Spoilage of fresh meat and poultry is a financial burden to producers and consumers. In addition, the growing avoidance of synthetics for preservation has driven the development of new antimicrobials and antioxidant ingredients to extend the shelf-life and overall safety and quality of the meat.

In turn, synthetic preservatives, such as butylated hydroxylanisole (BHA), butylated hydroxyltoluene (BHT) and tertiary butylhydroquinone (THBQ) — used to reduce microbial growth and thereby extend the shelf-life of meat — have become unwelcome ingredients, says Kantha Shelke, food scientist and principal at Corvus Blue, in Chicago.

“People want ‘healthier’ meals that are free of conventional chemical preservative,” she explains. “As a result, natural preservatives and environmentally friendly technologies are growing.”

Rodrigo Tarté, assistant professor of meat science and technology at Iowa State University in Ames, agrees the industry is moving away from the tried and true, traditional antimicrobial and antioxidant ingredients toward a new generation of ingredients that are considered to be more label-friendly or in many cases natural.

“In these cases, we are talking about ingredients that can be labeled with common names that most consumers would be able to recognize or that would be consistent with current USDA ‘natural’ labeling regulations …” he explains. “A few companies have opted to move away from antimicrobial ingredients in some or all of their products in favor of alternative non-ingredient-based technologies such as high-pressure processing.”

Regarding antimicrobials, over the last few years the industry has moved away from highly effective organic acid salts, such as sodium or potassium lactate and sodium diacetate. Instead, the processors are favoring organic acid-containing products, such as vinegar and microbial fermentates such as cultured sugar and cultured dextrose, which can be labeled in a more consumer-friendly manner and sourced more naturally.

“There are plant sources of natural antimicrobials, such as cinnamon, cloves, thyme, cranberries, garlic, onion and others, but their growth in the meat and poultry industry has been slower likely due to issues of compatibility and cost-in-use,” Tarté says.

In terms of antioxidants, the move has been away from synthetic compounds such as BHA, BHT and propyl gallate in favor of natural sources of antioxidant compounds, such as rosemary and oregano. The use of natural sources of sodium nitrite, which is both an antimicrobial and an antioxidant, such as celery and Swiss chard, also has seen significant growth, Tarté says.

Spices and herbs that are rich in phenolic compounds have been used to preserve meats and poultry for millennia, Shelke says. What’s new is that instead of just spices and herbs and having to deal with the prominent aroma, color, etc., of these ingredients, attention has been focused on functional extracts from herbs and spices to improve the sensory characteristics and shelf life of foods.

“Cloves, oregano, cinnamon, cayenne, green tea and rosemary are important aromatic spices that have been used as condiments to enhance the sensory quality of meats and poultry foods in several cuisines,” Shelke explains. “These, in addition to their health benefits, have been found to possess great antioxidant and antimicrobial activity. While each works well individually, there is a distinct synergistic effect when these ingredients are combined.”

For example, rosemary and green tea extracts effectively can preserve the appearance, taste and quality of meat by virtue of their individual phenolic compound content. Green tea extract has a lower negative flavor contribution to the final meat and poultry product than rosemary, so manufacturers are using a lower level of rosemary extract in combination with green tea extract to increase the natural plant extract usage rate and the extract blend works better than using rosemary alone.

Acerola cherry extract also is an effective antioxidant/preservative for meat and poultry. Combining it with green tea extract makes it even more efficient and cost-effective, Shelke says. Suppliers also offer proprietary blends of fruits and vegetable extracts, which work well, but also tie the manufacturer to the supplier, she adds.

While more than 100 varieties of spices and herbs produced around the world qualify for the preservation of meat and poultry, the United States sticks largely to pepper, nutmeg, rosemary, greet tea extract, cloves, allspice and oregano for now, Shelke says.

Challenges to overcome

Spices and herbs are agricultural crops and therefore pose a number of challenges.

“Their phenolic contents vary in composition and amount with variety, climate, crop and region where they are grown, and therefore inconsistent for use in an industry that requires consistency,” Shelke says. “Going the extra length to standardize these ingredients for their functional phytochemicals can add considerably to the bottom line.”

Spices and herbs are naturally prone to carrying a high-microbial load as well because of the way they are grown and processed. Irradiation, although a viable method to kill the microbial load, is not favored in products that carry an organic seal or in products destined to retailers such as Whole Foods Market that have stringent requirements forbidding radiation, Shelke says. Steam treatment is one option to replace irradiation, she adds.

Using spices and herbs or their extracts also is not a gram-for-gram slam-dunk replacement for synthetic preservatives. “The appropriate level depends on what else is in the formulation and small changes in the formulation require thorough testing to ensure the product is indeed safe,” Shelke says.

Another big challenge is that the model of antimicrobial activity of spices and herbs is far from understood. “While we know something works, we do not know why and therefore stand a big risk of disrupting the feasibility by inadvertently introducing antagonism with a process or ingredient,” Shelke says. “At best, we are in the quadrant where we know that we really don’t know how and why herbs and spices work in the preservation arena.”

Generally speaking, Tarté sees three primary challenges of using antimicrobial and antioxidant seasonings and spices in meat and poultry: efficacy, flavor and cost-in-use, all of which are interrelated. In terms of ingredient efficacy, in some cases, especially with the new generation antimicrobials and antioxidants, the active molecule or molecules isn’t or aren’t present in large enough concentrations. In other words, higher usage levels may be needed to achieve similar results or efficacy could be affected by unanticipated interactions between the ingredient and components in the food, Tarté says.

“As with conventional antimicrobials, one must understand the activity spectrum of each specific antimicrobial ingredient in order to optimize its use,” he explains. “In terms of flavor, many antimicrobials and antioxidants contribute objectionable flavors beyond a specific usage level, which varies by ingredient and product application. Because the next generation ingredients tend to be less refined than their conventional counterparts, they sometimes carry other undesirable flavor compounds which may cause them to reach their objectionable flavor threshold at usage levels lower than necessary for optimal functionality.”

Cost-in-use of an ingredient is determined by its price and its functional effect. “The cost-in-use of these ingredients is generally not low, and it tends to be higher for the new generation ingredients, driven mostly by the aforementioned limitations and high raw material and processing costs,” Tarté says.

Both processors and suppliers are working to overcome the challenges of using the new generation of antimicrobial and antioxidant ingredients.

“I can’t overstate the fact that suppliers of these ingredients have and continue to make great strides in addressing these limitations,” Tarté says. “Identification of new raw material sources, as well as mostly proprietary technological improvements has led to increases in efficacy, improvements in flavor and other sensory attributes, and lower cost-in-use. Processors should, however, still ensure that these ingredients are properly tested and validated for every intended application. Due to the less refined and more natural character of the new generation ingredients, these tend to be much less commoditized than conventional ones. Therefore, it is generally not advisable to extrapolate test results from one supplier’s offering to another supplier’s version of ‘the same thing.’ When in doubt, always test.”

Additionally, academic and industry researchers continue to search for new natural sources of bioactive compounds that could serve as food ingredients. As these natural ingredients are being constantly improved to make them more efficacious and cost-effective, the industry is also gaining more understanding of the way in which some of these new generation ingredients may be more effective when used in combination, Tarté says.

Coming ahead

As consumer interest in natural and clean label continues to gain in popularity across the marketplace, Tarté expects continued improvement of the ingredients that are currently in the market and perhaps the introduction of a few new ones.

“I do not expect much in terms of development of new synthetic antimicrobials and antioxidants,” he says. “Looking deeper into the future, however, I think one important area to watch is the intersection of antimicrobials and antioxidants with other potential benefits to human health. Many of these natural sources have been used for medicinal purposes for years, and as their health benefits become further elucidated, consumers and the industry may eventually begin to see these ingredients in a whole new light.”

Shelke also sees a combination of spices and herbs used for synergy. Additionally, she projects the use of spice oils in combination with other preservation techniques. For example: low pressure atmosphere enhances the susceptibility of E. coli and S. enteritidis to oregano, lemongrass or cinnamon essential oils in vitro. The antimicrobial activity in vitro (MIC) of cinnamon vapors for S. enteritidis decreases with reducing the water activity and pH, she says.

Another hurdle technology that can enhance the antimicrobial potential of essential oils of herbs and spices is the combination with negative air ions (NAI). Mild thermal processing in combination with spices and herbs also are effective.

“Non-thermal processing techniques such as high-pressure processing can go a long way to not only enhance the preservative effect of the spices, but also present the finished products in a premium fresh-from-the-kitchen packaging that appeals to consumers,” Shelke says. NP