Evaluating Alternative Meat Curing Methods: Beyond Direct Nitrite Addition

By Eben van Tonder, 3 Feb 25

Table of Contents

Introduction

For over fifteen years, I have been involved in evaluating alternative meat curing systems, extensively studying methods used from the most ancient antiquity to modern industrial practices. Traditional meat curing relies on sodium nitrite (NaNO₂) or sodium nitrate (NaNO₃) to preserve meat, stabilise colour, and enhance flavour. However, increasing consumer demand for nitrite-free alternatives and regulatory concerns over nitrosamine formation have driven researchers and manufacturers to explore curing systems that do not involve the direct addition of nitrites or nitrates.

This article evaluates four potential non-nitrite curing alternatives, ranking them from least likely to most likely to succeed in commercial applications. Each system is assessed based on biochemical feasibility, scalability, cost-effectiveness, and commercial viability. The methods covered include phenolic compound curing, L-arginine curing, zinc protoporphyrin (ZnPP) curing modified for rapid processing, and two-step ammonia curing.

1. Phenolic Compound Curing (Prosur-Type System) – Least Likely to Succeed

Phenolic compound curing is marketed as a natural alternative to nitrite-based curing, with companies such as Prosur claiming that plant-derived phenolic extracts can replace nitrites while stabilising meat colour. The system is based on using strong antioxidants, such as those derived from rosemary, green tea, and fruit extracts, to prevent myoglobin oxidation. It is claimed that these compounds allow the meat to maintain a stable colour without requiring nitrite or nitrate inclusion.

However, a critical issue with this system is that phenolic compounds do not generate nitric oxide, which is essential for forming nitrosylmyoglobin, the molecule responsible for cured meat colour. If no NO₂⁻ or NO₃⁻ is present, the meat will not undergo the characteristic colour change associated with traditional curing. Given that plant extracts are highly variable in composition, their ability to stabilise colour is inconsistent at best. In practice, many plant-based curing agents marketed as nitrite-free have been found to contain undeclared levels of nitrate, which may still undergo bacterial reduction to nitrite.

Despite its strong appeal to clean-label consumers, the absence of true nitrosylation in phenolic compound curing means that it cannot replicate the colour, flavour, or microbial protection of traditional nitrite curing. This makes it the least effective alternative for large-scale commercial meat processing.

Likelihood of Success: 3/10

2. L-Arginine Curing

L-arginine is a naturally occurring amino acid in meat and serves as a precursor to nitric oxide through microbial or enzymatic conversion. In this system, certain bacteria or enzymes metabolise L-arginine, releasing NO, which then binds to myoglobin to form nitrosylmyoglobin. This process mimics endogenous NO production in biological systems.

Although L-arginine curing presents an interesting theoretical pathway, it faces several major limitations. One of the most significant issues is the limited availability of free L-arginine in meat. Even if additional L-arginine is supplemented, its distinct taste restricts the amount that can be used before negatively impacting flavour. Furthermore, L-arginine is expensive, making large-scale commercial application cost-prohibitive. Another major drawback is the inconsistency in microbial NO production, which makes it difficult to regulate NO levels. Unlike nitrate-based curing, where the conversion to NO₂⁻ and then NO is well understood and easily controlled, the efficiency of enzymatic NO production from L-arginine varies depending on environmental conditions and microbial activity.

Given these limitations, L-arginine curing remains an unproven and unlikely alternative for large-scale nitrite-free curing. The issues of cost, flavour, and process control make it impractical for commercial application.

Likelihood of Success: 4/10

3. Zinc Protoporphyrin (ZnPP) Curing for Rapid Commercial Use

Zinc protoporphyrin curing is commonly associated with traditional dry-cured meats such as Parma ham, where long aging processes facilitate the natural replacement of iron in myoglobin with zinc, resulting in the formation of ZnPP. This molecule stabilises colour similarly to nitrosylmyoglobin but does not require NO₂⁻ or NO₃⁻. The possibility of adapting ZnPP curing for rapid commercial applications has been considered, with efforts focused on accelerating ZnPP formation through zinc ion supplementation, pH optimisation, and controlled processing conditions.

Despite these modifications, there is currently no commercially available curing system that applies ZnPP for rapid industrial production. Even with process acceleration, ZnPP formation is significantly slower than nitrite curing, making it unsuitable for high-throughput meat processing plants. Moreover, the ability to consistently produce ZnPP under industrial conditions remains uncertain, as the natural processes that drive ZnPP formation in dry-cured meats do not easily translate to wet curing or rapid production cycles.

Given that no large-scale commercial system using ZnPP for rapid curing exists, it is difficult to justify its viability as a practical alternative. The slow reaction kinetics and the absence of a proven commercial implementation mean that ZnPP curing is unlikely to be widely adopted in industrial meat production.

Likelihood of Success: 4/10

4. Two-Step Ammonia Curing – Most Likely to Succeed

Two-step ammonia curing is based on what Christa Berger and I speculate to be the curing pathway used in the Late Bronze Age Hallstatt curing vats. Archaeological evidence from Hallstatt suggests that meat stored in these vats may have undergone microbial processes that resulted in ammonia formation, which was then converted to nitrite and nitrate, leading to a natural curing effect.

The modern adaptation of this method employs a two-stage microbial fermentation process to generate nitrite and nitrate indirectly. In the first stage, specific bacteria deaminate lysine and other amino acids, releasing ammonia (NH₃). Once ammonia levels reach an optimal concentration, as verified using test strips, the first bacterial culture is inactivated through heating or other methods. The second stage introduces a separate bacterial culture capable of oxidising NH₃ into NO₂⁻ and NO₃⁻. The levels of nitrite and nitrate are then verified, and the fermented liquid is used as a brine for meat injection or immersion curing.

This system presents a major advantage over the other alternatives discussed, as it allows for full control over NO₂⁻ and NO₃⁻ levels, ensuring consistent curing results. It is also scalable for commercial production, as fermentation-based nitrite generation has already been successfully applied in various food industries. Unlike L-arginine curing, which is highly dependent on microbial efficiency, the ammonia pathway provides a predictable and measurable conversion to nitrite and nitrate, making it a reliable alternative.

While the process takes longer than direct nitrite curing, the ability to measure nitrite and nitrate levels before application ensures that this method can meet regulatory and safety standards. This makes two-step ammonia curing the most viable non-nitrite alternative for industrial meat curing.

Likelihood of Success: 8/10