measures for the Control and The fresh-cut produce category is pro- change in the time it takes for product to Reduction/Elimination of Microbial jected to evolve considerably in the years spoil and the type of bacteria that will Hazards on Fresh and Fresh-Cut ahead because of continual advances and cause this spoilage, it can create signifi- Produce.” In this study, it is noted that applications of packaging technology. cant additional risk. This is due to a sev- although only two MAP produce prod- New fresh-cut fruit offerings that incor- eral factors such as extremely low oxygen ucts (coleslaw mix and ready-to-eat salad porate MAP and other technologies are levels, lack of bacterial competition, pro- vegetables) have been implicated in food- now available, including pre-cut honey- longed shelf life and potential for tem- borne illness outbreaks to date (botulism dew, pineappl, and mixed fruit salads perature abuse—conditions which can and salmonellosis), the potential for with a 10- to 14-day shelf life, and pre- favor the growth of pathogenic organ- growth of pathogens is quite significant, sliced apples with a three- to six-week isms, which are otherwise quite fastidious especially in the fresh-cut produce indus- shelf life. Innovations in packaging tech- and less likely to grow. try. nologies also have created opportunities MAP and other forms of reduced oxy- Currently, there is concern that psy- for new product concepts, such as com- gen packaging minimize the activities of chrotrophic foodborne pathogens, such ponent products that allow the user to spoilage organisms that normally give as L. monocytogenes, Y. enterocolitica and A. combine fresh and processed ingredients warning about potentially unsafe condi- hydrophila, as well as non-proteolytic C. for a “freshly-prepared” or “freshly- tions. Concerns about modified atmos- botulinum, Salmonella spp., E. coli assembled” salad product. Such products phere packaging are well founded O157:H7 and Shigella spp., can be poten- are now being offered to foodservice because of the potential for growth of tial health risks when present on MAP operators and retail customers, in which anaerobic or facultative anaerobic bacte- produce. Because reduced microflora fresh and/or processed ingredients, dress- ria, such as Clostridia, which could cause exist in MAP products, L. monocytogenes, ings, and/or seasonings are separately food poisoning before food spoilage was for example, can grow at low tempera- tures to potentially harmful levels during the extended storage life, while remain- ing organoleptically acceptable. Because Suppliers of MAP Process many of these bacteria, in addition to A network of complementary suppliers is required to facilitate an effective MAP solution. enteric viruses such as hepatitis A, have This network includes suppliers of gas, packaging equipment, trays, film and analytical test- been implicated in produce outbreaks, ing equipment. These companies can serve as excellent resources for further information there is concern about their behavior on MAP applications.