Shelf Life and Stability, Naturally

Consumers are increasingly aware of the potential for foods to carry bad bugs like Salmonella, E. coli, and Listeria. They are demanding safe, nutritious foods, but at the same time, they are asking for natural products. Whats more, they dont have the time or desire to go to the grocery store multiple times per week. They want their foods to last on the shelf and in the refrigerator. Consumers want it all: longevity, fresh-like quality and a clean label.

Working toward defining natural

The first challenge developers face is agreeing on a definition for natural. Folks are lining up on all sides of the aisle in terms of what natural means or what should or should not be allowed for use in natural products, says Robin Peterson, business development manager, Purac America, Inc., Lincolnshire, IL. FDA has declined to define natural in the food products that it regulates, but USDA is in a position where it feels more pressure, from the industry and consumer groups, to define natural.

In 1982, USDA defined natural as products that are minimally processed and contained no chemical preservatives. Minimal process meant what grandma could do in her kitchen, says Peterson. There were some exclusions made in terms of chemical preservatives, and included things, like salt, sugar, juices from fruits such as lemon, as well as vinegar. USDA makes no distinction between chemical preservatives and natural antimicrobials; therefore, ingredients that extend the shelf life of the productexcept exempted ingredientsare not allowed.

USDA amended this policy in 1995. The amended policy honored the use of lactates in natural products and allowed for organic products to be considered natural, as well, says Peterson. Lactates are used in a wide variety of meat and poultry products for pathogen inhibition. Then, in Dec. 2006, USDA reversed its 1995 policy. When they made a reversal of their policy, it was like someone took a baseball bat and banged on a hornets nest, and the whole thing has gotten very buzzy ever since, she says.

Suddenly, lactates were not on the list of ingredients approved for use in USDA natural-labeled products, though those already on the market were grandfathered.

In Jan. 2007, USDA hosted a public meeting on the issue, indicating their intent to enter into rulemaking. However, to date, USDA has neither formally announced proposed rulemaking, nor provided an interim policy. As result, processors are operating under the original 1982 policy, because this policy does not allow for chemical preservatives, except those exempted. Ingredients approved as antimicrobials cannot be used in natural products.

However, opportunities for pathogen control still exist, says Peterson. Processing aids can be labeled as such, dont need to appear on product labels and can be used in natural products. You can have a highly synthesized, more than minimally processed ingredient, and as long as it qualifies as a processing aid, it can be used in a natural product, she says. The use of certain types of natural flavors is another way to add antimicrobial properties.

Using processing aids and natural flavors takes advantage of labeling loopholes and intended use. The USDA says you can use an ingredient that inhibits the growth of pathogens as long as it doesnt have an effect on shelf life. A natural flavor is OK to use if the intended use is for flavor contribution, not antimicrobial characteristics. If the intended use is about shelf life, then thats not OK, Peterson says.

Consider lactates made from corn, notes Peterson. The USDA considers lactate to be no more than minimally processed. The question then arises, is there difference between a chemical preservative and a natural antimicrobial? Should it be OK to use a natural antimicrobial in a natural product, either for food safety, shelf life extension, or both? These are questions which will need to be addressed when the rulemaking process takes place.

When the rules are ill-defined, its up to individual companies to decide which ingredients they believe can be used in naturally labeled USDA products. The most-popular alternatives for natural meat and poultry products are things that were specifically excluded in the original 1982 policy, says Peterson. Those would include things like smoke, lemon juice, vinegar or higher salt levels.

Natural antioxidants

Several companies have developed food-safety ingredients for natural products.

One option is derived from rosemary extracts. Rosemarys natural antioxidants can improve shelf life by reducing oxidative deterioration, notes Gary Augustine, director, product management, antioxidants, Kalsec, Inc., Kalamazoo, MI. Oxidation is a chain reaction, propagated by highly reactive free radicals generated during the initial oxidation stage. These free radicals react within a food and beverage system to form compounds which cause off odors and flavors. He notes that natural antioxidants contain naturally occurring phenolic compounds, which inhibit oxidation by stabilizing the highly reactive free radicals.

Depending on processing requirements, such natural antioxidants can be added to most applications at levels ranging between 0.025% and 0.200%. Augustine notes that a range of ingredients is available based on the specific processing needs of the food processor. Since food products are subject to oxidation from the outset, it is recommended to incorporate rosemary oleoresins as early as possible into the process to inhibit oxidation. Product forms have been developed that are compatible with aqueous solutions, such as marinades, brines and sauces; concentrated oil soluble forms for meat and poultry, baking and snack, dressings and sauces; dispersibility over large surface areas, such as ground meat and poultry; rapid aqueous dispersion in concentrated brines, such as poultry and pickle brines; dry products for dry processing and blending; and water solubility for stabilizing specific flavors in beverages.

Unlike their synthetic counterparts, usage levels are not legally restricted. However, historically, use of rosemary extracts have been limited due to their flavor and aroma contribution to the food and beverages. But, Augustine points out a solution, an innovative line of rosemary extracts that do not significantly contribute flavor or aroma to finished food and beverage product. These products not only provide the opportunity to increase oxidative stability in new flavor-sensitive applications, but to provide increased shelf life in existing applications by increasing the amount of rosemary extract used without imparting additional flavor or aroma.

Rosemary extract may be labeled as natural flavor, oleoresin rosemary or rosemary extract.

Another company combines green tea and rosemary, in addition to offering rosemary tocopherol combinations, delta-enriched tocopherols and mixed tocopherol formulations. These products are utilized in a variety of applications to extend the life of meats, seasonings, salad dressings, nuts, breads, bakery mixes and other high-fat matrices, says Jody Baxter, marketing manager, Kemin Food Ingredients, Des Moines, IA.

The rosemary plus green tea, a rather new product, was developed to help protect against color and flavor loss in processed meats and other applications, says Baxter. In a ground pork study, the rosemary and green tea combination product retained color seven days longer than green tea alone. She notes that sensory panelists voted products made with this rosemary and green tea combination had the best meaty flavor without green tea or herbal notes.

Our rosemary is a highly-refined, concentrated, homogeneous solution that has no insolubles, no settling, no separation, and is residual-free, giving you a more-consistent product, better dispersion and will not clog application nozzles during the manufacturing process, says Kristen Robbins, assistant research & development manager, Kemin Food Ingredients. Concentrated and dilute extracts are available with application rates ranging from 0.05% to 0.30%, respectively. It is important for the extract to be completely dispersed within the food, so that is why we offer various delivery systems in addition to the standard oil-soluble extract, such as water-soluble blends for use in brines or low-fat salad dressings, and dry blends for use in ground meats or cereals, she says.

Another option, mixed tocopherols, increase a foods shelf life and fulfill consumers expectations for all-natural additives and labeling, says Carrie Potaczek, global product manager, Cognis Nutrition & Health, Cincinnati. The line of antioxidants is isolated from vegetable oils and concentrated to contain naturally occurring d-alpha, d-beta, d-gamma and d-delta tocopherols, commonly known as mixed tocopherols. Mixed tocopherols are forms of natural vitamin E, and our products deliver these forms in their naturally occurring ratios. Food products are typically labeled mixed tocopherols (natural vitamin E) added to preserve freshness or natural vitamin E added to protect flavor. These natural antioxidants add nutritional value if there is a source of vitamin E already in the food.

Applications for mixed tocopherols include fats, oils, meat, poultry, bread, cereal, baked goods, fish, fish oil, seafood, nuts, dairy and candy. Mixed tocopherols can often be added in dosage levels similar or less than synthetic antioxidants BHT and/or BHA, Potaczek advises. These natural antioxidants are effective at very low concentrations and do not impart a flavor, color or odor to the finished food product. They also have superior carry-through in frying, baking, extruding and other processing. They are resistant to high temperatures and provide excellent stability in finished goods. Their low volatility and increased solubility, compared to synthetic antioxidants, provide optimum protection from oxidation during processing, she says.

Plum-based ingredients can also add antioxidant protection. Using the oxygen radical absorbance capacity (ORAC) method, dried plums contain 8,870 antioxidants per 100 grams. The two primary antioxidants in dried plums are chlorogenic acid, and neochlorogenic acid, says Jim Degen, consultant, California Dried Plum Board, Sacramento. Those two help to preserve not only the shelf life of foods, but also suppress the growth of both natural flora, as well as a number of nasty bacteria, such as E. coli, Listeria and Salmonella.

Maintaining moisture

For products like baked goods and meats, few characteristics say out of date as clearly as dryness. Fruit-derived additives can offer a natural solution. Enhanced citrus fiber has superior water-holding and water-retention capabilities through cooking or baking, says Nick Kovalenko, director of marketing and sales, Fiberstar, Inc., Wilmar, MN. Such enhanced citrus fiber can increase freshness and softness of the product, and provide cleaner taste and label declaration by replacing more-expensive hydrocolloids and other ingredients, such as phosphates, carrageenan, stabilizers, thickeners and emulsifiers. Another benefit is increased yields and product margins by reduced water and/or oil loss during baking. Increased yields are also gained because the enhanced citrus fiber supports the addition of extra water to the formula while maintaining the same water-activity level.

All these benefits for the finished product, as well as for the manufacturer, become possible due to superior high-water-holding and -retention capacity, emulsification properties, enhanced cell structure, and neutral taste, explains Kovalenko. He recommends using the product in bakery; meat processing; whole meat or poultry injections; dairy, sauces and dressings, and prepared salads for moisture management, yield increase, purge control, and fat replacement; and for emulsification and particle suspension in beverages. The suggested starting use rate is 0.25% to 0.75% of the total ingredient weight.

Plum products such as dried plum powder, purées, and juice concentrates can increase shelf life in a variety of products. Moisture retention is one area in which they excel. Several characteristics of this particular variety assists in shelf life preservation, says Degen. One of them is sorbitol. We dont know of any other food that has as much naturally occurring sorbitol as dried plums. Its about 15% sorbitol, which is used very often as a humectant in bakery products. Its also used to retain moisture in meat products. Sorbitol simply binds moisture in the natural cells of food products. The 7.5% fiber content of dried plums also helps bind moisture.

Degen recommends dried plum powder for bakery applications. You would incorporate that into the dried components of the formula, he says. He recommends a starting use rate of 5% flour basis. Weve done energy bars, breakfast bars and products that traditionally are very low in moisture and really have no flavor whatsoever in many cases, but when you add dried plum powder or fresh plum juice concentrate or even dried plum juice concentrate, you get a much more moist product over a very long period of time, he says.

Malic acid content (1.5% to 2.0%) is also a unique characteristic of the Petite dAgen plum variety used. Malic acid is a flavor poteniator. According to Degen, it is particularly beneficial in low-moisture or low-fat products, such as extra-lean meats and low-fat baked goods.

For meats, Degen suggests a dried plum purée or a fresh plum juice concentrate. We use fresh plum juice concentrate at about 3% of the raw meat block, he says, while a marinade using herbs, spices, water and salt might use fresh plum juice concentrate at 1.5% to 2% of the raw meat block. Tumbling the marinade and whole muscle in a vacuum tumbler for 20 to 30 minutes opens the pores of the meat, and the tumbling ensures that the liquid is absorbed into the pores, he says. That provides around 10% to 12% more moisture in the whole muscle and nets 5% to 7% more moisture after cooking.

Using the ORAC method, dried plums contain 8,870 antioxidants per 100 grams. The two primary antioxidants in dried plums are chlorogenic acid, and neochlorogenic acid. Those help to preserve not only the shelf life of foods but it also suppresses the growth of both natural flora as well as a number of nasty bacteria such as E. coli, Listeria and Salmonella, says Degan. Recent research at Texas A&M University, College Station, concluded dried plums naturally reduce the amount of lipid oxidation or warmed-over flavor as compared to artificial or synthetic preservatives (Meat Science, 2008; 80(4):997-1,004). We performed at equal to or better than both in terms of the bacteria growth and the oxidation, but also in terms of eating quality, he says.

Films at 10

The University of Arkansas, Fayetteville, has developed an edible film system designed to improve shelf life. We have prepared edible film solutions using proteins, starch, hydrocolloids or combinations of these and incorporated natural plant extracts during preparation, says Navam S. Hettiarachchy, Ph.D., professor, Department of Food Science and Institute of Food Science and Engineering, University of Arkansas. The edible film solutions were sprayed onto the products, or the products were dipped in the antimicrobial film solutions, dried, kept in storage, and the effectiveness of plant extracts in the film evaluated against the major pathogens, including Listeria monocytogenes, E. coli O157:H7 and Salmonella. She suggests the edible films could be used on poultry, meat, hot dogs, fresh fruits and vegetables, and minimally processed fruits and vegetables.

The shelf-life stability can be extended for over a week in refrigerated storage, says Hettiarachchy. The edible films form a barrier against the food product and the environment, while the antimicrobial plant extracts in the film either inhibit the growth or kill the pathogens.

A natural protein flavor coating system, developed by Flavex Protein Ingredients, a division of The Arnhem Group, Cranford, NJ, extends the shelf life of fresh and cooked meat, poultry and fish products. It creates a barrier to oxygen, resulting in products with reduced oxidation and reduced color deterioration. Microbial loads can be reduced by incorporation of natural microbials or specialty meat bacteriocides. According to company literature, these products are USDA-approved for use in any uncooked or cooked standard or non-standard meat or poultry product where flavorings are permitted.

Packaging technology can also extend shelf life. Hefestus, Caesarea Industrial Park, Israel, offers shelf-life booster sealing packaging machines that reportedly enable manufacturers to pack fresh meat and poultry with residual oxygen of less than 0.4%.

Worldwide, companies are striving to meet consumers demands for natural, fresh-tasting products. New technologies are continually developed to extend shelf life to support both distribution channels and increasingly infrequent grocery shopping. Hopefully, the government will soon come together to agree on clear labeling definitions that will benefit both consumers and the industry.

Cindy Hazen, a 20-year veteran of the food industry, is a freelance writer based in Memphis, TN. She can be reached at [email protected].