Consumer habits continue to drive food industry focus to ingredient statements and nutrition panels. The push for clean-label items is shifting the food industry to reevaluate the ingredients and their usage rates. This shift became more evident over 2020, when the COVID-19 pandemic significantly shifted consumer demand away from restaurants and foodservice to home meals and ready-to-eat (RTE) meat and poultry products. As a complement for more convenience-type items, consumers began focusing on product expiration dates to limit trips to retail markets. Combined with consumers' nutritional focus on sugar, sodium, fat content, and additives, meeting these expectations and requirements is a serious challenge for meat and poultry producers. The most common challenges for reformulation are reduction of sodium and replacing additives such as nitrite and preservatives.

In October 2021, the U.S. Food and Drug Administration (FDA) published a voluntary guidance for the food industry to reduce sodium in commercially processed, packaged, and prepared foods to decrease the excess sodium intake in the U.S. population.¹ Salt provides about 90 percent of the sodium in the human diet and is essential for the maintenance of cellular membrane potential and the absorption of nutrients in the small intestine. Furthermore, its presence determines the volume of extracellular fluid, thereby maintaining blood volume and pressure. However, excessive consumption of sodium is associated with negative health effects such as elevated blood pressure. For meat processors, the new guidelines lay out different short-term targets to reduce sodium for selected categories of products, such as targeting 860–980 mg sodium per 100 g for deli meats and 1,570 mg sodium per 100 g for bacon. According to FDA, these reduction targets should not degrade the nutritional quality of the food by increasing the sugar content, nor should the food safety properties of the food be negatively affected, which is a challenge to formulators.

In meat products, salt (sodium chloride, NaCl) is a multifunctional and indispensable component that is used as a preservative by acting through osmotic cellular dehydration. In addition to enhancing the taste, it supports the shelf life, texture, and color; reduces water activity; and regulates the solubility of proteins in meat products. Salt improves yield by increasing water holding capacity, aids in protein extraction, and improves flavor. Consequently, salt reduction is associated with decreased shelf life.

Reducing or removing salt from formulations may affect the antimicrobial properties of the food, reduce yields, and compromise texture and flavor. Several alternatives have been applied to reduce the sodium content in packaged meat products through reformulation by totally or partially replacing the sodium provided by NaCl, phosphates, nitrites, and nitrates with other salts or organic sources. Potassium chloride (KCl) is the most common salt replacement employed to reduce sodium content while maintaining most of the functional benefits of salt. However, KCl may impart a bitter or metallic aftertaste to the product. Replacing NaCl with KCl also has negative impacts on the water holding capacity, microbiological stability, and shelf life. In some cases, phosphates and hydrocolloids are needed in addition to the salt substitutes to compensate losses in protein functionality. Sea salt is another salt replacement alternative, which is also the most economical way to keep the salt perception while reducing the sodium levels, and it is perceived as a "healthy" or "healthier" ingredient by the general public.

Several issues are associated with salt reduction:

• It contributes to lower yields by purging more moisture from the meat
• It impacts tempering of frozen materials by increasing the freezing point of the products
• It causes issues with slice integrity, as well as a 50 percent reduction in shelf life due to high spoilage bacterial growth in bacon⁶
• It negatively impacts the flavor and reduces yield in hams⁶
• It yields to higher water activity (Aw) values in RTE products, which consequently requires further cooking and eventually causes yield losses to arrive at the target Aw
• It causes sensory issues and high spoilage bacterial growth in salami⁶ 
• It negatively impacts the texture, yield, and shelf life of deli-style roast beef.² 

Removing "unnatural"-sounding ingredients from formulas to satisfy consumer demands for a cleaner label is another challenge. Effective, traditional antimicrobials such as nitrites, organic acids, and phosphates are no longer acceptable to consumers seeking a "clean" label. Sodium nitrite is a multifunctional ingredient in meat products that provides the characteristic color and flavor of cured meats and controls the growth of microorganisms such as Listeria monocytogenes, Clostridium perfringens, and Clostridium botulinum.

The natural nitrite substitutes of celery juice powder as a nitrite source and cherry powder as an ascorbic acid source are primarily used in the U.S. At present, no regulatory limits are imposed on the use of these natural ingredients, although their usage tends to be self-limiting due to flavor implications and high cost. Therefore, product food safety becomes a major issue with naturally cured meat products because they might contain reduced nitrite levels when compared with traditionally cured meats. Previous studies confirm that the concentration of nitrite, rather than the source, is the primary factor impacting the safety of RTE meats. Additionally, naturally sourced nitrites are found to be equally effective for controlling Listeria; however, fully identifying and standardizing the active components of those ingredients are challenging.

The next functional ingredients for replacement with natural alternatives are traditional organic acids and their salts: sodium (or potassium) lactate and sodium diacetate (or acetate). Neutralized (buffered) vinegar is a clean-label solution with high potential to replace organic acids on the label statement due to its natural acetic acid content and minimal impact on the physical and sensory properties of the product. The efficacy of buffered vinegar in inhibiting L. monocytogenes in RTE products is well documented. Vinegar-derived antimicrobials are widely used in both cured and uncured RTE products, including reduced-sodium uncured poultry without adversely affecting the quality attributes. However, when traditional organic acids or their salts are replaced with their natural alternatives, their efficacy for controlling pathogen growth must be validated. Additionally, those reformulated products must be evaluated for shelf life.

Maintaining all of these quality and food safety indicators at the highest levels takes time, as completing all those shelf life and challenge studies requires months depending on the product's type. Cultured sugars, lemon juice, and lemon juice–vinegar concentrates are other available natural, clean-label preservatives with proven successful applications. Spice extracts, essential oils, and vegetable extracts contain naturally occurring antimicrobials and/or nitrates, but they may impart objectionable flavor to the formula due to their inherent volatile compounds. These extracts are more expensive than conventional ingredients and may require a higher usage rate as the extraction techniques may not result in pure compounds.

For naturally formulated meat products, the main goals are to reduce preservatives while maintaining flavor and color stability, microbial stability, and shelf life, and to decrease or remove the listing of chemical ingredients on the label. However, natural, uncured or preservative-free RTE meat and poultry products are at higher risk for bacterial growth than their conventional counterparts. To improve the food safety of these naturally formulated products, post-lethality interventions and/or hurdle technologies have been studied, with promising results. For example, high hydrostatic pressure processing (HPP) is considered as an alternative processing technique to develop sodium-reduced meat products. When HPP (100–600 MPa) is applied to sodium-reduced cooked ham either at the raw material (after injection or massage) or final product stages, good physicochemical (yield, texture, water holding capacity, color) value and sensory quality (saltiness perception) is achieved.³ Other examples are summarized as:

• In general, HPP provides an extra margin of microbiological safety on natural products
• On cured RTE ham, a combination of naturally sourced nitrite and HPP provides an additive effect on L. monocytogenes growth inhibition^4,5
• On naturally cured frankfurters, HPP, octanoic acid, and lauric arginate have bactericidal properties^6,7
• HPP contributes to developing reduced-sodium RTE chicken products with enhanced quality and microbiological safety.³

Reformulation with the core functional ingredients may require additional shelf life and/or challenge studies to evaluate the food safety and quality of the products, which may take months to complete. It is also important to balance consumer perceptions and expectations with operational objectives and food safety requirements. The ultimate challenge is to replace the critically important, functional ingredients with clean-label ingredients that provide the same functionality in a cost-effective way. Many potential ingredients are available, but some are simply too expensive to be economically feasible replacements. Research is needed for a better understanding of their potential usage levels and long-term functionality in the products.

References

1. U.S. Food and Drug Administration. 2021. Voluntary Sodium Reduction Goals Guidance. 86 FR 57156: 57156–57159.
2. Bower, C., et al. "Effect of salt reduction on the quality and shelf-life characteristics of deli-style roast beef." Nebraska Beef Cattle Report. (2017).
3. Orel, R., et al. "Effects of high hydrostatic pressure processing and sodium reduction on physicochemical properties, sensory quality, and microbiological shelf-life of ready-to-eat chicken breasts." LWT 127 (2020).
4. McDonnell, L. et al. "Identifying ingredients that delay outgrowth of Listeria monocytogenes in natural, organic, and clean-label ready-to-eat meat and poultry products." JFP 76, no. 8 (2013): 1366–1376.
5. Badvela, M., et al. "Inhibition of Listeria monocytogenes by buffered dry vinegar in reduced-sodium ready-to-eat uncured turkey stored at 4°C." JFP 79, no. 8 (2013): 1396–1403.
6. Aaslyng, M., et al. "The effect of salt reduction on sensory quality and microbial growth in hotdog sausages, bacon, ham, and salami." Meat Science 96 (2014): 47–55.
7. Lavieri, N., et al. "Investigating the control of Listeria monocytogenes on alternatively-cured frankfurters using natural antimicrobial ingredients or post-lethality interventions." Meat Science 97 (2014): 568–574.

Hayriye Cetin-Karaca, Ph.D., is a Research Scientist in the technical services department at Smithfield Foods. She provides scientific and technical support to food safety and leads the challenge study and research programs.

Shannon Glisan, Ph.D., is the Research and Development Manager at Smithfield Foods, where she leads projects in bacon, marinated fresh pork, and prepared foods. She graduated from Penn State University with a Ph.D. in food science.