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Innovations in Modified Atmosphere Packaging

Innovations in Modified Atmosphere Packaging

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 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 products includes potato chips 78.08% , 20.96% and product category and can vary dramati- and other snack foods; -ready fresh 0.03% . 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 . 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- 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 market, in become quite popular in restaurants, ) and other which precut lettuce was sold to salad such as chicken Caesar salad, chef salad, 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, 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. under modified atmosphere conditions. The FDA/IFT report recommends Suppliers of Gases • Convenience Food Systems that the elimination or significant inhibi- The following companies provide gases • Ilapak tion of spoilage should used for MAP applications in food packag- • Orics not be practiced, as their interaction with ing: • Hayssen pathogens may play an integral role in • BOC Group • Harpak product safety. It is generally believed • Air Liquide • CVP Systems that with the use of permeable films, • Praxair spoilage will occur before toxin produc- • Linde Film and Resin Suppliers tion is an issue; MAP of produce, how- • Air Products [need sentence here] ever, should always incorporate packag- ing materials that will not lead to an Suppliers of MAP Equipment • Cryovac Sealed Air anoxic package environment when the Other suppliers involved in MAP include • DuPont product is stored at the intended temper- companies whose packaging equipment • Eastman ature. This report recommends that the

incorporates gases just prior to sealing. percentage of O2 in a modified atmos- The sealing of the primary package can Analytical Equipment phere for fruits and vegetables for both occur in an in-line vertical or horizontal Instrumentation utilized to verify gas safety and quality fall between 1% and form-fill-seal machine, in a tray-sealing amounts are a critical part of the process. 5%. machine that uses preformed trays, or in a • PBI-Dansensor horizontal or vertical chamber or snorkel • Mocon APPLICATION OF HURDLE TECHNOLOGIES machine that seals preformed . Modified atmosphere packaging is but • Multivac one of many potential “hurdle” tech- • Robert Reiser & Co. nologies that can be applied to prolong product quality and increase shelf life. In the case of fresh-cut produce, for exam- important consideration. • Study of interactions of background ple, raw material control and superior Adequate food safety of refrigerated microflora with foodborne pathogens agricultural practices are critical first steps foods can only be achieved with a high in various modified atmospheres used towards an acceptable marketable prod- degree of assurance by formulating, for produce, as well as the effects of uct. Variety, source, season, initial matu- adapting and using a Hazard Analysis different gaseous environments on rity, processing maturity, slicing and cut- and Critical Control Point (HACCP) the survival and growth of bacterial ting equipment, chemical or other treat- approach. HACCP techniques assess foodborne pathogens on whole and ments and dips, packaging environment, everything from raw ingredients to prod- fresh-cut produce. temperature management, shipping, and uct packaging and distribution, define • Examination of the potential for handling all affect the sensory acceptabil- the locations at which potential hazards growth of C. botulinum in a wide ity and attainable shelf life of fresh-cut (microbial, chemical, and physical) may variety of modified atmosphere pack- produce—and impact product safety. occur, and establish a means of monitor- aged produce stored at mildly abusive New technologies have been recently ing these points to eliminate these haz- temperatures such as 7C-12C. introduced, and others are on the hori- ards. By judicious application of Evaluation of other hurdles besides zon, that will enable even greater alterna- HACCP systems, the food processor can temperature to prevent botulinum tives towards the development of refrig- implement a program whereby safe pro- toxin production. erated prepared products that meet con- duction conditions are achieved. • Examination of the influence of dif- sumer needs for safety, as well as quality, ferent atmospheres, background convenience and overall value. INNOVATIVE APPLICATIONS AND FURTHER microflora and storage temperatures It is essential that other hurdle tech- RESEARCH on the survival and growth of L. nologies be utilized in conjunction with Over the past few years, a number of monocytogenes on MAP fresh-cut MAP, because we cannot rely exclusively packers of fresh prepared green vegeta- produce. on the maintenance of refrigerated con- bles in the United Kingdom have begun • Investigation of the behavior of vero- ditions to assure the safety of perishable experimenting with oxygen levels that are toxin-producing E. coli on fresh and foods. In fact, refrigeration alone is not between 70% and 100%. This “oxygen fresh-cut product, both under MAP enough to prevent the growth of some shock” treatment of superatmospheric and without MAP. infectious or toxigenic microorganisms. oxygen levels has been found to be very • Exploration of the survival of the With so few bacterial cells necessary to effective in inhibiting enzymatic discol- enteric pathogens Y. enterocolitica cause certain types of foodborne disease, oration, preventing anaerobic fermenta- and Campylobacter spp. and the growth on infested produce, for example, tion reactions, and inhibiting aerobic and behavior of foodborne viruses and is not a requirement for human infec- anaerobic microbial growth since the protozoan parasites on MAP produce. tion, as with most other pathogens. In optimal oxygen level for growth (21% for • Examination of , or addition, post-process contamination, aerobes, 0-2% for anaerobes) is surpassed. the combination of novel methods of even at low levels, may create a situation As with most MAP gases, superatmos- food treatment and packaging, for in which pathogenic microorganisms pheric O2 has varied effects depending example, irradiation used with MAP may grow to high levels and cause illness on the commodity, and further research and antimicrobial films used in com- and potentially cause death. Therefore, in will be required to understand the appli- bination with MAP. the design of perishable food products, cation of this technique in the fresh-cut • Evaluation of the use of intelligent other barriers to microbial growth must produce industry. packaging systems. be incorporated into these foods to yield Another area of promise is the use of As the increases its a safe and stable system. Application of edible films, in which antimicrobial com- knowledge about the uses of modified these barrier technologies has been pounds are incorporated directly onto atmosphere packaging, it will not only shown to significantly reduce levels of the product, and in which the product is continue to achieve greater shelf life food spoilage and pathogenic microor- packaged under MAP conditions. There extension that consumers demand in ganisms such as E. coli O157:H7, have been many studies investigating the fresh and processed foods but increase Salmonella, and Campylobacter. migration of antimicrobials such as sodi- the safety attributes of these products, Hurdles can include the incorpora- um benzoate, benzoic acid, propionic as well. tion of acidulants, antimicrobial agents, acid and potassium sorbate from antioxidants, heat, and processes that into food. The FDA/IFT report con- H. Louis Cooperhouse is Director of the control water activity. In addition, non- cludes that the most advantageous use of Rutgers University Food Innovation Research thermal processing hurdles can be these films for antimicrobial properties & Extension Center, part of the New Jersey applied such as ultra high pressure pro- would be the formation of a monolayer Agricultural Experiment Station network. He cessing, irradiation, and pulsed light and lipid and sorbic acid film, or a bilayer can be contacted at 732-537-1901 or at coop- pulsed electric field processing. Hurdles film composed of a hydrophilic base [email protected]. can also be applied during the packaging layer coated with a thin layer of lipid con- process, and include the application of taining sorbic acid. Research is needed in READER SERVICE LINK clean room packaging, order to produce coatings with good sur- Circle # 00 for more information from systems, intelligent packaging systems, face tension that will stick to produce. FSM advertisers on MAP packaging and a variety of alternative packaging The FDA/IFT report identified the technology and services. materials, in addition to the usage of need for further research so that industry MAP. Temperature is, however, the most will be better able to safely apply modi- important and most obvious criterion for fied atmosphere packaging principles. maximizing the shelf life of refrigerated These areas included: prepared products. Synergistic results are •Investigation of the antimicrobial frequently achieved when hurdles are effect of superatmospheric oxygen used in combination, and are a very levels.

7 F OOD S AFETY M AGAZINE

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