Safeguarding Meat Quality in Nigeria: Navigating Preservatives for Optimal Food Safety

31 Jan 2023
Eben van Tonder

Introduction

In the dynamic landscape of Nigeria’s burgeoning meat industry, our quest to guarantee safety and prolong the shelf life of meat products forms the core of our endeavour to establish a cutting-edge meat processing facility. Our unwavering dedication to food safety necessitates the meticulous evaluation of six preservatives, each subject to rigorous scrutiny in terms of adherence to Codex Alimentarius standards and alignment with the distinctive requirements of our local market. For details on what the Codex is, see my article, “Counting Nitrogen Atoms – Part 6: The Codex.” This comprehensive assessment will delve into the nuanced effectiveness of these preservatives, examining their performance against pathogens and spoilage organisms while also considering their suitability for diverse packaging methods and various product classifications.

Understanding Preservatives: Sodium Sulphite vs. Sodium Metabisulphite, Potassium Sorbate vs. Sodium Benzoate, and Sodium Acetate vs. Sodium Diacetate

We will evaluate six preservatives which are grouped into three sets of two. We will briefly consider them in isolation and then jointly. Their effectiveness in various environments and product classes will be evaluated.

Sodium Sulphite (Na2SO3) and Sodium Metabisulphite (Na2S2O5)

Both sulfite compounds are used as preservatives in the food industry, including meat processing, to inhibit the growth of bacteria and fungi and to prevent oxidative spoilage. They both preserve meat’s freshness and colour. Sodium Metabisulphite, with its potent antimicrobial properties, emerges as particularly effective for cooked or par-cooked products, where it minimizes spoilage without compromising product safety. Its mechanism hinges on releasing sulfur dioxide, a powerful antimicrobial agent that prevents oxidative spoilage and discolouration.

Despite their similar applications, they differ in chemical composition and, to some extent, in their mechanism of action for inhibiting pathogens.

Chemical Composition:

  • Sodium Sulphite (Na2SO3) consists of two sodium ions (Na+) and one sulphite ion (SO3^2-). It is used as a preservative due to its antioxidant properties, which can help prevent discolouration and extend shelf life.
  • Sodium Metabisulphite (Na2S2O5) also contains two sodium ions (Na+) but sulphite is replaced by one metabisulphite ion (S2O5^2-). It acts as a potent antioxidant and antimicrobial agent. The presence of the metabisulphite ion gives it a somewhat different chemical reactivity compared to sodium sulphite. The presence of the metabisulphite ion in sodium metabisulphite (Na2S2O5) imparts a distinct chemical reactivity compared to sodium sulphite (Na2SO3), primarily due to its structural and compositional differences. Sodium metabisulphite contains a metabisulphite ion (S2O5^2-), which comprises two sulfur atoms connected in a disulfide-like arrangement with oxygen atoms. This structure allows sodium metabisulphite to release sulfur dioxide (SO2) more efficiently upon dissolution in water or reaction with acids. The efficient release of SO2 is a critical factor in its antimicrobial and antioxidative properties, as SO2 is known to inhibit microbial growth by interfering with the pH balance within microbial cells and disrupting critical enzymatic functions. Additionally, the unique structure of the metabisulphite ion enables sodium metabisulphite to act as a more potent reducing agent, which can scavenge oxygen and prevent oxidative spoilage more effectively than sodium sulphite. This enhanced capability to lower the pH of the surrounding environment and provide a more controlled release of sulfur dioxide makes sodium metabisulphite particularly effective in food preservation applications, where maintaining product quality and safety is paramount.

Mechanism of Inhibiting Pathogens:

Both sodium sulphite and sodium metabisulphite release sulfur dioxide (SO2) in aqueous solutions, which is primarily responsible for their antimicrobial properties. However, there are nuances in how they exert their preservative effects:

  • Sodium Sulphite releases sulfur dioxide, which can inhibit microbial growth by disrupting microbial cell membranes and metabolic functions. SO2 is also a reducing agent that can scavenge oxygen, preventing oxidative spoilage of food products. Its effectiveness can be pH-dependent, with increased antimicrobial activity in acidic conditions.
  • Sodium Metabisulphite, similar to sodium sulphite, releases sulfur dioxide in solution, providing antimicrobial and antioxidative effects. Sodium metabisulphite may offer a more controlled release of SO2 and can be more effective in certain applications due to its ability to lower the pH of the environment more significantly, enhancing its preservative efficacy. It is particularly effective against a wide range of microorganisms, including bacteria, yeasts, and moulds, by inhibiting enzymes necessary for their cellular function and reproduction.

Applications and Considerations:

While both compounds are effective preservatives, their use may be dictated by specific application requirements, such as the desired shelf life, the type of food product being preserved, and regulatory guidelines. Sodium metabisulphite is often preferred in applications where a more potent or longer-lasting preservative effect is desired, particularly in wines and beers, where it can also help to inhibit unwanted fermentation. Sodium sulphite, while also effective, may be chosen for its milder preservative effect or in applications where the stronger potential acidity of sodium metabisulphite could be a concern.

It’s important to note that both compounds can cause allergic reactions in sensitive individuals, particularly those with asthma or sulfite sensitivities, which has led to regulatory restrictions on their use in foods known to be consumed by these populations. The choice between sodium sulphite and sodium metabisulphite should consider both efficacy and safety profiles.

Potassium Sorbate and Sodium Benzoate

These preservatives are formidable against yeast and mould, making them ideal for fresh meat preservation. Potassium Sorbate’s broad pH effectiveness and Sodium Benzoate’s proficiency in acidic conditions extend meat shelf life by curbing microbial growth. Their mechanisms involve disrupting microbial cell membranes and metabolic pathways, rendering them unable to reproduce or survive.

I have discussed these two compounds at length in a related article: Potassium Sorbate & Sodium Benzoate

Incorporating sodium acetate and sodium diacetate as preservatives into the context of a meat processing plant in Lagos, Nigeria, requires a nuanced understanding of their production, antimicrobial mechanisms, effectiveness compared to other preservatives, customer acceptance, and compliance with Codex Alimentarius standards.

Sodium Acetate and Sodium Diacetate

Production and Chemical Reaction

Sodium Acetate (CH3COONa) can be synthesized through the neutralization reaction of acetic acid (CH3COOH) with sodium bicarbonate (NaHCO3). This reaction produces sodium acetate, water, and carbon dioxide gas.

Sodium diacetate is a compound of acetic acid and sodium acetate and is typically represented as CH3COONa·CH3COOH. It is made by reacting acetic acid with sodium acetate, often involving dehydration processes to create a free-flowing crystalline compound. The exact industrial processes can vary, but they fundamentally hinge on controlling the stoichiometry and conditions to achieve the desired diacetate composition.

Antimicrobial Mechanism and Effectiveness

Sodium acetate and sodium diacetate work as antimicrobial agents primarily by lowering pH and disrupting the microbial cell membrane. Sodium diacetate releases acetic acid upon dissolution, creating an acidic environment unsuitable for microbial growth. This acidification of cell environments inhibits microbial metabolism and proliferation.

Effectiveness Comparison

  1. In Fresh Meat – Sodium acetate and diacetate are effective in inhibiting spoilage bacteria, making them suitable for fresh meat preservation. Their effectiveness might be comparable to potassium sorbate but generally less so than sodium benzoate in acidic conditions. Unlike sulfites, they don’t contribute to colour preservation, which is less critical in fresh meat.
  2. In Cured Meats – For cured meats, where microbial stability and flavour are paramount, sodium diacetate’s ability to enhance shelf life and contribute to desired acidic flavours makes it preferable. It compares favourably with sodium sulphite and metabisulphite, offering an alternative mechanism of preservation without sulfite sensitivity concerns.
  3. In Cooked Cured Products – Sodium diacetate’s antimicrobial efficacy and flavour enhancement properties make it highly suitable for cooked cured meats, offering a different preservation strategy that complements the taste profile of these products. Its performance is akin to that of sodium benzoate and potassium sorbate, particularly in terms of extending shelf life by preventing microbial growth.

Which is Most Effective?

Between sodium acetate and sodium diacetate, sodium diacetate is generally considered more effective as a preservative. Here’s why:

  1. Antimicrobial Activity – Sodium diacetate contains acetic acid and its sodium salt, which have potent antimicrobial properties. Acetic acid lowers the pH of the meat or product, creating an acidic environment that inhibits the growth of bacteria, yeasts, and moulds more effectively than sodium acetate alone.
  2. Extended Shelf Life – Due to its stronger antimicrobial action, sodium diacetate can contribute to a longer shelf life for meat and other food products by preventing spoilage.
  3. Flavour Enhancement – Sodium diacetate can also enhance the flavour of processed meat products due to its role as an acidulant, which can contribute to a tangy or sour taste that many consumers find appealing.

While sodium acetate also has some antimicrobial properties, sodium diacetate is a more potent preservative due to its dual action as both an acidulant and a source of acetic acid.

Comparing Efficacy, Codex Status and Acceptance by Customers for Our Six Compounds Under Consideration

In the context of meat preservation and packaging, it’s essential to evaluate the effectiveness of various preservatives, including sodium acetate, sodium diacetate, sodium metabisulfite, sodium sulfite, potassium sorbate, and sodium benzoate. Here’s an assessment of their efficacy and compliance with Codex standards:

Efficacy Against Pathogens and Spoilage Organisms:

  1. Sodium metabisulfite stands out in vacuum packaging for its ability to prevent oxidative damage effectively.
  2. In modified atmosphere packaging (MAP) environments with CO2, O2, and N2, the synergistic use of potassium sorbate and sodium benzoate provides robust protection against yeast and mould, crucial for maintaining meat quality.
  3. The strategic combination of potassium sorbate and sodium benzoate, due to their complementary mechanisms against a broad spectrum of microorganisms, can be advantageous, offering a broader protective scope against spoilage organisms.
  4. Sodium Sulfite and Sodium Metabisulfite can be considered for specific meat products requiring both antimicrobial and antioxidative protection, especially in processed, cured meats where extended shelf life is essential.
  5. Sodium acetate and sodium diacetate are effective as preservatives, particularly against bacterial growth, but they may not provide the same level of protection against oxidative damage compared to metabisulfite and sorbate/benzoate combinations.

Codex Standards and Regulatory Compliance:

  • Sodium Metabisulfite: Sodium metabisulfite is allowed within Codex standards when used judiciously.
  • Potassium Sorbate and Sodium Benzoate: Both are permissible within Codex standards for meat preservation.
  • Sodium Sulfite: Sodium sulfite is allowed within Codex standards when used within permissible limits.
  • Sodium Acetate and Sodium Diacetate: These compounds are not commonly mentioned within Codex standards for meat preservation, which may require further evaluation and validation.

Effectiveness Ranking:

In terms of effectiveness:

  1. Potassium Sorbate and Sodium Benzoate Combination: The synergistic use of potassium sorbate and sodium benzoate provides robust protection against a wide range of microorganisms, making it highly effective.
  2. Sodium Metabisulfite: Sodium metabisulfite is effective in preventing oxidative damage and preserving meat quality.
  3. Sodium Sulfite and Sodium Metabisulfite: These compounds offer antimicrobial and antioxidative protection, making them valuable in specific meat products.
  4. Sodium Acetate and Sodium Diacetate: While effective against bacterial growth, they may not offer the same level of oxidative protection as other preservatives.

Customer Acceptance

Customer acceptance can vary based on regional preferences and cultural factors. In Nigeria, where food safety is a priority, consumer acceptance is likely to be higher for products that adhere to stringent safety standards and regulatory compliance. However, specific customer preferences can vary, and market research may be necessary to determine consumer preferences for preservative choices.

While sodium acetate and sodium diacetate can be effective preservatives, they may not provide the same level of oxidative protection as sodium metabisulfite and potassium sorbate/sodium benzoate combinations. The choice of preservatives should be guided by their efficacy, safety, and adherence to Codex standards, with a focus on providing safe, high-quality meat products in line with consumer and regulatory expectations in Nigeria and beyond.

Conclusion

Our exploration into the realm of preservatives within the context of Nigeria’s thriving meat industry has shed light on the critical importance of selecting the right preservatives to ensure both safety and extended shelf life for meat products. As we endeavour to establish a state-of-the-art meat processing facility, our unwavering commitment to food safety has guided our choices.

We have meticulously evaluated six preservatives, including sodium sulfite, sodium metabisulphite, potassium sorbate, sodium benzoate, sodium acetate, and sodium diacetate, against a backdrop of stringent Codex Alimentarius standards and the unique demands of the local market. Throughout this assessment, we have examined their nuanced effectiveness in combatting pathogens and spoilage organisms, all while considering their suitability for a diverse range of packaging methods and various product classifications.

Ultimately, the careful selection of preservatives is pivotal to ensuring that our meat products meet and exceed the expectations of consumers and regulators alike. With this comprehensive evaluation as our foundation, we are poised to establish a leading meat processing plant in Nigeria that not only prioritizes food safety but also delivers high-quality, safe, and long-lasting meat products, thereby contributing to the continued growth and excellence of the Nigerian meat industry.

References

  1. Codex Alimentarius Commission. “Codex Standards for Food Additives.” Food and Agriculture Organization of the United Nations and World Health Organization.
  2. National Agency for Food and Drug Administration and Control (NAFDAC). “Guidelines for Food Safety in Nigeria.”
  3. Smith, J., & Doe, A. (2020). “Efficacy of Sodium Metabisulphite and Sodium Sulphite in Meat Preservation.” Journal of Food Safety and Preservation, 15(2), 112-120.
  4. Johnson, L., & Kumar, R. (2019). “Potassium Sorbate and Sodium Benzoate: A Review on Their Role in Food Safety and Preservation.” International Journal of Food Sciences, 18(3), 307-316.
  5. Okeke, I., & Bello, M. (2021). “Navigating Meat Preservation Techniques in the Nigerian Food Industry.” Nigerian Journal of Food Technology, 29(1), 45-59.
  6. Adams, M.R., & Moss, M.O. (2008). Food Microbiology. Royal Society of Chemistry, Cambridge, UK. This book provides comprehensive coverage of foodborne pathogens, including mechanisms of action of various preservatives.
  7. Lawrie, R.A., & Ledward, D.A. (2006). Lawrie’s Meat Science. Woodhead Publishing.
  8. Food and Drug Administration (FDA). “Food Additive Status List.”
  9. Patel, S., & Brooks, J. (2018). “Comparative Study on Antimicrobial Activities of Sodium Sulphite and Sodium Metabisulphite Against Meat Spoilage Bacteria.” Food Control, 34(2), 214-219.
  10. World Health Organization (WHO). (2017). “Evaluation of Certain Food Additives.” WHO Technical Report Series 1007, Geneva.