Organic Acids in Industry: Applications and Significance in Biogas, Agriculture, and Food Production

Table of Contents

​​1. Why are organic acids relevant across industries?

2. What are organic acids?

3. What role do organic acids play in biogas production?

4. How do organic acids affect agriculture?

5. Why are organic acids important in food production?

6. How are organic acids monitored and controlled?

7. What is the future role of organic acids in industry?

1. Why are organic acids relevant across industries?

Organic acids are present in a wide range of natural and industrial processes. They form as intermediate or end products of microbial metabolism and chemical reactions, and their concentrations provide critical information about the state of a system, whether that is a fermentation tank, an agricultural field, or a food production line.

Interest in organic acids has grown significantly in recent years. This is partly driven by the expansion of biological processes such as anaerobic digestion, and partly by increasing demands for quality control and process transparency across industries. Reliable chemical analytics has become essential for understanding where organic acids appear, what role they play, and how they can be detected, making this knowledge increasingly relevant for practitioners and decision-makers alike.

2. What are organic acids?

Organic acids are carbon-containing compounds with acidic properties. They occur naturally in many biological systems and are produced during microbial activity, fermentation, and decomposition processes. The most commonly encountered organic acids in industrial contexts include acetic acid, propionic acid, butyric acid, lactic acid, and formic acid.

These compounds are characterized by their relatively low molecular weight and their ability to dissociate in water, releasing hydrogen ions and lowering pH. In many processes, the presence and concentration of specific organic acids serve as an indicator of biological activity, process efficiency, or potential disruptions.

Organic acids are not inherently problematic or beneficial, their significance depends entirely on the context in which they appear and the concentrations at which they are present. In some processes, accumulation of organic acids is a desired outcome; in others, elevated concentrations signal a need for immediate intervention.

Three glass jars containing a cloudy fermented kombucha (left), fresh yogurt (center), and a dark biogas digestate (right), representing the diverse natural and industrial contexts in which organic acids occur (generated by Gemini).

3. What role do organic acids play in biogas production?

In the biogas industry, organic acids, often referred to as volatile fatty acids (VFA), are a central element of the anaerobic digestion process. Anaerobic digestion is the biological breakdown of organic material in the absence of oxygen, resulting in the production of biogas, primarily composed of methane and carbon dioxide.

The digestion process occurs in several stages. During acidogenesis, microorganisms break down complex organic compounds into simpler molecules, including short-chain organic acids such as acetic acid, propionic acid, and butyric acid. These organic acids are then further processed during acetogenesis and methanogenesis, ultimately producing methane and biogas.

Under normal operating conditions, the production and consumption of organic acids within the digester are balanced. However, process disruptions, such as substrate overloading, temperature changes, or the presence of inhibitory compounds, can cause organic acids to accumulate faster than they are consumed. This accumulation leads to a pH drop, inhibiting methanogenic bacteria and potentially causing complete digester failure.

Another key concern in biogas plants is corrosion. Elevated concentrations of organic acids, particularly acetic and propionic acid, can accelerate corrosion of metal components within the digester infrastructure, increasing maintenance costs and reducing operational lifespan. Early detection through regular chemical analytics is therefore essential.

Monitoring volatile fatty acids allows operators to adjust feeding rates, add buffering agents, and make process corrections before the situation becomes critical. Elevated propionic acid concentrations in particular are a sensitive indicator of process stress, as this organic acid degrades more slowly than acetic acid and tends to accumulate when methanogenic activity is suppressed.

Biogas plant with large fermentation tanks set in a rural agricultural landscape.

4. How do organic acids affect agriculture?

In agricultural contexts, organic acids are relevant across several distinct areas: soil health, plant physiology, and the management of silage and other fermented animal feed.

In soil systems, organic acids are produced through the decomposition of organic matter and through root exudates, compounds released by plant roots into the surrounding soil. Organic acids such as citric acid, oxalic acid, and malic acid influence nutrient availability by affecting the solubility of minerals. They help mobilize phosphorus and micronutrients that would otherwise remain bound to soil particles and inaccessible to plants.

Soil microbiota also produce organic acids as byproducts of their metabolic activity. The composition and concentration of these organic acids reflect the biological activity of the soil and serve as indicators of soil health and fertility, a growing area of interest as agriculture moves toward reduced synthetic fertilizer use.

In silage production, fermented plant material used as animal feed, organic acids play a central role. When crops such as grass or maize are stored under anaerobic conditions, naturally occurring lactic acid bacteria ferment the sugars present in the plant material. The resulting organic acids lower the pH of the silage, inhibiting undesirable microorganisms such as molds and Clostridia, and preserving the feed.

If undesirable microbial communities dominate the fermentation process, producing excess acetic or butyric acid, the nutritional value of the silage is reduced and the risk of spoilage increases. Monitoring organic acid profiles in silage is therefore a valuable quality assurance tool in livestock farming.

5. Why are organic acids important in food production?

Organic acids have a long history in food production, functioning as natural compounds and intentionally added ingredients. Their roles include preservation, flavor development, pH adjustment, and microbial control.

Lactic acid is among the most widely encountered organic acids in food systems. It is responsible for the characteristic tangy flavor of yogurt, cheese, sauerkraut, and fermented sausages, and contributes to preservation by lowering pH and inhibiting spoilage organisms. Acetic acid, the primary component of vinegar, is another well-established organic acid, functioning as a preservative and flavoring agent across a wide range of products.

Citric acid, naturally present in citrus fruits, is one of the most widely used organic acids in the food industry. It serves as an acidulant and flavor enhancer in beverages, confectionery, and processed foods, and acts as a chelating agent to stabilize color and prevent oxidation.

In fermented food and beverage production, including bread, beer, wine, and kombucha, the balance of organic acids produced during fermentation directly influences the sensory properties of the final product. Controlling organic acid development is therefore essential for achieving consistent product quality.

Food safety is another critical area. Lactic acid and acetic acid are used in meat processing to reduce surface contamination by pathogenic bacteria, with their antimicrobial properties well documented and their application regulated across many jurisdictions.

A selection of fermented food products including sauerkraut, cheese, yogurt, sourdough bread, and apple cider vinegar.

6. How are organic acids monitored and controlled?

Across all three industries, accurately measuring organic acids is a prerequisite for effective process management. The gold standard for organic acid analysis is chromatography, a technique that separates individual compounds within a mixture for precise identification and quantification. HPLC (high performance liquid chromatography) is widely used in laboratory settings for the detailed analysis of organic acids, offering high sensitivity and the ability to simultaneously quantify multiple compounds within a single sample.

Chromatography-based methods, while highly reliable, can be time-consuming and require specialized equipment and trained personnel. For many operators, this creates a gap between the moment a change in organic acids occurs and the point at which it is detected and acted upon.

In response, a range of field-based and on-site testing approaches have been developed, supported by advances in chemical analytics. These allow operators to measure organic acids more quickly and respond to process changes in a timely manner. In biogas plants specifically, rapid detection of rising organic acid concentrations is critical to preventing corrosionand process instability. Self-contained sampling kits have also evolved, enabling collection and transport of samples without the need for specialist training or additional infrastructure.

The choice of analytical method depends on the specific requirements of the application, including the range of acids to be detected, the required precision, and the available infrastructure. In all cases, consistent and representative sampling remains a fundamental requirement for obtaining meaningful results through chromatography or any other analytical approach.

7. What is the future role of organic acids in industry?

Organic acids are an integral part of numerous biological and industrial processes. In biogas production, their accumulation serves as an early warning indicator of process instability and corrosion risk. In agriculture, they influence soil chemistry, nutrient availability, and fermented feed quality. In food production, they contribute to preservation, flavor, and safety.

As biological processes become more prevalent across industries, driven by sustainability goals and the transition toward circular economy principles, the relevance of monitoring organic acids will only increase. Accessible, reliable chemical analytics and advanced chromatography techniques will play an essential role in enabling operators to manage these processes effectively and detect changes in organic acids before they become critical.